Two-dimensional piezoelectric motor based on principle of reducing friction force through opposite movement and use method of two-dimensional piezoelectric motor

Abstract

The invention relates to the technical field of scanning probe microscopes, in particular to a two-dimensional piezoelectric motor based on the principle of reducing friction force through opposite movement and a use method of the two-dimensional piezoelectric motor. Through the unique structural design of the base, the upper-layer piezoelectric cross and the lower-layer piezoelectric cross, four-point horizontal sliding contact is formed between the upper-layer piezoelectric cross and the lower-layer piezoelectric cross, relative sliding displacement can be generated, and the ingenious structure can effectively reduce interference in the movement process; therefore, the displacement precision is remarkably improved, the strict requirement of the scanning probe microscope for high-precision displacement is met, and a reliable hardware basis is provided for more accurate sample detection and analysis. And meanwhile, the structure is simple and compact, the pre-tightening elastic force is self-adjusted, the output thrust is large, the electromagnetic interference is immune, the moving range is large, and the integration degree is high.

Description

Technical Field

[0001] The present invention relates to the technical field of scanning probe microscopes, and in particular to a two-dimensional piezoelectric motor based on the principle of reducing friction by moving toward each other and a method for using the same. Background Art

[0002] As the core component of multi-degree-of-freedom precision drive technology, the two-dimensional piezoelectric motor converts electrical energy into mechanical displacement through the inverse piezoelectric effect, which can achieve nanometer-level positioning in the plane. The piezoelectric material produces repeatable and accumulative electrostrictive deformation, which can achieve micrometer-level positioning and even millimeter-level travel. This composite motion capability is widely integrated into high-end equipment such as optoelectronic device packaging, biomedical operations, ultra-precision machine tool micro-feed systems, and scanning probe microscopes.

[0003] Although this type of motor has the characteristics of self-locking when power is off and no electromagnetic interference, in the existing technology, traditional SPM mostly uses a single-axis piezoelectric scanner stack to achieve two-dimensional motion, but it has problems such as large size and significant coupling errors, and it is difficult to meet the scanning requirements of high precision, high thrust and high stability.

[0004] In order to realize a high-precision, long-stroke piezoelectric motor with a simple structure, patent application CN112290826A discloses an X-electrode-divided cross multidimensional piezoelectric motor and a control method and a scanning probe microscope, the scanning probe microscope includes a slide and a cross-shaped piezoelectric body, an X-shaped electrode dividing line is arranged at the center of the cross-shaped piezoelectric body, the four arm electrodes of the cross-shaped piezoelectric body in the +X, -X, +Y, -Y directions are independent, and four equal positive pressures are set to press the free ends of the four arms on the sliding surface of the slide. The patent application has a simple and compact structure, the elastic force on the cross-shaped piezoelectric body is self-adjusting, the piezoelectric material has high efficiency of use, large thrust, wide stroke, and high symmetry.

[0005] Although the cross-shaped piezoelectric body is compatible with four directions and two degrees of freedom, it is easy to cause coupling errors, and even cause the displacement direction to deviate after the stroke is accumulated. Although the use of spring sheets makes the positive pressure of the four contact points between the cross-shaped piezoelectric body and the skateboard roughly equal, and the elastic force can basically be self-adjusted, the piezoelectric body has high strength in the vertical direction, and the preload force still depends on the parameters, structure and deformation degree of the spring sheet. The minimum operating voltage of the motor is still relatively high. Due to the weight of the piezoelectric body itself, a certain friction force is required for large thrust matching, and the minimum voltage required for stepping is still relatively high, resulting in low accuracy of displacement adjustment, so it needs to be solved urgently. Summary of the invention

[0006] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions. The present invention can effectively improve the displacement accuracy.

