JP2008039614A - Sensor for acceleration and angular velocity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the detection precision of the acceleration (G) and the angular velocity (Yaw) by inhibiting the deformation other than the direction of deformation of detection electrode relating to the sensor for acceleration and angular velocity, by detecting the displacement of the first and second oscillators moving based on the Coriolis force with the first and second detector electrodes. <P>SOLUTION: The sensor for acceleration and angular velocity constituted moveable to driving direction (Y1 and Y2) and detection direction (X1 and X2) comprises: the first and second oscillators 11 and 12 arranged oppositely and symmetrically; the first and second driving electrodes 13 and 14 for driving each oscillator 11 and 12 for making oscillate in the driving direction; and the first and second detection electrode 15 and 16 for detecting the movement of the first and second oscillator 11 and 12 in the detection direction as a static capacitance change. The first and second detection electrodes 15 and 16 are separately arranged outside of the first and second oscillators 11 and 12, and also the first and second detection spring 18 and 19 for movably supporting the first and second detection electrode 15 and 16 in a detection direction are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an acceleration angular velocity sensor, and more particularly to an acceleration angular velocity sensor that detects acceleration and angular velocity by detecting displacements of first and second vibrators that are displaced based on Coriolis force with first and second detection electrodes. .

2. Description of the Related Art Conventionally, as an in-vehicle sensor, an acceleration sensor that detects a vehicle acceleration (G) and an angular velocity sensor that detects an angular velocity (Yaw) of the vehicle are known. In recent years, an acceleration angular velocity sensor that can detect both acceleration and angular velocity of a vehicle with a single sensor has also been provided (see Patent Document 1).

  FIG. 7 shows an acceleration angular velocity sensor 50 which is a conventional example. The acceleration angular velocity sensor 50 includes first and second vibrators 51 and 52, first and second drive electrodes 53 and 54, first and second detection electrodes 55 and 56, and the like.

  The first vibrator 51 is connected to the first main frame 63 via the first detection spring 58. Further, the second vibrator 52 is connected to the second main frame 64 via the second detection spring 59. The first vibrator 51 and the second vibrator 52 are separated and are configured independently of each other. The first and second detection springs 58 and 59 support the first and second vibrators 51 and 52 so that they can be displaced in the directions of arrows X1 and X2 (referred to as detection directions) in the drawing.

  The first detection spring 58 is provided on the first main frame 63, and the first main frame 63 is disposed up and down in the drawing with the first vibrator 51 interposed therebetween. Further, the first main frame 63 can be displaced in the directions of arrows Y1 and Y2 (referred to as drive directions) by the first drive spring 60. Further, the first main frame 63 is configured to be oscillated and biased in the directions of arrows Y1 and Y2 by the first drive electrode 53.

  The second detection spring 59 is provided on the second main frame 64, and the second main frame 64 is disposed up and down in the drawing with the second vibrator 52 interposed therebetween. The second main frame 64 can be displaced in the directions of the arrows Y1 and Y2 by the second drive spring 61. Further, the second main frame 64 is configured to be oscillated and biased in the directions of the arrows Y1 and Y2 by the second drive electrode 54.

  The first detection electrode 55 is disposed inside the first vibrator 51, and the second detection electrode 56 is disposed inside the second vibrator 52. The first and second detection electrodes 55 and 56 are configured to be able to detect displacement of the first and second vibrators 51 and 52 as capacitance change.

  The detection principle of the acceleration (G) and angular velocity (Yaw) of the acceleration angular velocity sensor 50 having the above-described configuration will be described. In order to detect the acceleration (G) and the angular velocity (Yaw) using the acceleration angular velocity sensor 50, the first and second main frames 63 and 64 and the first and second main frames 63 and 64 by the first and second drive electrodes 53 and 54, respectively. The first and second vibrators 51 and 52 are vibrated in the Y1 and Y2 directions (driving directions) via the second detection springs 58 and 59.

  When acceleration (G) is applied to the acceleration angular velocity sensor 50 in this state, inertial force is generated in the first and second vibrators 51 and 52, and the first and second vibrations are generated as shown in FIG. The children 51 and 52 are displaced in the same phase in the X1 and X2 directions (detection direction). Therefore, the acceleration (G) can be obtained by taking the sum of the detection signal detected by the first detection electrode 55 and the detection signal detected by the second detection electrode 56.

