JP5301767B2 - Inertial sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect acceleration in an excitation direction simultaneously with angular velocity of one shaft and acceleration in a detection direction, in one inertial sensor. <P>SOLUTION: An excitation-direction acceleration detection part 8 is arranged on objects vibrating in the excitation direction in phases opposite to each other, for instance, right and left mass parts 3 by interposing elastic bodies 25. Thereby, when acceleration is applied in the excitation direction, the right and left mass parts 3 normally vibrating at the same amplitude and in phases opposite to each other resultantly have amounts of displacements in the same phase, and acceleration in the excitation direction can be detected by detecting the amounts of displacements in the same phase as a change of capacitance by the excitation-direction acceleration detection part 8. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an inertial sensor technology, and more particularly to a technology effective when applied to a MEMS inertial sensor manufactured by MEMS (Micro Electro Mechanical Systems) technology.

  An example of a conventional inertial sensor is shown in FIG. In this inertial sensor, the mass unit 500 is fixed to the substrate by the support unit 502 via the beam 501. The left and right mass units 500 vibrate in the opposite phase in the X-axis direction by the excitation unit 503, and are displaced in the Z-axis direction when an angular velocity around the Y-axis or an acceleration in the Z direction (detection direction) is applied. The amount of displacement in the Z-axis direction is detected by the detection unit 504 as the applied angular velocity or acceleration.

  The excitation unit 503 of this type of inertial sensor includes a capacitive element in which the fixed electrode portion and the movable electrode portion are arranged so that the comb teeth mesh with each other, and a DC bias is provided between the fixed electrode portion and the movable electrode portion. By applying an AC excitation signal having an appropriate phase difference together with the voltage, electrostatic attraction is alternately generated between the fixed electrode portion and the movable electrode portion, and the left and right mass portions 500 are vibrated in opposite phases. Is.

  In addition, the detection unit 504 uses the mass unit 500 as a movable electrode, disposes a fixed electrode on the substrate side so as to face the movable electrode unit, and determines the displacement amount of the mass unit 500 in the Z direction as a capacitance. By detecting it as a change, a detection signal corresponding to the angular velocity or acceleration is output.

  Here, since the left and right mass parts 500 vibrate in mutually opposite phases, when an angular velocity around the Y axis is applied, the amount of displacement in the Z axis direction due to the Coriolis force also has an opposite phase. However, when an acceleration in the Z-axis direction is applied, it is displaced in the Z-axis direction at the same phase regardless of the vibration in the X-axis direction. Accordingly, the applied acceleration can be measured by adding the respective capacitance change signals detected from the two mass parts. Also, the acceleration component can be removed by subtracting the respective capacitance change signals, and the applied angular velocity can be measured.

  For example, an angular velocity sensor that is already known based on the specification of Japanese Patent Application Laid-Open No. 2004-4119 (Patent Document 1) causes a pair of mass parts arranged on a substrate to vibrate in mutually opposite phases, so that two mass parts are respectively detected. When detecting the differential of the detected yaw rate, the acceleration component can be accurately removed.

  Further, for example, a known mechanical quantity detection device based on Japanese Patent No. 351004 (Patent Document 2) causes two mass parts to vibrate by vibrating a pair of mass parts arranged on a substrate in mutually opposite phases (tuning fork vibration). By comparing the difference in the phase of the signals detected from each, the applied angular velocity and the acceleration acting in the detection direction can be separated.

Further, for example, the angular velocity sensor described in JP-T-2004-518969 (Patent Document 3) is composed of three elements of an excitation element, a Coriolis element, and a detection element, and the excitation element is soft in the excitation direction and is in the detection direction. Is supported by a hard beam, and is movable in the excitation direction and difficult to move in the detection direction.
Japanese Patent Laid-Open No. 2004-4119 Japanese Patent No. 351004 JP-T-2004-518969

  By the way, none of the inertial sensors studied by the present inventors can measure or distinguish the acceleration in the detection direction as well as the angular velocity in the detection direction, but none of them can measure the acceleration in the excitation direction at the same time.

  Therefore, when it is necessary to measure the acceleration in the excitation direction together with the angular velocity, it is necessary to use an acceleration sensor separately from the angular velocity sensor. Then, since it is necessary to form an angular velocity sensor and an acceleration sensor on a board | substrate, there exists a problem which cannot achieve size reduction of an inertial sensor.

  In addition, there is a problem that the acceleration applied in the excitation direction adversely affects the performance of the inertial sensor, for example, the linearity of the beam is deteriorated. That is, since the acceleration in the excitation direction cannot be detected at the same time, it is not possible to correct the displacement error due to the mass part bias due to the acceleration in the excitation direction. For this reason, it is difficult to maintain vibration in a stable excitation direction, and there is a problem in that the accuracy of detecting the angular velocity is deteriorated.

  Therefore, an object of the present invention is to provide a technique capable of simultaneously measuring the acceleration in the excitation direction as well as the angular velocity and the acceleration in the detection direction for detecting the angular velocity.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  An inertial sensor according to the present invention includes: (a) a substrate having a main surface; and (b) a first sensor unit and a second sensor unit arranged along a first direction on the main surface of the substrate. Each of the one sensor unit and the second sensor unit includes (b1) an excitation element that vibrates in the excitation direction that is the first direction, and (b2) an excitation unit that vibrates the excitation element in the excitation direction. The excitation element of the first sensor unit and the excitation element of the second sensor unit vibrate in opposite phases, and (c) is elastic to the excitation element of the first sensor unit and the excitation element of the second sensor unit. An excitation direction acceleration detection unit connected through a body and detecting acceleration in the excitation direction is provided.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  That is, in the inertial sensor, an excitation direction acceleration detection unit connected via an elastic body is provided between a plurality of mass units (excitation elements) vibrating in opposite phases, and the displacement amount of the same phase in the plurality of mass units Thus, the acceleration in the excitation direction can be detected. For this reason, the acceleration in the excitation direction that causes the fundamental vibration for measuring the angular velocity can be measured simultaneously with the angular velocity and the acceleration in the detection direction for detecting the angular velocity.

  In addition, since the acceleration in the excitation direction can be measured or identified, it is possible to correct a displacement error due to the mass part bias caused by the acceleration, and to maintain stable excitation vibration that is resistant to disturbances and always stable. Therefore, the detection accuracy of angular velocity can be improved.

  In the following embodiments, the description will be divided into a plurality of embodiments, but unless otherwise specified, they are not irrelevant to each other, and one is a modification of some or all of the other, detailed description There is a relationship such as supplementary explanation. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), particularly when clearly indicated or in principle limited to a specific number, etc. Except, it is not limited to the specific number, and may be more or less than the specific number. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., the shape is substantially the same unless otherwise specified or otherwise apparent in principle. And the like are included. The same applies to numerical values and ranges. Also, components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof is omitted as much as possible. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The inertial sensor of the first embodiment is a sensor that measures a physical quantity that appears due to the inertia of an object such as acceleration, angular velocity (gyro), and the like. In the first embodiment, an inertial sensor capable of simultaneously measuring angular velocity and acceleration (acceleration in the detection direction and acceleration in the excitation direction) will be described as an example.

  First, the basic principle of the inertial sensor will be described. When an angular velocity Ω is applied around an axis orthogonal to the excitation direction (excitation axis) to a mass part (excitation element) having a weight m that vibrates in a certain first direction (excitation direction), A force is generated in a detection direction (detection axis) perpendicular to the excitation axis and the axis to which the angular velocity is applied. The inertial sensor detects the angular velocity Ω using the principle that the mass portion is displaced in the detection direction by the Coriolis force. That is, as the angular velocity increases, the Coriolis force increases, and the amount of displacement in the detection direction differs according to the magnitude of this Coriolis force. Therefore, the angular velocity can be measured by detecting the amount of displacement in the detection direction. The amount of displacement of the mass portion due to the Coriolis force is shown in Equation 3. Also, the displacement amount of the mass part when the acceleration in the detection direction is applied is shown in Formula 4. The displacement amount of the mass part can be output as the value of the applied acceleration and angular velocity using, for example, a detection unit including a capacitive element that can detect a change in capacitance.

Fc = 2 mΩv Equation 1
Where Fc is the Coriolis force, m is the mass of the mass part, Ω is the angular velocity, and v is the velocity of the mass part in the excitation direction. Here, the velocity v is the first derivative of the displacement amount y in the excitation direction, and is defined as Equation 2.

v = y ′ = Awcos (wt) Equation 2
Where y is the displacement amount in the excitation direction, A is the maximum amplitude value in the excitation direction, and w is the angular frequency in the excitation direction.

x = Qs (Fc / ksense) Equation 3
Where x is the amount of displacement of the mass portion in the detection direction due to Coriolis force, Qs is the quality factor in the detection direction, and ksense is the spring constant in the detection direction.

x = A (ma / ksense) Equation 4
However, x is the amount of displacement of the mass part in the detection direction due to the applied acceleration, a is the acceleration, and A is a constant including the influence of attenuation of air or the like.

  First, a method for detecting the angular velocity Ω will be described with reference to Equations 1 to 3 described above. From Equation 1, it can be seen that the Coriolis force Fc is defined by the mass m of the mass part, the angular velocity Ω, and the velocity v in the excitation direction. Therefore, the angular velocity Ω can be detected if the Coriolis force Fc, the mass m of the mass part, and the velocity v in the excitation direction are known. Here, the mass m of the mass part is known. The speed v in the excitation direction is the first derivative of the displacement amount y in the excitation direction as shown in Equation 2, and the vibration in the excitation direction is a known reference vibration, so that the speed v in the excitation direction can also be known. become. Next, regarding the Coriolis force Fc, this Coriolis force Fc satisfies the relationship of Equation 3. In Equation 3, since the quality factor Qs in the detection direction and the spring constant in the detection direction are constants, the Coriolis force Fc can be obtained if the displacement amount x in the detection direction is known. From this, if the displacement amount x in the detection direction can be measured, the Coriolis force Fc can be found from Equation 3, and if the Coriolis force Fc is known, the angular velocity Ω can be found from Equation 1. That is, the angular velocity Ω can be obtained by measuring the displacement amount x in the detection direction. In order to measure the displacement amount x in the detection direction, for example, a capacitance element arranged in a comb shape is used, and the distance between the electrodes forming the capacitance element is changed in accordance with the change in the displacement amount x in the detection direction. With this configuration, the displacement amount x in the detection direction can be obtained as a change in the capacitance of the capacitive element. In this way, the angular velocity Ω can be measured.

  Next, a method for detecting the acceleration in the detection direction will be described using Equation 4. As shown in Equation 4, the displacement amount x in the detection direction of the mass part due to the applied acceleration a is found to be proportional to the acceleration a in the detection direction. Therefore, if the displacement amount x in the detection direction is measured, the acceleration in the detection direction can be detected. The displacement amount x in the detection direction can be obtained from the capacitance change of the capacitive element as described above.