[0007] To achieve the above object, the present invention provides the following technical solutions: A two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion comprises a base, on which an upper piezoelectric cross and a lower piezoelectric cross are stacked in sequence from top to bottom; a sample holder is fixedly mounted on the upper piezoelectric cross, and the lower piezoelectric cross is fixedly mounted on the base; each arm of the upper piezoelectric cross and the lower piezoelectric cross can be deformed along the length direction of the arm, and a single-point contact is formed between the upper and lower corresponding arms of the upper piezoelectric cross and the lower piezoelectric cross, so that four-point horizontal contact is formed between the upper piezoelectric cross and the lower piezoelectric cross, and the upper and lower arms corresponding to each contact point can independently produce relative sliding displacement; a horizontally arranged spring sheet is cross-bracketed on the upper piezoelectric cross, and both ends of the spring sheet are fixedly mounted on the base, and the center of the spring sheet and the center of the upper piezoelectric cross are abutted against each other through a rolling ball, so that the spring sheet forms a seesaw structure.

[0008] As a further solution of the present invention: a sphere is fixedly mounted on the bottom of the telescopic end of each arm of the upper piezoelectric cross, and each sphere is pressed tightly on the corresponding arm of the lower piezoelectric cross thereunder to form the single-point contact.

[0009] As a further solution of the present invention: a rolling ball is sandwiched between the spring sheet and the upper piezoelectric cross, and the center of the rolling ball, the centroid of the upper piezoelectric cross, the centroid of the lower piezoelectric cross and the centroid of the spring sheet are located on the same plumb line in an initial state where no relative sliding displacement occurs.

[0010] As a further solution of the present invention: both ends of the spring sheet are fixedly mounted on the base through support blocks.

[0011] As a further solution of the present invention: both ends of the spring sheet are fixed to the support block by bolts, and the bolts can be tightened by threads to adjust the downward pressure of the spring sheet.

[0012] As a further solution of the present invention: the sample holder comprises a sample holder fixedly mounted on the upper piezoelectric cross, and a horizontally arranged slide is also fixedly mounted on the sample holder.

[0013] As a further solution of the present invention: an avoidance hole is provided on the sample holder to provide a rolling space for the rolling ball.

[0014] As a further solution of the present invention: a sapphire sleeve is fixedly installed on the telescopic end of each arm of the upper piezoelectric cross, and the ball is fixed on the bottom of the sapphire sleeve above it.

[0015] As a further solution of the present invention: the lower piezoelectric cross is connected to the fixing block by low-temperature vacuum glue, so as to be fixedly installed on the base.

[0016] A method for using a two-dimensional piezoelectric motor, the method using the above-mentioned two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions, and realizing one-step walking along the +X direction according to the following time sequence deformation steps: A1, the first upper arm of the upper piezoelectric cross is extended to its longest length, and the other arms remain stationary; A2, the third upper arm of the upper piezoelectric cross shrinks to its shortest, and the other arms remain stationary; A3, the upper first arm of the upper piezoelectric cross is in an extended state, and the upper third arm of the upper piezoelectric cross is in a contracted state; The upper second arm and the upper fourth arm of the upper piezoelectric cross are now simultaneously in an extended, contracted or undeformed state; A4, the upper first arm of the upper piezoelectric cross contracts in the opposite direction, while the upper third arm extends in the opposite direction, and the upper second arm and the upper fourth arm of the upper piezoelectric cross simultaneously perform periodic expansion and contraction deformation in the opposite direction for at least half a period, during which the lower second arm and the lower fourth arm of the lower piezoelectric cross perform reverse movement in the opposite direction to the upper second arm and the upper fourth arm of the upper piezoelectric cross, that is, the lower second arm moves in the opposite direction to the upper second arm, and the lower fourth arm moves in the opposite direction to the upper fourth arm; A5, the upper first arm of the upper piezoelectric cross is contracted to the shortest, and the upper third arm is extended to the longest, thus completing one step in the +X direction; The walking principle in other directions is the same as that in the +X direction.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a unique structural design of a base, an upper piezoelectric cross and a lower piezoelectric cross, so that four points of horizontal sliding contact are formed between the upper piezoelectric cross and the lower piezoelectric cross, and relative sliding displacement can be generated. This ingenious structure can effectively reduce errors and interferences during the movement process, thereby significantly improving the displacement accuracy, meeting the strict requirements of the scanning probe microscope for high-precision displacement, and providing a reliable hardware foundation for more accurate sample detection and analysis.

