JP5800759B2 - Angular acceleration detection device and detection method - Google Patents

Description

  The present invention relates to an angular acceleration detection device and a detection method.

  Conventionally, as an angular acceleration detection device, an angular acceleration that detects angular acceleration around an axis perpendicular to a plane from a difference between outputs from two acceleration sensors arranged at a distance on one plane of a moving body. A detection device is known (see, for example, Patent Document 1).

  Conventionally, as an acceleration sensor, a capacitance-type acceleration sensor that detects an applied acceleration based on a change in capacitance in the sensor caused by the action of acceleration is also known. Further, in this capacitance type acceleration sensor, there has been proposed one that uses this acceleration sensor as a servo type in order to improve detection resolution and prevent malfunction or damage due to contact between the movable electrode and the substrate ( For example, see Patent Document 2). That is, due to the acceleration acting on the servo-type acceleration sensor, the movable electrode in the sensor is twisted around the torsion beam, and the static electrode between the left and right sides of the movable electrode centering on the torsion beam and each drive electrode. An imbalance occurs in the capacity. The unbalance amount is fed back, a voltage corresponding to the unbalance amount is applied to the drive electrode, and the torsion of the movable electrode is returned to the position of the displacement 0 by the electrostatic force generated between the movable electrode and the drive electrode. To do. The applied acceleration is determined based on the applied voltage to the drive electrode for returning to the position of zero displacement at this time.

JP-A-62-70766 International Publication No. WO2003 / 044539

In the servo acceleration sensor described above, the magnitude of the electrostatic force generated between the movable electrode and the drive electrode is proportional to the square of the voltage applied to the drive electrode. Therefore, when obtaining the acceleration acting based on the voltage applied to the drive electrode, a multiplication circuit for calculating the square of the voltage value is required.
In an arithmetic processing circuit, in general, a multiplication process such as a square operation has a larger circuit scale than an addition process and a subtraction process. For example, if the scale of the addition and subtraction circuit between n-bit numeric values is 1, the scale of the multiplication circuit between the numeric values is approximately the square of n. Therefore, when the angular acceleration detecting device is configured by using the two servo acceleration sensors described above, one multiplication circuit is required for each acceleration sensor, and a total of two are required. Therefore, there is a problem that the circuit scale is generally increased.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an angular acceleration detection device and a detection method capable of reducing the circuit scale as compared with the prior art.

In order to achieve the above object, the present invention is configured as follows.
That is, the angular acceleration detection device according to one aspect of the present invention is arranged with respect to a line segment that is arranged at a distance from one plane of a rotatable structure and that has acceleration detection directions parallel to each other and connecting the arrangement positions. An angular acceleration detection device comprising a pair of sensors arranged orthogonally and an arithmetic processing circuit electrically connected to these sensors, wherein each of the sensors is movable so as to be displaced by the action of acceleration. A driving electrode that is arranged opposite to the electrode and the movable electrode and that drives the movable electrode by an electrostatic force generated between the movable electrode by applying a voltage, and a detection unit that detects displacement of the movable electrode caused by the action of acceleration And a servo control unit for applying a servo voltage for driving the movable electrode to a predetermined position in accordance with the displacement of the movable electrode detected by the detection unit. Calculating the sum and difference of the servo voltage the servo control unit of the record is applied to the drive electrodes, by multiplying the resulting sum value and the difference value is output as the angular acceleration, and wherein the.

  According to the angular acceleration detection device of one aspect of the present invention, the sensor includes a pair of sensors and an arithmetic processing circuit, and the arithmetic processing circuit calculates the sum and difference of the servo voltages applied to the drive electrodes by the servo control unit of each sensor. The sum value obtained by the calculation and the difference value are multiplied and output as angular acceleration. Therefore, the arithmetic processing circuit has one multiplication circuit, and can reduce the number of multiplication circuits and reduce the scale of the arithmetic processing circuit as compared with the conventional circuit. As a result, it is possible to reduce the size and energy of the angular acceleration detection device.