  Next, a method of detecting acceleration in the excitation direction is possible. This method can be obtained in the same manner as the method of detecting acceleration in the detection direction. That is, since the displacement amount in the excitation direction and the acceleration in the excitation direction have a proportional relationship, the acceleration in the excitation direction can be obtained by measuring the displacement amount in the excitation direction. The displacement amount in the excitation direction can also be obtained from the capacitance change of the capacitive element as described above.

  From the above, it can be seen that the angular velocity, the acceleration in the detection direction, and the acceleration in the excitation direction can be obtained in principle. In the first embodiment, an inertial sensor capable of simultaneously obtaining the above-described angular velocity, acceleration in the detection direction, and acceleration in the excitation direction will be described. That is, one of the features of the present invention is that the inertial sensor can simultaneously determine the angular velocity, the acceleration in the detection direction, and the acceleration in the excitation direction.

  FIG. 1 is a diagram schematically showing the configuration of the inertial sensor according to the first embodiment. The inertial sensor according to the first embodiment will be briefly described with reference to FIG. As shown in FIG. 1, a support portion 26 is provided on the substrate 2. And between the support parts 26, the two mass parts (excitation element) 3 are provided along the Y-axis direction (1st direction), and the one side of each mass part 3 is via the elastic body 25. As shown in FIG. And connected to the support portion 26. The sensor unit is formed so as to include each of the two left and right mass portions 3. For example, a sensor unit including the left mass unit 3 is referred to as a first sensor unit, and a sensor unit including the right mass unit 3 is referred to as a second sensor unit. Each of the first sensor unit and the second sensor unit is provided with an excitation unit (not shown) that vibrates the mass unit 3 in the excitation direction. This excitation part has the structure which vibrates the mass part 3 in an excitation direction using the electrostatic attraction by a capacitive element, for example. An excitation direction acceleration detection unit 8 is provided between the mass units 3 via the elastic body 25. That is, the excitation direction acceleration detection unit 8 is formed between the first sensor unit and the second sensor unit. In the excitation direction acceleration detector 8, a movable electrode 8b is formed. The movable electrode 8b forms a capacitive element with the fixed electrode 8a provided on the fixed portion 8c. That is, the movable electrode 8b and the fixed electrode 8a are arranged in a comb shape to form a capacitive element. In the inertial sensor according to the first embodiment configured as described above, the mass unit 3 can vibrate in the excitation direction (Y-axis direction). Similarly, the excitation direction acceleration detector 8 can also vibrate in the excitation direction (Y-axis direction). Further, although not shown in FIG. 1, a Coriolis element is formed inside the mass portion 3, and this Coriolis element can be displaced in the excitation direction (Y-axis direction) and the detection direction (X-axis direction). It has become. And the detection part which detects the displacement amount of the detection direction of a Coriolis element is also formed. This detection part is also formed from a capacitive element arranged in a comb shape.

  The inertial sensor in the first embodiment is configured as described above, and the operation thereof will be described below. First, an operation for detecting acceleration in the excitation direction, which is one of the features of the present invention, will be described.

  First, the left and right mass parts 3 vibrate in the excitation direction (Y-axis direction) in opposite phases. Since the left and right mass units 3 vibrate in the excitation direction (Y-axis direction) in opposite phases, the excitation direction acceleration detection unit 8 connected via the elastic body 25 between the left and right mass units 3 When no acceleration in the excitation direction (Y-axis direction) is applied, the amount of displacement of the left and right mass portions 3 is canceled out. For this reason, the excitation direction acceleration detection part 8 maintains a stop state. If there is a variation in the amount of displacement of the left and right mass portions 3, the excitation direction acceleration detecting portion 8 vibrates by the difference, but since it is always a constant amount, it can be corrected and stopped. It is. Since the excitation direction acceleration detection unit 8 maintains the stopped state, the distance between the movable electrode 8b and the fixed electrode 8a does not change, and the capacitance of the capacitive element does not change. Therefore, the displacement amount in the excitation direction is zero, and the acceleration in the excitation direction is detected as zero.

  Subsequently, when acceleration is applied in the excitation direction (Y-axis direction), the left and right mass portions 3 are displaced in the same direction. That is, the left and right mass portions 3 are displaced in the same phase. This amount of displacement is proportional to the magnitude of acceleration applied to the mass part 3 in the same phase. Since the displacement amounts at this time are in phase with each other, they are not canceled out by the excitation direction acceleration detection unit 8 and the movable electrode 8b of the excitation direction acceleration detection unit 8 is displaced. Therefore, the distance between the movable electrode 8b and the fixed electrode 8a changes. For this reason, the capacitance of the capacitive element composed of the movable electrode 8b and the fixed electrode 8a changes. By measuring the change in the capacitance of the capacitive element, the displacement amount of the excitation direction acceleration detector 8 can be obtained, so that the acceleration finally applied in the excitation direction can be obtained.

  As described above, one of the features of the first embodiment is that the excitation direction acceleration detection unit 8 is provided through the elastic body 25 in the mass unit 3 oscillating in the excitation direction (Y-axis direction) in mutually opposite phases. There is. That is, by connecting the excitation direction acceleration detection unit 8 to the mass unit 3 vibrating in the opposite phase, when no acceleration is applied in the excitation direction (Y-axis direction), the excitation direction acceleration detection unit 8 is Instead, when acceleration is applied in the excitation direction (Y-axis direction), the fact that the excitation direction acceleration detector 8 is displaced is utilized. Thereby, in the inertial sensor having the mass part 3 that vibrates in the excitation direction (Y-axis direction) with an opposite phase, the acceleration in the excitation direction (Y-axis direction) can be detected.

  Next, the operation of detecting the angular velocity with the inertial sensor in the first embodiment will be described. First, the left and right Coriolis elements vibrate in the excitation direction with opposite phases. In this state, it is assumed that the rotation having the central axis in the direction perpendicular to the excitation direction (Y-axis direction) and the detection direction (X-axis direction) is performed. Then, the left and right Coriolis elements are displaced in the detection direction (X-axis direction) by Coriolis force. The amount of displacement in the detection direction (X-axis direction) depends on the magnitude of the angular velocity. The angular velocity can be detected by detecting the amount of displacement in the detection direction (X-axis direction) as, for example, a change in capacitance by a detection unit formed of a comb-like capacitive element.

  Next, an operation for detecting the acceleration in the detection direction (X-axis direction) with the inertial sensor according to the first embodiment will be described. When acceleration is applied in the detection direction (X-axis direction), the left and right Coriolis elements are displaced in the detection direction (X-axis direction). By detecting this amount of displacement as, for example, a change in capacitance with a detection unit formed of a comb-like capacitive element, acceleration in the detection direction (X-axis direction) can be detected.

  Here, it is assumed that the rotational motion having the central axis in the direction perpendicular to the excitation direction (Y-axis direction) and the detection direction (X-axis direction) and the acceleration in the detection direction (X-axis direction) are simultaneously applied. Then, the Coriolis element is displaced in the detection direction (X-axis direction) by the Coriolis force due to the rotational motion, and the Coriolis element is also displaced in the detection direction (X-axis direction) by the acceleration in the detection direction. Therefore, only by measuring the displacement amount in the detection direction (X-axis direction), it is not possible to separate the displacement amount due to the rotational motion and the displacement amount due to the acceleration applied in the detection direction (X-axis direction). That is, the angular velocity and the acceleration in the detection direction (X-axis direction) cannot be obtained. Therefore, the Coriolis elements connected to the left and right mass portions 3 are vibrated in the opposite phase in the excitation direction (Y-axis direction). When the left and right Coriolis elements are vibrated in opposite phases in the excitation direction (Y-axis direction), the amount of displacement in the detection direction (X-axis direction) due to the Coriolis force is reversed by the left and right Coriolis elements. In contrast, the amount of displacement in the detection direction (X-axis direction) of the Coriolis element due to the acceleration applied in the detection direction (X-axis direction) has the same phase. Using this difference, if the difference between the displacement amounts in the detection direction (X-axis direction) of the left and right Coriolis elements is taken, the displacement amount in the same phase is canceled and only the displacement amount in the opposite phase due to the Coriolis force can be extracted. it can. Therefore, the angular velocity in the rotational motion can be detected by taking the difference between the displacement amounts in the detection direction (X-axis direction) of the left and right Coriolis elements. On the other hand, by adding the displacement amounts in the detection direction (X-axis direction) of the left and right Coriolis elements, the displacement amount in the opposite phase is canceled, and only the displacement amount in the same phase can be extracted. For this reason, the acceleration of a detection direction (X-axis direction) is detectable by adding the displacement amount of the detection direction (X-axis direction) of a left and right Coriolis element.

  As described above, according to the inertial sensor in the first embodiment, it is possible to simultaneously detect the angular velocity, the acceleration in the detection direction (X-axis direction), and the acceleration in the excitation direction (Y-axis direction) with one inertial sensor. I understand that I can do it. In other words, an excitation direction acceleration detection unit connected via an elastic body is provided between a plurality of mass parts (excitation elements) that vibrate in opposite phases, and the displacement direction of the plurality of mass parts is determined in the excitation direction. Acceleration can be detected. For this reason, the acceleration in the excitation direction that causes the fundamental vibration for measuring the angular velocity can be measured simultaneously with the angular velocity and the acceleration in the detection direction for detecting the angular velocity. Therefore, it is not necessary to separately provide an inertial sensor that measures acceleration in the angular velocity and detection direction (X-axis direction) and an inertial sensor that measures acceleration in the excitation direction (Y-axis direction). Can do.

  In addition, since the acceleration in the excitation direction (Y-axis direction) can be measured or identified, it is possible to correct the displacement error due to the mass part bias caused by the acceleration, which is resistant to disturbances and always provides stable excitation vibration. Since it can be maintained, the detection accuracy of the angular velocity can be improved.

  Next, an example of a specific configuration of the inertial sensor according to the first embodiment will be described with reference to the drawings. FIG. 2 is a plan view illustrating an example of the inertial sensor according to the first embodiment, and FIG. 3 is a cross-sectional view taken along line x1-x1 in FIG. In FIG. 2, the sealing cap is removed to make the drawing easier to see. 2 indicates the first direction, and the X-axis direction indicates a second direction orthogonal to the first direction (Y-axis direction).