On the other hand, when an angular velocity (Yaw) is applied to the acceleration angular velocity sensor 50 in the above-described vibration state, a Coriolis force is generated in the first and second vibrators 51 and 52 in this case. As shown in FIG. 9, the first and second vibrators 51 and 52 are displaced in the opposite phases in the X1 and X2 directions (detection directions). Therefore, the angular velocity (Yaw) can be obtained by taking the difference between the detection signal detected by the first detection electrode 55 and the detection signal detected by the second detection electrode 56.
JP 2004-28869 A

  However, in the conventional acceleration angular velocity sensor 50, the first detection electrode 55 and the first drive electrode 53 are mechanically connected via the first detection spring 58, and the second detection electrode 56 and the second detection electrode 56 are connected to each other. Since the second drive electrode 54 is also mechanically connected via the second detection spring 59, the displacement of the vibrators 51 and 52 in the Y1 and Y2 directions (drive direction) also leaks to the detection electrodes 55 and 56. As a result, there is a possibility that detection signal noise of acceleration (G) and angular velocity (Yaw) may increase.

  In addition, when the upper and lower drive springs 60 and 61 have dimensional variations due to manufacturing variations, as shown in FIG. A difference occurs between the force generated in the drive spring 60 and the force generated in the lower drive spring 60 (shown as a difference in the length of the arrow indicating the force).

  This difference in force acts as a force for rotating the second detection electrode 56, so that the second detection electrode 56 is displaced in a direction other than the displacement direction (X 1, X 2 direction), which also causes acceleration ( G) and angular velocity (Yaw) detection signal noise may increase.

  The present invention has been made in view of the above points, and an acceleration angular velocity sensor that reduces detection signal noise of acceleration (G) and angular velocity (Yaw) by suppressing displacement other than the displacement direction of the detection electrode is provided. The purpose is to provide.

  In order to solve the above-described problems, the present invention is characterized by the following measures.

The invention described in claim 1
First and second vibrators that are configured to be displaceable in the driving direction and the detection direction, and that are opposed to each other so as to be symmetrical with each other;
First and second driving units for vibrating the first and second vibrators in a driving direction;
In an acceleration angular velocity sensor having first and second detection electrodes for detecting displacement of the first and second vibrators in the detection direction as capacitance changes,
The first and second detection electrodes are arranged separately from the first and second vibrators, and the first and second detection electrodes are supported to be displaceable in the detection direction. A member is provided.

The invention according to claim 2
The acceleration angular velocity sensor according to claim 1,
The first and second vibrators and the first and second detection electrodes buffer displacement in the driving direction of the first and second vibrators and detect the first and second vibrators. It is connected by the connection spring which transmits the displacement of a direction to the said 1st and 2nd detection electrode.

The invention according to claim 3
The acceleration angular velocity sensor according to claim 1 or 2,
A spring member for connecting the first detection electrode and the second detection electrode in the driving direction is provided.

  According to the present invention, the first and second detection electrodes are disposed separately from the first and second vibrators, and the first and second detection electrodes are detected by the support member. Therefore, the vibration in the driving direction of the first and second vibrators can be prevented from being applied to the first and second detection electrodes, and the detection signal noise of acceleration and angular velocity can be prevented. Can be reduced.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an acceleration angular velocity sensor 10 according to an embodiment of the present invention. The acceleration angular velocity sensor 10 includes first and second vibrators 11 and 12, first and second drive electrodes 13 and 14, first and second detection electrodes 15 and 16, a link spring 38, and the like. It is configured.

  The first vibrator 11 is configured to be held movably in the directions of arrows Y1 and Y2 by a pair of first drive springs 20 disposed on both left and right sides (both sides in the Y1 and Y2 directions). ing. Further, the first drive electrode 13 is connected to the first drive spring 20 located on the left side in the drawing among the pair of first drive springs 20. The first drive electrode 13 has a function of driving the first vibrator 11 in the directions of arrows Y1 and Y2 in the figure (hereinafter, the Y1 and Y2 directions are referred to as drive directions).

