JP6533518B2 - Angular velocity sensor - Google Patents

Description

  The present invention relates to an angular velocity sensor which excites piezoelectric vibration and measures an angular velocity.

  In FIG. 1 of JP 2007-93329 A (Patent Document 1), the angular velocity detection element 20 aligned in the stacking direction, the circuit board 30, the pedestal 60, and the mounting surface 13 of the package are respectively joined with an adhesive. A vibration type angular velocity sensor is disclosed in which the wall surface 14 and the pedestal 60 are bonded with an adhesive. In the vibration type angular velocity sensor shown in Patent Document 1, the angular velocity acting on the angular velocity sensor is measured by measuring the change of the output of the angular velocity detecting element 20 which changes according to the operation of the vibrating body relative to the support portion supporting the vibrating body. It is detected.

JP 2007-93329 A

  BACKGROUND In recent years, miniaturization of electronic devices such as mobile devices in which angular velocity sensors are mounted has been promoted. Thereby, the miniaturization of the angular velocity sensor is further advanced. The angular velocity sensor utilizing the coleoli force is to vibrate the vibrator and detect the coleoli force generated when the user feels the angular velocity to measure the angular velocity. However, due to the miniaturization of the angular velocity sensor, the weight ratio between the vibrating body of the angular velocity sensor and the supporting portion for supporting and fixing the vibrating body becomes small, and the supporting portion must be essentially stationary due to the vibration of the vibrating body Is vibrating, and the vibrating body can not be vibrated accurately with respect to the support portion, which causes a problem that the detection accuracy of the angular velocity is deteriorated. In addition, the vibration energy of the vibrator is transmitted to the support portion to cause vibration loss, which lowers the mechanical Q value for the vibration of the vibrator, reduces the sensor sensitivity of the angular velocity sensor, degrades the temperature characteristics, etc. Serious problems of

  In the angular velocity sensor of Patent Document 1, in order to increase the weight of the entire angular velocity sensor device, the pedestal 60 is joined by an adhesive with a low elastic modulus. However, the pedestal 60 is provided to widen the frequency range of the external vibration absorbed by the angular velocity sensor, and therefore, the pedestal 60 does not have a weight sufficient to suppress movement of the support portion due to the vibration of the vibrator. I can not vibrate my body precisely.

  The object of the present invention is to reduce the mechanical Q value (hereinafter sometimes referred to simply as the Q value) even if it is downsized, and therefore to measure the angular velocity at which the sensitivity is large and the temperature characteristic of sensitivity is reduced. It is in providing a sensor.

  Another object of the present invention is to provide an angular velocity sensor that can accurately measure the angular velocity by suppressing movement of the support portion due to the vibration of the vibrator even if it is miniaturized, that is, obtaining stable and accurate vibration. It is in.

  According to the present invention, a diaphragm-shaped vibration excitation unit, a vibrator formed at the center of the vibration excitation unit, which vibrates in at least one direction of X direction, Y direction or Z direction, and peripheral support for supporting the periphery of the vibration excitation unit An angular velocity sensor consisting of In the specification of the present application, the “diaphragm type vibration excitation portion” means one in which a vibration excitation layer such as a piezoelectric vibration film is formed on the diaphragm. The “central part of the vibration excitation part” includes not only the central part of the excitation vibration part but also an error range centered on the central part. The angular velocity sensor of the present invention further includes a vibration stabilizing portion joined to the peripheral support portion. The contour of the outer peripheral portion of the peripheral support portion has a rectangular shape, the contour of the outer shape of the vibration excitation portion has an octagonal shape, and the vibrator has a cylindrical cylindrical shape. In the specification of the present application, “rectangular” is a shape such as a square or a rectangle, and the angle of the four corners is not only completely 90 degrees, but also the angle of the four corners is within the error range of 90 degrees. It has a small radius (curvature) in the part, and also includes one in which the pair of opposite sides do not have exactly the same size but fall within the error range. In addition, “an octagonal shape” means that the inner angle of the eight corner parts falls within the error range of 45 degrees, the one with small rounded corners, and the opposite pair of sides do not have exactly the same size Are those that fall within the error range. Furthermore, the term “cylindrical shape” includes not only those whose cross section becomes a perfect circle, but also those whose cross section falls within the error range of a true circle.

  In the present invention, the vibration stabilizing portion is joined to the peripheral support portion by the adhesive having the property of being soft when the frequency of vibration is low and rigid when the frequency of vibration is high. The thickness of this adhesive after curing is 10 to 50 μm. The vibration stabilizing portion in the angular velocity sensor of the present invention may be composed of a single substance, or may be a composite in which a plurality of substances or materials are combined. The vibration stabilizing portion has a weight such that the total weight with the peripheral support portion is at least 20 times the weight of the vibrating body.

  According to the above configuration, when the cylindrical vibrating body vibrates, the peripheral support portion vibrates due to the vibration of the vibrating body. At this time, if the weight of the peripheral support portion is larger than the weight of the vibrator, the peripheral support supporting the diaphragm-type vibration excitation portion having an outer peripheral contour having a rectangular shape and an outer contour having an octagonal shape. The part vibrates at a vibration amplitude smaller than that of the vibrator.

