CN108036912B - A MEMS microstructure three-axis off-chip excitation device based on inverse piezoelectric effect - Google Patents

Abstract

The invention discloses a MEMS microstructure triaxial off-chip vibration device based on the inverse piezoelectric effect, which includes a sleeve, stacked piezoelectric ceramics, a pressure sensor, upper and lower connecting blocks and a MEMS microstructure; It is equipped with a support plate and an electric screw drive mechanism connected with the lower connecting block; the upper end of the lower connecting block is a hemispherical round head and rests on the bottom surface of the upper connecting block; the piezoelectric ceramic is clamped between the pressure sensor and the elastic support; Between the upper connection block and the sleeve, ball plungers are evenly distributed on the circumference, and the steel balls at the inner ends of the ball plunger are pushed into the chutes on the outer edge of the upper connection block respectively, and there are evenly distributed ball plungers in the sleeve that pass through the lower connection. The guide axis of the block. The device can flexibly apply different sizes of pre-tightening force to the stacked piezoelectric ceramics, so that the measured value of the pre-tightening force is more accurate, and the adjustment process of compensating the parallelism error of the two working surfaces of the stacked piezoelectric ceramics becomes smoother and smoother. , reducing the shear force between the layers of the stacked piezoelectric ceramics, which is convenient for testing the dynamic characteristic parameters of the MEMS microstructure.

Description

A MEMS microstructure three-axis off-chip excitation device based on inverse piezoelectric effect

technical field

The invention belongs to the technical field of micromechanical electronic systems, and in particular relates to a MEMS microstructure three-axis off-chip excitation device based on the inverse piezoelectric effect.

Background technique

Due to the advantages of low cost, small size and light weight, MEMS microdevices have broad application prospects in many fields such as automobile, aerospace, information communication, biochemistry, medical treatment, automatic control and national defense. For many MEMS devices, the micro-displacement and micro-deformation of their internal microstructures are the basis for the realization of device functions. Therefore, accurate testing of dynamic characteristic parameters such as the amplitude, natural frequency, and damping ratio of these microstructures has become the key to developing MEMS products. important content.

In order to test the dynamic characteristic parameters of the microstructure, it is first necessary to make the microstructure vibrate, that is, to excite the microstructure. Due to the small size, light weight and high natural frequency of MEMS microstructures, the excitation methods and excitation devices in traditional mechanical mode testing cannot be applied to the vibration excitation of MEMS microstructures. In the past thirty years, researchers at home and abroad have conducted a lot of explorations on the vibration excitation methods of MEMS microstructures, and have developed some excitation methods and corresponding excitation devices that can be used for MEMS microstructures. Among them, the base excitation device using stacked piezoelectric ceramics as the excitation source has the advantages of large excitation bandwidth, simple device, easy operation, and strong applicability, so it has been widely used in the field of MEMS microstructure dynamic characteristic testing. In the article "A base excitation test facility fordynamic testing of microsystems", David et al. introduced a base excitation device based on piezoelectric ceramics. In this device, stacked piezoelectric ceramics are directly bonded on a fixed base. The stacked piezoelectric ceramics is a multi-layer bonding structure, so the stacked piezoelectric ceramics can withstand a large pressure, but it cannot bear the tensile force. The tensile force will cause the damage of the stacked piezoelectric ceramics. When the stacked piezoelectric ceramics are in When in use, applying a certain pre-tightening force is beneficial to prolong the service life of stacked piezoelectric ceramics, but this device does not consider the above problems; Wang et al. in the article "Dynamic characteristic testing forMEMS micro-devices with base excitation" This paper introduces a base excitation device based on piezoelectric ceramics. In this device, the problem of applying a certain pre-tightening force to the stacked piezoelectric ceramics is considered. Electric ceramics, and the size of the pre-tightening force can be changed by turning the adjusting screw, but this device does not take into account that when the above-mentioned mechanism is used to apply the pre-tightening force to the stacked piezoelectric ceramics, due to the two working surfaces of the stacked piezoelectric ceramics The parallelism error will generate a shear force between the layers of the stacked piezoelectric ceramics, which will cause mechanical damage to the stacked piezoelectric ceramics. In addition, the device cannot measure the applied preload. If the size is not adjusted properly, it will also cause mechanical damage to the stacked piezoelectric ceramics.