[0018] 2. A spherical ball is fixedly installed at the bottom of the telescopic end of each arm of the upper piezoelectric cross, and pressed against each arm corresponding to the lower piezoelectric cross to achieve single-point contact. This single-point contact design can further optimize the contact mode between the upper piezoelectric cross and the lower piezoelectric cross, reduce the contact area, reduce friction, make relative sliding smoother, and also help improve the sensitivity and accuracy of displacement, ensuring that the displacement can be more accurately controlled during the scanning process.

[0019] 3. A horizontally arranged spring sheet is placed on the upper piezoelectric cross, and the spring sheet is connected to the upper piezoelectric cross through a rolling ball, and the center of the rolling ball, the centroid of the upper piezoelectric cross, the centroid of the lower piezoelectric cross, and the centroid of the spring sheet are located on the same plumb line in the initial state. It not only provides a stable support structure for the upper piezoelectric cross, but the elasticity of the spring sheet can also buffer the impact force during movement to a certain extent. At the same time, the rolling characteristics of the rolling ball make the movement of the upper piezoelectric cross more flexible and precise, which helps to further improve the movement stability and displacement accuracy of the entire two-dimensional piezoelectric motor.

[0020] 4. Both ends of the spring sheet are fixedly mounted on the base through support blocks, which provides a reliable installation foundation for the spring sheet and ensures the position stability of the spring sheet during operation, so that the spring sheet can continue to effectively play its supporting and buffering role on the upper piezoelectric cross, enhancing the stability and reliability of the overall structure of the two-dimensional piezoelectric motor.

[0021] 5. Both ends of the spring sheet are fixed to the support block by bolts, and the bolts can be tightened through threads to adjust the downward pressure of the spring sheet. It has strong flexibility and practicality. The downward pressure of the spring sheet can be easily adjusted according to actual work requirements and sample characteristics, thereby optimizing the working performance of the two-dimensional piezoelectric motor to adapt to different scanning tasks and working conditions, thereby improving the versatility and applicability of the equipment.

[0022] 6. The sample holder provides a stable and horizontal platform for placing samples, ensuring the position accuracy of the samples during the scanning process, allowing the scanning probe microscope to accurately detect and analyze the samples. It also facilitates the installation and replacement of samples and improves work efficiency.

[0023] 7. An avoidance hole is opened on the sample holder to provide rolling space for the ball, which fully considers the movement requirements of the ball, avoids the interference of the sample holder on the rolling of the ball, and ensures that the ball can roll freely between the spring sheet and the upper piezoelectric cross, thereby ensuring the flexible movement of the upper piezoelectric cross and further improving the movement accuracy and stability of the two-dimensional piezoelectric motor.

[0024] 8. Sapphire sleeves are fixedly installed on the telescopic ends of each arm of the upper piezoelectric cross and the lower piezoelectric cross, and the ball is fixed to the bottom of the sapphire sleeve above it. Sapphire has excellent properties such as high hardness and good wear resistance. Installing a sapphire sleeve can effectively protect the telescopic end of the piezoelectric stack and extend its service life. At the same time, it improves the stability and reliability of the contact between the ball and the piezoelectric stack, reduces the displacement error caused by wear, and thus ensures the long-term stable operation and high-precision displacement performance of the two-dimensional piezoelectric motor.

[0025] 9. The lower piezoelectric cross is fixed on the base through a fixing block. This fixing method provides a firm installation structure for the lower piezoelectric cross, ensures the position stability of the lower piezoelectric cross during operation, and makes the structure of the entire two-dimensional piezoelectric motor more stable, which helps to improve the reliability and accuracy of the equipment during operation and ensure that relative sliding displacement can be accurately generated between the upper piezoelectric cross and the lower piezoelectric cross. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0027] Figure 2 It is a schematic diagram of the split structure of the present invention.