It is a figure which shows the structure of the angular acceleration detection apparatus in Embodiment 1 of this invention. It is a block diagram which shows the function of the angular acceleration detection apparatus shown in FIG. It is a block diagram which shows the function of each servo type acceleration sensor shown in FIG. FIG. 3 is a plan view showing a sensor element structure of the servo acceleration sensor shown in FIG. 2. It is a top view which shows the structure except the displacement member from the sensor element structure shown in FIG. It is sectional drawing of the AA part shown in FIG. It is sectional drawing for demonstrating the electrostatic capacitance formed in the servo-type acceleration sensor shown in FIG. It is a figure which shows the structure of the capacity | capacitance-voltage conversion circuit shown in FIG. It is sectional drawing of a sensor element structure which shows the state which the acceleration of the positive direction acted on the servo-type acceleration sensor which comprises the angular acceleration detection apparatus shown in FIG. It is sectional drawing of a sensor element structure which shows the state which the acceleration of the positive direction acted on the servo-type acceleration sensor which comprises the angular acceleration detection apparatus shown in FIG. It is sectional drawing of the sensor element structure which shows the state which the acceleration of the positive direction and the electrostatic force acted on the servo-type acceleration sensor which comprises the angular acceleration detection apparatus shown in FIG. 2 is a graph showing a relationship between an applied acceleration and a voltage at which the displacement of a displacement member becomes zero in the servo acceleration sensor constituting the angular acceleration detection device shown in FIG. 1. 2 is a graph showing a relationship between applied acceleration and sensor output in the servo-type acceleration sensor constituting the angular acceleration detection device shown in FIG. 1. It is the figure which showed the force, ie, acceleration, which a servo type acceleration sensor receives when the angular acceleration detection apparatus shown in FIG. 1 rotates. It is a top view which shows the sensor element structure with which the servo-type acceleration sensor which comprises the angular acceleration detection apparatus in Embodiment 2 of this invention is equipped. It is sectional drawing of the BB part shown in FIG. It is sectional drawing for demonstrating the electrostatic capacitance formed with the servo type acceleration sensor shown in FIG. It is sectional drawing for demonstrating the electrostatic capacitance formed with the servo type acceleration sensor shown in FIG.

  An angular acceleration detection device and an angular acceleration detection method executed by the angular acceleration detection device according to an embodiment of the present invention will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

Embodiment 1 FIG.
The angular acceleration detection device according to Embodiment 1 of the present invention will be described below.
FIG. 1 is a diagram illustrating a configuration of an angular acceleration detection device 301 according to the first embodiment. The angular velocity detection device 301 includes two servo acceleration sensors 101 and 102 and an arithmetic processing circuit 201. The two servo-type acceleration sensors 101 and 102 are arranged at a distance R on a structure 103 that can rotate about the center of rotation, that is, capable of acting on acceleration, and is further separated from each other. These acceleration detection directions are parallel to each other, and are arranged orthogonal to a line segment 104 connecting each other position, for example, each center position. Here, the acceleration detection direction is indicated as a detection axis DA. In FIG. 1, the arithmetic processing circuit 201 is also arranged in the structure 103, but the arithmetic processing circuit 201 may be provided separately from the structure 103.

  A block diagram showing the functions of the angular acceleration detection device 301 is shown in FIG. In the servo-type acceleration sensors 101 and 102, as will be described in detail below, when the acceleration acts on the structure 103, the inertia mass bodies included in the servo-type acceleration sensors 101 and 102 are displaced. Each servo-type acceleration sensor 101, 102 outputs a voltage (servo voltage) for generating an electrostatic force necessary to return this displacement to a state where no acceleration is applied, that is, to a position of zero displacement. The arithmetic processing circuit 201 calculates the sum and difference of the servo voltage values, which are the outputs of the two servo acceleration sensors 101 and 102, and multiplies the sum value and the difference value. The operation of the arithmetic processing circuit 201 will be described in detail below.

  FIG. 3 is a block diagram showing the functions of the servo acceleration sensors 101 and 102 in the angular acceleration detection device 301 described above. Each servo acceleration sensor 101, 102 includes a sensor element structure 15, a capacitance-voltage conversion circuit 20, and a servo control circuit 30. Here, the capacitance-voltage conversion circuit 20 corresponds to an example that functions as a “detection unit”, and the servo control circuit 30 corresponds to an example that functions as a “servo control unit”. Further, since the servo type acceleration sensors 101 and 102 have the same configuration, FIG. 3 illustrates the servo type acceleration sensor 101 as an example, the sensor element structure 15 in the servo type acceleration sensor 102, and capacitance-voltage conversion. Illustration of the circuit 20 and the servo control circuit 30 is omitted.