  The second vibrator 12 is held by a pair of second drive springs 21 disposed on the left and right side portions (both sides in the Y1 and Y2 directions) so as to be movable in the drive direction (arrow Y1 and Y2 directions). It is set as the structure.

  The second drive electrode 14 is connected to the second drive spring 21 located on the right side in the drawing among the pair of second drive springs 21. The second drive electrode 14 has a function of driving the second vibrator 12 in the drive direction (arrow Y1, Y2 direction in the figure). The first vibrator 11 and the second vibrator 12 are separated from each other and are configured independently of each other.

  The first detection electrode 15 is separated from the first vibrator 11. A pair of the first detection electrodes 15 are disposed so as to sandwich the first vibrator 11 from the X1 and X2 directions in the figure (hereinafter, the X1 and X2 directions are referred to as detection directions).

  The pair of first detection springs 18 are disposed so as to sandwich the first detection electrode 15 from the detection direction (X1, X2 direction), and support the first detection electrode 15. Further, both end portions of each first detection spring 18 are fixed to anchors 45 disposed on the substrate 30.

  The first detection electrode 15 is configured to be displaceable in the detection direction (X1, X2 direction) because the first detection spring 18 is elastically deformed. FIG. 2 shows a state where the first detection electrode 15 is displaced in the arrow X1 direction.

  As described above, both ends of the first detection spring 18 are fixed to the substrate 30 by the anchor 45, and the first detection electrode 15 is disposed at the center position of the first detection spring 18. Therefore, when an external force in the direction of arrow X1 (Coriolis force described later) acts on the first detection electrode 15, the first detection spring 15 is elastically deformed as shown in FIG. Displacement in the direction of arrow X1. The first detection electrode 15 is provided with a comb electrode (not shown), and the displacement of the first detection electrode 15 is detected as a capacitance change between the comb electrodes.

  The first detection electrode 15 having the above configuration is connected to the first vibrator 11 by the first connection spring 40. As shown in an enlarged view in FIG. 3, the first connection spring 40 is configured to be inserted into a recess formed in the first vibrator 11. The first connection spring 40 is configured to be easily elastically deformed in the driving direction (Y1, Y2 direction), but is not configured to be deformed in the detection direction (X1, X2 direction).

  Therefore, when the first vibrator 11 is displaced in the driving direction (Y1, Y2 direction), the first detection electrode 15 is not displaced, but the first vibrator 11 is in the detection direction (X1, X2 direction). Is displaced to the first detection electrode 15 via the first connection spring 40, and the first detection electrode 15 is also displaced in the detection direction (X1, X2 direction).

  The second detection electrode 16 is also separated from the second vibrator 12. The arrangement structure of the second detection electrode 16 and the second vibrator 12 is basically the same as the arrangement structure of the first detection electrode 15 and the first vibrator 11 described above.

  That is, a pair of second detection electrodes 16 are arranged so as to sandwich the second vibrator 12 from the detection direction, and a pair of second detection springs 19 connect the second detection electrode 16 in the detection direction. And the second detection electrode 16 is supported. Further, both ends of each second detection spring 19 are fixed to the anchor 45.

  The second detection electrode 16 is configured to be displaceable in the detection direction because the second detection spring 19 is elastically deformed. Therefore, when an external force in the detection direction acts on the second detection electrode 16, the second detection spring 19 is elastically deformed, so that the second detection electrode 16 is displaced in the detection direction. The second detection electrode 16 is also provided with a comb electrode, and the displacement is detected as a change in capacitance between the comb electrodes.

  Further, the second detection electrode 16 is connected to the first vibrator 11 by a second connection spring 41. The second connection spring 41 has the same action as the first connection spring 40 described above. That is, the second connection spring 41 is inserted into a recess formed in the second vibrator 12, and is easily elastically deformed in the driving direction (Y1, Y2 direction). However, it is set as the structure which does not deform | transform with respect to a detection direction (X1, X2 direction).

  Therefore, when the second vibrator 12 is displaced in the driving direction (Y1, Y2 direction), the second detection electrode 16 is not displaced, but the second vibrator 12 is in the detection direction (X1, X2 direction). Is displaced to the second detection electrode 16 via the second connection spring 41, and the second detection electrode 16 is also displaced in the detection direction (X1, X2 direction).

