JP2009092430A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity sensor capable of bonding easily a vibrator body and weights to a support member, and bonding both members firmly. <P>SOLUTION: A pair of board-like weights 5 spreading in the X-axis direction and in the Y-axis direction are arranged on both ends in the X-axis direction of the vibrator body 3. Both ends in the Y-axis direction of each of the pair of weights 5 are supported on a base member 1 by four springy members 7, so that the vibrator body 3 can be moved in the three-dimensional directions. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an angular velocity sensor (gyroscope) that measures an angular velocity using a piezoelectric element.

  Japanese Patent Application Laid-Open No. 3-34613 (Patent Document 1) and the like describe first and third elongated vibrators, and first to third angular speeds which are respectively formed on a triangular prism surface of the vibrator to detect the angular velocity of the vibrator. An angular velocity sensor having a piezoelectric element and a support member that supports a vibrator body on a base member is shown. In this angular velocity sensor, the vibrator is vibrated in a direction orthogonal to the first piezoelectric element by a drive signal. When the vibrator rotates around the axis of the vibrator in this state, the vibration direction of the vibrator changes due to the Coriolis force. Therefore, an output difference is generated between the second and third piezoelectric elements. By measuring this output difference, the angular velocity of the vibrator is detected. In such an angular velocity sensor, in order to reduce the size of the device, it has been required to reduce the length of the vibrator. However, when the length of the vibrator is reduced, the resonance frequency of the vibrator is increased. For this reason, fluctuations occur during driving, and noise is likely to occur in the detection circuit.

Therefore, as shown in Japanese Patent Laid-Open No. 8-23258 (Patent Document 2), a pair of weights are respectively disposed at both ends of the vibrator in the longitudinal direction, and positioned between the pair of weights and the pair of weights. An angular velocity sensor that constitutes a vibrator from a vibrator main body has been proposed. By arranging a pair of weights in this way, the length dimension of the vibrator can be reduced without increasing the resonance frequency.
JP-A-3-34613 JP-A-8-23258

  However, in the conventional angular velocity sensor, when the width dimension of the vibrator main body located between the pair of weights is reduced, it becomes difficult to join the vibrator main body and the support member, and the vibrator main body is supported by the base member. It becomes difficult to let you. Further, the bonding between the vibrator main body and the support member may be weakened.

  An object of the present invention is to provide an angular velocity sensor in which a vibrator main body, a weight, and a support member can be easily joined, and both can be firmly joined.

  Still another object of the present invention is to provide an angular velocity sensor capable of reducing the thickness dimension (dimension in the Z-axis direction) of the vibrator body and the weight.

  Still another object of the present invention is to provide an angular velocity sensor that can reduce the stress against an external impact.

  Still another object of the present invention is to provide an angular velocity sensor that can be easily manufactured by simple processing.

  Still another object of the present invention is to provide an angular velocity sensor that can prevent the vibrator main body and the pair of weights from moving more than necessary and being damaged.

  The angular velocity sensor according to the present invention detects an angular velocity of the transducer body formed on the transducer body and an elongated transducer body extending in the X-axis direction, the Y-axis direction, and the Z-axis direction orthogonal to each other. A pair of piezoelectric elements, a pair of plate-shaped weights disposed at both ends of the vibrator body in the X-axis direction and extending in the X-axis direction and the Y-axis direction, and the vibrator body so as to move in a three-dimensional direction. And four spring-like members having spring properties for supporting both ends of each of the weights in the Y-axis direction on the base member. In the present invention, since both ends of the plate-shaped weight in the Y-axis direction are supported by the base member by the support member (spring-shaped member), two or more locations facing the weight in the Y-axis direction are connected to the spring-shaped member. Will be. Therefore, it is possible to easily and firmly join the vibrator main body and the weight and the spring-like member. Further, since the vibrator body is elongated and the weight has a plate shape, the thickness dimension (dimension in the Z-axis direction) of the vibrator body and the weight can be reduced. In order to support the weight on the base member, the shape and dimensions of the vibrator body and the pair of weights are set so that the node point (weight balance point) is located on the weight. The weight may be supported on the base member by a spring-like member in the vicinity.