[0028] Figure 3 It is a side structural schematic diagram of the present invention.

[0029] Figure 4 It is a schematic diagram of the upper piezoelectric cross structure in the present invention.

[0030] Figure 5 It is a schematic diagram of the coordination structure of the upper piezoelectric cross and the lower piezoelectric cross in the present invention.

[0031] Figure 6 It is a curve diagram of voltage variation of each arm in the present invention.

[0032] Figure 7 It is a schematic diagram of the structure of the scanning probe microscope in the present invention.

[0033] Figure 8 It is a schematic diagram of the structure of the inner and outer frames of the present invention.

[0034] Fig. 9 It is a schematic diagram of the structure of the scanner device in the present invention.

[0035] In the figure: 1, base; 11, fixing block; 111, diamond groove; 12, supporting block; 13, spring sheet; 14, rolling ball; 22, piezoelectric stack; 23, sapphire sleeve; 231, sphere; 24, sample rack; 241, sample holder; 2411, avoidance hole; 242, specimen slide; 25, upper piezoelectric cross; 251, upper first arm; 252, upper second arm; 253, upper third arm; 254, upper fourth arm; 26, lower piezoelectric cross; 261, lower first arm; 262, lower second arm; 263, lower third arm; 264, lower fourth arm. 3. Outer frame; 31. Spring; 32. Hollow square hole; 33. Probe holder; 34. Sliding rod; 35. Light-entering square hole; 36. Light-receiving square hole; 37. Scanner device; 38. Inertial piezoelectric motor device. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] See also Figure 1 to Figure 5 In an embodiment of the present invention, a two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions comprises a base 1, on which an upper piezoelectric cross 25 and a lower piezoelectric cross 26 are stacked in sequence from top to bottom. A cross-shaped four-electrode dividing line is provided at the center of the upper piezoelectric cross 25. A pair of non-adjacent piezoelectric stacks 22 in the upper piezoelectric cross 25 are deformed along the +X or -X direction, which are referred to as the upper first arm 251 and the upper third arm 253. Another pair of non-adjacent piezoelectric stacks 22 are deformed along the +Y or -Y direction, which are referred to as the upper second arm 252 and the upper fourth arm 254. The telescopic ends of the upper first arm 251, the upper second arm 252, the upper third arm 253 and the upper fourth arm 254 are all fixedly sleeved with a sapphire sleeve 23. And a round ball 231 is fixedly installed at the bottom center of each sapphire sleeve 23. The upper first arm 251, the upper second arm 252, the upper third arm 253 and the upper fourth arm 254 are all arranged symmetrically about the vertical axis of motion at the center of the upper piezoelectric cross 25. A sample holder 24 is fixedly mounted on the upper plate surface of the upper piezoelectric cross 25. The sample holder 24 includes a sample holder 241 fixedly mounted on the upper plate surface. A horizontally arranged specimen slide 242 is also fixedly mounted on the sample holder 241. The sample is placed on the specimen slide 242 for subsequent scanning and detection. In order to make the center of gravity of the upper piezoelectric cross 25 coincide with the center of gravity of the sample holder 24, when the sample holder 24 is set, its axis of symmetry coincides with the above-mentioned vertical axis of motion, so that the pressure exerted by the four balls 231 on the lower piezoelectric cross 26 is the same.

[0038] There is also a cross-shaped four-electrode dividing line at the center of the lower piezoelectric cross 26. A pair of non-adjacent arms in the lower piezoelectric cross 26 are deformed along the +X or -X direction, which are called the lower first arm 261 and the lower third arm 263. Another pair of non-adjacent arms are deformed along the +Y or -Y direction, which are called the lower second arm 262 and the lower fourth arm 264. The telescopic ends of the lower first arm 261, the lower second arm 262, the lower third arm 263 and the lower fourth arm 264 are all fixedly sleeved with a sapphire sleeve 23. And each sapphire sleeve 23 is in contact with the sphere 231 above it. The lower first arm 261, the lower second arm 262, the lower third arm 263 and the lower fourth arm 264 are all arranged symmetrically with an auxiliary vertical axis perpendicular to the plate surface of the lower piezoelectric cross 26 and passing through its center. An outwardly extending diamond-shaped piece is provided between the lower first arm 261, the lower second arm 262, the lower third arm 263 and the lower fourth arm 264. Two fixing blocks 11 are fixedly mounted on the base 1, and diamond-shaped grooves 111 are provided on the opposite end surfaces of the two fixing blocks 11. The diamond-shaped piece is clamped in the diamond-shaped groove 111 to fix the lower piezoelectric cross 26 on the base 1.

