JP2006266984A - Vibrating gyroscope element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibrating gyroscope element provided with satisfactory sensitivity in detecting angular velocity and excellent in shock resistance. <P>SOLUTION: The vibrating gyroscope element 1 is provided in the same plane with a base part 11, a pair of detection vibrating arms 12 linearly extended to both sides from the base part 11, a pair of connecting arms 14 extended to both sides from the base part 11 in directions intersecting with the detection vibrating arms 12 at right angles, and a pair of drive vibrating arms 16 extended to both sides from a tip part of each connecting arm 14 in directions of intersecting with it at right angles and has groove parts 20 each in one main surfaces and the other main surfaces of at least the detection vibrating arms 12. A terminal 25 of the groove part 20 positioned on the side of the base part 11 of the detection vibrating arm 12 is arranged on a line connecting points (b) of change in the arm width of the detection vibrating arm 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vibrating gyro element having a groove on a vibrating arm.

In recent years, gyro sensors that detect angular velocities are often used for camera shake correction of imaging devices and attitude control of mobile navigation systems such as vehicles using GPS satellite signals.
As a vibrating gyro element constituting the gyro sensor, for example, a so-called double T-type vibrating gyro element in which a substantially T-shaped driving vibration system is arranged symmetrically with respect to a central detection vibration system is known. This double T-type vibrating gyro element is substantially composed of a supporting arm having a thickness in the Z-axis direction and extending from the base to both sides in the X-axis direction and a driving vibrating arm extending from the supporting arm in the Y-axis direction. A T-shaped drive vibration system and a detection vibration system extending from the base in the Y-axis direction are provided.
Then, when rotation about the Z-axis occurs, the Coriolis force generated in the drive vibration arm that performs bending vibration in the X-axis direction is transmitted to the detection vibration arm via the support arm and the base, and in the X-axis direction. The configuration is such that the angular velocity is recognized by detecting the distortion of the vibrating vibrating arm.

Such a vibration gyro element has a configuration in which grooves are provided on one main surface and the other main surface of the drive vibration arm and the detection vibration arm of each vibration gyro element to increase the electric field efficiency of each vibration arm and to reduce the size of the vibration gyro element. It has been proposed (see Patent Document 1).
In Patent Document 1, in order to improve the sensitivity of the vibration gyro element, the optimum groove position in the detection vibration mode (vibration on the XY plane) is considered, and the terminal position of the groove provided on each vibration arm is determined. It is supposed to be arranged at a position of 5% or more of the arm width from the base of the base.

JP 2004-245605 A

  However, by providing such a groove in each vibrating arm to reduce the size, the rigidity of each vibrating arm is lowered. However, as the use of gyro sensors in portable devices has expanded, the falling of portable devices, etc. There is an urgent need to improve the impact resistance of the vibrating gyro element so that it can withstand the impact force.

For evaluation of impact resistance, usually, an impact force such as dropping is applied in the X, Y, and Z axis directions of the vibration gyro element, and the fluctuation of the frequency and the destruction (breaking) of the vibrating arm are investigated. . In particular, the destruction of the vibrating arm greatly depends on the force in the Z-axis direction applied to the vibrating gyro element. Further, the detection vibrating arm tends to be destroyed rather than the driving vibrating arm with respect to the force in the Z-axis direction. This is because the drive vibration arm is connected from the fixed base via the connection arm, and the support arm acts as a buffer even when a force in the Z-axis direction is applied, while the detection vibration arm is directly connected to the base. Because it is susceptible to impact force.
Thus, in order to improve the impact resistance of the vibration gyro element, it is necessary to examine the strength of the detection vibration arm when a force is applied in the Z-axis direction.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vibration gyro element having a good angular velocity detection sensitivity and excellent impact resistance.

  In order to solve the above problems, in the present invention, a base, a pair of detection vibrating arms linearly extending from the base to both sides, and extending from the base to both sides in a direction perpendicular to the detection vibrating arms. A pair of connected connecting arms and a pair of driving vibrating arms extending from the front end portion of each connecting arm to both sides perpendicularly to the connecting arms, on at least one of the detecting vibrating arms A vibration gyro element having a groove on each of the principal surface and the other principal surface, wherein a terminal end of the groove located on the base side of the detection vibration arm is on a line connecting a change point of the arm width of the detection vibration arm It is characterized by being arranged in.