  In the present invention, the adhesion between the peripheral support portion and the vibration stable portion is softened at low frequencies, and uses a layer of adhesive that hardens at high frequencies such as the vibration of the vibrator, so a temperature change results. Vibrations with low displacement or low frequency, such as displacement or vibration or external displacement or vibration, are absorbed by the soft adhesive. In addition, the vibration of the columnar vibration body having a high frequency excited by the vibration excitation unit is not absorbed by the hard adhesive layer. In the present invention, the thickness of the adhesive after curing is 10 to 50 μm. This is because when the thickness of the adhesive after curing is greater than 50 μm, the peripheral support portion and the vibration stable portion are not sufficiently integrated, and the support portion easily vibrates independently, so the vibration of the vibrating body leaks to the support Since the mechanical Q value is low, it is desirable to make the thickness 50 μm or less. In addition, when the thickness of the adhesive after curing becomes smaller than 10 μm, the peripheral support portion and the cylinder supporting the vibration excitation portion having a rectangular outer peripheral contour shape and an octagonal outer contour shape The influence of the temperature change of the output of the angular velocity sensor and the external vibration becomes large without being able to suppress the influence of the change of the dimension between the members due to the difference of the thermal expansion coefficient of the vibrating body of the shape and the external vibration. Therefore, the thickness of the adhesive after curing is preferably 10 μm or more. Furthermore, in the present invention, the peripheral support portion and the vibration stabilization portion are integrated, and the total weight of the peripheral support portion and the vibration stabilization portion is configured to be 20 times or more of the weight of the vibrator. In addition, by setting the vibration stabilizing portion to a composite structure such as a laminated structure in which a plurality of materials are stacked, the mechanical Q value of the vibration stabilizing portion can be set low, so that temperature changes and vibrations from the surroundings can be attenuated further. As a result, it is possible to further reduce the influence of temperature changes and vibrations from the surroundings.

  Therefore, in the present invention, the weight difference between the weight of the cylindrical vibrating body and the total weight of the peripheral support portion and the vibration stabilizing portion whose outer peripheral contour has a rectangular shape becomes large, and the vibration of the vibrating body causes peripheral It is possible to suppress movement of the support, that is, vibration of the vibrating body from leaking to the peripheral support. Therefore, the vibrating body can be vibrated accurately with respect to the peripheral support portion that supports the vibration excitation portion having an octagonal contour shape. In addition, movement of the peripheral support portion supporting the vibration excitation portion having an octagonal contour shape can suppress leakage of vibration from the angular velocity sensor to the outside, so that loss is caused to vibration energy of the vibrator. As a result, the Q value of the vibrator does not decrease. From the above, according to the present invention, even if the sensor is miniaturized, the Q value does not decrease, so the sensor sensitivity can be increased, the temperature change of the sensor output does not become large, and the vibrator accurately vibrates. It is possible to obtain an angular velocity sensor that can accurately detect the angular velocity.

  Further, according to the present invention, the contour of the outer periphery of the peripheral support portion has a rectangular shape, the contour of the outer shape of the vibration excitation portion has an octagon shape, and the vibrator has a cylindrical shape. The vibration of the cylindrical vibration member is difficult to be transmitted to the octagonal vibration excitation portion, and the vibration of the octagonal vibration excitation portion is transmitted to the peripheral support portion whose outer peripheral contour is rectangular. Hateful. It also has the feature that it is difficult to transmit the reverse of the vibration propagation direction. Therefore, the vibration of the vibrator is accurately performed, and the weight difference between the weight of the vibrator and the total weight of the peripheral support portion and the vibration stabilizing portion described above is large, and it is soft when the frequency is low and hard when the frequency is high. Even if it is miniaturized, combined with the effect of the agent, the Q value does not decrease, so the sensor sensitivity can be increased, the temperature change of the sensor output does not become large, and the vibrating body is vibrated accurately and the angular velocity accurately. It is possible to provide an angular velocity sensor capable of detecting

  The adhesive used to bond the vibrator and the peripheral support is preferably a silicone adhesive. In the case of the silicone adhesive after curing, the property of being soft when the frequency of the vibrator is low and being hard when the frequency of the vibrator is high is particularly remarkable. Further, in order to control the thickness of the adhesive, it is effective to mix predetermined particles or fibers in the adhesive.

  Of course, the vibration stabilizing unit may include a package on which the angular velocity sensor is fixed and mounted. The vibration stabilizing portion may include, for example, a metal material having a large specific gravity. In particular, materials made of tungsten (with a thermal expansion coefficient of 4.5 ppm) or molybdenum (with a thermal expansion coefficient of 4.8 ppm) having a thermal expansion coefficient close to the thermal expansion coefficient (2.6 ppm) of silicon with a low thermal expansion coefficient It is preferred to include. In the vibration-stable portion, two or more materials selected from various materials such as metal materials such as tungsten and molybdenum, materials such as ceramic, silicon substrates, organic materials such as rubber, epoxy resin and silicon resin are combined. Alternatively, a composite material formed by laminating may be included. Depending on the combination of materials selected, the mechanical Q value is low, that is, external vibration can be reduced, and a heavy weight vibration stable portion can be formed. If the vibration stabilization portion is configured to include such a material, the vibration stabilization portion can be made smaller, and the miniaturization of the angular velocity sensor is not hindered. In addition, since the thermal expansion coefficient can be adjusted by selecting the material, even when the thermal expansion coefficient of the circuit board or the like on which the angular velocity sensor is mounted is large, the vibration stabilizing portion functions as a buffer layer, and the influence of the thermal expansion of the circuit substrate or the like Can be made smaller. When it is necessary to reduce the height dimension of the angular velocity sensor, the vibration stabilizing unit may be formed of a silicon substrate on which the angular velocity sensor is mounted, or a combination of a silicon substrate and a package.