  First, the sensor element structure 15 provided in the servo acceleration sensors 101 and 102 will be described with reference to FIGS. 4 and 5 are plan views of the sensor element structure 15, and FIGS. 6 and 7 are cross-sectional views taken along line AA of FIG.

  As shown in FIGS. 4 and 5, the sensor element structure 15 includes a substrate 1, an anchor 5 fixed on the substrate 1 via an insulator 9, and a displacement member 2 supported by the anchor 5. ing. The displacement member 2 includes a torsion beam 6, a detection frame 7, a link beam 4, and an inertia mass body 3. The torsion beam 6 is connected to the anchor 5 and can be twisted around the torsion axis 6a in the direction around the axis. The detection frame 7 is supported by the torsion beam 6 so as to be rotatable about the torsion shaft 6a. The link beam 4 is connected to the detection frame 7 at a position away from the torsion beam 6, and is displaced in the vertical direction with respect to the substrate 1 when acceleration is applied.

As shown in FIG. 6, the sensor element structure 15 further includes a pair of drive electrodes 11 a and 11 b and a pair of detection electrodes 8 a and 8 b on the insulator 9.
The drive electrodes 11a and 11b are provided so as to face the detection frame 7 with a distance d in the vertical direction which is the thickness direction of the substrate 1, and when the voltage is applied to the drive electrodes 11a and 11b, The detection frame 7 is driven by the electrostatic force generated during the period.
The detection electrodes 8 a and 8 b are provided so as to face the detection frame 7 with the gap d therebetween, and detect the displacement of the detection frame 7 as a change in capacitance between the detection electrodes 7 and the detection frame 7. In the first embodiment, the detection frame 7 corresponds to an example of performing the function of “movable electrode”.

  The sensor element structure 15 configured as described above is manufactured by a semiconductor microfabrication technique in which processes such as film formation, patterning, and etching on the substrate 1 are repeated, so-called MEMS (Micro Electro Mechanical Systems) device manufacturing technique.

  As the substrate 1, a silicon substrate or a glass substrate can be used. As the anchor 5, the torsion beam 6, the detection frame 7, the link beam 4, the inertia mass body 3, the drive electrodes 11a and 11b, and the detection electrodes 8a and 8b, a conductive polysilicon film can be used. This conductive polysilicon film desirably has low stress and no stress distribution. As the insulator 9, a silicon nitride film or a silicon oxide film can be used.

The anchor 5, the torsion beam 6, the detection frame 7, the link beam 4, and the inertia mass body 3 are electrically connected so as to have an equipotential. The substrate 1, the drive electrodes 11a and 11b, and the detection electrodes 8a and 8b are not electrically connected to any part of the anchor 5, the torsion beam 6, the detection frame 7, the link beam 4, and the inertia mass body 3.
In the use of the servo acceleration sensors 101 and 102, the sensor element structure 15 and the capacitance − are used for converting the capacitance into a voltage and applying a voltage to the electrodes 11a, 11b, 8a, and 8b. The voltage conversion circuit 20 and the servo control circuit 30 are electrically connected. Although this electrical connection is not shown, it is possible to use a wiring pattern or a bonding wire on the substrate 1.

  FIG. 7 shows the capacitance formed by the servo acceleration sensors 101 and 102. As shown in FIG. 7, capacitances Cda and Cdb are formed between the detection electrodes 8a and 8b and the detection frame 7, respectively. Similarly, electrostatic capacitances Csa and Csb are formed between the drive electrodes 11a and 11b and the detection frame 7, respectively.