According to the configuration in which the end of the groove located on the base side of the detection vibrating arm is arranged on a line connecting the change points of the arm width of the detection vibrating arm, when a force in the Z-axis direction is applied to the detection vibrating arm, Compared to the case where the groove is arranged at another position, the stress received by the detection vibrating arm is small, the occurrence of breakage can be reduced, and a vibration gyro element having excellent impact resistance can be obtained.
Further, the distortion of the detection vibrating arm in the detection of the angular velocity becomes maximum near the base of the detection vibrating arm connected to the base, and it is desirable to detect the distortion of this part. According to the present invention, the groove portion can be formed near the base of the detection vibration arm having a large strain, and a large strain can be detected by providing the detection electrodes on the side surface of the detection vibration arm and the wall surface of the groove portion. From this, it is possible to provide a vibrating gyro element having a good angular velocity detection sensitivity.

  In the vibrating gyro element of the present invention, a weight portion may be formed at the tip of the detection vibrating arm.

  In this case, by providing a weight at the tip of the detection vibrating arm, the amplitude of the detection vibrating arm is increased to prevent a decrease in angular velocity detection sensitivity associated with downsizing of the vibrating gyro element. On the other hand, when an impact force is applied to the detection vibration arm in the Z-axis direction due to dropping or the like, a greater force is applied to the detection vibration arm due to the inertial force of the weight portion than in the configuration in which the weight portion is not provided. . Even in such a case, the stress received by the detection vibrating arm is smaller than when the groove portion is arranged at another position, the occurrence of breakage can be reduced, and a vibration gyro element having excellent impact resistance can be obtained. Can do.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
(First embodiment)

FIG. 1 is a schematic plan view showing the configuration of the vibrating gyro element of this embodiment. FIG. 2 is an enlarged plan view of the detection vibrating arm. 3 is a cross-sectional view taken along the line AA in FIG.
In FIG. 1, a vibrating gyro element 1 is made of quartz that is a piezoelectric material. Quartz has an X axis called an electric axis, a Y axis called a mechanical axis, and a Z axis called an optical axis. The vibrating gyro element 1 has a predetermined thickness in the Z-axis direction, and is formed by etching from a quartz plate having main surfaces of the front and back XY planes.

  The vibrating gyro element 1 includes a pair of detection vibrating arms 12 that linearly extend from the base 11 to both the upper and lower sides (Y-axis direction) in the drawing, and the left and right in the drawing in a direction perpendicular to the detection vibrating arm 12 from the base 11. A pair of connecting arms 14 extending in both sides (X-axis direction) and a pair of left and right extending in the upper and lower sides (Y-axis direction) in the figure in parallel with the detection vibrating arm 12 from the tip of each connecting arm 14 Drive vibration arm 16.

A weight portion 17 is provided at each tip of the drive vibration arm 16, and a groove portion 21 is formed in the drive vibration arm 16. Similarly, a weight portion 13 is provided at each tip of the detection vibrating arm 12, and a groove portion 20 is formed in the detection vibrating arm 12.
By providing weight portions 17 and 13 at the distal ends of the drive vibration arm 16 and the detection vibration arm 12, respectively, the amplitudes of the drive vibration arm 16 and the detection vibration arm 12 are increased, and the angular velocity accompanying the downsizing of the vibration gyro element 1 is achieved. This prevents a decrease in detection sensitivity.

The detection vibrating arm 12 will be described in detail with reference to FIGS.
In FIG. 2, the detection vibrating arm 12 is connected to the base portion 11 via a connecting portion 22 whose arm width increases as it approaches the base portion 11, and similarly connected to the weight portion 13 via a connecting portion 23. The detection vibrating arm 12 is a name including the connecting portions 22 and 23.