The Chinese invention patent with the publication number CN101476970A discloses a base excitation device based on piezoelectric ceramics. In this device, a cross spring plate is used to apply a preload to the stacked piezoelectric ceramics, and the bottom of the stacked piezoelectric ceramics is installed On a movable base structure to reduce the shear force on the piezoelectric ceramics, in addition, a pressure sensor is also provided in the device to detect the pre-tightening force applied to the piezoelectric ceramics and stack piezoelectric ceramics output force at work. But this device still has following shortcoming:

1. The movable base structure of the device is composed of an upper connection block, a steel ball and a lower connection block. The steel ball, the upper connection block and the lower connection block are in line contact. When it is necessary to compensate the top surface of the stacked piezoelectric ceramics and the When the movable base structure is adjusted by itself due to the parallelism error of the two working surfaces on the bottom surface, the steel ball cannot rotate smoothly, and may even be stuck;

2. There is no direct connection between the upper connection block and the lower connection block and the sleeve, but are installed in the sleeve in turn by means of clearance fit. If the parallelism error of the two working surfaces of the stacked piezoelectric ceramics is large , there is not enough space to adjust the movable base structure;

3. The pressure sensor is installed at the bottom of the lower connecting block. Since the movable base structure is self-adjusted, there is a certain inclination between the bottom of the lower connecting block and the working surface of the piezoelectric ceramic, so the pre-tightening force measured by the pressure sensor Or the output force of piezoelectric ceramics is not accurate; in addition, if the movable base structure causes the upper coupling block or the lower coupling block to contact the sleeve after adjustment, the error of the measurement result will further increase;

4. In the device, one side of the cross spring is used to compress the stacked piezoelectric ceramics, and the other side of the cross spring is bonded to the micro device for testing. When the piezoelectric ceramics are working, the deformation of the cross spring is relatively large. Cause the colloid between the micro-device and the cross spring to crack, causing the micro-device to fall off;

5. In this device, gaskets of different thicknesses are used to change the magnitude of the pre-tightening force applied to the stacked piezoelectric ceramics, resulting in a complicated adjustment process and insufficient flexibility.

Contents of the invention

The technical problem to be solved by the present invention is to provide a MEMS microstructure three-axis off-chip excitation device based on the inverse piezoelectric effect, which can more flexibly apply different sizes of preload to the stacked piezoelectric ceramics, At the same time, the measured value of the pre-tightening force obtained is more accurate, and the adjustment process of compensating the parallelism error of the two working surfaces of the stacked piezoelectric ceramics becomes smoother and smoother, which greatly reduces the gap between the layers of the stacked piezoelectric ceramics. The shear force is convenient for testing the dynamic characteristic parameters of the MEMS microstructure.

In order to solve the above problems, the present invention adopts the following technical solutions:

A MEMS microstructure three-axis off-chip vibration device based on the inverse piezoelectric effect, including a sleeve and a bottom plate, and a stacked piezoelectric ceramic, a pressure sensor, an upper connection block and a lower connection block are arranged in the sleeve. There are elastic supports and MEMS microstructures on the sleeve, which are characterized by:

An annular top plate is provided on the upper end of the sleeve, and the MEMS microstructure is installed on the annular top plate through an elastic support; guide shafts are evenly distributed on the outer circumference of the sleeve between the annular top plate and the bottom plate, and along the circumferential direction on the sleeve wall U-shaped notches corresponding to the guide shafts are evenly distributed, and guide arms are evenly distributed on the outer periphery of the lower coupling block, and each guide arm is respectively passed through the corresponding U-shaped notch and fitted on the guide shaft;

The upper end of the lower connecting block is a hemispherical round head and is pushed against the center of the bottom plane of the upper connecting block, so that a point contact is formed between the upper and lower connecting blocks; the pressure sensor is embedded in the center hole on the top surface of the upper connecting block Inside, stacked piezoelectric ceramics are clamped between the pressure sensor and the elastic support;