[0039] In order to install the upper piezoelectric cross 25 on the lower piezoelectric cross 26, two support blocks 12 are fixedly installed on the base 1, and a spring sheet 13 is installed on the top of the two support blocks 12 at the same time. The two ends of the spring sheet 13 are fixed to the support blocks 12 by bolts, and the bolts can be tightened through threads to adjust the downward pressure of the spring sheet 13. A rolling ball 14 is sandwiched between the spring sheet 13 and the upper piezoelectric cross 25, and the center of the rolling ball 14 is located on the moving vertical axis. At the same time, the moving vertical axis and the auxiliary vertical axis coincide with each other. This is called the initial state where no relative sliding displacement occurs. When it is necessary to adjust the downward pressure of the spring sheet 13, by synchronously tightening the bolts at both ends of the spring sheet 13, the two ends of the spring sheet 13 can be synchronously raised or lowered, thereby changing the pressure of the spring sheet 13 on the upper piezoelectric cross 25. At the same time, the sample holder 241 is provided with an avoidance hole 2411 to provide a rolling space for the ball 14, so that when the upper piezoelectric cross 25 and the lower piezoelectric cross 26 have a relative sliding displacement, the ball 14 moves in the avoidance hole 2411 to prevent the ball 14 from escaping from the coverage of the spring sheet 13. The upper piezoelectric cross 25 relies on its own elasticity and the downward pressure of the spring sheet 13 to achieve point contact with the lower piezoelectric cross 26 in four directions, and exert four equal positive pressures on the lower piezoelectric cross 26.

[0040] The base 1 can be processed with structures such as long grooves and holes to facilitate the lead-out of electrode wires and the integrated and modular production of two-dimensional piezoelectric motors.

[0041] The spring sheet 13 applies pressure to the rolling ball 14 to press the upper piezoelectric cross 25 onto the lower piezoelectric cross 26. It is difficult for the four arms of the upper piezoelectric cross 25 and the lower piezoelectric cross 26 to contact each other accurately at the same time. The upper piezoelectric cross 25 and the lower piezoelectric cross 26 are made of piezoelectric materials with a thickness of only a few tenths of a millimeter. Therefore, when the spring sheet 13 and the rolling ball 14 are used to press the upper piezoelectric cross 25 onto the lower piezoelectric cross 26, it is difficult for the four arms of the upper piezoelectric cross 25 and the lower piezoelectric cross 26 to contact each other accurately at the same time. The ball 231 is set at the center of the two-dimensional plane of the upper piezoelectric cross 25. Since each piezoelectric stack 22 itself has only two layers, it maintains elasticity that can be deformed in the vertical direction. Therefore, the rolling ball 14 automatically distributes the vertical force to the four arms, similar to the seesaw principle, so that the positive pressure from the spring sheet 13 on the four arms of the lower piezoelectric cross 26 is automatically adjusted to be equal to ensure four-point contact. Therefore, when the four arms of the upper piezoelectric cross 25 are deformed, the friction forces they receive will also automatically be equal.

[0042] A spring sheet 13 is placed above the upper piezoelectric cross 25, and a rolling ball 14 is used to transmit pressure. This can fully protect the cross-shaped upper piezoelectric cross 25, reduce the wear of the upper piezoelectric cross 25, and provide sufficient preload between the upper piezoelectric cross 25 and the lower piezoelectric cross 26.