  In order to detect acceleration (G) and angular velocity (Yaw) using the acceleration angular velocity sensor 10 having the above-described configuration, the first and second vibrators 11, 14 are driven by the first and second drive electrodes 13, 14. 12 is vibrated in the driving direction (Y1, Y2 direction). When acceleration (G) is applied to the acceleration angular velocity sensor 10 in this state, inertial force is generated in the first and second vibrators 11 and 12, and the first and second vibrators 11 and 12 are detected. Displacement in the same direction (X1, X2 direction).

  As described above, the first and second detection electrodes 15 and 16 are not displaced when the first and second vibrators 11 and 12 are displaced in the driving direction, but when they are displaced in the detection direction. Is displaced via the first connection springs 40, 41. Therefore, the acceleration (G) can be obtained by taking the sum of the detection signal detected by the first detection electrode 15 and the detection signal detected by the second detection electrode 16.

  On the other hand, when an angular velocity (Yaw) is applied to the acceleration angular velocity sensor 10 in the above-described vibration state, a Coriolis force is generated in the first and second vibrators 11 and 12 in this case, and the first and second The vibrators 11 and 12 are displaced in the detection direction (X1 and X2 directions) in reverse phase. Therefore, the angular velocity (Yaw) can be obtained by taking the difference between the detection signal detected by the first detection electrode 15 and the detection signal detected by the second detection electrode 16.

  In the configuration in which the detection electrodes 55 and 56 are disposed inside the vibrators 51 and 52 as in the conventional acceleration angular velocity sensor 50 described with reference to FIG. 7, the detection electrodes 55 and 56 are detected in the detection direction (X1, X2). (Displacement direction) as well as the drive direction (Y1, Y2 direction), there is a possibility that disturbance may enter the detection signal. However, in the acceleration angular velocity sensor 10 according to the present embodiment, since the detection electrodes 15 and 16 are disposed at positions outside the vibrators 11 and 12, the detection electrodes 15 and 16 are displaced in the driving direction (Y1, Y2 direction). It can be set as the structure which does not.

  Specifically, in this embodiment, the first vibrator 11 and the first detection electrode 15 are connected by the first connection spring 40, and the second vibrator 12 and the second detection electrode 16 are connected. Since the second connecting spring 41 is used for the connection, only the displacement in the detection direction (X1, X2 direction) of each vibrator 11, 12 is transmitted to the detection electrodes 35, 36, and the driving direction (Y1, Y2 direction). The displacement of can be cut off. As a result, the detection electrodes 15 and 16 can be displaced only in the detection direction, so that it is possible to detect the acceleration (G) and the angular velocity (Yaw) with high accuracy and little influence of disturbance.

  By the way, when acceleration (G) is applied to the acceleration angular velocity sensor 10, the first and second detection electrodes 15 and 16 are displaced in the X1 and X2 directions (detection direction) by the inertial force, and the angular velocity ( When Yaw) is applied, it is displaced in reverse phase by Coriolis force. Therefore, even if the acceleration angular velocity sensor 10 has a configuration in which the detection electrodes 15 and 16 are separated from the vibrators 11 and 12, if manufacturing variations occur in the detection electrodes 15 and 16 in the manufacturing process or the like, the manufacturing variations are caused. May be reflected in variations in the displacement of the detection electrodes 15 and 16 as they are.

  Therefore, in the acceleration angular velocity sensor 10 according to the present embodiment, the first detection electrode 15 and the second detection electrode 16 are connected by a connection link spring 38. The connection link spring 38 connects the first detection electrode 15 and the second detection electrode 16 in the driving direction (Y1, Y2 direction). It is arranged. The connecting link spring 25 is made of a leaf spring material.

  Next, the operation of the connecting link spring 38 when the acceleration angular velocity sensor 10 detects acceleration (G) and angular velocity (Yaw) will be described.

  When acceleration (G) is applied to the acceleration angular velocity sensor 10, inertial force is generated in the first and second vibrators 11 and 12 as described above, and the first and second vibrators 11 and 12 It is displaced in the same phase in the X1 and X2 directions (detection direction). At this time, since the detection electrodes 15 and 16 are also displaced in the X1 and X2 directions (detection directions) in the same phase, the connecting link spring 38 is not deformed.