Between the upper connection block and the sleeve, ball plungers are evenly distributed on the circumference, and the outer ends of the ball plungers are respectively connected in the plunger mounting seats arranged on the wall of the sleeve along the circumferential direction, and the steel balls at the inner ends of the ball plungers They are pushed into the chutes uniformly distributed on the outer edge of the upper connection block along the circumferential direction, and are used to assist the upper connection block to compensate for the adjustment of the parallelism error of the two working surfaces of the stacked piezoelectric ceramics;

A supporting plate is arranged at the lower part of the sleeve, and an electric screw drive mechanism is installed vertically in the center of the support plate. The screw nut of the electric screw drive mechanism is connected with the lower connecting block for driving the lower connecting block to move up and down.

As a further preference, screw holes are evenly distributed along the circumferential direction on the wall of the sleeve, and the plunger mounting seats are respectively installed in the screw holes through threads.

As a further preference, the number of the U-shaped notches is equivalent to that of the screw holes and they are arranged equidistantly from each other along the circumferential direction of the sleeve.

As a further preference, the elastic support member is composed of a cylindrical pressing piece and three supporting pieces whose circumference is evenly distributed on the outer edge of the pressing piece, the thickness of the supporting pieces is smaller than the thickness of the pressing piece; to reduce the pressure of the pressing piece The amount of deformation can avoid the MEMS microstructure falling off due to colloidal cracking.

As a further preference, the outer ends of the three supporting sheets of the elastic supporting member are respectively supported and fixed on the annular top plate through pillars.

As a further preference, there are three guide shafts.

As a further preference, a mounting sleeve is fastened on the upper end of the stacked piezoelectric ceramics, and the elastic support is pressed on the mounting sleeve to avoid the stacked piezoelectric ceramics caused by the roughness of the top working surface of the stacked piezoelectric ceramics. Poor contact between ceramic and elastic supports.

As a further preference, each guide arm is respectively provided with a through hole for passing the guide shaft, and a shaft sleeve is respectively embedded in the through hole.

As a further preference, adjusting rods corresponding to the U-shaped notches are evenly distributed on the outer circumference of the upper connecting block, and the outer ends of the adjusting rods protrude from the corresponding U-shaped notches respectively; for realizing the reset of the upper connecting block after the test .

The beneficial effects of the present invention are:

1. Since the upper end of the lower connecting block is a hemispherical round head and is pushed against the center of the bottom plane of the upper connecting block, a point contact is formed between the upper and lower connecting blocks; when it is necessary to compensate the parallelism of the two working surfaces of the stacked piezoelectric ceramics When the movable base is adjusted according to the error, the upper connecting block will swing with the contact point with the lower connecting block as the center of rotation. Shear force between layers.

2. Since the ball plunger is evenly distributed on the circumference between the upper connection block and the sleeve, the outer ends of the ball plunger are respectively connected in the plunger mounting seats arranged on the wall of the sleeve along the circumferential direction, and the ball plunger The steel balls at the inner end are pushed into the chutes uniformly distributed on the outer edge of the upper connection block along the circumferential direction; when it is necessary to compensate the parallelism error of the two working surfaces of the stacked piezoelectric ceramics to adjust the movable base, the ball head column can be used to adjust the movable base. The spring in the plug cooperates with the steel ball to realize the swing of the upper connecting block in different directions, and the adjustable space is larger.

3. Since the pressure sensor is embedded in the center hole on the top surface of the upper connection block, the stacked piezoelectric ceramics are clamped between the pressure sensor and the elastic support, so when the pre-tightening force is applied to the stacked piezoelectric ceramics, avoid The interference of the movable base structure on the pressure sensor can be eliminated, and more accurate pre-tightening force data can be obtained; when the stacked piezoelectric ceramics work, the measured value of the excitation force obtained is also more accurate.