  For example, the peripheral support portion and the vibration stabilizing portion can be joined by an adhesive at four positions through which a pair of virtual orthogonal planes passing through the center of the vibrator, for example, pass. In this case, the vibrator is configured to vibrate along the virtual orthogonal plane. According to this structure, since the adhesive is present in the direction in which the peripheral support moves by the vibration of the vibrator, the movement of the peripheral support can be reliably suppressed by the adhesive, and the vibration of the vibrator leaks to the outside. Can be reliably prevented. Of course, the peripheral support portion and the vibration stabilizing portion may be joined at more points including the above four places, or the peripheral support portion may be joined to the vibration stabilizing portion all around.

  If the adhesive sticks out to the inner periphery of the peripheral support portion and adheres to the vibration excitation portion, the angular velocity sensor does not operate properly. In particular, when the angular velocity sensor is miniaturized, high accuracy is required for applying the adhesive. Therefore, when the contour shape of the outer periphery of the peripheral support portion is formed in a rectangular shape, the adhesive of the peripheral support portion and the vibration stabilizing portion at four positions through which the virtual diagonal surface of the peripheral support portion passes. It is preferable to join by Since the gap between the outer periphery and the inner periphery can be wider at the position where the virtual diagonal surface of the peripheral support portion passes, the application of the adhesive can be easily performed. .

  As a result of many studies, it has been found that the weight of the vibration stabilizing portion needs to be at least 20 times the weight of the vibrating body, and preferably at least 40 times as large as the weight of the vibrating body. . According to this structure, the vibrator can vibrate more accurately with respect to the peripheral support portion regardless of the weight of the peripheral support portion.

  The peripheral support portion may support the outer peripheral portions of the two vibration excitation portions. Then, the vibration body formed in the central region of one vibration excitation portion detects an angular velocity in the direction perpendicular to the vibration excitation portion, and the vibration body formed in the central region of the other vibration excitation portion To detect an angular velocity in a direction parallel to In this case, the angular velocity in the direction perpendicular to the vibration excitation unit and the angular velocity in the direction parallel to the vibration excitation unit can be separately detected by the two vibrators. Therefore, since it is not necessary to switch the vibration direction of the vibrator, the response performance of the angular velocity sensor can be enhanced.

  The present invention can be applied not only to angular velocity sensors but also to other devices having a vibrating portion and a supporting portion, such as MEMS mirrors and acceleration sensors.

(A) is a top view which shows an example of the electrode structure in the angular velocity sensor as a 1st Embodiment of this invention, (B) is a bottom view of a state which removed the vibration stabilization part. It is sectional drawing of the virtual surface CL1-CL1 line | wire of FIG. 1 (A) which shows the state attached to the package. In the angular velocity sensor of FIG. 1, it is a graph which shows the result of the experiment which measured the value of Q value in, when the total weight of a periphery support part and a vibration stable part is changed. It is a graph which shows the result of the experiment which measured the temperature change of the value of Q value, and the output in, when the thickness of the adhesive agent of a peripheral support part and a vibration stable part is changed in the angular velocity sensor of FIG. (A) is a top view of the angular velocity sensor as a 2nd embodiment of the present invention, (B) is a bottom view in the state where a vibration stabilization part was removed. (A) and (B) respectively indicate four angular velocity detections obtained when the vibration excitation electrode is driven to vibrate the weight sensor in the X-axis direction according to the embodiment of FIGS. 1 and 5 It is a figure which shows a part of output in the predetermined frequency range obtained from the electrode. (A) is a bottom view of a state in which the vibration stabilizing portion of the angular velocity sensor according to the third embodiment of the present invention is removed, and (B) is a view showing a state of being attached to a package. It is a figure which shows a VII line cross section typically.

  Hereinafter, embodiments of the angular velocity sensor of the present invention will be described with reference to the drawings.

  FIG. 1A is a plan view of an example of the angular velocity sensor 1 according to the first embodiment of the present invention, and FIG. 1B is a state in which a silicon plate 19 constituting a vibration stabilizing portion described later is removed. Bottom view of FIG. FIG. 2 is a cross-sectional view taken along line CL1-CL1 of FIG. 1 (A) showing a state in which the angular velocity sensor 1 is attached to a package. Note that in the present specification, the dimensions of some of the parts are exaggerated for ease of understanding.