  The spring-shaped member can employ various shapes. For example, in order to form a meandering pattern, four or more extending portions extending in the Y-axis direction, a connecting portion extending in the X-axis direction and connecting an end of the extending portion, and a connecting portion positioned in the center in the X-axis direction And a support extending portion that is connected at one end to the extending portion and extends in parallel with the extending portion. In this case, the extending portions at both ends in the X-axis direction of the spring-like member may be connected to the base member, and the other end of the supporting extending portion may be connected to the weight. In this way, the thickness dimension (dimension in the Z-axis direction) of the spring-like member can be reduced similarly to the vibrator main body and the weight. Further, since the extending portions at both ends in the X-axis direction of the spring-like member are connected to the base member, one spring-like member is connected to the base member at two locations. Therefore, the stress with respect to the impact from the outside of the angular velocity sensor can be reduced, and the strength of the angular velocity sensor can be increased.

  In such an angular velocity sensor, the vibrator body, the pair of weights, the four spring-like members, and the base member can be integrally formed by cutting a plate material whose thickness direction is the Z-axis direction. it can. In this way, the angular velocity sensor can be easily mass-produced only by cutting the plate material.

  When the base member has a frame shape surrounding the vibrator main body, the pair of weights, and the four spring-like members, the base member has the X-axis direction and Y It preferably has a size and shape that abuts the vibrator body and the pair of weights when moving in the axial direction and stops the movement of the vibrator body and the pair of weights. In this way, it is possible to prevent the vibrator body and the pair of weights from moving more than necessary in the X axis direction and the Y axis direction and being damaged. Such a structure can be easily formed by adjusting the cutting position of the plate material.

  According to the present invention, since both ends of the plate-shaped weight in the Y-axis direction are supported by the base member by the spring-shaped member, two or more locations facing the weight in the Y-axis direction are connected to the spring-shaped member. It will be. Therefore, it is possible to easily and firmly join the vibrator main body and the weight and the support member. Further, since the vibrator body is elongated and the weight has a plate shape, the thickness dimension (dimension in the Z-axis direction) of the vibrator body and the weight can be reduced. As a result, the vibrator body and the weight and the support member can be easily and firmly joined, and the angular velocity sensor can be downsized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a plan view of an angular velocity sensor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. As shown in each figure, the angular velocity sensor of this example has a base 1, a vibrator body 3, a pair of weights 5, and four support members (spring-like members) 7, and is made of silicon (Si). It is integrally formed. The base 1 has a rectangular frame shape surrounding the vibrator body 3, the pair of weights 5, and the four spring-like members 7. The vibrator body 3 has an elongated rod-like shape with a rectangular cross section extending in one direction (X-axis direction). 1 to 3 also show the X axis direction, the Y axis direction, and the Z axis direction orthogonal to each other. As shown in FIG. 4 (enlarged view of IV part in FIG. 1) and FIG. 5 (cross-sectional view taken along the line VV in FIG. 4), a piezoelectric element 9 is formed on one surface 3a of the vibrator body 3. Yes. For easy understanding, the thickness dimension of the piezoelectric element 9 is exaggerated in FIG. The piezoelectric element 9 has a lower electrode 11, a dielectric layer 13, and an upper electrode 15. The lower electrode 11 can be formed by, for example, a multilayer structure in which a Pt thin film layer is formed on a Ti thin film layer, or a multilayer structure in which an Ir thin film layer is formed on a Ti thin film layer. The dielectric layer 13 is formed on the lower electrode 11 and is made of lead zirconate titanate (PZT) and has a thickness of 2 μm. The upper electrode 15 is formed on the dielectric layer 13, for example, a multilayer structure in which a Pt thin film layer is formed on a Ti thin film layer, a multilayer structure in which an Ir thin film layer is formed on a Ti thin film layer, a Cr thin film A multilayer structure in which an Au thin film layer is formed on the layer or an Al thin film layer can be used. The upper electrode 15 has a central electrode 15A and two side electrodes 15B and 15C arranged in parallel in the X-axis direction. The two side electrodes 15B and 15C are arranged side by side on both sides of the center electrode 15A. The operation of the piezoelectric element 9 will be described in detail later.