A groove portion 20 is formed in the detection vibrating arm 12, and a terminal end 25 of the groove portion 20 is disposed on the line BB connecting the arm width change point b on the base portion 11 side. The BB line connecting the arm width change points b includes a range of ± 3 μm from the BB line in consideration of manufacturing variations.
Further, as shown in FIG. 3, the groove 20 is provided on one main surface (front surface) and the other main surface (back surface) of the detection vibrating arm 12.

A detection electrode (not shown) is formed on the detection vibration arm 12, and a drive electrode (not shown) is formed on the drive vibration arm 16.
The arrangement of the detection electrode and the drive electrode is not limited. For example, the detection electrode is provided so as to face the side surface of the detection vibrating arm 12 and the wall surface of the groove portion 20, and the side surface of the drive vibration arm 16 and the wall surface of the groove portion 21 are provided. Drive electrodes are provided so as to face each other.
In this way, the detection vibration arm 12 constitutes a detection vibration system that detects the angular velocity, and the connecting arm 14 and the drive vibration arm 16 constitute a drive vibration system that drives the vibration gyro element 1.
Note that the vibrating gyro element 1 supports the base 11 to detect the angular velocity around the Z axis.

Next, the detection operation of the angular velocity in the vibration gyro element 1 having such a configuration will be briefly described.
The drive vibration arm 16 is driven by applying an alternating voltage to the drive electrode, and the drive vibration arm 16 performs bending vibration on the XY plane. When an angular velocity about the Z axis is applied in this state, a Coriolis force is applied to the drive vibrating arm 16, and the detection vibrating arm 12 performs flexural vibration on the XY plane in response to the Coriolis force. The detection electrode can detect the distortion generated in the detection vibration arm 12 due to the bending vibration, and the angular velocity can be recognized.

Next, in the vibration gyro element 1 as described above, the process of reaching the above-described arrangement of the groove 20 formed in the detection vibration arm 12 will be described.
When a force is applied to the detection vibrating arm 12 in the Z-axis direction, a large stress is applied in the vicinity of the connecting portion 22 that connects the base 11 and the detection vibrating arm 12, and the detection vibrating arm 12 is also broken from this portion. ing. The inventor considered that the magnitude of the stress generated in the detection vibrating arm 12 is changed by changing the arrangement of the groove 20 formed in the vicinity of the connecting portion 22.

For this reason, an analysis model as shown in FIG. 4 was constructed, and stress analysis was performed by the finite element method when the position of the groove was changed.
FIG. 4 shows an example of an analysis model. The analysis model includes a base 30, a vibrating arm 31 extending from the base 30, and a weight portion 32 provided at the tip of the vibrating arm 31. Grooves 33 are provided on the front and back sides.

  As an analysis condition, one surface 35 of the base portion 30 is a fixed surface (displacement in the X, Y, and Z-axis directions is 0), and a force F in the Z-axis direction is applied to the tip of the weight portion 32. The displacement is constant. At this time, the maximum stress applied to the vibrating arm 31 when the arrangement of the terminal end 34 of the groove 33 was changed with respect to the line BB connecting the arm width changing point b of the vibrating arm 31 was compared.

FIG. 5 is an explanatory diagram comparing types 1 to 5 in the arrangement of the groove 33 of the vibrating arm 31 and the maximum stress applied to the vibrating arm 31 of each type.
In the type 1 analysis model, the end 34 of the groove 33 is disposed at a position 20 μm away from the base 30 with respect to the line BB connecting the change points of the arm width of the vibrating arm 31.
In the type 2 analysis model, the end 34 of the groove 33 is arranged on the line BB connecting the changing points of the arm width of the vibrating arm 31.
In the type 3 analysis model, the end 34 of the groove 33 is disposed at the middle position of the boundary line where the base 30 and the vibrating arm 31 are connected to the line B-B connecting the changing points of the arm width of the vibrating arm 31.
In the type 4 analysis model, the end 34 of the groove 33 is arranged at the boundary where the base 30 and the vibrating arm 31 are connected.
In the type 5 analysis model, the end 34 of the groove 33 is disposed at a position 20 μm from the boundary where the base 30 and the vibrating arm 31 are connected to the center of the base.