  The angular velocity sensor 1 according to the present embodiment includes a flat diaphragm 3 having an octagonal outer periphery, a weight 5 as a cylindrical vibrator disposed at the center of the back surface of the diaphragm 3, and an outer peripheral portion of the diaphragm 3. A peripheral support 7 having a rectangular outer peripheral portion to be supported, a lower electrode 11 formed on the surface of the diaphragm 3 with an insulating film 9 interposed therebetween, a piezoelectric thin film 13 formed on the lower electrode 11, and a piezoelectric thin film 13 The four vibration excitation electrodes 15 and the four angular velocity detection electrodes 17 formed on top of each other. In the present embodiment, the diaphragm 3 and the piezoelectric thin film 13 constitute a film-like vibration excitation portion. The diaphragm 3, the weight 5, and the peripheral support 7 have shapes corresponding to the end face of the weight 5 and the end of the peripheral support 7 on one surface of the semiconductor silicon substrate having a crystal orientation of (100). It is integrally formed by disposing a mask having the same and performing dry etching from this mask side. The weight 5 can also be configured partially or entirely of other materials such as tungsten and molybdenum. In the present embodiment, the piezoelectric thin film 13 is expanded and contracted by giving drive electric signals to the four vibration excitation electrodes 15 to cause the weight 5 to vibrate with a motion component in the direction of a predetermined vibration axis. To induce. The angular velocity detection electrode 17 detects the displacement in the direction of the displacement axis generated in the weight 5 based on the Coriolis force.

  The outline of the outer peripheral portion of the diaphragm 3 has a substantially octagonal shape having straight portions C1 to C4 at four corners of sides S1 to S4 each having a side length of about 0.4 mm. The thickness of the diaphragm 3 is about 0.009 mm. In the present embodiment, the diaphragm 3 is configured such that the lengths of the linear portions C1 to C4 are longer than the lengths of the sides S1 to S4. In the present embodiment, small rounded portions are formed at the intersections of the square sides S1 to S4 and the straight portions C1 to C4. There is no problem in operation even if there is no radius part. And the weight 5 has a cylindrical shape. The diameter of the weight 5 is 0.4 mm.

  The peripheral support portion 7 is formed in a tubular shape. The outline shape of the outer peripheral portion of the peripheral support portion 7 has a rectangular shape, and in the present embodiment, it has a substantially square shape, but may have a rectangular shape. The length of one side is about 1.1 mm, and the length dimension (thickness) from the surface on which the diaphragm 3 is provided to the tip to which the silicon plate 19 is bonded is about 0.408 mm. Further, the inner peripheral portion of the peripheral support portion 7 is composed of surfaces F1 to F4 continuous with the sides S1 to S4 of the diaphragm 3 and four surfaces FC1 to FC4 continuous to linear portions C1 to C4 at four corners of the diaphragm 3, respectively. The contour shape of the inner peripheral portion of the peripheral support portion 7 is the same as the contour shape of the outer peripheral portion of the diaphragm 3. In the peripheral support portion 7, a square silicon plate 19 is bonded by an adhesive 21 to the end face 7 a in the direction away from the diaphragm 3.

  In this embodiment, as shown in FIG. 1A, when an XYZ three-dimensional orthogonal coordinate system is defined in which the origin O is at the center position of the diaphragm 3 and the surface of the diaphragm 3 is included in the XY plane. The X axis and the Y axis are defined. A first imaginary line L1 orthogonal to the two opposing sides S1 and S3 of the diaphragm 3 and bisecting the two sides S1 and S3 and two other sides orthogonal to the remaining two opposing sides S2 and S4 of the diaphragm 3 A first imaginary diagonal plane CL1 passing through the centers of the two opposing straight portions C1 and C3 of the diaphragm 3, and the other two remaining straight portions C2 of the diaphragm 3 opposite to each other. Assume a second virtual diagonal plane CL2 passing through the center of C4. Then, the outline shape of the outer peripheral portion of the diaphragm 3 is made to be a line symmetrical with respect to the first imaginary line L1 or the second imaginary line L2. In the present embodiment, four vibration excitation electrodes 15 and four angular velocity detection electrodes 17 are respectively formed in four regions partitioned by first and second virtual diagonal surfaces CL1 and CL2. . In the present embodiment, the first virtual line L1 and the second virtual line L2 respectively coincide with the axis of the X axis and the axis of the Y axis.

  The contours of the four vibration excitation electrodes 15 are: an outer side 15A located radially outward of the weight 5, an inner side 15B radially opposite the outer side 15A, an outer side 12A, and an inner side 12B And a pair of connecting sides 15C and 15D. The shape of the outer side 15A is similar to the shape of a part of the outer peripheral part of the diaphragm 3 (a part extending between a part of two adjacent sides and a linear part). Further, the shape of the inner side 15B of the contour of the vibration excitation electrode 15 is also similar to the shape of the outer side. When the four vibration excitation electrodes 15 have such a shape, vibration can be generated efficiently. The vibration excitation electrode 15 can also be formed into an arc shape.