Next, the capacitance-voltage conversion circuit 20 provided in the servo acceleration sensors 101 and 102 will be described with reference to FIG.
The capacitance-voltage conversion circuit 20 outputs a voltage corresponding to the difference when there is a difference in the capacitances Cda, Cdb between the connected detection electrodes 8a, 8b and the detection frame 7. Here, as shown in FIG. 8, the capacitances Cda and Cdb are connected in series. A constant potential Vd is applied to one end of the capacitance Cda, and one end of the capacitance Cdb is grounded. In addition, a terminal is provided at a connection portion between the electrostatic capacitance Cda and the electrostatic capacitance Cdb. The output potential Vout of this terminal is expressed by the following equation (1).

  When the detection frame 7 is rotationally displaced about the torsion shaft 6a, the capacitances Cda and Cdb change so that their directions of increase and decrease are different from each other. That is, due to the rotational displacement, the capacitance Cdb decreases if the capacitance Cda increases, and the capacitance Cdb increases if the capacitance Cda decreases. In a region where the displacement of the detection frame 7 is sufficiently small relative to the distance between the detection electrodes 8a and 8b and the detection frame 7, the capacitance (Cda + Cdb) is constant and the capacitance (Cda−Cdb) is displaced. Since it changes in proportion, the capacitance-voltage conversion circuit 20 can obtain the output potential Vout according to the rotational displacement of the detection frame 7.

Next, the servo control circuit 30 provided in the servo acceleration sensors 101 and 102 will be described.
In FIG. 3, the servo control circuit 30 selects which of the drive electrodes 11 a and 11 b the voltage is applied by the switch 32 according to the output level of the capacitance-voltage conversion circuit 20, and the sensor element structure 15. A voltage is applied to the drive electrode 11a or the drive electrode 11b. That is, the servo control circuit 30 applies to the drive electrode 11b when the output potential Vout of the capacitance-voltage conversion circuit 20 is larger than (Vd / 2), and when the output potential Vout is smaller than (Vd / 2). A voltage is applied to the driving electrode 11a to return the displacement of the detection frame 7 to the position of the displacement 0, that is, the state of the detection frame 7 when acceleration is not acting.

The operation of the servo acceleration sensors 101 and 102 configured as described above will be described below with reference to FIGS. 9 to 11 show a state where the acceleration in the positive direction 401 is applied to the servo acceleration sensors 101 and 102. FIG.
When the acceleration G in the positive direction 401 is applied to the servo acceleration sensors 101 and 102, the inertial mass body 3 is displaced in a direction away from the substrate 1 receiving the inertial force Fi (negative direction 402) as shown in FIG. To do. At this time, the link beam 4 is displaced in the negative direction 402 together with the inertia mass body 3. The detection frame 7 receives a force in the negative direction 402 due to the displacement of the link beam 4, and is rotationally displaced about the torsion shaft 6 a so as to balance the restoring force due to the deformation of the link beam 4 and the torsion beam 6. Due to this rotational displacement, the distance between the detection frame 7 and the detection electrodes 8a and 8b changes, the capacitance Cda decreases, and the capacitance Cdb increases. The capacitance-voltage conversion circuit 20 detects the displacement of the detection frame 7 based on changes in the capacitances Cda and Cdb.

  Here, when the voltage Vs11a is applied to the drive electrode 11a, an electrostatic force Fs11a is generated as shown in FIG. The electrostatic force Fs11a is expressed by the following equation (2) using the applied voltage Vs11a, the interval d, and the area S11 where the drive electrode 11a faces the detection frame 7. Here, ε is a dielectric constant.

Since the generated electrostatic force Fs11a can be changed by changing the applied voltage Vs11a, the applied voltage Vs11a can be controlled so that the displacement of the detection frame 7 becomes zero. Here, an applied voltage for setting the displacement of the detection frame 7 to 0 is V11a, and an electrostatic force generated at this time is F11a. The applied voltage V11a is a monotone function with respect to the displacement of the detection frame 7, and the displacement of the detection frame 7 is a monotone function with respect to the applied acceleration. Therefore, the applied voltage V11a is uniquely determined for the applied acceleration.
As shown in FIG. 11, the detection frame 7 is rotated by the electrostatic force F11a in a direction in which the rotational displacement of the detection frame 7 about the torsion shaft 6a is restored. As a result, the detection frame 7 is displaced to a position where the electrostatic force F11a, the restoring force of the link beam 4 and the torsion beam 6, and the inertial force Fi are balanced, and the displacement returns to zero.