As shown in FIG. 3, the substrate 2 constituting the inertial sensor 1 </ b> A has a first main surface (front surface) and a second main surface (back surface) located on opposite sides along the thickness direction. The planar shape of the 1st main surface and the 2nd main surface of the board | substrate 2 is formed in the rectangular shape, for example, The area is 12 mm < ² >, for example. For example, an SOI (Silicon On Insulator) substrate is used as the substrate 2. That is, the substrate 2 is configured to have the active layer 2c on the support substrate 2a via the insulating layer 2b. The support substrate 2a is made of, for example, silicon (Si), and the insulating layer 2b is made of, for example, silicon oxide (SiO ₂ ). The active layer 2c is made of, for example, conductive silicon. The total thickness of the support substrate 2a and the insulating layer 2b is, for example, several tens to several hundreds of micrometers, and the thickness of the active layer 2c is, for example, several to several tens of micrometers. However, the substrate 2 is not limited to the SOI substrate and can be variously changed. For example, conductive polysilicon using surface MEMS technology or plating metal such as nickel (Ni) is used as the active layer 2c. May be. As the substrate 2, a normal semiconductor substrate made of silicon single crystal can also be used.

  An outer peripheral wall W is formed on the outer periphery of the first main surface of the substrate 2. The outer peripheral wall W is formed of a laminate of an insulating layer 2b and an active layer 2c formed thereon. Two sensor units SUA1 and SUA2 are formed in a region surrounded by the outer peripheral wall W of the first main surface of the substrate 2 (see FIG. 2). The two sensor units SUA1 and SUA2 are arranged side by side symmetrically on a first axis extending in the first direction (Y-axis direction) of the substrate 2. In the first embodiment, the two sensor units SUA1 and SUA2 are vibrated in opposite phases. That is, the two sensor units SUA1 and SUA2 vibrate in the first phase (Y-axis direction) with opposite phases.

  As shown in FIG. 2, each of the sensor units SUA1 and SUA2 includes an excitation element (mass part) 5, an excitation means (excitation part) 6, an excitation direction amplitude monitor means 7, an excitation direction acceleration detection part 8, Excitation direction acceleration servo means 9 and excitation direction resonance frequency tuning means 10 are provided. Further, the Coriolis element 11, the detection element 12, the detection means (detection unit) 13 (13-1 to 13-4), the angular velocity servo means 14, the detection direction acceleration servo means 15, and the detection direction resonance frequency tuning means. 16 and beams (elastic bodies) 17a to 17g.

  The excitation element 5 is formed by patterning the active layer 2c into a substantially planar frame shape. The excitation element 5 is disposed on the first main surface of the substrate 2 in a state where the lower insulating layer 2b is removed and separated from the support substrate 2a, that is, in a floating state. The excitation element 5 is disposed along the first main surface of the substrate 2 so as to be displaced only in the excitation direction (first direction, Y-axis direction). Since this excitation element 5 is necessary for vibrating a Coriolis element 11 described later in the excitation direction (first direction, Y-axis direction), the excitation element 5 itself may be rigid enough to prevent deformation, and Coriolis force. In order to minimize the amount of displacement of the excitation element 5 in the detection direction (second direction, X-axis direction) by the design, the mass is designed to be small. Such an excitation element 5 is designed and arranged with the beam 17a integrally connected in the vicinity of the four corners of the outer periphery thereof and the excitation element 5 for the purpose of causing the vibration energy to leak into each other and acting as a tuning fork. They are connected to the support portions 18a and 18b via 17b and 17c, respectively.

  The beams 17a, 17b, and 17c are formed by patterning the active layer 2c so as to be narrower than the pattern of the excitation element 5. The insulating layer 2b under the active layer 2c is removed and the substrate is floated in the same manner as the excitation element 5. 2 on the first main surface. The beams 17a and 17b have a relatively long planar shape in the detection direction (second direction, X-axis direction) and a relatively short shape in the excitation direction (first direction, Y-axis direction). And has a function as a leaf spring.

  However, the beams 17a and 17b are soft in the excitation direction (first direction, Y-axis direction) and in the detection direction (second direction, X-axis direction) in the excitation direction (first direction, Y-axis direction). The excitation element 5 is arranged to vibrate only in the excitation direction (first direction, Y-axis direction). One end of the beam 17b is connected to the excitation element 5, and the other end is connected to the beam 17c.

  The beam 17c is formed in a long shape in the excitation direction (first direction, Y-axis direction), and the beam 17b is connected thereto. The beam 17c is pulled by the beam 17b and displaced in the detection direction (second direction, X-axis direction) when the excitation elements 5 vibrate in opposite phases. That is, the beam 17c serves as a path through which the vibration energy of the excitation element 5 leaks to each other. As a result, the excitation element 5 can vibrate while stably maintaining the opposite phase. That is, a stable tuning fork vibration is generated.

  The support portions 18 a are installed at eight locations on the outer periphery of the excitation element 5. The support portion 18a is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18a has a function as an electrode for supplying an electric signal to the beam 17a and the excitation element 5 which are suspended.

  The support portion 18b is disposed between the sensor units SUA1 and SUA2. The support portion 18b is formed in a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. In this way, the excitation element 5 of the sensor unit SUA1 and the excitation element 5 of the sensor unit SUA2 are connected to each other by the beams 17b and 17c, and the beams 17b and 17c are connected to the support portion 18b fixed to the substrate 2. Has been. Here, the support portion 18b is fixed to the substrate 2 in the first embodiment, but the effect of the present invention can be obtained even if it floats from the substrate 2 in principle. Further, even if the beam 17c serving as a path through which the vibration energy of the excitation element 5 leaks is formed as a simple folded beam as shown in FIG. 4, the effect of the present invention can be obtained. As shown in FIG. 4, the same effect as in the first embodiment can be obtained without fixing the beam 17b and the beam 17c to the support portion. That is, the beam 17b and the beam 17c connecting the excitation elements 5 of the sensor unit SUA1 and the sensor unit SUA2 may be fixed to the substrate 2 via the support portion 18b or may not be fixed to the substrate 2. Good.

  Next, the excitation means 6 of each sensor unit SUA1, SUA2 is means for causing the excitation elements 5 of each sensor unit SUA1, SUA2 to vibrate in mutually opposite phases along the excitation direction (first direction, Y-axis direction). Yes, it is disposed in the vicinity of the four corners on both sides of the excitation element 5 in the excitation direction (first direction, Y-axis direction). The excitation means 6 is formed by an electrostatic comb tooth drive. That is, the excitation means 6 is configured by alternately arranging a plurality of movable electrodes 6a and a plurality of fixed electrodes 6b along the detection direction (second direction, X-axis direction) so as to be engaged with each other. .

  The fixed electrode 6b of the excitation means 6 is formed by patterning the active layer 2c. The fixed electrode 6b has an active layer 2c formed integrally with the active layer 2c of the support portion 18c, and is fixed to the substrate 2 by being connected to the support portion 18c. The support portion 18c is installed on the outer periphery of the excitation element 5 in the excitation direction (first direction, Y-axis direction). The support portion 18c is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18c has a function as an electrode that gives an electric signal to the fixed electrode 6b.

  On the other hand, the movable electrode 6a of the excitation means 6 is formed by patterning the active layer 2c. The insulating layer 2b under the movable electrode 6a is removed, and is arranged in a floating state on the first main surface of the substrate 2. The movable electrode 6 a has an active layer 2 c formed integrally with the excitation element 5 and connected thereto, and is connected to the excitation element 5 so as to be displaced together with the excitation element 5. The excitation means 6 having such a configuration applies an electrostatic excitation signal together with a DC bias voltage between the fixed electrode 6b and the movable electrode 6a, thereby generating an electrostatic attractive force between the fixed electrode 6b and the movable electrode 6a. It occurs alternately, and the excitation elements 5 of the sensor units SUA1 and SUA2 are vibrated in mutually opposite phases in the excitation direction (first direction, Y-axis direction).

FIG. 5 shows a drive circuit for driving such excitation means 6. In FIG. 5, the excitation means 6 is indicated by a capacitor, the support portions 18a and 18c are indicated by wires, and the same reference numerals are given as equivalent circuits in this figure. _Reference sign V _bias is a direct current bias voltage applied to the excitation means 6, and reference sign V _drive is an alternating current excitation signal applied to the excitation means 6. By appropriately applying this AC excitation signal, the excitation elements 5 of the sensor units SUA1 and SUA2 can be vibrated in opposite phases.

  Here, since the excitation element 5 vibrates only in the excitation direction (first direction, Y-axis direction), in principle, the interval between the fixed electrode 6b and the movable electrode 6a of the excitation means 6 is set to the excitation direction (first direction, Y-axis). (Axial direction) and detection direction (second direction, X-axis direction) can be narrower than when there is vibration coupling. Therefore, according to the inertial sensor 1A in the first embodiment, the use efficiency of the excitation energy can be increased.

  The excitation direction amplitude monitoring means 7 is a means for monitoring the vibration state of the excitation element 5 (for example, the amplitude in the excitation direction (first direction, Y-axis direction)). The excitation direction of the excitation element 5 (first direction, It is arranged in the vicinity of the center of both ends in the direction (second direction, X-axis direction) orthogonal to the Y-axis direction. The excitation direction amplitude monitor means 7 is alternately arranged along a direction (second direction, X-axis direction) orthogonal to the excitation direction so that the plurality of fixed electrodes 7a and the plurality of movable electrodes 7b are engaged with each other. It is composed of that.

  The excitation direction amplitude monitor means 7 has a function of monitoring the vibration amplitude of the excitation element 5 in the excitation direction (first direction, Y-axis direction). The vibration amplitude in the excitation direction (first direction, Y-axis direction) is kept constant based on the measurement result of the excitation direction amplitude monitor means 7. That is, based on the amplitude measured by the excitation direction amplitude monitor means 7, the vibration of the excitation element 5 by the excitation means 6 described above is adjusted, or the measurement result is fed back to the excitation direction resonance frequency tuning means 10 to be described later to resonate. The deviation is corrected.

  The fixed electrode 7a of the excitation direction amplitude monitor means 7 is formed by patterning the active layer 2c. The fixed electrode 7a is formed integrally with the active layer 2c of the support portion 18d, and is fixed to the substrate 2 by being connected to the support portion 18d. The support portion 18d is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18d has a function as an electrode that gives an electric signal to the fixed electrode 7a.

  On the other hand, the movable electrode 7b of the excitation direction amplitude monitor means 7 is formed by patterning the active layer 2c. The movable electrode 7b is arranged in a state where it floats on the first main surface of the substrate 2 with the insulating layer 2b below it being removed. The movable electrode 7b has an active layer 2c integrally formed and connected to the active layer 2c of the excitation element 5, and is connected and fixed to the excitation element 5. The excitation direction amplitude monitor means 7 having such a configuration monitors the vibration state of the excitation element 5 by detecting the change in capacitance between the opposed surfaces of the fixed electrode 7a and the movable electrode 7b, and the monitor signal is monitored. It is designed to output.