  The contours of the four angular velocity detection electrodes 17 are: an outer side 17A located radially outward of the weight 5, an inner side 17B radially opposite the outer side 17A, an outer side 17A, and an inner side 17B And a pair of connecting sides 17C and 17D. In the present embodiment, the outer side 17A and the inner side 17B each have a concentric arc shape. The angular velocity detection electrode 17 can also be contoured like the vibration excitation electrode 15. Here, the angular velocity detection electrode may be used as a vibration excitation electrode, and the vibration excitation electrode may be used as an angular velocity detection electrode.

  In the present embodiment, the four vibration excitation electrodes 15 and the four angular velocity detection electrodes 17 are formed so as not to cross the boundary between the diaphragm 3 and the weight 5 and the boundary between the diaphragm 3 and the peripheral support portion 7. It is done. When the four vibration excitation electrodes 15 and the four angular velocity detection electrodes 17 are formed as described above, the amplitudes of output signals from the four angular velocity detection electrodes 17 can be made larger.

  In order to induce a vibration having a motion component in the direction of a predetermined vibration axis with respect to a weight 5 as a cylindrical vibration body, drive signals are applied to four vibration excitation electrodes 15. Then, based on the Coriolis force, the displacement in the direction of the displacement axis generated in the weight 5 is detected from the four electrodes 17 for detecting angular velocity to obtain the angular velocity. In this angular velocity sensor, one of the X axis and the Z axis is the vibration axis, and the other orthogonal axis is the displacement axis, and the angular velocity around the Y axis is detected based on the detection value from the angular velocity detection electrode 17 constituting the displacement detection unit. To detect. In order to detect the angular velocity around the X axis and around the Y axis, the weight 5 is vibrated in the Z direction. Therefore, the vibration in the X-axis direction and the Y-axis direction necessary for detecting the angular velocity around the Z-axis becomes clear. In addition, the vibration in the Z-axis direction necessary for detecting the angular velocity around the X axis and the Y axis is not impaired. Therefore, the angular velocity sensor can detect the Coriolis force, and can sufficiently vibrate the weight in the X axis direction or the Y axis direction to detect the angular velocity around the Z axis. Further, in order to detect an angular velocity around the Z axis, the weight 5 is vibrated in the X axis direction or the Y axis direction. In the present embodiment, the weight is vibrated in the X-axis direction of FIG.

  The silicon plate 19 is a silicon IC substrate having a thickness of about 0.1 mm (for example, it may have a function of generating an electrical signal for vibration excitation, detecting an electrical signal for detecting an angular velocity, and detecting an angular velocity) It has a square-shaped outline with a side length of about 1.7 mm. The silicon plate 19 is integrated with the package 23 made of FR 4 by an epoxy adhesive 22. In the present embodiment, the silicon plate 19, the epoxy adhesive 22 and the package 23 constitute the vibration stabilizing member 24 of the present invention. The vibration stabilizing portion 24 composed of the silicon plate 19 of the present embodiment, the epoxy adhesive 22 and the package 23 has 40 times the weight of the weight 5 which is a vibrating body.

  The peripheral support portion 7 and the silicon plate 19 are joined by an adhesive 21 applied to two regions through which the first virtual diagonal surface CL1 passes and to two regions through which the second virtual diagonal surface CL2 passes. ing. In the present embodiment, in particular, the adhesive 21 is applied to the surfaces FC1 to FC4 of the peripheral support portion 7 at intervals from the surfaces FC1 to FC4 so that the adhesive 21 is not exposed.

  In the present embodiment, a silicon-based conductive adhesive manufactured by Three Bond Co., Ltd. is used as the adhesive 21. This adhesive has the property of being soft when the vibration frequency is low and stiffening when the vibration frequency is high. The adhesive 21 after curing is formed to a thickness of 10 to 50 μm.

  For the angular velocity sensor 1 configured as in the above embodiment, an experiment was conducted to confirm the relationship between the ratio of the weight of the weight 5, the total weight of the peripheral support 7 and the vibration stabilizing unit 24, and the Q value. . FIG. 3 is a graph showing the results of experiments in which the value of the Q value was measured when the weights of the peripheral support portion 7 and the vibration stabilizing portion 24 were changed in the angular velocity sensor 1 according to the present embodiment. In this experiment, the ratio (W1: W2) of the weight W1 of the weight 5 to the total weight W2 of the peripheral support portion 7 and the vibration stabilizing portion 24 is 1:10, 1:20, 1:30, 1:40. The weight of the vibration stabilizing portion 24 was determined so as to be 1:80 and 1: 160, and the Q value when vibrating in the X axis direction and the Z axis direction in FIG. 1 was measured. The Q value when vibrating in the X-axis direction increases as the weight ratio increases, and is saturated at about 600. When the range from the saturated Q value of 600 to the difference of 10% is a usable weight ratio, the usable weight ratio is 1:20 or more in the vibration in the X-axis direction. The Q value when vibrating in the Z-axis direction is as large as the weight ratio is large, and is saturated at 300. When the range from the saturated Q value of 300 to the difference of 10% is taken as the usable weight ratio, the usable weight ratio is 1:10 in the vibration in the Z-axis direction. Therefore, if the specific weight ratio of the weight of the weight 5 to the total weight of the peripheral support portion 7 and the vibration stabilizing portion 24 is 1:20 or more, good Q values can be obtained in both the X axis direction and the Z axis direction. That is, as a result of many studies, it has been found that a practical and practical angular velocity sensor having high sensitivity and stability can be obtained. If the specific weight ratio of the weight 5 to the total weight of the peripheral support 7 and the vibration stabilizing unit 24 is 1:40 or more, a Q value saturated in both the X-axis direction and the Z-axis direction can be obtained. That is, in the angular velocity sensor 1, when the temperature is constant and external disturbance such as vibration can be ignored, the specific weight ratio of the weight of the weight 5 to the total weight of the peripheral support portion 7 and the vibration stabilizing portion 24 is 1:20. As a result of many studies, it has been found for the first time that stable operation can be realized if the above, preferably 1:40 or more.