  The displacement of the inertial mass body 3 caused by the applied acceleration is proportional to the applied acceleration, and the restoring force due to the deformation of the link beam 4 and the torsion beam 6 is proportional to the displacement of the inertial mass body 3, so that The electrostatic force F11a necessary for returning is proportional to the applied acceleration.

  FIG. 12 is a diagram showing the relationship between the applied acceleration G and the voltage V11a that makes the displacement caused by the applied acceleration zero. In FIG. 12, the horizontal axis indicates the acceleration acting on the acceleration sensor, and the vertical axis indicates the applied voltage for setting the displacement to zero. With reference to the above equation (2), since the magnitude of the electrostatic force is proportional to the square of the applied voltage when the distance d is constant, the applied acceleration G and the application that makes the displacement zero. The relationship with the voltage V11a is expressed as the following equation (3), and the square of the applied voltage is proportional to the acceleration G.

Similarly, when acceleration in the negative direction 402 is applied to the servo acceleration sensors 101 and 102, the switch 32 applies the voltage V11b to the drive electrode 11b instead of the drive electrode 11a, so that the detection frame 7 is displaced. Can be set to zero. The square of the applied voltage is proportional to the magnitude of acceleration.
Further, as described above, the direction (positive, negative) of the applied acceleration can be known as positive if the output Vout of the capacitance-voltage conversion circuit 20 is larger than (Vd / 2), and negative if smaller.

  In the angular acceleration detection device 301 of the first embodiment, the servo acceleration sensors 101 and 102 output voltages to be applied to the drive electrodes 11a and 11b in order to return the detection frame 7 to the position of displacement 0, but the acceleration is positive. When applied in the direction 401, the applied voltage V11a is output, and when the acceleration is applied in the negative direction 402, the applied voltage V11b is inverted in sign and output as -V11b. That is, the output V of the servo acceleration sensors 101 and 102 is expressed by the following equation (4).

  FIG. 13 is a diagram illustrating the relationship between the applied acceleration and the outputs of the servo acceleration sensors 101 and 102. In FIG. 13, the horizontal axis indicates the acceleration acting on the servo acceleration sensors 101 and 102, and the vertical axis indicates the output of the servo acceleration sensors 101 and 102. The two servo acceleration sensors 101 and 102 respectively output voltages V1 and V2 according to the acceleration acting in the detection axis direction, that is, the force.

Next, the operation of the angular acceleration detection device 301 of Embodiment 1 will be described below.
FIG. 14 is a diagram showing the force, that is, the acceleration received by the servo-type acceleration sensors 101 and 102 when the angular acceleration detection device 301 of the first embodiment rotates around the rotation center O.
When the angular acceleration detection device 301 shown in FIGS. 1 and 2 rotates with a change in angular velocity about a rotation center O with a rotation axis RA as a vertical direction with respect to the paper surface as shown in FIG. As shown in FIG. 14, each of the type acceleration sensors 101 and 102 receives a centrifugal force due to the rotation of the angular velocity Ω and a force Fc accompanying the angular acceleration ∂Ω / ∂t. Centrifugal force is generated in the radial direction of rotation (501, 502), and the force accompanying the angular velocity is generated in the circumferential direction of rotation (601, 602). The centrifugal force Fr1 caused by rotation and the force Fc1 caused by angular acceleration received by the servo acceleration sensor 101 are expressed by the following equations (5) and (6). Here, as shown in FIG. 14, R1 is a distance from the rotation center O to the servo acceleration sensor 101, and θ1 is an angle formed by the sensor detection axis and a line segment connecting the rotation center O and the sensor. .

  Since the centrifugal force Fr1 and the force Fc1 associated with the angular acceleration are forces in the radial direction and the circumferential direction, respectively, the servo acceleration sensor 101 can detect the sum of the detected axial direction components of these forces. . That is, from the drawing shown in FIG. 14, the cos θ1 component can be detected for the centrifugal force Fr1, and the sin θ1 component can be detected for the force Fc1 accompanying the angular acceleration. Therefore, the force F1 that the servo acceleration sensor 101 receives in the detection axis direction is expressed by the following equation (7).