4. Since the guide arms are evenly distributed on the outer edge of the lower connection block and each guide arm passes through the corresponding U-shaped notch and is fitted on the guide shaft, an electric screw is installed in the center of the support plate along the vertical direction. Transmission mechanism, the screw nut of the electric screw transmission mechanism is connected with the lower connection block. When it is necessary to apply different sizes of pretightening force to the stacked piezoelectric ceramics, the upper connection block and the lower connection block can be driven by controlling the electric screw transmission mechanism. Realized by a movable base composed of blocks, the adjustment process becomes simple and flexible.

Description of drawings

Fig. 1 is a schematic diagram of the three-dimensional structure of the present invention.

Figure 2 is a top view of the present invention.

Fig. 3 is a cross-sectional view along line A-A of Fig. 2 .

Fig. 4 is a top view of the present invention with the annular top plate removed.

Fig. 5 is a schematic perspective view of the lower connection block.

Fig. 6 is a schematic perspective view of the three-dimensional structure of the elastic support.

Fig. 7 is a schematic perspective view of the three-dimensional structure of the sleeve.

In the figure: 1. Sleeve, 101. U-shaped notch, 102. Screw hole, 2. Annular top plate, 3. Bottom plate, 4. MEMS microstructure, 5. Microstructure mounting plate, 6. Elastic support, 601. Pressure Sheet, 602. Support sheet, 7. Prop, 8. Mounting sleeve, 9. Ball plunger, 10. Stacked piezoelectric ceramics, 11. Pressure sensor, 12. Adjusting rod, 13. Upper connecting block, 1301. Slide Groove, 14. Plunger mounting seat, 15. Lower coupling block, 1501. Guide arm, 16. Screw nut, 17. Support plate, 18. Linear stepping motor, 19. Guide shaft, 20. Bushing, 21. lead screw.

Detailed ways

As shown in Figures 1 to 7, a MEMS microstructure three-axis off-chip vibration device based on the inverse piezoelectric effect involved in the present invention includes a hollow sleeve 1, and a stack pressure device is arranged in the sleeve 1. The electric ceramic 10, the pressure sensor 11 and the movable base composed of the upper connecting block 13 and the lower connecting block 15 are provided with an elastic support 6 and a MEMS microstructure 4 on the sleeve 1 .

An annular top plate 2 and a bottom plate 3 are respectively fixed on the upper surface and the bottom surface of the sleeve 1 by screws, and the MEMS microstructure 4 is mounted on the annular top plate 2 through an elastic support 6 . Described elastic support member 6 is made of a cylindrical pressing piece 601 and three supporting pieces 602 that the circumference is evenly distributed on pressing piece 601 outer edge, and the thickness of described supporting piece 602 is less than the thickness of pressing piece 601; The amount of deformation of the sheet 601 can prevent the MEMS microstructure 4 from falling off due to cracking of the colloid. The outer ends of the three supporting pieces 602 of the elastic supporting member 6 are respectively supported and fixed on the annular top plate 2 through the hollow pillar 7 with screws, and are on the same axis as the sleeve 1 . The MEMS microstructure 4 is fixed on the center of the upper surface of the pressing piece 601 of the elastic support 6 through the microstructure mounting plate 5 .

Both the upper coupling block 13 and the lower coupling block 15 are cylindrical and fit with the inner wall of the sleeve 1 with a large gap respectively. Make point contact between the upper and lower connecting blocks.

The pressure sensor 11 is embedded and bonded in the center hole of the top surface of the upper connecting block 13, the stacked piezoelectric ceramic 10 is cylindrical and the lower end is bonded to the pressure sensor 11, and the two ends of the stacked piezoelectric ceramic 10 are clamped Hold between the pressure sensor 11 and the pressure piece 601 of the elastic support member 6 . A mounting sleeve 8 is fastened and bonded to the upper end of the stacked piezoelectric ceramics 10, and the pressing piece 601 of the elastic support member 6 is pressed on the mounting sleeve 8 to avoid roughness of the top working surface of the stacked piezoelectric ceramics 10. The problem of poor contact between the stacked piezoelectric ceramics 10 and the elastic support 6 caused by unevenness.