  Next, regarding the angular velocity sensor 1 configured as in the above-described embodiment, the stabilization of the operation in consideration of the addition of external disturbances such as temperature and vibration will be described. With respect to the angular velocity sensor 1, an experiment was performed to measure the temperature change of the Q value and the output when the thickness of the adhesive 21 is changed. FIG. 4 is a graph showing the results of experiments in which the temperature change of the Q value and the output was measured when the thickness of the adhesive 21 was changed in the angular velocity sensor 1 of the present embodiment. In this experiment, the thickness of the adhesive 21 was varied between 5 μm and 60 μm. Moreover, the temperature of the angular velocity sensor was changed between -40 ° C and 85 ° C. As a representative example, as a result of investigating the vibration in the X-axis direction, when the thickness of the adhesive 21 is thinner than 10 μm, the Q value of the vibration in the X-axis direction is 600 or more, but between -40 ° C and 85 ° C. When the temperature is changed, the rate of change in sensor output exceeds 50%. This is because when the thickness of the adhesive is small, the difference in the dimensional change of each member due to the difference in the coefficient of thermal expansion can not be absorbed by the adhesive layer, and the mutual influence can not be suppressed. When the thickness of the adhesive 21 is greater than 50 μm, the rate of temperature change of the output when changing the temperature between -40 ° C. and 85 ° C. is within 45%, so the coefficient of thermal expansion is The influence of the difference in the change in dimension of each member due to the difference can be suppressed. However, the Q value of the vibration in the X-axis direction decreases, and the difference between the saturation value 600 and 10% or more. When the thickness of the adhesive 21 is 10 μm to 50 μm, the ratio of the temperature change of the output when changing the temperature between -40 ° C. and 85 ° C. is within 45%, and the value of Q value Both were stable, and both were in the range of a saturated Q value of 600 to 10% difference. That is, when the thickness of the adhesive 21 is 10 μm to 50 μm, the temperature characteristics of the Q value and the sensor output are good. The same applies to the vibration in the Z-axis direction, although the absolute value of the Q value is different. The characteristics shown here are one example, but similar results were obtained even if the sensor size is approximately 0.5 to 3 times.

  In the above embodiment, since the ratio of the weight of the weight 5 as a vibrator to the total weight of the peripheral support portion 7 and the vibration stabilizing portion 24 is 1:20 or more, the peripheral support portion is vibrated by the vibration of the weight 5. Can be controlled to vibrate the weight 5 with respect to the peripheral support 7 precisely. Further, the movement of the peripheral support portion 7 suppresses the leakage of the vibration from the angular velocity sensor 1 to the outside, thereby preventing the Q value of the vibration of the weight 5 from being lowered. In addition, since the thickness of the silicon adhesive is 10 to 50 μm, and the peripheral support 7 and the vibration stabilizing unit 24 are joined, the vibration of the peripheral support 7 with low frequency is absorbed by the soft adhesive. Vibration of the peripheral support 7 with high frequency is not absorbed by the hardened adhesive, and loss of vibration energy of the vibrator causes the Q value of the weight 5 to be lowered. There is no Therefore, according to the present invention, even when the size is reduced, the Q value does not decrease and the temperature change of the output does not become large, and furthermore, the vibrator can be vibrated accurately, so that high sensitivity is stably achieved. Can be obtained.

  In addition, since the vibration stabilizing portion 24 is composed of a plurality of parts such as the silicon plate 19, the epoxy adhesive 22, and the package 23, a composite structure such as lamination and columns can be adopted. Therefore, the above embodiment has an excellent feature that the Q value to the vibration can be lowered, the weight to the vibrator can be increased, and the thermal expansion coefficient can be easily controlled. Unwanted external vibration can be reduced by the low Q to the vibration. Since a stable vibration of the vibrating body can be obtained by increasing the weight of the vibrating body, a high Q value can be obtained for the vibration of the vibrating body. The easy control of the thermal expansion coefficient can reduce the temperature characteristic of sensitivity. Therefore, according to the above embodiment, even if the device is miniaturized, the Q value of the angular velocity sensor does not decrease, and the temperature change of the output does not become large, and the vibrating body can be vibrated accurately. Therefore, it is possible to obtain an angular velocity sensor which is stable, accurate and high in sensitivity.