  When the maximum stress applied to the vibrating arm 31 in each of the types 1 to 5 was compared, the maximum stress in the type 1 was the largest and the maximum stress in the type 2 was the smallest. That is, in the comparison of types 1 to 5 of this analysis model, when an equivalent force is applied to the vibrating arm 31 in the Z direction, the vibrating arm 31 of the type 1 is most easily broken and the vibrating arm 31 of the type 2 is most broken. It turns out that it is hard to be done.

  As described above, since the terminal end 25 of the groove portion 20 located on the base 11 side of the detection vibrating arm 12 is arranged on the line BB connecting the change point b of the arm width of the detection vibrating arm 12, the detection vibration is detected. When a force in the Z-axis direction is applied to the arm 12, the stress received by the detection vibrating arm 12 is smaller than when a groove is disposed at another position, and the occurrence of breakage can be reduced, resulting in improved shock resistance. An excellent vibration gyro element 1 can be obtained.

  In particular, in the vibrating gyro element 1 having the weight 13 at the tip of the detection vibrating arm 12, when the impact force is applied to the detection vibrating arm 12 in the Z-axis direction due to dropping or the like, the weight 13 is not provided. As compared with the above, a large force acts on the detection vibrating arm 12 due to the inertial force of the weight portion 13. When a large force is exerted in the Z-axis direction due to such an inertial force, the stress received by the detection vibrating arm 12 is smaller than when the groove is disposed at another position, and the impact resistance of the vibrating gyro element 1 is improved. Is big.

Further, according to the present embodiment, the groove portion 20 can be formed near the base of the detection vibration arm 12 having a large strain. By providing the detection electrode on the side surface of the detection vibration arm 12 and the wall surface of the groove portion 20, Can be detected. From this, it is possible to provide the vibrating gyro element 1 having good angular velocity detection sensitivity.
(Second Embodiment)

FIG. 6 is a schematic plan view showing the configuration of the vibrating gyro element in the second embodiment.
In this embodiment, a weight portion is not provided on each vibrating arm of the vibrating gyro element 1 shown in the first embodiment, and a similar angular velocity detecting operation is performed.

In FIG. 6, the vibrating gyro element 2 includes a pair of detection vibrating arms 42 linearly extending from the base 41 to both the upper and lower sides (Y-axis direction) in the figure, and a direction orthogonal to the detection vibrating arms 42 from the base 41. A pair of connecting arms 44 extending to the left and right sides (X-axis direction) in the drawing, and left and right extending to the upper and lower sides (Y-axis direction) in the drawing parallel to the detection vibrating arm 42 from the tip of each connecting arm 44 And a pair of drive vibrating arms 46.
Further, a groove 52 is formed in the drive vibration arm 46 along the length direction of the drive vibration arm 46, and a groove 50 is formed in the detection vibration arm 42 along the length direction of the detection vibration arm 42. Yes.

The detection vibrating arm 42 will be described in detail with reference to FIG.
In FIG. 7, the detection vibrating arm 42 is connected to the base portion 41 via a connecting portion 53 whose arm width increases as it approaches the base portion 41. The detection vibrating arm 42 is a name including the connecting portion 53.

A groove portion 50 is formed in the detection vibrating arm 42, and a terminal end 55 of the groove portion 50 is disposed on the line CC connecting the arm width change point c. The CC line connecting the arm width change points c includes a range of ± 3 μm from the CC line in consideration of manufacturing variations.
The groove 50 is provided on one main surface (front surface) and the other main surface (back surface) of the detection vibrating arm 12.

The detection vibrating arm 42 is formed with a detection electrode (not shown), and the driving vibration arm 46 is formed with a driving electrode (not shown).
The arrangement of the detection electrode and the drive electrode is not limited. For example, the detection electrode is provided so as to face the side surface of the detection vibrating arm 42 and the wall surface of the groove portion 50, and the side surface of the drive vibration arm 46 and the wall surface of the groove portion 52 are provided. Drive electrodes are provided so as to face each other.
Thus, the detection vibration system that detects the angular velocity is configured by the detection vibration arm 42, and the drive vibration system that drives the vibration gyro element 2 is configured by the connecting arm 44 and the drive vibration arm 46.
Note that the vibration gyro element 2 supports the base 41 to detect the angular velocity.