Between the annular top plate 2 and the bottom plate 3, there are three guide shafts 19 evenly distributed on the outside of the sleeve 1 through screws, and three U-shaped notches corresponding to the guide shafts 19 are uniformly distributed along the circumference of the sleeve wall. 101. There are three guide arms 1501 evenly distributed on the outer edge of the lower coupling block 15, and each guide arm 1501 passes through the corresponding U-shaped notch 101 and is sleeved on the guide shaft 19 through clearance fit. Through holes for penetrating the guide shafts are respectively provided on the top, and shaft sleeves 20 are respectively embedded in the through holes.

Between the upper coupling block 13 and the sleeve 1, ball plungers 9 are evenly distributed on the circumference. In this embodiment, three ball plungers 9 are taken as an example. The direction is evenly arranged in the plunger mounting seat 14 on the sleeve wall, and there are three screw holes 102 evenly distributed along the circumferential direction on the sleeve wall. 1. The outer side is screwed into the screw hole 102 by threads. The steel balls at the inner end of the ball plunger 9 are respectively driven into three rectangular chute 1301 distributed uniformly on the outer edge of the upper coupling block along the circumferential direction. The chute 1301 is parallel to the axis of the sleeve 1 and is used to assist the upper coupling. The block compensates the adjustment of the parallelism error of the two working surfaces of the stacked piezoelectric ceramics.

The number of U-shaped notches 101 is equivalent to the number of screw holes and are arranged at equal distances from each other along the circumferential direction of the sleeve 1. The center line of each U-shaped notch 101 and the center of the circle between the center line of the adjacent screw hole 102 and the axis of the sleeve The angle is 60 degrees.

A support plate 17 is fixed by screws at the bottom step of the sleeve 1, and an electric screw drive mechanism is installed in the center of the support plate 17 along the vertical direction. The lead screw 21 of the output shaft of the stepping motor 18 and the screw nut 16 are formed, wherein the linear stepping motor 18 is installed on the bottom surface of the support plate 17, the upper end of the screw screw 21 is inserted into the center hole of the bottom surface of the lower connecting block 15, and the screw nut 16 is connected with the lower The blocks 15 are connected by screws evenly distributed on the circumference, and are used to drive the lower coupling block 15 to slide up and down in the sleeve 1 in the vertical direction under the guidance of the guide shaft 16 .

The outer edge of the upper coupling block 13 is evenly distributed on the circumference of the outer edge of the connecting block 12, and the adjusting rod 12 corresponding to the U-shaped notch 101 is connected one by one. Type notch 101 stretches out; For realizing the reset of upper connection block 13 after the test.

When working, firstly control the linear stepper motor 18 to push up the movable base composed of the upper coupling block 13 and the lower coupling block 15 through the transmission of the lead screw 21 and the nut 16 to apply a pre-tightening force to the stacked piezoelectric ceramics 10, and at the same time The pre-tightening force data measured by the pressure sensor 11 is monitored, and when the pre-tightening force reaches a set value, the linear stepper motor 18 is controlled to stop working. Then, an external power supply is used to apply a pulse signal or a frequency sweep signal between the two electrodes of the stacked piezoelectric ceramics 10, and the inverse piezoelectric effect of the stacked piezoelectric ceramics 10 is used to excite the MEMS microstructure 4. The contact vibration measuring device detects the vibration response of the MEMS microstructure 4 , and the pressure sensor 11 is used to detect the output force of the stacked piezoelectric ceramics 10 . Finally, after the excitation of the MEMS microstructure 4 is completed, the linear stepping motor 18 is controlled to drive the lower coupling block 15 to move downward, and then the upper coupling block 13 is driven to move downward by manually adjusting the adjustment lever 12, so that the stacked piezoelectric ceramics 10 The top mounting sleeve 8 is separated from the elastic support member 6 to prevent the stacked piezoelectric ceramics 10 from being under stress all the time.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (9)