  Further, the contour of the outer periphery of the peripheral support portion 7 has a rectangular shape, the contour of the outer shape of the diaphragm 3 has an octagon shape, and the vibrating body 5 has a cylindrical shape. Since the shape is different, the vibration of the cylindrical vibrating body 5 is hard to be transmitted to the octagonal diaphragm 3, and the vibration of the octagonal diaphragm 3 is hard to be transmitted to the peripheral supporting portion 7 whose outer peripheral contour is rectangular. Vibration in the opposite direction of propagation is also less likely to be transmitted. Therefore, the vibration of the vibrating body is accurately performed, the weight ratio of the weight of the vibrating body to the total weight of the peripheral support portion and the vibration stabilizing portion is as large as 1:20 or more, soft when the frequency is low and hard when the frequency is high Combined with the effect of the adhesive, even if it is miniaturized, the Q value does not decrease, so the sensor sensitivity can be increased, the temperature change of the sensor output does not become large, and the vibrating body is vibrated accurately to be accurate. An angular velocity sensor capable of detecting an angular velocity can be provided.

  FIG. 5A is a plan view of an angular velocity sensor according to a second embodiment of the present invention, and FIG. 5B is a bottom view of a state in which a silicon plate is removed. In the embodiment shown in FIG. 5, the same members as those in the embodiment in FIGS. 1 and 2 are given the same reference numerals as those in FIGS. I omit it.

  In this example, four vibration excitation electrodes 115 are respectively formed in the four regions partitioned by the first virtual line L1 and the second virtual line L2. The four angular velocity detection electrodes 117 are also formed in the four regions divided by the first virtual line L1 and the second virtual line L2, respectively. In the embodiment, the first virtual diagonal surface CL1 and the second virtual diagonal surface CL2 coincide with the X axis axis and the Y axis axis, respectively. In the present embodiment, the diaphragm 103 is configured such that the lengths of the sides S1 to S4 are longer than the lengths of the straight portions C1 to C4. The peripheral support portion 107 and the silicon substrate 119 are bonded by an adhesive 121 on the first virtual diagonal surface CL1 and the second virtual diagonal surface CL2. In the present embodiment, the weight 105 vibrates along the second virtual diagonal surface CL2. The width of the peripheral support portion 107 along the vibration direction of the weight 105, that is, along the first virtual diagonal surface CL1 and the second virtual diagonal surface CL2 is larger than that of the angular velocity sensor according to the first embodiment. Therefore, since the adhesive 121 is present in the direction in which the peripheral support portion 107 moves due to the vibration of the weight 105, the movement of the support portion 107 is reliably suppressed by the adhesive 121 to prevent the vibration from leaking outside. There is.

  6A and 6B show the angular velocity sensor of the embodiment of FIGS. 1 and 5, respectively, when a drive signal is applied to the vibration excitation electrode 115 so as to vibrate the weight in the X-axis direction. It is a figure which shows a part of output in the predetermined | prescribed frequency range obtained from four electrodes for angular velocity detection obtained. As can be seen from FIGS. 6A and 6B, in the embodiment of FIG. 5, compared with the embodiment of FIG. 1, the peak frequency of the vibration in the X-axis direction and the vibration in the Y-axis direction The peak frequencies are clearly separated. Therefore, as shown in FIG. 5, when the positional relationship between the four vibration excitation electrodes 115 and the four angular velocity detection electrodes 117 is determined, a signal that can clearly distinguish the vibration in the X axis direction and the vibration in the Y axis direction is selected. It can be reliably obtained from two angular velocity detection electrodes 117.

  FIG. 7A is a bottom view of the state where the silicon substrate 219 of the angular velocity sensor 201 according to the third embodiment of the present invention is removed, and FIG. 7B shows a state where it is attached to the package 223. It is a figure which shows typically the VIIB-VIIB line cross section of FIG. In the embodiment shown in FIG. 7, the same members as in the first embodiment shown in FIGS. 1 and 2 are given the same reference numerals as those in FIGS. And the explanation is omitted. The angular velocity sensor 201 according to the present embodiment includes two diaphragms 203A and 203B, and cylindrical weights 205A and 205B are disposed at the center of the back surface of the diaphragms 203A and 203B. The peripheral support portion 207 is bonded to the silicon substrate 219 by an adhesive 221. The silicon substrate 219 is bonded to the package 223 by an epoxy adhesive 222.

  The contours of the outer peripheral portions of the diaphragms 203A and 203B have a substantially octagonal shape having straight portions C1 to C4 at four corners of a side having a side length of about 0.95 mm. The weights of the diaphragms 203A and 203B are each 0.0896 mg. The peripheral support portion 207 has a weight of 1.4662 mg, and a total of six places of the four corners of the peripheral support portion 207 and the middle in the longitudinal direction of the peripheral support portion 207 are bonded to the silicon substrate 219.

  The silicon substrate 219 has a rectangular shape with an outline shape of 2.2 mm × 2.3 mm, a thickness of about 0.1 mm, and an integrated circuit (not shown) is formed. The silicon substrate 219 has a rectangular shape of 2.2 mm × 2.3 mm. In the present embodiment, the silicon substrate 219 and the package 223 constitute a vibration stabilization member. The total weight of the silicon substrate 2019 and the package 223 is 5 mg.