FIG. 6 shows a detection circuit for detecting the monitor signal obtained by such excitation direction amplitude monitor means 7. In FIG. 6, the excitation direction amplitude monitor means 7 is indicated by a capacitor, the support portions 18a and 18d are indicated by wirings, and the same reference numerals are given as equivalent circuits in this figure. Further, reference numeral OP is an operational amplifier, reference numeral AmD the amplitude detection circuit, the code C _R reference capacitor, numeral V _bias is the bias voltage applied to the operational amplifier OP, the sign Vout is the output voltage.

Here, it is assumed that the capacitance of the excitation direction amplitude monitoring unit 7 varies by ΔC due to the displacement of the excitation element 5 in the excitation direction (first direction, Y-axis direction). Since the voltage applied to the excitation direction amplitude monitoring means 7 is always V _bias by the operational amplifier OP, the charge ΔQ = ΔC · V _bias needs to flow into the excitation direction amplitude monitoring means 7 due to the change in capacitance. This charge to become equal to the charge flowing out of the reference capacitor _{C R,} the voltage of the reference capacitor _{C R} is varied by _{(ΔC / C R) V bias} . Therefore, the output voltage Vout is Vout = (1 + ΔC / C _R ) V _bias . The output result is fed back to the excitation means 6 that vibrates the excitation element 5 and the excitation direction resonance frequency tuning means 10, whereby stable vibration in the excitation direction can be obtained.

  Further, the acceleration in the excitation direction (first direction, Y-axis direction) can also be detected by processing the signals from the excitation direction amplitude monitor means 7 of each sensor unit SUA1, SUA2. For example, the sum of the capacitance change values of the excitation direction amplitude monitor means 7 arranged in the + direction of the excitation direction of each sensor unit SUA1, SUA2 and the electrostatic capacitance of the excitation direction amplitude monitor means 7 arranged in the-direction. By taking the difference from the sum of the capacitance change values, the change in capacitance due to the anti-phase vibration of the excitation element 5 is canceled, and an output proportional to the in-phase vibration (acceleration) applied in the excitation direction can be obtained. .

  However, in this method, the comb-shaped electrode in which the fixed electrode 7a and the movable electrode 7b are installed in parallel with the excitation direction (first direction, Y-axis direction) does not change the capacitance sufficient for acceleration detection. In order to obtain, it is necessary to enlarge the scale of the electrode. Further, in the parallel plate type electrode in which the fixed electrode 7a and the movable electrode 7b are installed perpendicular to the excitation direction (first direction, Y-axis direction), the interval between the fixed electrode 7a and the movable electrode 7b is set to the opposite phase of the excitation element 5. In order to obtain a change in capacitance sufficient to detect acceleration, it is necessary to use an electrode having a large scale, although it is smaller than the above-mentioned comb-shaped electrode. In addition, the parallel plate type electrode has a comb-teeth shape in order that the viscosity of the viscous fluid (air) between the movable electrode 7b and the fixed electrode 7a interferes with the reverse-phase vibration of the excitation element 5 to obtain the required amplitude. A high drive voltage is required compared to the electrodes.

  Next, the excitation direction acceleration detection unit 8 is for detecting acceleration applied in the excitation direction, and is connected to the excitation element 5 via the elastic body 17d and disposed between the excitation elements 5. . The excitation direction acceleration detector 8 is configured by alternately arranging a plurality of fixed electrodes 8a and a plurality of movable electrodes 8b along the excitation direction (first direction, Y-axis direction) so as to be engaged with each other. ing.

  The fixed electrode 8a of the excitation direction acceleration detector 8 is formed by patterning the active layer 2c. The fixed electrode 8a is formed integrally with the active layer 2c of the support portion 18e, and is fixed to the substrate 2 by being connected to the support portion 18e. The support portion 18e is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18e has a function as an electrode that gives an electric signal to the fixed electrode 8a.

  On the other hand, the movable electrode 8b of the excitation direction acceleration detector 8 is formed by patterning the active layer 2c. The movable electrode 8b is arranged in a state where it floats on the first main surface of the substrate 2 with the insulating layer 2b below the movable electrode 8b removed. The movable electrode 8b has an active layer 2c connected to the active layer 2c of the excitation element 5 in the excitation direction (first direction, Y-axis direction) via a soft beam 17d. The excitation direction acceleration detector 8 having such a configuration is not displaced when the excitation element 5 vibrates in the opposite phase with the same amplitude, and is excited by applying acceleration in the excitation direction (first direction, Y-axis direction). When the element 5 vibrates in the same phase, it follows the movement and is displaced. This vibration state is detected by a change in capacitance between the opposed surfaces of the fixed electrode 8a and the movable electrode 8b, and the detection signal is output as an acceleration in the excitation direction. The movable electrode 8b may be rigid to such an extent that the movable electrode 8b itself is not deformed, and is designed to reduce the mass in order to minimize the phase delay of the acceleration response due to the inertial force of the movable electrode 8b itself.

  One of the features of the inertial sensor 1A in the first embodiment is that the excitation direction acceleration detector 8 vibrates in the excitation direction (first direction, Y-axis direction) in opposite phases with each other via the beam 17d. Being connected. By providing the excitation direction acceleration detection unit 8 in this way, it is possible to detect the acceleration in the excitation direction while causing the excitation elements 5 to vibrate in mutually opposite phases. That is, when no acceleration is applied in the excitation direction (first direction, Y-axis direction), vibrations in opposite phases are applied to the excitation direction acceleration detection unit 8 from the left and right excitation elements 5, so Is canceled out, and the interval between the capacitive elements constituting the excitation direction acceleration detector 8 does not change. For this reason, the excitation direction acceleration detector 8 does not detect acceleration in the excitation direction (first direction, Y-axis direction). On the other hand, when acceleration is applied in the excitation direction (first direction, Y-axis direction), the left and right excitation elements 5 change in phase. Accordingly, since the left and right excitation elements 5 are displaced in the same phase, the excitation direction acceleration detection unit 8 connected to the left and right excitation elements 5 is also displaced. For this reason, the space | interval of the capacitive element which comprises the excitation direction acceleration detection part 8 changes, and the electrostatic capacitance of a capacitive element changes. By detecting this change in capacitance, the acceleration in the excitation direction can be detected. As described above, according to the first embodiment, even if the left and right excitation elements 5 change in phase due to the acceleration in the excitation direction and the excitation elements that vibrate in opposite phases are connected to each other, the acceleration in the excitation direction is increased. When no voltage is applied, it is understood that there is a feature that the excitation direction acceleration detecting unit 8 is provided, focusing on the fact that there is no in-phase displacement in the excitation direction.

  Next, further advantages of the excitation direction acceleration detection unit 8 provided in the inertial sensor according to the first embodiment will be described. There is a relationship shown in Equation 5 between the displacement amount in the excitation direction (first direction, Y-axis direction) and the acceleration in the excitation direction (first direction, Y-axis direction).

y = ma / kdrive... Formula 5
Where y is the amount of displacement in the excitation direction (first direction, Y-axis direction), a is the acceleration applied in the excitation direction (first direction, Y-axis direction), and kdrive is the excitation direction (first direction, Y-axis direction). The spring constant m) is the sum of the mass of the excitation element 5, the Coriolis element 11 disposed in the excitation element 5, and the movable electrode 8b of the excitation direction acceleration detector 8.

  Further, kdrive satisfies the relationship expressed by Equation 6.

kdrive = (Ebh ³ / L ³ ) Equation 6
Where E is the longitudinal elastic modulus of the beam, b is the thickness of the beam (thickness of the active layer 2c), h is the width of the beam, and L is the length of the beam.

  From Equation 5 and Equation 6 above, in order to accurately measure the acceleration a applied in the excitation direction (first direction, Y-axis direction), it is necessary to increase the mass m and decrease the spring constant kdrive. .

  For example, as shown in FIG. 7, for the purpose of measuring the acceleration in the excitation direction (first direction, Y-axis direction), the small excitation direction acceleration detector 8 is not connected to the excitation element 5, and the support 18f. Are connected to each other via a beam 17d and fixed to the substrate 2. In this case, the value of m shown in Equation 5 is the mass of only the movable electrode 8b of the excitation direction acceleration detector 8. Since only the mass of the movable electrode 8b is small, the spring constant kdrive can only be reduced to obtain the required sensitivity. However, from Equation 6, in order to reduce the spring constant kdrive, it is necessary to reduce the width of the beam 17d or increase the length of the beam 17d. However, the width of the beam 17d is limited due to processing limitations. Further, if the width of the beam 17d is narrowed, it is easily broken by an external impact. In addition, it is not preferable to increase the length of the beam 17d in terms of miniaturization. Thus, it is difficult to achieve both sensitivity and strength simply by providing the excitation direction acceleration detector 8.

  Therefore, in the first embodiment, as shown in FIG. 2, the excitation direction acceleration detector 8 is connected to the excitation element 5 by a beam 17d. In this case, in the excitation direction acceleration detection unit 8, since the mass of the excitation element 5 and the Coriolis element 11 is included in addition to the movable electrode 8b as m in Equation 5, the mass can be increased. That is, since the mass can be increased, the detection sensitivity of the acceleration in the excitation direction (first direction, Y-axis direction) can be improved. Furthermore, since sufficient detection sensitivity can be obtained by increasing the mass, it is not necessary to reduce the spring constant kdrive. Therefore, the strength of the beam can be maintained. Furthermore, there are few restrictions on the processing of the beam 17d, which is advantageous for downsizing. As described above, according to the inertial sensor in the first embodiment, acceleration in the excitation direction (first direction, Y-axis direction) can be detected with high sensitivity, and the strength of the beam can be maintained. Further, it is possible to reduce the size of the inertial sensor 1A in which the excitation direction acceleration detector 8 is formed.

  The excitation direction acceleration detection unit 8 is not limited to being connected to the excitation element 5 that vibrates in the opposite phase, and is, for example, in the opposite phase in the excitation direction (first direction, Y-axis direction) of the beam 17b or the like. If it is connected to the structure that vibrates in the same manner, it is possible to obtain the same effect as in the case of connection to the excitation element 5 that vibrates in the opposite phase.

  Further, as shown in FIG. 8, a portion that becomes a node of antiphase vibration of the excitation element 5, for example, not a portion oscillating in an antiphase in the excitation direction (first direction, Y-axis direction), for example, The effect of the present invention can be obtained even if the beams 17c and 17c are connected directly or via the beam 17d. That is, as shown in FIG. 8, when the connection between the excitation elements 5 that vibrate in opposite phases is performed by the beams 17b and 17c, there are always nodes that do not vibrate in the beams 17b and 17c. This node is not displaced when no acceleration is applied in the excitation direction (first direction, Y-axis direction). On the other hand, when acceleration is applied in the excitation direction (first direction, Y-axis direction), the position of the node also changes. Accordingly, by providing the excitation direction acceleration detection unit 8 at the node position, the excitation direction (first direction, Y-axis direction) is the same as when the excitation direction acceleration detection unit 8 is connected to the excitation elements 5 that vibrate in mutually opposite phases. ) Acceleration can be detected.