  Similarly, the force F2 that the servo acceleration sensor 102 receives in the detection axis direction is expressed by the following equation (8). Here, R2 is a distance from the rotation center O to the servo acceleration sensor 102, and θ2 is an angle formed by a detection axis of the servo acceleration sensor 102 and a line segment connecting the rotation center O and the sensor.

  The inertial mass bodies 3 of the servo acceleration sensors 101 and 102 are displaced by the force F received in the detection axis direction, and the two servo acceleration sensors 101 and 102 output a voltage V1 and a voltage V2, respectively. Based on equation (3), there is a relationship of the following equations (9) and (10).

  Here, if the proportionality constant is set as k, these equations are expressed as the following equations (11) and (12).

  Here, considering the product of the sum of the applied voltage V1 and the applied voltage V2, which are the output voltages of the two servo acceleration sensors 101 and 102, and the difference between the applied voltage V1 and the applied voltage V2, Equation (13) is obtained.

を用いれば、次の（１６）式を得る。 Further, as is clear from FIG. 14, the relationship between the distances R, R1, and R2 expressed by the following equations (14) and (15):

Is used, the following equation (16) is obtained.

であり、

を得る。即ち、２つのサーボ型加速度センサ１０１，１０２が出力する各印加電圧値から回転の角加速度に応じた出力を得ることができる。 If you arrange both sides and set a new constant C,

And

Get. That is, an output corresponding to the angular acceleration of rotation can be obtained from the applied voltage values output from the two servo acceleration sensors 101 and 102.

  Here, focusing on the number of multiplication processes for calculating the angular acceleration, according to the angular acceleration detection apparatus 301 of the first embodiment, the multiplication process is performed once. In the conventional method, the multiplication processing is performed twice, and the angular acceleration detection device 301 of the first embodiment can reduce the number of multiplication circuits and reduce the circuit scale of the arithmetic processing as compared with the conventional method.

  Such a portion that calculates the product of the sum of the applied voltage V1 and the applied voltage V2, which are output voltages of the servo acceleration sensors 101 and 102, and the difference between the applied voltage V1 and the applied voltage V2, This is an arithmetic processing circuit 201 shown in FIG.

  In the angular acceleration detection device 301, the inertial mass body 3 can be displaced by electrostatic force generated by applying a voltage to the drive electrodes 11a and 11b even when no acceleration is applied. It is also possible to self-diagnose whether or not the structure 15 is destroyed.

  Also, the angular velocity of rotation can be obtained by integrating the output of the angular acceleration detection device 301 of the first embodiment.

  In the first embodiment, the capacitance-voltage conversion circuit 20 is used to convert the difference in capacitance formed between the detection frame 7 and the detection electrodes 8a and 8b into a voltage, thereby changing the displacement of the detection frame 7. Although what is detected is shown, this does not depend on the circuit method, the detection method, or the like if a signal corresponding to the displacement is obtained.

Embodiment 2. FIG.
Next, an angular acceleration detection device 302 according to Embodiment 2 of the present invention will be described below with reference to FIGS. 15 to 18.
The angular acceleration detection device 302 according to the second embodiment has a configuration in which the structure of the sensor element structure 15 in the servo acceleration sensors 101 and 102 described above is different, and the other capacitance-voltage conversion circuit 20 and servo control. The configurations of the circuit 30, the analog-digital conversion circuit 40, and the arithmetic processing circuit 201 are the same as those of the angular acceleration detection device 301. Therefore, only the sensor element structure part which is a different part will be described below.

That is, FIG. 15 shows a plan view of the sensor element structure 15-2 of the angular acceleration detection device 302 of the second embodiment, and FIG. 16 shows a cross-section of the BB section shown in FIG. Has been.
As shown in FIG. 15, the sensor element structure 15-2 of the angular acceleration detection device 302 according to the second embodiment includes a substrate 1, an anchor 5 fixed to the substrate 1 via an insulator 9, and an anchor 5 And a displacement member 2 supported by the. The displacement member 2 includes a support beam 56 and an inertial mass body 3.