  On the other hand, when an angular velocity (Yaw) is applied to the acceleration angular velocity sensor 10, a Coriolis force is generated in the first and second vibrators 11 and 12, and the first and second vibrators 11 and 12 have X1, Displacement in the opposite phase in the X2 direction (detection direction). As described above, when the first and second vibrators 11 and 12 are displaced in the opposite phase, the first and second detection electrodes 15 and 16 are also displaced in the opposite phase.

  Further, the first and second detection electrodes 15 and 16 are also displaced in opposite phases, so that the first detection springs 18 and 19 (the spring constant is K2) and the connection link spring 38 (the spring constant is K1). Will also deform. Therefore, the resonance frequency when detecting the angular velocity (Yaw) is determined by both the spring constant k of each of the detection springs 18 and 19 and the spring constant K of the connecting link spring 25.

  Therefore, in the acceleration angular velocity sensor 10 according to the present embodiment, the acceleration (G) is determined by the spring constant K2 of each detection spring 18 and 19, and the angular velocity (Yaw) is connected to the spring constant K2 of each detection spring 18 and 19. It is determined by both the spring constant K1 of the link spring 38. Therefore, by adjusting the spring constant K1 of the connecting link spring 38, it is possible to separate the resonance frequencies by the acceleration (G) and the angular velocity (Yaw), and to keep them away from each other. The acceleration (G) and the angular velocity (Yaw) Detection accuracy can be increased.

  In the acceleration angular velocity sensor 10 according to this embodiment, the spring constant K2 of the detection springs 18 and 19 is set to be larger than the spring constant K1 of the connecting link spring 38 (K2> K1). Hereinafter, the reason why the spring constants K1 and K2 are set in this way will be described.

  FIG. 4 shows an acceleration angular velocity sensor as a reference example, and shows an enlarged view of the vicinity of a connection spring 37 (corresponding to the connection link spring 38). The acceleration angular velocity sensor shown in the figure is configured such that the spring constant (K1) of the connecting spring 37 is set larger than the spring constant (K2) of the detection spring 18.19 (K1> K2).

When an angular velocity (Yaw) is applied to the acceleration angular velocity sensor configured as described above, a force F ₀ acts on the first and second detection electrodes 15 and 16 in opposite directions due to the Coriolis force. Accordingly, the connection spring 37 is elastically deformed, the elastic restoring force (shown in Figure 4 by the arrow F ₁₎ is generated and the connection spring 37 on the bonding position of the respective detection electrodes 15 and 16. As described above, when the force F ₁ partially acts on the position where each detection electrode 15, 16 is joined to the connecting spring 37, in other words, a part of each detection electrode 15, 16, Moment force M is generated.

  In the case of the reference example, the spring constant K2 of the detection springs 18 and 19 indicated by the arrow A1 is smaller than the spring constant K1 of the coupling spring 37 indicated by the arrow B1 (K1> K2). Thus, the detection electrodes 15 and 16 are rotationally displaced. Since the rotational displacements of the detection electrodes 15 and 16 are also detected as capacitance changes, the detection accuracy is lowered in the configuration of the reference example shown in FIG.

  On the other hand, when the spring constant K2 of the detection springs 18 and 19 is set larger than the spring constant K1 of the connecting link spring 38 (K2> K1) as in this embodiment, the detection electrodes 15 and 16 are displaced in opposite phases. Thus, even if the connecting spring 37 is elastically deformed as shown by an arrow B2 in FIG. 5 and a moment force M is generated at each of the detection electrodes 15, 16, the moment force M is applied to each of the detection springs as shown by an arrow A2. It can be pressed down with 18 and 19 spring force. Thereby, it is possible to suppress the rotation of the first and second detection electrodes 15 and 16 when the angular velocity (Yaw) is applied, and thus it is possible to prevent disturbance from being mixed into the output, thereby improving the detection accuracy. be able to.