[0043] It can be seen that the upper piezoelectric cross 25 and the lower piezoelectric cross 26 are stacked with fewer layers of piezoelectric materials on the basis of ensuring the basic displacement capability, which not only reduces the deadweight of the motion structure, but also reduces the minimum voltage of the motor operation, enriching the use scenarios. Moreover, the structure is simple, the assembly process is easy, and the use and maintenance costs are reduced.

[0044] like Figure 6 As shown, S1 is the control signal waveform of the upper first arm 251 in the upper piezoelectric cross 25, S2 is the control signal waveform of the upper third arm 253 in the upper piezoelectric cross 25, S3 is the control signal waveform of the upper second arm 252 and the upper fourth arm 254 in the upper piezoelectric cross 25, S4 is the control signal waveform of the lower second arm 262 and the lower fourth arm 264 in the lower piezoelectric cross 26, A demonstrates the movement process of the upper piezoelectric cross 25; Vmax represents the maximum voltage value, Vmin represents the minimum voltage value; Te represents one cycle.

[0045] Taking the upper piezoelectric cross 25 moving one step along the +X direction as an example, the working process of the two-dimensional piezoelectric motor is demonstrated as follows: During operation, the upper second arm 252 and the upper fourth arm 254 are first placed in an extended, contracted or original length state at the same time. Next, the upper first arm 251 is kept extended to the longest state, and the upper third arm 253 is kept contracted to the shortest state. Subsequently, the upper first arm 251 and the upper third arm 253 are simultaneously deformed in the opposite direction until the upper first arm 251 is contracted to the shortest state, and the upper third arm 253 is extended to the longest state. During this process, the upper second arm 252 and the upper fourth arm 254 are simultaneously subjected to periodic expansion and contraction deformation at a higher frequency. Also during this process, synchronously, the lower second arm 262 and the lower fourth arm 264 of the lower piezoelectric cross 26 are subjected to periodic expansion and contraction deformation at a higher frequency relative to the upper piezoelectric cross 25.

[0046] Because when the upper second arm 252 and the upper fourth arm 254 are deformed toward each other, the two sliding friction forces along their length directions cancel each other out, and the sliding friction force perpendicular to the length direction of a single arm is also reduced to negligible. The deformation directions of the upper first arm 251 and the upper third arm 253 are the same, so that the upper piezoelectric cross 25 is subjected to two static friction forces in the same direction. The only problem is that the upper second arm 252 and the upper fourth arm 254 of the upper piezoelectric cross 25 must overcome the static friction force to evolve to the stage of being subjected to very small dynamic friction force, which leads to a larger starting working voltage and also causes the asymmetric amplification effect of the tiny friction force, resulting in the coupling of the freedom of movement, or even the jamming of the movement at a certain position. Therefore, the lower piezoelectric cross 26 is used to make the arms of the upper and lower piezoelectric crosses move in anti-phase, and as a result, the upper piezoelectric cross 25 will definitely overcome the static friction force and move, and thus be subjected to very small dynamic friction force. Finally, the sum of the maximum static friction forces on the upper second arm 252 and the upper fourth arm 254 is greater than the sum of the dynamic friction forces on the upper second arm 252 and the upper fourth arm 254. This will cause the center of the upper piezoelectric cross 25 to move a distance relative to the base 1. Then, the upper first arm 251 stretches and deforms to its longest length, and the other three arms remain stationary. Finally, the upper third arm 253 contracts and deforms to its shortest length, and the other three arms remain stationary. In this process, only one arm is deformed at a time, and the sum of the static friction forces on the other three arms is much greater than the sliding friction forces on one arm when it is deformed. Therefore, the center of the upper piezoelectric cross 25 remains unchanged relative to the base 1 during this process. At this point, the upper piezoelectric cross 25 has taken a step in the +X direction. Repeat the motion control process to achieve walking in the +X direction. Because the upper piezoelectric cross 25 is symmetrical in four directions, the motor can complete stepping in all four directions according to the above principle. It should be pointed out that in the above-mentioned stepping process, when the upper first arm 251 and the upper third arm 253 are simultaneously deformed in the opposite direction, the upper second arm 252 and the upper fourth arm 254 should have completed at least more than half a cycle of relative movement; otherwise, the working efficiency of the motor will be reduced or even unable to work. This is because: if the upper first arm 251 and the upper third arm 253 have begun to shrink or stretch for a period of time, and the upper second arm 252 and the upper fourth arm 254 are still in a static state, then during this period, the upper first arm 251 and the upper third arm 253 need to overcome the static friction between the upper second arm 252 and the upper fourth arm 254, and the lower second arm 262 and the lower fourth arm 264 to work. If the thrust output by the upper first arm 251 and the upper third arm 253 is greater than the static friction between the two layers, the motor can still work, but the output efficiency of the motor is reduced; otherwise, the motor cannot work normally.The higher the frequency of the periodic movement of the upper second arm 252 and the upper fourth arm 254, the less likely it is to produce a weak connection at the microscopic level of the contact surface, and the dynamic friction in the +X direction should also be reduced. The above analysis is also valid for the stepping motion process of the motor in four directions.