  As shown in FIG. 1, the pair of weights 5 are respectively disposed at both ends in the longitudinal direction (X-axis direction) of the vibrator body 3. The pair of weights 5 has a rectangular plate shape that extends in the X-axis direction and a direction (Y-axis direction) orthogonal to the X-axis direction.

  The four spring-like members 7 support the ends of the pair of weights 5 in the Y-axis direction on the base member 1 so that the vibrator main body 3 moves in a three-dimensional direction. The four spring-like members 7 all have the same shape. As shown in FIG. 6, one spring-like member 7 has a meandering pattern shape, and has 28 extending portions 17, 27 connecting portions 19, and one support extending portion 21. ing. The extending portion 17 extends in the Y-axis direction. The connecting portion 19 extends in the X-axis direction and connects the ends of two adjacent extending portions 17 so that the spring-like member 7 forms a meandering pattern. The support extending portion 21 extends in parallel with the extending portion 17 with one end 21 a connected to the connecting portion 19 located in the center in the X-axis direction. End portions 17a of the extending portions 17 at both ends in the X-axis direction facing the base member 1 have a shape in which the width dimension (dimension in the X-axis direction) increases toward the base member 1. These end portions 17 a are connected to the base member 1. As a result, one spring-like member 7 is connected to the base member 1 at two locations. The other end 21 b of the support extending portion 21 has a shape in which the width dimension (dimension in the X-axis direction) increases toward the weight 5. The other end 21 b is connected to the weight 5. It should be noted that the vibrator body 3 and the pair of weights 5 are arranged such that the position connected to the support extension portion 21 of the weight 5 (the position connected to the other end 21 b) is the node of the vibrator body 3 and the pair of weights 5. The shape and dimensions are set so as to be in the vicinity of the point.

  In this example, the base 1, the vibrator body 3, the pair of weights 5, and the four spring-like members 7 are integrated by cutting a silicon (Si) plate material whose thickness direction is the Z-axis direction. Molded into.

  The angular velocity sensor of this example detects the angular velocity as follows. First, a voltage is applied between the center electrode 15A and the lower electrode 11 to vibrate the vibrator body 3 in the Z-axis direction. When the vibrator body 3 rotates around the X axis in this state, the vibration direction of the vibrator body 3 changes due to the Coriolis force. For this reason, an output difference is generated between the side electrode 15B and the side electrode 15C. By measuring this output difference, the angular velocity of the vibrator body 3 is detected.

  According to the angular velocity sensor of this example, since both ends of the plate-like weight 5 in the Y-axis direction are supported by the base member by the spring-like member 7, two or more locations facing the weight 5 in the Y-axis direction are springs. It will be connected to the shaped member 7. Therefore, the vibrator body 3 and the weight 5 and the spring-like member 7 can be joined easily and firmly after reducing the thickness dimension (dimension in the Z-axis direction) of the vibrator body 3 and the weight 5. Can do.

Next, the angular velocity sensor of this example in which one spring-like member is connected to the base member at two locations (hereinafter simply referred to as a two-point connection angular velocity sensor) and one spring-like member is connected to the base member at one location. The angular velocity sensor (hereinafter, simply referred to as a one-point connection angular velocity sensor) was manufactured, and the stress when an impact was applied to each angular velocity sensor was examined. In the one-point connection angular velocity sensor, the four spring-like members 107 have the shape shown in FIG. 7, and the rest has the same structure as the two-point connection angular velocity sensor shown in FIGS. The spring-like member 107 has approximately half the size of the spring-like member 7 of the two-point connection angular velocity sensor, and has 15 extending portions 117 and 14 connection portions 119. The end 117a of the extending portion 117 at one end in the X-axis direction that faces the base member 101 is connected to the base member 101, and the weight of the extending portion 117 at the other end in the X-axis direction. An end portion 117 b facing 105 is connected to the weight 105. Next, a 1 G impact was applied to each angular velocity sensor from the X-axis direction, the Y-axis direction, and the Z-axis direction, and the stress in each axial direction of each angular velocity sensor was measured. Table 1 shows the measurement results. In Table 1, the two-point connection angular velocity sensor is indicated as two points, and the one-point connection angular velocity sensor is indicated as one point.