  FIGS. 6A and 6B show the results of a simulation that demonstrates the effect of setting the spring constant K2 of the detection springs 18 and 19 to be larger than the spring constant K1 of the connecting link spring 38 (K2> K1). FIG. A model corresponding to the acceleration angular velocity sensor according to the present embodiment as shown in FIG. 6A is created, and the second detection electrode of the model when the angular velocity (Yaw) is applied to the acceleration angular velocity sensor is applied to this model. The displacement of the position shown to AD in 16 figures was simulated. The result is shown in FIG.

  In FIG. 6B, the horizontal axis indicates the length of the second detection spring 19, and the vertical axis indicates the displacement in the driving direction (X1, X2 direction). The length of the second detection spring 19 shown on the horizontal axis becomes easier to deform as the length becomes longer, and becomes difficult to deform as the length becomes shorter.

  Since both ends of the second detection spring 19 are fixed by anchors 45, the second detection spring 19 is equivalent to a leaf spring supported at both ends. Therefore, the spring constant decreases as the length of the second detection spring 19 increases (goes to the right side of the horizontal axis), and as the length of the second detection spring 19 decreases (to the left side of the horizontal axis). It can be considered that the spring constant has increased as we go. In the simulation, the connection link spring 38 was simulated without changing the characteristics.

  As shown in FIG. 6B, when the length (spring constant) of the second detection spring 19 is changed, the length of the second detection spring 19 is the same at any position of the second detection spring 19. It has been found that the displacement amount in the driving direction is smaller when the second detection spring 19 is shorter (larger spring constant) than when it is long (small spring constant). Therefore, from the simulation result of FIG. 6, the rotation (displacement) of the second detection electrode 16 can be prevented by making the spring constant K2 of the second detection spring 19 larger than the spring constant K1 of the connecting link spring 38. It was demonstrated that the detection accuracy of the acceleration angular velocity sensor can be improved.

FIG. 1 is a configuration diagram of an acceleration angular velocity sensor according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the vicinity of the first detection electrode of the acceleration angular velocity sensor which is an embodiment of the present invention. FIG. 3 is an enlarged view showing the vicinity of the first connection spring of the acceleration angular velocity sensor according to the embodiment of the present invention. FIG. 4 is a diagram for explaining a phenomenon that occurs due to a difference in spring constant between the detection spring and the coupling spring (part 1). FIG. 5 is a diagram for explaining a phenomenon that occurs due to a difference in spring constant between the detection spring and the coupling spring (part 2). FIG. 6 is a diagram for explaining the effect of the present invention. FIG. 7 is a configuration diagram of an acceleration angular velocity sensor as an example of the prior art. FIG. 8 is a diagram for explaining the operation of an acceleration angular velocity sensor as an example of the prior art (part 1). FIG. 9 is a diagram for explaining the operation of an acceleration angular velocity sensor which is a conventional example (part 2). FIG. 10 is a diagram for explaining a problem of a conventional acceleration angular velocity sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Acceleration angular velocity sensor 11 1st vibrator | oscillator 12 2nd vibrator | oscillator 13 1st drive electrode 14 2nd drive electrode 15 1st detection electrode 16 2nd detection electrode 18 1st detection spring 19 2nd Detection spring 20 First drive spring 21 Second drive spring 30 Substrate 37 Connection spring 38 Connection link spring 40 First connection spring 41 Second connection spring 45 Anchor

Claims (3)

First and second vibrators that are configured to be displaceable in the driving direction and the detection direction, and that are opposed to each other so as to be symmetrical with each other;
First and second driving units for vibrating the first and second vibrators in a driving direction;
In an acceleration angular velocity sensor having first and second detection electrodes for detecting displacement of the first and second vibrators in the detection direction as capacitance changes,
The first and second detection electrodes are arranged separately from the first and second vibrators, and the first and second detection electrodes are supported to be displaceable in the detection direction. An acceleration angular velocity sensor comprising a member.   The first and second vibrators and the first and second detection electrodes buffer displacement in the driving direction of the first and second vibrators and detect the first and second vibrators. 2. The acceleration angular velocity sensor according to claim 1, wherein the acceleration angular velocity sensor is connected by a connection spring that transmits a displacement in a direction to the first and second detection electrodes. The acceleration angular velocity sensor according to claim 1 or 2, further comprising a connecting spring member that connects the first detection electrode and the second detection electrode in the driving direction.

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