  Further, since the gap between the fixed electrode 8a and the movable electrode 8b of the excitation direction acceleration detector 8 can be made narrower than the antiphase amplitude of the excitation element 5 by arranging it at the node portion, the excitation direction amplitude monitor means 7 High-sensitivity measurement can be performed with a smaller-scale electrode than the method of detecting the acceleration in the excitation direction using the.

  Furthermore, by arranging in a portion that becomes a node, the fixed electrode 8a and the movable electrode 8b of the excitation direction acceleration detection unit 8 can be made into a parallel plate type provided perpendicular to the excitation direction (first direction, Y-axis direction). The viscosity of the viscous fluid between the fixed electrode 8a and the movable electrode 8b does not disturb the antiphase vibration of the excitation element 5. Therefore, by installing the excitation direction acceleration detector 8, the excitation energy is not lost and the negative phase amplitude is not affected.

  Further, the excitation direction acceleration detection unit 8 does not have to be one, and may be plural as shown in FIG. In this case, it is possible to detect the acceleration by comparing the capacitance changes of the excitation direction acceleration detectors 8-1 and 8-2 and taking the differential. That is, as shown in FIG. 9, a plurality of excitation direction acceleration detectors 8-1 and 8-2 may be provided between the left and right excitation elements 5. In this case, the left excitation direction acceleration detection unit 8-1 has a movable electrode 8-1b and a fixed electrode 8-1a fixed to the fixed unit 8-1c. Similarly, the right excitation direction acceleration detector 8-2 also has a movable electrode 8-2b and a fixed electrode 8-2a fixed to the fixed portion 8-2c.

  Next, the excitation direction acceleration servo means 9 detects the amount of displacement detected by the acceleration detected by the excitation direction acceleration detector 8 (in-phase displacement) so that the amplitude due to the acceleration applied to the excitation element 5 is always zero. Accordingly, the rebalancing force is generated in response to the active control, and is actively controlled, and is disposed opposite to the excitation means 6. The excitation direction acceleration servo means 9 is configured by alternately arranging a plurality of fixed electrodes 9a and a plurality of movable electrodes 9b along the detection direction (second direction, X-axis direction) so as to engage with each other. ing. The rebalancing force is generated by applying a bias voltage between the plurality of fixed electrodes 9a and the plurality of movable electrodes 9b of the excitation direction acceleration servo means 9. Therefore, it is possible to measure the applied acceleration by outputting the bias voltage itself.

  The excitation direction acceleration detector 8 includes a capacitive element composed of a fixed electrode 8a and a movable electrode 8b, and when acceleration occurs in the excitation direction (first direction, Y-axis direction), the fixed electrode 8a and the movable electrode The distance to 8b changes. And it has the structure which detects the acceleration of an excitation direction (1st direction, Y-axis direction) using the electrostatic capacitance of a capacitive element changing according to the distance between the fixed electrode 8a and the movable electrode 8b. . That is, when acceleration is generated in the excitation direction (first direction, Y-axis direction), the movable electrode 8b of the excitation-direction acceleration detector 8 is displaced to detect acceleration in the excitation direction (first direction, Y-axis direction). To do. When the acceleration in the excitation direction (first direction, Y-axis direction) increases, the displacement amount of the movable electrode 8b also increases. The movable electrode 8b is connected to the beam, and the movable electrode 8b is displaced according to the amount of displacement of the beam. When the acceleration in the excitation direction (first direction, Y-axis direction) increases, the movable electrode 8b is connected to the movable electrode 8b. The displacement of the beam is also increased. While the acceleration in the excitation direction (first direction, Y-axis direction) is small, the linearity of the displacement of the beam is maintained, but when the acceleration in the excitation direction (first direction, Y-axis direction) is large, the beam It becomes difficult to maintain the linearity of the displacement, and the detection sensitivity of the acceleration in the excitation direction (first direction, Y-axis direction) changes. In addition, when an attempt is made to widen the dynamic range in which acceleration in the excitation direction (first direction, Y-axis direction) can be detected, the movable electrode 8b is fixed to the movable electrode 8b so that the movable electrode 8b does not contact the fixed electrode 8a even when a large acceleration is applied. It is necessary to increase the distance between the electrodes 8a. As the distance between the movable electrode 8b and the fixed electrode 8a is narrower, the acceleration detection sensitivity is improved. Therefore, if the distance between the movable electrode 8b and the fixed electrode 8a is increased, the acceleration detection sensitivity is lowered.

  Therefore, in the first embodiment, the excitation direction acceleration servo means 9 is provided. The excitation direction acceleration servo means 9 generates a rebalancing force based on the detection result of the excitation direction acceleration detection unit 8 so that the displacement amount of the movable electrode 8b of the excitation direction acceleration detection unit 8 becomes zero. ing. That is, the excitation direction acceleration servo means 9 forcibly eliminates the displacement amount of the movable electrode 8b of the excitation direction acceleration detector 8 by the rebalance force. That is, the acceleration in the excitation direction (first direction, Y-axis direction) is detected by the excitation direction acceleration servo means 9 with the amount of displacement of the movable electrode 8b indirectly as the rebalance force. Since the rebalance force that cancels the displacement amount of the movable electrode 8b changes according to the displacement amount of the movable electrode 8b, the acceleration in the excitation direction (first direction, Y-axis direction) is measured by measuring the rebalance force. Can be detected.

  By providing this excitation direction acceleration servo means 9, the following effects can be obtained. That is, even when acceleration in the excitation direction (first direction, Y-axis direction) is applied, the amount of displacement of the movable electrode 8b does not occur due to the rebalance force, so the beam connected to the movable electrode 8b There is no burden. For this reason, the linearity of the beam is good, and the acceleration can be detected stably. Moreover, since the displacement amount of the movable electrode 8b does not occur, the distance between the fixed electrode 8a and the movable electrode 8b can be reduced. That is, even when the distance between the fixed electrode 8a and the movable electrode 8b is narrowed, it is possible to prevent contact when a large acceleration is applied. Therefore, the distance between the fixed electrode 8a and the movable electrode 8b can be reduced, and the acceleration detection sensitivity can be improved. On the other hand, an acceleration detection range (dynamic range) can be secured. In the first embodiment, the excitation direction acceleration servo means 9 is provided, but it may not be provided. That is, the acceleration may be directly detected from the displacement amount of the movable electrode 8b of the excitation direction acceleration detector 8.

  The fixed electrode 9a of the excitation direction acceleration servo means 9 is formed by patterning the active layer 2c. The active layer 2c of the fixed electrode 9a is formed integrally with the active layer 2c of the support portion 18g, and is connected to the support portion 18g and fixed to the substrate 2. The support portion 18g is disposed outside the excitation element 5 and inside the outer peripheral wall W in consideration of wiring removal after cap (MCP) sealing. The support portion 18g is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18g has a function as an electrode for supplying an electric signal to the fixed electrode 9a and a wiring inside the sensor unit.

  On the other hand, the movable electrode 9b of the excitation direction acceleration servo means 9 is formed by patterning the active layer 2c. The movable electrode 9b is arranged in a state of being floated on the first main surface of the substrate 2 with the insulating layer 2b below the movable electrode 9b removed. The movable electrode 9 b has an active layer 2 c formed and connected integrally with the active layer 2 c of the excitation element 5, and is connected to the excitation element 5.

  Next, the excitation direction resonance frequency tuning means 10 is for actively controlling the variation of the resonance frequency of the excitation element 5 caused by the change in ambient temperature, the degree of vacuum, or the processing variation. In the detection direction (second direction, X-axis direction). This excitation direction resonance frequency tuning means 10 is configured by alternately arranging a plurality of fixed electrodes 10a and a plurality of movable electrodes 10b along the excitation direction (first direction, Y-axis direction) so as to engage with each other. Has been.

  The excitation element 5 is configured to vibrate in the excitation direction (first direction, Y-axis direction) by the excitation means 6, but it is necessary to vibrate the excitation element 5 at the resonance point in order to stably maintain this vibration. There is. However, when the temperature around the inertial sensor 1A changes, the vibration of the excitation element 5 deviates from the resonance point. When the vibration of the excitation element 5 deviates from the resonance point, the amplitude of the vibration decreases rapidly, and it becomes difficult to stably maintain the vibration. Therefore, in the inertial sensor 1A according to the first embodiment, the excitation direction resonance frequency tuning means 10 is provided. According to this excitation direction resonance frequency tuning means 10, when the vibration of the excitation element 5 deviates from the resonance point, the deviation can be corrected so that the vibration of the excitation element 5 is performed at the resonance point. Therefore, it is possible to stably maintain the vibration of the excitation element 5 in the excitation direction (first direction, Y-axis direction).

  The fixed electrode 10a of the excitation direction resonance frequency tuning means 10 is formed by patterning the active layer 2c. The fixed electrode 10a has an active layer 2c formed integrally with the active layer 2c of the support portion 18h, and is fixed to the substrate 2 by being connected to the support portion 18h. The support portion 18h is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18h has a function as an electrode for giving an electric signal to the fixed electrode 10a.

  On the other hand, the movable electrode 10b of the excitation direction resonance frequency tuning means 10 is formed by patterning the active layer 2c. The insulating layer 2b under the movable electrode 10b is removed, and the movable electrode 10b is arranged in a floating state on the first main surface of the substrate 2. The movable electrode 10b has an active layer 2c integrally formed with and connected to the active layer 2c of the excitation element 5, and is connected and fixed to the excitation element 5.

  Subsequently, a Coriolis element 11 is disposed inside the excitation element 5. The Coriolis element 11 is formed by patterning the active layer 2c into a plane substantially frame shape. The Coriolis element 11 is also disposed on the first main surface of the substrate 2 in a state where the underlying insulating layer 2b is removed and floated. The Coriolis element 11 is designed so that it can be displaced both in the excitation direction (first direction, Y-axis direction) and in the detection direction (second direction, X-axis direction). The Coriolis element 11 also vibrates along the first main surface of the substrate 2. Such a Coriolis element 11 is connected to the excitation element 5 through a beam 17e. Thus, the Coriolis element 11 vibrates in the excitation direction (first direction, Y-axis direction) with the same amplitude and phase as the excitation element 5. When the angular velocity around the Z-axis is applied, the Coriolis element 11 is displaced in the detection direction (second direction, X-axis direction) by Coriolis force. That is, the mass of the Coriolis element 11 is m in Equation 1. Therefore, the Coriolis element 11 is designed to have a large mass in order to achieve high sensitivity.