1. A MEMS microstructure triaxial off-chip vibration device based on the inverse piezoelectric effect, including a sleeve and a bottom plate, and a stacked piezoelectric ceramic, a pressure sensor, an upper connection block and a lower connection block are arranged in the sleeve , with elastic supports and MEMS microstructures on the sleeve, which is characterized by: An annular top plate is provided on the upper end of the sleeve, and the MEMS microstructure is installed on the annular top plate through an elastic support; guide shafts are evenly distributed on the outer circumference of the sleeve between the annular top plate and the bottom plate, and along the circumferential direction on the sleeve wall U-shaped notches corresponding to the guide shafts are evenly distributed, and guide arms are evenly distributed on the outer periphery of the lower coupling block, and each guide arm is respectively passed through the corresponding U-shaped notch and fitted on the guide shaft; The upper end of the lower connecting block is a hemispherical round head and is pushed against the center of the bottom plane of the upper connecting block, so that a point contact is formed between the upper and lower connecting blocks; the pressure sensor is embedded in the center hole on the top surface of the upper connecting block Inside, stacked piezoelectric ceramics are clamped between the pressure sensor and the elastic support; Between the upper connection block and the sleeve, ball plungers are evenly distributed on the circumference, and the outer ends of the ball plungers are respectively connected in the plunger mounting seats arranged on the wall of the sleeve along the circumferential direction, and the steel balls at the inner ends of the ball plungers They are pushed into the chutes uniformly distributed on the outer edge of the upper connection block along the circumferential direction, and are used to assist the upper connection block to compensate for the adjustment of the parallelism error of the two working surfaces of the stacked piezoelectric ceramics; A supporting plate is arranged at the lower part of the sleeve, and an electric screw drive mechanism is installed vertically in the center of the support plate. The screw nut of the electric screw drive mechanism is connected with the lower connecting block for driving the lower connecting block to move up and down. 2. A kind of MEMS microstructure triaxial type off-chip excitation device based on inverse piezoelectric effect according to claim 1, it is characterized in that: screw holes are evenly distributed along the circumferential direction on the sleeve wall, and the column The plug mounting seats are respectively installed in the screw holes by threads. 3. A MEMS microstructure three-axis off-chip vibration device based on the inverse piezoelectric effect according to claim 2, characterized in that: said U-shaped notch is equivalent to the number of screw holes and mutually along the circumferential direction of the sleeve. Equidistantly spaced. 4. A MEMS microstructure triaxial off-chip excitation device based on the inverse piezoelectric effect according to claim 1, characterized in that: the elastic support is composed of a cylindrical pressing piece and a circumference uniformly distributed on the The three supporting sheets on the outer edge of the pressing sheet are formed, and the thickness of the supporting sheet is smaller than that of the pressing sheet; in order to reduce the deformation of the pressing sheet and prevent the MEMS microstructure from falling off due to colloidal cracking. 5. A MEMS microstructure triaxial off-chip vibration device based on the inverse piezoelectric effect according to claim 4, characterized in that: the outer ends of the three support pieces of the elastic support are respectively supported and fixed by pillars on top of the ring top. 6. A MEMS microstructure three-axis off-chip excitation device based on inverse piezoelectric effect according to claim 1 or 3, characterized in that: there are three guide shafts. 7. A MEMS microstructure three-axis off-chip excitation device based on the inverse piezoelectric effect according to claim 1, 3 or 4, characterized in that: a mounting sleeve is buckled on the upper end of the stacked piezoelectric ceramics, The elastic support is pressed on the mounting sleeve to avoid poor contact between the stacked piezoelectric ceramics and the elastic support due to the roughness of the top working surface of the stacked piezoelectric ceramics. 8. A kind of MEMS microstructure three-axis type off-chip excitation device based on the inverse piezoelectric effect according to claim 6, characterized in that: each guide arm is respectively provided with a passage for passing through the guide shaft. Holes and sleeves are respectively embedded in the through holes. 9. A MEMS microstructure three-axis off-chip vibration device based on the inverse piezoelectric effect according to claim 1 or 3, characterized in that: U-shaped notches are evenly distributed on the outer edge of the upper connecting block One-to-one corresponding adjustment rods, the outer ends of the adjustment rods protrude from the corresponding U-shaped notches; they are used to realize the reset of the upper coupling block after the test.