  In the present embodiment, the angular velocity around the X axis (or around the Y axis) is detected by vibrating the weight 205A in the Z axis direction. Further, the angular velocity around the Z axis is detected by vibrating the weight 205A in the X axis direction (or Y axis direction). Therefore, in the angular velocity sensor according to the present embodiment, since it is not necessary to switch the vibration direction of the weight, the response performance of the angular velocity sensor can be enhanced.

  The present invention is, of course, not limited to the dimensions, materials, and the like of each layer in the above-described embodiment.

  According to the angular velocity sensor of the present invention, the periphery of the outer peripheral portion supporting the diaphragm-type vibration excitation portion having the cylindrical vibrating body in the center and the outline of the outer shape having the octagonal shape has the rectangular shape. The vibration-stable portion is joined to the support with an adhesive that has the property of being soft when the frequency of vibration is low and stiff when the frequency of vibration is high, so that the vibration of the peripheral support with low frequency is soft. Vibrations of the high frequency peripheral support absorbed by the adhesive are not absorbed by the hardened adhesive. Further, since the thickness of the cured adhesive layer is 10 to 50 μm, the peripheral support portion and the vibration stable portion are integrated, the Q value does not decrease, and the difference is caused by the thermal expansion coefficient. The influence of the dimensional change between the members can be suppressed, and the temperature change of the output of the angular velocity sensor does not become large. Furthermore, since the peripheral support portion with a total weight with the vibration stable portion of 20 times or more is integrated with the vibration stable portion, the weight ratio between the vibrating body and the peripheral support portion is increased, and the vibration is caused by the vibration of the vibrating body. The movement of the support can be suppressed. Therefore, the vibrator can be vibrated accurately with respect to the peripheral support portion. Further, since movement of the peripheral support portion can suppress leakage of vibration from the angular velocity sensor to the outside, a loss occurs in the vibration energy of the vibrating body, and the Q value of the vibrating body is not lowered. Therefore, according to the present invention, the high stability and high sensitivity angular velocity can be made to vibrate the vibrator accurately without the temperature change of the output becoming large without lowering the Q value even if it is miniaturized. A sensor can be obtained.

1 angular velocity sensor 3 diaphragm 5 weight (oscillator)
Reference Signs List 7 peripheral support portion 9 insulating film 11 lower electrode 13 piezoelectric thin film 15 vibration excitation electrode 17 angular velocity detection electrode 19 silicon substrate 21 adhesive 22 adhesive 23 package 24 vibration stabilization portion

Claims (9)

A diaphragm-type vibration excitation unit, a vibrator formed at the center of the vibration excitation unit, which vibrates in at least one of the X direction, Y direction or Z direction, and a peripheral support unit for supporting the periphery of the vibration excitation unit An angular velocity sensor consisting of
It further comprises a vibration stabilization unit joined to the peripheral support unit,
The vibration stabilizing portion is joined to the peripheral support portion by a silicon-based adhesive having a property of being soft when the frequency of vibration is low and rigid when the frequency of vibration is high,
The contour of the outer peripheral portion of the peripheral support portion has a rectangular shape, the contour of the outer shape of the vibration excitation portion has an octagon shape, and the vibrator has a cylindrical shape.
The thickness of the silicone adhesive after curing is 10 to 50 μm,
The angular velocity sensor according to claim 1, wherein the vibration stabilizing portion has a weight such that a total weight thereof with the peripheral support portion is at least 20 times a weight of the vibrator. The angular velocity sensor according to claim 1 , wherein the vibration stabilizing unit includes a silicon substrate. The angular velocity sensor according to claim 2 , wherein the vibration stabilizing unit includes a package in which the angular velocity sensor is fixed. The angular velocity sensor according to claim 1 , wherein the vibration stabilizing unit includes a metal plate made of tungsten or molybdenum. The vibration stabilizer is tungsten, the angular velocity sensor according molybdenum metal materials, silicon substrate, to claim 1 comprising a composite material formed by or laminated combining two or more materials selected from an organic material . The peripheral support portion and the vibration stabilizing portion are joined by the adhesive at four positions through which at least a pair of virtual orthogonal planes passing through the center of the vibrating body pass;
The angular velocity sensor according to any one of claims 1 to 5 , wherein the vibrator vibrates along the virtual orthogonal plane. The contour of the outer periphery of the peripheral support portion has a rectangular shape,
According to any one of the peripheral supporting portion of the virtual diagonal plane to claim 1 and said peripheral supporting portion at the position of the four points at least passing the vibration stabilization part is bonded by the adhesive 6 Angular velocity sensor. The angular velocity sensor according to any one of claims 1 to 7 , wherein a weight of the vibration stabilizing portion is 40 times or more of a weight of the vibrator. The peripheral support portion supports outer peripheral portions of the two vibration excitation portions,
The vibrator formed in the central region of one vibration excitation unit detects an angular velocity in a direction perpendicular to the vibration excitation unit;
The angular velocity sensor according to any one of claims 1 to 8 , wherein the vibrator formed in the central region of the other vibration excitation unit detects an angular velocity in a direction parallel to the vibration excitation unit.