  The Coriolis elements 11 are respectively arranged inside the left and right excitation elements 5, and the respective Coriolis elements 11 vibrate in the excitation directions (first direction and Y-axis direction) in opposite phases as in the left and right excitation elements 5. . For this reason, when an angular velocity around the Z-axis is applied, the left and right Coriolis elements 11 are displaced in the detection direction (second direction, X-axis direction) by the Coriolis force. Since the left and right Coriolis elements 11 vibrate in the opposite phase in the excitation direction (first direction, Y-axis direction), the amount of displacement in the detection direction (second direction, X-axis direction) due to Coriolis force is in the opposite phase.

  The beam 17e is formed by patterning the active layer 2c to be thinner than the pattern of the Coriolis element 11 (that is, the beam 17e is formed integrally with the excitation element 5 and the active layer 2c of the Coriolis element 11). The lower insulating layer 2b is removed and arranged on the first main surface of the substrate 2 in a floating state in the same manner as the excitation element 5 and the Coriolis element 11. The beam 17e has a relatively long portion extending linearly in the excitation direction (first direction, Y-axis direction) and a relative extension extending linearly in the detection direction (second direction, X-axis direction) perpendicular thereto. And a short part. Both ends of this relatively long portion are connected to the inner periphery of the excitation element 5. In addition, one end of the relatively short portion is connected to the center in the longitudinal direction of the relatively long portion, and the other end is connected to the center of the edge in the detection direction (second direction, X-axis direction) of the Coriolis element 11. ing. This beam 17e also has a function as a leaf spring. However, the beam 17e is hard in the excitation direction (first direction, Y-axis direction), and compared with the rigidity in the excitation direction (first direction, Y-axis direction) in the detection direction (second direction, X-axis direction). The structure is soft. For this reason, vibration in the excitation direction (first direction, Y-axis direction) of the excitation element 5 is transmitted to the Coriolis element 11 as it is, but vibration in the detection direction (second direction, X-axis direction) of the Coriolis element 11 is absorbed, The excitation element 5 is not transmitted.

  The detection element 12 is disposed inside the Coriolis element 11. The detection element 12 is formed by patterning the active layer 2c into a substantially planar frame shape. The detection element 12 is also disposed on the first main surface of the substrate 2 in a state where the insulating layer 2b below the detection element 12 is removed and floated. This detection element 12 is connected to the Coriolis element 11 via a beam 17f, and connected to a support portion 18i via a beam 17g and fixed to the substrate 2. Accordingly, the detection element 12 vibrates with the same amplitude and the same phase as the vibration of the Coriolis element 11 in the detection direction (second direction, X-axis direction). In addition, the detection element 12 also vibrates along the first main surface of the substrate 2.

  The beam 17f is formed by patterning the active layer 2c to be thinner than the pattern of the Coriolis element 11 and the detection element 12 (that is, the beam 17f is formed integrally with the excitation layer 5 and the active layer 2c of the Coriolis element 11). The lower insulating layer 2b is removed, and is disposed on the first main surface of the substrate 2 in a floating state like the excitation element 5 and the like.

  The beam 17f has a relatively long portion extending linearly in the detection direction (second direction, X-axis direction) and a relative extension extending linearly in the excitation direction (first direction, Y-axis direction) perpendicular thereto. And a short part. Both ends of a relatively long portion of the beam 17f are connected to the inner periphery of the Coriolis element 11. Also, one end of the relatively short portion of the beam 17f is connected to the center in the longitudinal direction of the relatively long portion, and the other end is on the edge of the detection element 12 in the excitation direction (first direction, Y-axis direction). It is connected. This beam 17f also has a function as a leaf spring. However, the beam 17f is soft in the excitation direction (first direction, Y-axis direction), and compared with the rigidity in the excitation direction (first direction, Y-axis direction) in the detection direction (second direction, X-axis direction). It has a hard structure. Therefore, the vibration in the detection direction (second direction, X-axis direction) of the Coriolis element 11 is transmitted to the detection element 12 as it is, but the vibration in the excitation direction (first direction, Y-axis direction) is absorbed. Yes. That is, the detection element 12 is displaced only in the detection direction (second direction, X-axis direction).

  The beam 17g has a relatively long portion extending linearly in the excitation direction (first direction, Y-axis direction) and a relative extension extending linearly in the detection direction (second direction, X-axis direction) perpendicular thereto. Short part. Both ends of a relatively short portion of the beam 17g are connected to the outer periphery of the detection element 12. One end of the relatively long portion of the beam 17g is connected to one end in the longitudinal direction of the relatively short portion, and the other end is near the center of the detection direction of the detection element 12 (second direction, X-axis direction). And is fixed to the substrate 2 by being connected to the support portion 18i. This beam 17g also has a function as a leaf spring. However, the beam 17g is soft in the detection direction (second direction, X-axis direction), and compared with the rigidity in the excitation direction (second direction, X-axis direction) in the excitation direction (first direction, Y-axis direction). It has a hard structure. Therefore, the vibration in the detection direction (second direction, X-axis direction) of the Coriolis element 11 is directly transmitted to the detection element 12, but the vibration in the excitation direction (first direction, Y-axis direction) is absorbed by the beam 17g. It has become. Therefore, the detection element 12 only needs to be rigid to the extent that the detection element 12 itself is not deformed, and the mass is designed to be small in order to improve detection sensitivity and prevent generation of unnecessary signals.

  Next, the detection means 13 (13-1 to 13-4) is disposed inside the detection element 12. The detection units 13-1 to 13-4 are formed by a comb-shaped detector. That is, the detection means 13-1 to 13-4 are alternately arranged along the detection direction (second direction, X-axis direction) so that the plurality of fixed electrodes 13a and the plurality of movable electrodes 13b are engaged with each other. It is composed of that. In the detection means 13-1 to 13-4, when the detection element 12 is displaced in the detection direction (second direction, X-axis direction) by the acceleration or angular velocity in the detection direction (second direction, X-axis direction), the detection electrode A displacement amount is detected as a change in capacitance between the fixed electrode 13a and the movable electrode 13b. That is, a change in electrostatic capacitance that changes as the fixed electrode 13a and the movable electrode 13b move toward or away from each other is detected based on the amount of displacement of the detection element 12 in the detection direction (second direction, X-axis direction).

  The fixed electrodes 13a of the detection means 13-1 to 13-4 are formed by patterning the active layer 2c. The fixed electrode 13a has an active layer 2c formed integrally with the active layer 2c of the support portion 18j, and is fixed to the substrate 2 by being connected to the support portion 18j. The support portion 18j is disposed on the outer periphery of each sensor unit SUA1, SUA2. The support portion 18j is formed by patterning the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18j functions as an electrode for supplying an electric signal to the fixed electrode 13a and a wiring.

  On the other hand, the movable electrode 13b of the detection means 13-1 to 13-4 is formed by patterning the active layer 2c. The insulating layer 2b under the movable electrode 13b is removed, and the movable electrode 13b is arranged in a floating state on the first main surface of the substrate 2. The movable electrode 13 b has an active layer 2 c formed integrally with and connected to the active layer 2 c of the detection element 12, and is connected to the detection element 12. The detection means 13-1 to 13-4 having such a configuration detect the vibration state of the detection element 12 by a change in electrostatic capacitance between the opposed surfaces of the fixed electrode 13a and the movable electrode 13b, and detect the detection signal. The acceleration or angular velocity measurement result in the direction (second direction, X-axis direction) is output.

  FIG. 10 schematically shows a method of detecting acceleration and angular velocity values in the detection direction (second direction, X-axis direction) from the change in capacitance obtained by such detection means 13-1 to 13-4. Is shown. The symbol OP is an operational amplifier. That is, the applied angular velocity can be detected by taking the difference between the value obtained by adding the capacities of the detection means 13-1 and the detection means 13-4 and the value obtained by adding the detection means 13-2 and the detection means 13-3. It has become. Further, by taking the difference between the value obtained by adding the detection means 13-1 and the detection means 13-2 and the value obtained by adding the detection means 13-3 and the detection means 13-4, the detection direction (second direction, X-axis direction) is obtained. ) Can be detected. That is, when an angular velocity around the Z axis is applied, a Coriolis force is generated, and the Coriolis element 11 is displaced in the detection direction (second direction, X axis direction) by this Coriolis force. Since the left and right Coriolis elements 11 vibrate in opposite phases to the excitation direction (first direction, Y-axis direction), the amount of displacement in the detection direction (second direction, X-axis direction) due to Coriolis force is the left and right Coriolis elements. 11 is the opposite phase. For this reason, the amount of displacement in the detection direction (second direction, X-axis direction) of the left and right detection elements 12 also has an opposite phase. Therefore, the applied angular velocity is detected by taking the difference between the value obtained by adding the capacities of the detection means 13-1 and the detection means 13-4 and the value obtained by adding the detection means 13-2 and the detection means 13-3. Can do. On the other hand, when acceleration in the detection direction (second direction, X-axis direction) is applied, the left and right Coriolis elements 11 are displaced in phase in the detection direction (second direction, X-axis direction). For this reason, the left and right detection elements 12 also change in the same phase in the detection direction (second direction, X-axis direction). Therefore, by taking the difference between the value obtained by adding the detection means 13-1 and the detection means 13-2 and the value obtained by adding the detection means 13-3 and the detection means 13-4, the detection direction (second direction, X-axis direction) is obtained. ) Can be detected.

  As described above, according to the inertial sensor 1A according to the first embodiment, it is possible to simultaneously detect the angular velocity, the acceleration in the detection direction (X-axis direction), and the acceleration in the excitation direction (Y-axis direction) with one inertial sensor. Recognize. That is, an excitation direction acceleration detector 8 connected via an elastic body is provided between a plurality of excitation elements 5 that vibrate in opposite phases, and the acceleration in the excitation direction is determined from the amount of displacement in the same phase in the plurality of excitation elements 5. Can be detected. For this reason, the acceleration in the excitation direction that causes the fundamental vibration for measuring the angular velocity can be measured simultaneously with the angular velocity and the acceleration in the detection direction for detecting the angular velocity. Therefore, it is not necessary to separately provide an inertial sensor that measures acceleration in the angular velocity and detection direction (X-axis direction) and an inertial sensor that measures acceleration in the excitation direction (Y-axis direction). Can do.

  In addition, since the acceleration in the excitation direction (Y-axis direction) can be measured or identified, it is possible to correct the displacement error due to the mass part bias caused by the acceleration, which is resistant to disturbances and always provides stable excitation vibration. Since it can be maintained, the detection accuracy of the angular velocity can be improved.

  Since the detection element 12 vibrates only in the detection direction (second direction, X-axis direction), in principle, the area of the opposing surface between the fixed electrode 13a and the movable electrode 13b of the detection means 13-1 to 13-4 is determined. In comparison with a technique in which the excitation direction and the detection direction have a vibration coupling, it can be widely used. For this reason, the sensitivity and stability of the inertial sensor 1A can be improved.

