A two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion and its use method

Abstract

The present invention relates to the field of scanning probe microscope technology, and specifically to a two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion, and a method for using the same. The present invention uses a unique base, as well as the structural design of the upper piezoelectric cross and the lower piezoelectric cross, to form a four-point horizontal sliding contact between the upper piezoelectric cross and the lower piezoelectric cross, and can generate relative sliding displacement. This ingenious structure can effectively reduce interference 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 achieving more accurate sample detection and analysis. At the same time, the present invention has a simple and compact structure, self-adjusting preload elastic force, large output thrust, immunity to electromagnetic interference, large range of movement, and high integration.

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 in opposite directions and a method for using the same. Background Art

[0002] As a 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, enabling nanometer-level positioning within a plane. By generating repeatable and accumulative electrostrictive deformation through piezoelectric materials, it 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 characteristics such as self-locking when power is off and no electromagnetic interference, in existing technologies, traditional SPMs mostly use a stack of single-axis piezoelectric scanners to achieve two-dimensional motion, but they have problems such as large size and significant coupling errors, making it difficult to meet the scanning requirements of high precision, high thrust and high stability.

[0004] To achieve high-precision, long-stroke piezoelectric motors while maintaining a simple structure, patent application CN112290826A discloses an X-electrode-segmented cross-shaped multidimensional piezoelectric motor, control method, and scanning probe microscope. The scanning probe microscope comprises a slide and a cross-shaped piezoelectric element, with an X-shaped electrode dividing line defined at its center. The cross-shaped piezoelectric element has four independent arm electrodes in the +X, -X, +Y, and -Y directions, each bearing four equal positive pressures that press the free ends of the four arms against the slide surface. This patent application boasts a simple and compact structure, self-regulating elastic forces acting on the cross-shaped piezoelectric element, efficient piezoelectric material utilization, high thrust, a wide stroke, and high symmetry.

[0005] Although the cross-shaped piezoelectric element 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 accumulates. Although the use of spring sheets makes the positive pressure at the four contact points between the cross-shaped piezoelectric element and the slide roughly equal, and the elastic force can basically be self-adjusted, the piezoelectric element 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 element itself, a certain amount of friction is required for large thrust. The minimum voltage required for stepping is still relatively high, resulting in low accuracy of displacement adjustment, which 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 displacement accuracy.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion includes 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 generate relative sliding displacement; a horizontally arranged spring sheet is horizontally mounted 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 in contact with each other through a rolling ball, so that the spring sheet forms a seesaw structure.

[0009] As a further solution of the present invention: a ball is fixedly installed at the bottom of the telescopic end of each arm of the upper piezoelectric cross, and each ball is pressed tightly on the corresponding arm of the lower piezoelectric cross thereunder to form the single-point contact.

[0010] 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.

[0011] As a further solution of the present invention: both ends of the spring sheet are fixedly mounted on the base via support blocks.

[0012] 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.

[0013] As a further solution of the present invention: the sample holder includes a sample holder fixedly mounted on the upper piezoelectric cross, and a horizontally arranged slide is also fixedly mounted on the sample holder.

[0014] As a further solution of the present invention, a avoidance hole is opened on the sample holder to provide rolling space for the rolling ball.

[0015] 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 to the bottom of the sapphire sleeve above it.

[0016] 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.

[0017] A method for using a two-dimensional piezoelectric motor, which applies the above-mentioned two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion, to achieve one-step walking along the +X direction according to the following time-sequence deformation steps:

[0018] A1, the first upper arm of the upper piezoelectric cross is extended to its longest length, and the other arms remain stationary;

[0019] A2, the third upper arm of the upper piezoelectric cross is retracted to its shortest position, while the other arms remain stationary;

[0020] 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;

[0021] The upper second arm and the upper fourth arm of the upper piezoelectric cross are simultaneously in an extended, contracted or undeformed state at this time;

[0022] 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. The upper second arm and the upper fourth arm of the upper piezoelectric cross simultaneously perform periodic expansion and contraction deformation in opposite directions for at least half a cycle. During this process, the lower second arm and the lower fourth arm of the lower piezoelectric cross perform opposite motions 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.

[0023] A5: The first arm of the upper piezoelectric cross shrinks to its shortest position, while the third arm of the upper piezoelectric cross extends to its longest position, completing one step in the +X direction.

[0024] The walking principle in other directions is the same as that in the +X direction.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention utilizes a unique structural design of a base, an upper piezoelectric cross, and a lower piezoelectric cross to form four-point horizontal sliding contact between the upper and lower piezoelectric crosses and generate relative sliding displacement. This ingenious structure can effectively reduce errors and interference during movement, thereby significantly improving displacement accuracy, meeting the strict requirements of scanning probe microscopes for high-precision displacement, and providing a reliable hardware foundation for more accurate sample detection and analysis.