In the vibrating gyro element 2 having the above-described configuration, five types of analysis models in which the position of the groove portion 50 in the detection vibrating arm 42 is changed are configured in the same manner as described in the first embodiment, and similar analysis is performed. Stress analysis by finite element method was performed under the conditions. This analysis model has a configuration in which each type of weight portion 32 shown in FIG. 5 is not provided, and the arm width of the vibrating arm 31 extends to the tip thereof.
When the results of the maximum stress applied to the vibrating arm are compared, the maximum stress in the type (corresponding to type 1 in FIG. 5) in which the end of the groove is located farther from the base than the line connecting the change points of the arm width is the highest. The result that the maximum stress was the smallest in the type (corresponding to type 2 in FIG. 5) in which the end of the groove portion was arranged on the line connecting the arm width change points was obtained.

  As described above, since the terminal end 55 of the groove 50 located on the base 41 side of the detection vibrating arm 42 is arranged on the line CC connecting the arm width change point c of the detection vibrating arm 42, the detection vibration is detected. When a force in the Z-axis direction is applied to the arm 42, the stress received by the detection vibrating arm 42 is smaller than when the groove portion 50 is disposed at another position, and the occurrence of breakage can be reduced. Can be obtained.

  Further, according to the present embodiment, the groove portion 50 can be formed near the base of the detection vibration arm 42 having a large strain. By providing the detection electrodes on the side surface of the detection vibration arm 42 and the wall surface of the groove portion 50, Can be detected. From this, it is possible to provide the vibrating gyro element 2 having good angular velocity detection sensitivity.

  The shape of the groove provided on the detection vibrating arm can be arbitrarily set. For example, the groove end can be formed in an arc shape, or the corner of the groove end can be chamfered.

Further, as a material for the vibration gyro element of the present invention, in addition to quartz, gallium phosphate (GaPO ₄ ), lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), langasite (La ₃ Ga ₅ SiO _14). ) Or a constant elastic material typified by an eriba material.

FIG. 3 is a schematic plan view showing the configuration of the vibrating gyro element in the first embodiment. The enlarged plan view of a detection vibrating arm. Sectional drawing of a detection vibrating arm. The perspective view which shows an analysis model. Explanatory drawing which compares and shows a stress analysis result. The schematic plan view which shows the structure of the vibration gyro element in 2nd Embodiment. The enlarged plan view of a detection vibrating arm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Vibration gyro element, 11 ... Base part, 12 ... Detection vibration arm, 13 ... Weight part, 14 ... Connection arm, 16 ... Drive vibration arm, 17 ... Weight part, 20 ... Groove part of detection vibration arm, 21 ... Drive Groove part of vibration arm, 22 ... connection part on base side, 23 ... connection part on weight side, 25 ... terminal end of groove part, 41 ... base part, 42 ... detection vibration arm, 44 ... connection arm, 46 ... drive vibration arm, 50 ... Detection vibration arm groove 52. Drive vibration arm groove 55. End of groove, b and c Arm width change point.

Claims (2)

The base,
A pair of detection vibrating arms linearly extending from the base to both sides;
A pair of connecting arms extending from the base to both sides in a direction perpendicular to the detection vibrating arm;
A pair of drive vibrating arms extending from the front end of each of the connecting arms to both sides orthogonally to it, and provided on the same plane,
A vibration gyro element having at least one groove on each of the principal surface and the other principal surface of the detection vibration arm,
The vibrating gyro element according to claim 1, wherein an end of the groove located on the base side of the detection vibrating arm is arranged on a line connecting a change point of an arm width of the detection vibrating arm. The vibrating gyro element according to claim 1,
A vibrating gyro element in which a weight is formed at the tip of the detection vibrating arm.

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