  Next, the angular velocity servo means 14 applies the rebalancing force according to the detected displacement amount detected from the detection means 13 so that the amplitude due to the angular velocity applied to the detection element 12 (the amplitude of the opposite phase) is always zero. It is a means for generating and actively controlling, and is disposed inside the detection element 12. That is, the angular velocity servo means 14 has a function equivalent to that of the excitation direction acceleration servo means 9 described above. The angular velocity servo means 14 is configured by alternately arranging a plurality of fixed electrodes 14a and a plurality of movable electrodes 14b along the detection direction (second direction, X-axis direction) so as to engage with each other. .

  The fixed electrode 14a of the angular velocity servo means 14 is formed by patterning the active layer 2c. The fixed electrode 14a has an active layer 2c integrally formed with the active layer 2c of the support portion 18k, and is fixed to the substrate 2 by being connected to the support portion 18k. The support portion 18k is disposed outside the excitation element 5 and inside the outer peripheral wall W in consideration of wiring removal after cap (MCP) sealing. The support portion 18k is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18k has a function as an electrode for supplying an electric signal to the fixed electrode 14a and wiring inside the sensor units SUA1 and SUA2.

  The detection direction acceleration servo means 15 rebalances according to the detected displacement amount (displacement amount of the same phase) by the acceleration detected from the detection means 13 so that the amplitude due to the acceleration applied to the detection element 12 is always zero. It is a means for generating force and actively controlling it, and is arranged inside the detection element 12. That is, the detection direction acceleration servo means 15 has the same function as the excitation direction acceleration servo means 9 described above. This detection direction acceleration servo means 15 is configured by alternately arranging a plurality of fixed electrodes 15a and a plurality of movable electrodes 15b along the detection direction (second direction, X-axis direction) so as to engage with each other. ing. The rebalancing force is generated by applying a bias voltage between the plurality of fixed electrodes 15a and the plurality of movable electrodes 15b of the detection direction acceleration servo means 15. Therefore, the applied acceleration is measured by outputting the bias voltage itself.

  The fixed electrode 15a of the detection direction acceleration servo means 15 is formed by patterning the active layer 2c. The fixed electrode 15a has an active layer 2c formed integrally with the active layer 2c of the support portion 18l, and is fixed to the substrate 2 by being connected to the support portion 18l. The support portion 18l is arranged outside the excitation element 5 and inside the outer peripheral wall W in consideration of wiring extraction after sealing the cap (MCP). The support portion 18l is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18l has a function as an electrode for supplying an electric signal to the fixed electrode 15a and a wiring inside the sensor units SUA1 and SUA2.

  On the other hand, the movable electrodes 14b and 15b of the angular velocity servo means 14 and the detection direction acceleration servo means 15 are formed by patterning the active layer 2c. The movable electrodes 14 b and 15 b are arranged in a state of being floated on the first main surface of the substrate 2 with the underlying insulating layer 2 b removed. The movable electrodes 14 b and 15 b have the active layer 2 c formed and connected integrally with the active layer 2 c of the detection element 12, and are connected to the detection element 12.

  Next, the detection direction resonance frequency tuning means 16 is for actively controlling the resonance frequency of the detection element 12, and is arranged inside the detection element 12. The detection direction resonance frequency tuning means 16 has the same function as the excitation direction resonance frequency tuning means 10 described above. The detection direction resonance frequency tuning means 16 is configured by alternately arranging a plurality of fixed electrodes 16a and a plurality of movable electrodes 16b along the detection direction (second direction, X-axis direction) so as to engage with each other. ing.

  The fixed electrode 16a of the detection direction resonance frequency tuning means 16 is formed by patterning the active layer 2c. The fixed electrode 16a has an active layer 2c formed integrally with the active layer 2c of the support portion 18m, and is fixed to the substrate 2 by being connected to the support portion 18m. The support portion 18m is formed by a laminated pattern of the active layer 2c and the insulating layer 2b, and is firmly bonded and fixed to the support substrate 2a of the substrate 2. Here, the support portion 18m has a function as an electrode that gives an electric signal to the fixed electrode 16a.

  On the other hand, the movable electrode 16b of the detection direction resonance frequency tuning means 16 is formed by patterning the active layer 2c. The insulating layer 2b under the movable electrode 16b is removed, and the movable electrode 16b is arranged in a floating state on the first main surface of the substrate 2. The active layer 2c of the movable electrode 16b is integrally formed and connected to the active layer 2c of the detection element 12, and is connected and fixed to the detection element 12.

  A sealing cap MCP is anodically bonded on the first main surface of the substrate 2. Thereby, sensor unit SUA1 and SUA2 are sealed so that the movable part may be installed in an appropriate pressure atmosphere. The sealing cap MCP is made of, for example, Pyrex glass, and a plurality of electrodes 19 are provided so as to penetrate the upper and lower surfaces (see FIG. 3). The electrode 19 is an electrode for supplying a desired electric signal from the outside of the inertial sensor 1A to the internal sensor units SUA1 and SUA2, and is electrically connected to the support portions 18a to 18m.

  However, the sealing configuration is not limited to the sealing configuration by anodic bonding, and can be variously changed. For example, the sealing cap MCP may be bonded to the substrate 2 with an adhesive. Further, after wire bonding, the entire sensor units SUA1 and SUA2 may be sealed in a package. Alternatively, the control circuit such as the excitation unit 6 and the detection unit 13 may be packaged on the substrate 2 in a mixed state. Further, an electrode for supplying a desired electric signal to the sensor units SUA1 and SUA2 may be taken from the second main surface side (back surface side) of the substrate 2. Alternatively, the sensor units SUA1 and SUA2 may be sealed by forming a sealing thin film on the sensor units SUA1 and SUA2 by using a chemical vapor deposition (CVD) method, a sputtering method, or the like.

(Embodiment 2)
In the second embodiment, an example in which a Coriolis element and a detection element of an inertial sensor are integrated will be described. FIG. 11 is a plan view showing an example of the inertial sensor 1C of the second embodiment. In FIG. 11, the sealing cap is omitted for easy understanding of the drawing.

  In the second embodiment, the element 20 is arranged inside the excitation element 5 inside the excitation element 5 of the sensor units SUA1 and SUA2. The element 20 is obtained by integrating the Coriolis element 11 and the detection element 12 and has both functions of the Coriolis element 11 and the detection element 12. The element 20 is connected to and supported by the excitation element 5 via a beam 17e, and is formed by patterning the active layer 2c in a plane substantially frame shape. Then, the lower insulating layer 2 b is removed, and the insulating layer 2 b is arranged in a floating state on the first main surface of the substrate 2.

  When the element 20 is displaced in the detection direction (second direction, X-axis direction) by the acceleration or angular velocity in the detection direction (second direction, X-axis direction), the detection means 13-1 to 13-4 are displaced. Is detected. On the inner periphery of the element 20, the movable electrode 13 b of the detection means 13 is integrally formed and connected to the active layer 2 c of the element 20.

  The angular velocity servo means 14 and the detection direction acceleration servo means 15 are actively controlled so that the amplitude of the element 20 in the detection direction (second direction, X-axis direction) is always zero. At both ends of the detection direction (second direction, X-axis direction), the movable electrodes 14b and 15b of the angular velocity servo means 14 and the detection direction acceleration servo means 15 are integrated with the active layer 2c of the element 20 at the inner periphery of the element. Formed and connected. The other configuration is the same as that of the first embodiment.

  In the second embodiment, in addition to the effects obtained in the first embodiment, the following effects can be obtained. In other words, the sensor units SUA1 and SUA2 can be easily formed by integrating the Coriolis element and the detection element. Moreover, the inertial sensor 1C can be reduced in size by integrating the Coriolis element and the detection element. In FIG. 11, the invention effect is described based on the configuration of FIG. 4, but the same effect can be obtained with the configuration of FIG. 2 or FIG.

(Embodiment 3)
In the third embodiment, application examples of the inertial sensors 1A and 1C of the first and second embodiments will be described.

  FIG. 12 shows an example in which the inertial sensor 1A or the inertial sensor 1C is applied to an automobile skid prevention device. Reference numeral 30 is a vehicle, 31 is a control unit (control device), 32 is a steering operated by a driver, 33 is a snake angle sensor that detects an operation amount of the steering 32, 34 is a tire, and 35 is a rotation speed of each tire. The rotation sensor 36 to detect is a brake. The control unit 31 includes an inertial sensor 1A or an inertial sensor 1C.

  First, the driver of the vehicle 30 operates the steering 32 to direct the vehicle in the intended direction. Then, the operation amount of the steering wheel 32 is detected by the horn angle sensor 33, and the detection signal is input to the control unit (control device) 31. The speed of the vehicle 30 is detected by the rotation sensor 35, and the detection signal is input to the control unit (control device) 31. Here, when the vehicle 30 skids on a snowy road and starts to spin against the driver's intention, the control unit (control device) 31 calculates the vehicle calculated from the operation amount of the steering 32 and the vehicle speed. The difference between the 30 movements (angular velocity and acceleration) and the actual movement (angular velocity and acceleration) of the vehicle 30 detected from the inertial sensor 1A or the inertial sensor 1C according to the present embodiment is detected, so that skidding is less likely to occur. The brake 36 is controlled.

  According to the present embodiment, as described above, the stability, sensitivity, and reliability of the inertial sensor 1A or the inertial sensor 1C can be improved. For this reason, higher control can be realized and the vehicle 30 can be guided to a safer state.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In the above description, the case where the invention made mainly by the present inventor is applied to an automobile skid prevention device, which is a field of use as a background, has been described. However, the present invention is not limited to this and can be applied in various ways. For example, it can be applied to other automobile devices such as automobile airbag collision detection devices and car navigation systems, sensors for measuring the posture and motion state of robots, posture recognition sensors for mobile phones, and notebook personal computers. It can also be applied to sensors used for attitude control of portable electronic devices such as digital cameras, for example, camera shake correction, drop detection, and the like.

  The present invention can be widely applied to the manufacturing industry of MEMS inertial sensors.

It is explanatory drawing explaining the basic concept of this invention. It is a top view which shows an example of the inertial sensor in Embodiment 1 of this invention. FIG. 3 is a cross-sectional view taken along line x1-x1 in FIG. FIG. 9 is a plan view showing an example of an inertial sensor in a modification of the first embodiment. It is a circuit diagram which shows the excitation circuit in an inertial sensor. It is a circuit diagram which shows the amplitude detection circuit (monitor circuit) in the excitation direction of an inertial sensor. It is a top view which shows an example of the inertial sensor which the present inventors examined. FIG. 9 is a plan view showing an example of an inertial sensor in a modification of the first embodiment. It is a figure which shows the basic composition of the inertial sensor which provided multiple excitation direction acceleration detection parts. It is explanatory drawing which shows an example of the detection circuit in an inertial sensor. 6 is a plan view showing an example of an inertial sensor in a second embodiment. FIG. It is explanatory drawing which shows the example which applied the inertial sensor in Embodiment 3 to the skid prevention apparatus of a motor vehicle. It is explanatory drawing which shows an example of the inertial sensor which the present inventors examined.