[0047] According to the above stepping process, the stepping in other directions can be completed. The maximum displacement in each direction is combined with each other to form a square area, and the two-dimensional piezoelectric motor can move arbitrarily in the square area.

[0048] like Figure 7~Figure 9 As shown, the two-dimensional piezoelectric motor of the present invention can also be used to make a corresponding scanning probe microscope, as follows: an outer frame 3 is sleeved on the outside of the base 1, and the outer frame 3 is installed on the corresponding fixed end through four springs 31 on its top.

[0049] A hollow square hole 32 is provided on one side of the outer frame 3, for the probe holder 33 to be grasped by the manipulator and transferred to the slide bar 34. At the same time, the manipulator grasping head can transfer the sample holder 24 to the avoidance hole 2411 of the sample holder 241, and place it on the sample holder 241 only by gravity.

[0050] The slide bar 34 clamps the probe holder 33 , so that by replacing different probe holders 33 , different scanning probes can be matched to achieve switching of functions of a series of scanning probe microscopes such as STM, AFM, MFM, and PFM.

[0051] On both sides of the hollow square hole 32 on the outer frame 3, there are completely symmetrical light-entering square holes 35 and light-receiving square holes 36, which can serve as a light source for STM atomic imaging driven by THz light, and characterize the electric field intensity and time domain information of THz scattered light. They can serve as a window for the interaction between light and matter, provide a path for light to irradiate samples, provide a platform for the detection and intensity characterization of weak THz light, and provide an optical path for infrared and far-infrared near-field imaging based on atomic force microscopy.

[0052] The two-dimensional piezoelectric motor is fixed to the outer frame 3 through the base 1 by screws, and an inertial piezoelectric motor device 38 is also installed in the outer frame 3, and the inertial piezoelectric motor device 38 drives the slide bar 34 to move up and down along the Z axis. A scanner device 37 is installed at the lower end of the slide bar 34, and a probe is installed on the probe frame 33 in the scanner device 37. When scanning, the two-dimensional piezoelectric motor can drive the sample to be tested to move on the XY two-dimensional plane, and the inertial piezoelectric motor device 38 drives the slide bar 34 to push the scanner device 37 fixed on the slide bar 34 to move in the Z axis direction, and then the scanner device 37 scans the sample to be tested through the probe on the probe frame 33.