  From Table 1, the two-point connection angular velocity sensor is more sensitive than the one-point connection angular velocity sensor in any axial direction of each angular velocity sensor, regardless of the X-axis direction, Y-axis direction, or Z-axis direction. It can be seen that the stress can be reduced.

  FIG. 8 is a plan view of an angular velocity sensor according to another embodiment of the present invention. The angular velocity sensor of this example has the same structure as the angular velocity sensor shown in FIGS. Therefore, portions having the same structure as the angular velocity sensor shown in FIGS. 1 to 6 are denoted by reference numerals obtained by adding 200 to the reference numerals attached to FIGS. 1 to 6 and description thereof is omitted. The base 201 of the angular velocity sensor of this example includes a pair of frame portions 231 and 233 extending in the X direction, a pair of frame portions 235 and 237 extending in the Y direction, and the vibrator main body 203 side from the pair of frame portions 231 and 233. Projections 239 and 241 projecting from each other. The surfaces 235a and 237a of the pair of frame portions 235 and 237, which face the pair of weights 205, respectively, correspond to the pair of weights when the vibrator body 203 and the pair of weights 205 move more than necessary in the X-axis direction. 205 abuts. The surfaces 239a and 241a of the protrusions 239 and 241 that face the vibrator body 203 respectively contact the vibrator body 203 when the vibrator body 203 and the pair of weights 205 move more than necessary in the Y-axis direction. . As described above, the base 201 of the angular velocity sensor of this example has the vibrator body 203 and the pair of weights when the vibrator body 203 and the pair of weights 205 move more than necessary in the X-axis direction and the Y-axis direction. Dimension and shape to stop 205 movements.

  According to the angular velocity sensor of this example, it is possible to prevent the vibrator main body 203 and the pair of weights 205 from moving more than necessary in the X axis direction and the Y axis direction and being damaged.

It is a top view of the angular velocity sensor of one embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. It is the elements on larger scale of the IV section of FIG. It is the VV sectional view taken on the line of FIG. It is a top view of the spring-like member of the angular velocity sensor of FIG. It is a top view of the spring-like member of the angular velocity sensor of the comparative example used for the test. It is a top view of the angular velocity sensor of other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 3 Vibrator body 5 Weight 7 Spring-like member 9 Piezoelectric element 17 Extending part 19 Connection part 21 Support extending part

Claims (4)

An elongated vibrator body extending in the X-axis direction of the X-axis direction, the Y-axis direction, and the Z-axis direction orthogonal to each other;
A piezoelectric element that is formed on the vibration body and detects an angular velocity of the vibration body;
A pair of plate-like weights disposed at both ends of the vibration body in the X-axis direction and extending in the X-axis direction and the Y-axis direction;
An angular velocity sensor having four spring-like members having spring properties for supporting both ends of the pair of weights in the Y-axis direction on a base member so that the vibrator main body moves in a three-dimensional direction. The spring-like member includes four or more extending portions extending in the Y-axis direction, a connecting portion extending in the X-axis direction and connecting an end portion of the extending portion, and the X-axis so as to form a meandering pattern. One end is connected to the connection part located in the center of the direction and has a support extension part extending in parallel with the extension part,
Extending portions at both ends in the X-axis direction of the spring-like member are connected to the base member,
The angular velocity sensor according to claim 1, wherein the other end of the support extending portion is connected to the weight.   The plate material whose thickness direction is the Z-axis direction is cut, and the vibrator main body, the pair of weights, the four spring-like members, and the base member are integrally formed. 2. An angular velocity sensor according to 2. The base member has a frame shape surrounding the vibrator main body, the pair of weights, and the four spring-like members,
The base member contacts the vibrator body and the pair of weights when the vibrator body and the pair of weights move more than necessary in the X-axis direction and the Y-axis direction, The angular velocity sensor according to claim 3, wherein the angular velocity sensor has a size and a shape for stopping movement of the vibrator body and the pair of weights.

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