Explanation of symbols

1A, 1C Inertial sensor 2 Substrate 2a Support substrate 2b Insulating layer 2c Active layer 3 Mass part 5 Excitation element 6 Excitation means 6a Movable electrode 6b Fixed electrode 7 Excitation direction amplitude monitor means 7a Fixed electrode 7b Movable electrode 8 Excitation direction acceleration detection part 8a Fixed electrode 8b Movable electrode 8c Fixed part 8-1, 8-2 Excitation direction acceleration detector 8-1a, 8-2a Fixed electrode 8-1b, 8-2b Movable electrode 8-1c, 8-2c Fixed part 9 Excitation direction Acceleration servo means 9a Fixed electrode 9b Movable electrode 10 Excitation direction resonance frequency tuning means 10a Fixed electrode 10b Movable electrode 11 Coriolis element 12 Detection element 13 (13-1 to 13-4) Detection means 13a Fixed electrode 13b Movable electrode 14 Angular velocity servo means 14a Fixed electrode 14b Movable electrode 15 Detecting direction acceleration servo means 15a Fixed electricity Electrode 15b Movable electrode 16 Detection direction resonance frequency tuning means 16a Fixed electrode 16b Movable electrode 17a-17g Beam 18a-18m Supporting part 19 Electrode 20 Element 25 Elastic body 26 Supporting part 30 Vehicle 31 Control unit 32 Steering 33 Serpentine angle sensor 34 Tire 35 Rotation sensor 36 Brake 500 Mass part 501 Beam 502 Support part 503 Excitation part 504 Detection part W Outer peripheral wall SUA1, SUA2 Sensor unit MCP Sealing cap

Claims (20)

A substrate having a main surface;
A first excitation element connected to the substrate via a first elastic body having higher rigidity in a second direction intersecting the first direction than rigidity in a first direction parallel to the main surface;
A first Coriolis element connected to the first excitation element via a second elastic body whose rigidity in the second direction is lower than the rigidity in the first direction;
A first excitation unit that vibrates the first excitation element in the first direction;
A second excitation element connected to the substrate via a third elastic body having a rigidity in the second direction higher than the rigidity in the first direction;
A second Coriolis element connected to the second excitation element via a fourth elastic body having a rigidity in the second direction lower than the rigidity in the first direction;
A second excitation unit that vibrates the second excitation element in the first direction;
An excitation direction acceleration detector connected to the first excitation element via a fifth elastic body and connected to the second excitation element via a sixth elastic body,
The first excitation unit and the second excitation unit vibrate the first excitation element and the second excitation element in mutually opposite phases in the first direction ,
The excitation direction acceleration detection unit includes a displacement based on the vibration of the first excitation element in the first direction by the first excitation unit, and the second excitation element in the first direction by the second excitation unit. Placed at a position where the displacement based on vibration cancels,
The excitation direction acceleration detecting unit is a displacement amount based on the acceleration in the first direction applied from the outside, and calculates a displacement amount in the first phase of the first excitation element and the second excitation element in the first direction. by detecting, inertial sensor characterized that you detect the acceleration in the first direction. The inertial sensor according to claim 1 ,
The excitation direction acceleration detecting unit is formed of a capacitive element arranged in a comb shape, and detects an acceleration in the first direction based on a capacitance change of the capacitive element. The inertial sensor according to claim 1,
The first excitation unit and the second excitation unit are formed of capacitive elements arranged in a comb-teeth shape, and the first excitation element and the second excitation element are arranged based on electrostatic attraction applied to the capacitive element. An inertial sensor that vibrates in the first direction. The inertial sensor according to claim 1,
The inertial sensor according to claim 1, wherein a plurality of the excitation direction acceleration detectors are formed. The inertial sensor according to claim 1,
An inertial sensor, wherein an elastic body connecting the first excitation element and the second excitation element is fixed to the substrate. The inertial sensor according to claim 1,
An inertial sensor, wherein an elastic body connecting the first excitation element and the second excitation element is not fixed to the substrate. The inertial sensor according to claim 1,
A first detection unit for detecting a displacement amount in the second direction based on vibration in the second direction of the first Coriolis element;
An inertial sensor comprising: a second detection unit configured to detect a displacement amount in the second direction based on vibration of the second Coriolis element in the second direction. The inertial sensor according to claim 7 ,
The first detection unit and the second detection unit are formed of capacitive elements arranged in a comb shape, and detect a displacement amount in the second direction based on a capacitance change of the capacitive element. Inertial sensor. The inertial sensor according to claim 7 ,
An angular velocity and an acceleration in the second direction are detected based on the displacement amount in the second direction detected by the first detection unit and the displacement amount in the second direction detected by the second detection unit. An inertial sensor characterized by that. The inertial sensor according to claim 1,
A first detection element connected to the first Coriolis element and vibrating in the second direction in phase with the vibration of the first Coriolis element in the second direction;
A first detection unit that detects a displacement amount in the second direction based on vibration of the first detection element in the second direction;
A second sensing element connected to the second Coriolis element and oscillating in the second direction in phase with the vibration of the second Coriolis element in the second direction;
An inertial sensor comprising: a second detection unit configured to detect a displacement amount in the second direction based on vibration of the second detection element in the second direction. The inertial sensor according to claim 10 ,
The first detection unit and the second detection unit are formed of capacitive elements arranged in a comb shape, and detect a displacement amount in the second direction based on a capacitance change of the capacitive element. Sensor. The inertial sensor according to claim 10 ,
An angular velocity and an acceleration in the second direction are detected based on the displacement amount in the second direction detected by the first detection unit and the displacement amount in the second direction detected by the second detection unit. An inertial sensor characterized by that. The inertial sensor according to claim 1,
The inertial sensor, wherein the substrate is an SOI substrate. The inertial sensor according to claim 1,
The first excitation element, the first Coriolis element, the first excitation part, the second excitation element, the second Coriolis element, and the second excitation part are made of conductive silicon, conductive polysilicon, or metal. An inertial sensor characterized by A substrate having a main surface;
A first excitation element connected to the substrate via a first elastic body having higher rigidity in a second direction intersecting the first direction than rigidity in a first direction parallel to the main surface;
A first Coriolis element connected to the first excitation element via a second elastic body whose rigidity in the second direction is lower than the rigidity in the first direction;
A first excitation unit that vibrates the first excitation element in the first direction;
A first structure that vibrates in phase with the first excitation element;
A second excitation element connected to the substrate via a third elastic body having a rigidity in the second direction higher than the rigidity in the first direction;
A second Coriolis element connected to the second excitation element via a fourth elastic body having a rigidity in the second direction lower than the rigidity in the first direction;
A second excitation unit that vibrates the second excitation element in the first direction;
A second structure that vibrates in phase with the second excitation element;
An excitation direction acceleration detector connected between the first structure and the second structure,
The first excitation unit and the second excitation unit vibrate the first excitation element and the second excitation element in mutually opposite phases in the first direction ,
The excitation direction acceleration detection unit includes a displacement based on the first structure that vibrates in the same phase as a vibration of the first excitation element in the first direction by the first excitation unit, and the second excitation unit The second excitation element is disposed at a position where the displacement based on the second structure that vibrates in the same phase as the vibration in the first direction cancels.
The excitation direction acceleration detection unit is a displacement amount based on the acceleration in the first direction applied from the outside, and the displacement amount in the same phase in the first direction of the first structure body and the second structure body. by detecting, inertial sensor characterized that you detect the acceleration in the first direction. The inertial sensor according to claim 15 ,
The excitation direction acceleration detecting unit is formed of a capacitive element arranged in a comb shape, and detects an acceleration in the first direction based on a capacitance change of the capacitive element. A substrate having a main surface;
A first excitation element connected to the substrate via a first elastic body having higher rigidity in a second direction intersecting the first direction than rigidity in a first direction parallel to the main surface;
A first Coriolis element connected to the first excitation element via a second elastic body whose rigidity in the second direction is lower than the rigidity in the first direction;
A first excitation unit that vibrates the first excitation element in the first direction;
A second excitation element connected to the substrate via a third elastic body having a rigidity in the second direction higher than the rigidity in the first direction;
A second Coriolis element connected to the second excitation element via a fourth elastic body having a rigidity in the second direction lower than the rigidity in the first direction;
A second excitation unit that vibrates the second excitation element in the first direction;
An excitation direction acceleration detector for detecting the acceleration in the first direction,
The first excitation element and the second excitation element are connected via an elastic body,
The first excitation unit and the second excitation unit vibrate the first excitation element and the second excitation element in mutually opposite phases in the first direction,
The excitation direction acceleration detection unit is connected to a node of the elastic body ,
The node of the elastic body includes the displacement of the elastic body based on the vibration of the first excitation element in the first direction by the first excitation unit, and the first excitation element of the second excitation element by the second excitation unit. A position where the displacement of the elastic body based on vibration in a direction cancels,
The excitation direction acceleration detecting unit is a displacement amount based on the acceleration in the first direction applied from the outside, and calculates a displacement amount in the first phase of the first excitation element and the second excitation element in the first direction. by detecting, inertial sensor characterized that you detect the acceleration in the first direction. The inertial sensor according to claim 17 ,
The inertial sensor according to claim 1, wherein the excitation direction acceleration detecting unit detects the acceleration in the first direction by detecting that the position of the node of the elastic body is displaced in the first direction. The inertial sensor according to claim 18 , wherein
The excitation direction acceleration detecting unit is formed of a capacitive element arranged in a comb shape, and detects an acceleration in the first direction based on a capacitance change of the capacitive element. The inertial sensor according to claim 1,
The excitation direction acceleration detection unit detects an acceleration in the first direction by detecting a displacement amount of the same phase in the first direction of the first excitation element and the second excitation element,
Furthermore, the inertial sensor includes:
A first detector that detects a displacement amount in the second direction based on vibration of the first Coriolis element in the second direction;
A second detector that detects a displacement amount in the second direction based on vibration in the second direction of the second Coriolis element;
Detecting an angular velocity based on a difference between the displacement amount in the second direction detected by the first detection unit and the displacement amount in the second direction detected by the second detection unit;
The acceleration in the second direction is detected based on the addition of the displacement amount in the second direction detected by the first detection unit and the displacement amount in the second direction detected by the second detection unit. An inertial sensor characterized by that.

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