[0053] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions, characterized in that: The invention comprises a base (1), on which an upper piezoelectric cross (25) and a lower piezoelectric cross (26) are stacked in order from top to bottom; a sample holder (24) is fixedly mounted on the upper piezoelectric cross (25), and the lower piezoelectric cross (26) is fixedly mounted on the base (1); each arm of the upper piezoelectric cross (25) and the lower piezoelectric cross (26) can be deformed along the length direction of the arm, and a single support is formed between the upper and lower corresponding arms of the upper piezoelectric cross (25) and the lower piezoelectric cross (26). Point contact is formed so that four points of horizontal contact are formed between the upper piezoelectric cross (25) and the lower piezoelectric cross (26), and the upper and lower arms corresponding to each contact point can independently generate relative sliding displacement; a horizontally arranged spring sheet (13) is horizontally mounted on the upper piezoelectric cross (25), both ends of the spring sheet (13) are fixedly mounted on the base (1), and the center of the spring sheet (13) and the center of the upper piezoelectric cross (25) are abutted against each other through a rolling ball (14), so that the spring sheet (13) forms a seesaw structure.

2. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 1, characterized in that: A sphere (231) is fixedly mounted at the bottom of the telescopic end of each arm of the upper piezoelectric cross (25), and each sphere (231) is pressed tightly against the corresponding arm of the lower piezoelectric cross (26) thereunder to form the single point contact.

3. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 1 or 2, characterized in that: The center of the rolling ball (14), the center of the upper piezoelectric cross (25), the center of the lower piezoelectric cross (26) and the center of the spring sheet (13) are located on the same plumb line in an initial state where no relative sliding displacement occurs.

4. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 3, characterized in that: Both ends of the spring sheet (13) are fixedly mounted on the base (1) via support blocks (12).

5. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 4, characterized in that: Both ends of the spring sheet (13) are fixed to the support block (12) by bolts, and the bolts can be tightened by threads to adjust the downward pressure of the spring sheet (13).

6. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 5, characterized in that: The sample holder (24) comprises a sample holder (241) fixedly mounted on an upper piezoelectric cross (25), and a horizontally arranged object slide (242) is also fixedly mounted on the sample holder (241).

7. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 6, characterized in that: The sample holder (241) is provided with an avoidance hole (2411) for providing a rolling space for the rolling ball (14).

8. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 7, characterized in that: A sapphire sleeve (23) is fixedly mounted on the telescopic end of each arm of the upper piezoelectric cross (25), and a round ball (231) is fixed to the bottom of the sapphire sleeve (23) above it.

9. A two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions according to claim 8, characterized in that: The lower piezoelectric cross (26) is connected to the fixing block (11) by glue, thereby being fixedly mounted on the base (1).

10. A method for using a two-dimensional piezoelectric motor, the method using the two-dimensional piezoelectric motor based on the principle of reducing friction by moving in opposite directions as claimed in claim 9, characterized in that: A one-step walk along the +X direction is achieved by following the following sequential deformation steps: A1, the upper first arm (251) of the upper piezoelectric cross (25) is extended to its longest length, and the remaining arms remain stationary; A2, the third upper arm (253) of the upper piezoelectric cross (25) is contracted to its shortest position, and the remaining arms remain stationary; A3, the upper first arm (251) of the upper piezoelectric cross (25) is in an extended state, and the upper third arm (253) of the upper piezoelectric cross (25) is in a contracted state; The upper second arm (252) and the upper fourth arm (254) of the upper piezoelectric cross (25) are simultaneously in an extended, contracted or undeformed state; A4, the upper first arm (251) of the upper piezoelectric cross (25) contracts in the opposite direction, while the upper third arm (253) stretches in the opposite direction, and the upper second arm (252) and the upper fourth arm (254) of the upper piezoelectric cross (25) simultaneously perform periodic expansion and contraction deformation in the opposite direction for at least half a cycle. During this process, the lower second arm (262) and the lower fourth arm (264) of the lower piezoelectric cross (26) perform opposite movement in the opposite direction to the upper second arm (252) and the upper fourth arm (254) of the upper piezoelectric cross (25), that is, the lower second arm (262) moves in the opposite direction to the upper second arm (252), and the lower fourth arm (264) moves in the opposite direction to the upper fourth arm (254); A5, the upper first arm (251) of the upper piezoelectric cross (25) is contracted to the shortest, and the upper third arm (253) is extended to the longest, thus completing a one-step walk along the +X direction; The walking principle in other directions is the same as that in the +X direction.

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