The support beam 56 is connected to the anchor 5. The inertial mass body 3 is supported by the support beam 56, and is displaced in the in-plane direction with respect to the substrate 1 by the action of acceleration.
The inertial mass body 3 has a plurality of movable electrode portions 12. In the second embodiment, the movable electrode portion 12 functions as a “movable electrode”.
On the substrate 1, drive electrodes 11 a and 11 b and detection electrodes 8 a and 8 b are provided in a comb shape so as to face the movable electrode portion 12.
15 and 16, the electrodes are shown separately for the sake of drawing, but the electrodes indicated by the same hatching are formed by a wiring pattern (not shown) provided on the substrate 1. Are connected so as to be electrically equipotential.

  FIGS. 17 and 18 show the respective capacitances formed between the drive electrodes 11 a and 11 b and the detection electrodes 8 a and 8 b and the movable electrode portion 12. That is, also in the sensor element structure 15-2 of the second embodiment, as shown in FIG. 17, the electrostatic capacitance Cda, between the detection electrodes 8a and 8b and the movable electrode portion 12, as in the first embodiment. As shown in FIG. 18, capacitances Csa and Csb are formed between the drive electrodes 11a and 11b and the movable electrode portion 12, respectively.

  Also in the angular acceleration detection device 302 having the sensor element structure 15-2 having the above-described configuration, the angular acceleration can be detected in the same manner as the angular acceleration detection device 301 of the first embodiment, and arithmetic processing is performed. Since the circuit 201 is provided, it is possible to reduce the number of multiplication circuits and reduce the circuit scale of arithmetic processing.

  In the angular acceleration detection device 302 of the second embodiment, the drive electrodes 11a and 11b are arranged outside the detection electrodes 8a and 8b. However, the detection electrodes 8a and 8b and the drive electrodes 11a and 11b are movable electrodes. Any position and arrangement may be used as long as an electrostatic capacity can be formed between the drive electrode 11a and 11b and the movable electrode portion 12 by forming an electrostatic capacitance between the drive electrode 11a and 11b. The displacement member 2 only needs to be able to detect in-plane acceleration relative to the substrate 1 in accordance with the applied acceleration, and does not depend on the form of the support beam 56 or the method of supporting the inertial mass body 3.

7 detection frame, 11a, 11b drive electrode, 12 movable electrode part,
15, 15-2 sensor element structure,
20 capacity-voltage conversion circuit, 30 servo control circuit,
101, 102 servo type acceleration sensor, 201 arithmetic processing circuit,
301, 302 Angular acceleration detection device.

Claims (2)

A pair of sensors arranged at a distance on one plane of the rotatable structure and arranged in a direction perpendicular to a line segment in which the acceleration detection directions are parallel to each other and connect each other; An angular acceleration detection device comprising an arithmetic processing circuit electrically connected to a sensor,
Each of the above sensors
A movable electrode that is displaced by the action of acceleration;
A drive electrode that is disposed opposite to the movable electrode and drives the movable electrode by an electrostatic force generated between the movable electrode and the application of voltage;
A detector that detects displacement of the movable electrode caused by the action of acceleration;
A servo control unit that applies a servo voltage for driving the movable electrode to a predetermined position in accordance with the displacement of the movable electrode detected by the detection unit, to the drive electrode;
The arithmetic processing circuit is
Each servo control unit calculates the sum and difference of each servo voltage applied to the drive electrode, multiplies the obtained sum value and difference value, and outputs as angular acceleration,
An angular acceleration detection device characterized by that. A pair of sensors arranged at a distance on one plane of the rotatable structure and arranged in a direction perpendicular to a line segment in which the acceleration detection directions are parallel to each other and connect each other; An angular acceleration detection method executed by an angular acceleration detection device including an arithmetic processing circuit electrically connected to a sensor,
For each of the above sensors,
The displacement of the movable electrode due to the action of acceleration is detected by the detection unit, and a servo voltage for driving the movable electrode to a predetermined position according to the displacement of the movable electrode detected by the detection unit is applied from the servo control unit to the drive electrode,
In the above arithmetic processing circuit,
Each servo control unit calculates the sum and difference of each servo voltage applied to the drive electrode, multiplies the obtained sum value and difference value, and outputs as angular acceleration,
An angular acceleration detection method characterized by the above.

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