[0027] 2. By fixing a ball at the bottom of the telescopic end of each arm of the upper piezoelectric cross and pressing it against the corresponding arm of the lower piezoelectric cross, single-point contact is achieved. This single-point contact design can further optimize the contact between the upper and lower piezoelectric crosses, reducing the contact area, lowering friction, and making relative sliding smoother. It also helps to improve the sensitivity and accuracy of displacement, ensuring more accurate control of displacement during the scanning process.

[0028] 3. A horizontally arranged spring sheet rests on the upper piezoelectric cross, connected to the upper piezoelectric cross via a rolling ball. Initially, 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 all lie on the same vertical line. This not only provides a stable support structure for the upper piezoelectric cross, but the spring sheet's elasticity also cushions impact forces during movement. The rolling nature of the rolling ball also enhances the flexibility and precision of the upper piezoelectric cross's movement, further improving the overall stability and displacement accuracy of the 2D piezoelectric motor.

[0029] 4. Both ends of the spring sheet are fixedly mounted on the base through support blocks, providing a reliable installation foundation for the spring sheet and ensuring 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, thereby enhancing the stability and reliability of the overall structure of the two-dimensional piezoelectric motor.

[0030] 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, and improving the versatility and applicability of the equipment.

[0031] 6. The sample holder provides a stable and level platform for placing samples, ensuring the position accuracy of the samples during the scanning process, enabling the scanning probe microscope to accurately detect and analyze the samples. It also facilitates the installation and replacement of samples, improving work efficiency.

[0032] 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.

[0033] 8. Sapphire sleeves are fixed to the telescopic ends of each arm of the upper and lower piezoelectric crosses, 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 the sapphire sleeve effectively protects the telescopic ends of the piezoelectric stack, extending its service life. It also improves the stability and reliability of the contact between the ball and the piezoelectric stack, reducing displacement errors caused by wear, thereby ensuring the long-term stable operation and high-precision displacement performance of the two-dimensional piezoelectric motor.

[0034] 9. The lower piezoelectric cross is fixed on the base through a fixing block. This fixing method provides a firm mounting 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 ensures that relative sliding displacement can be accurately generated between the upper piezoelectric cross and the lower piezoelectric cross. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0036] Figure 2 It is a schematic diagram of the split structure of the present invention.

[0037] Figure 3 It is a side structural schematic diagram of the present invention.

[0038] Figure 4 Schematic diagram of the upper piezoelectric cross structure in the present invention.

[0039] Figure 5 This is a schematic diagram of the coordination structure between the upper piezoelectric cross and the lower piezoelectric cross in the present invention.

[0040] Figure 6 Graph showing voltage variation of each arm in the present invention.

[0041] Figure 7 Schematic diagram of the structure of the scanning probe microscope in the present invention.

[0042] Figure 8 It is a structural diagram of the inner and outer frames of the present invention.

[0043] Figure 9 Schematic diagram of the structure of the scanner device in the present invention.

[0044] 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 holder; 241. sample holder; 2411. avoidance hole; 242. 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 entrance square hole; 36. Light receiving square hole; 37. Scanner device; 38. Inertial piezoelectric motor device. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0046] See also Figures 1 to 5In an embodiment of the present invention, a two-dimensional piezoelectric motor based on the principle of reducing friction through opposite motion includes a base 1 on which are stacked, from top to bottom, an upper piezoelectric cross 25 and a lower piezoelectric cross 26, both of which are cross-shaped. The center of the upper piezoelectric cross 25 has a cross-shaped four-electrode dividing line. A pair of non-adjacent piezoelectric stacks 22 in the upper piezoelectric cross 25 deform along the +X or -X direction, referred to as the upper first arm 251 and the upper third arm 253. Another pair of non-adjacent piezoelectric stacks 22 deform along the +Y or -Y direction, 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 fixedly sheathed with a sapphire sleeve 23. A sphere 231 is fixedly mounted 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 slide 242 is also fixedly mounted on the sample holder 241. The sample is placed on the 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 and the above-mentioned vertical axis of motion coincide with each other, so that the pressure exerted by the four balls 231 on the lower piezoelectric cross 26 is the same.

[0047] The center of the lower piezoelectric cross 26 also has a cross-shaped four-electrode dividing line. A pair of non-adjacent arms in the lower piezoelectric cross 26 deforms along the +X or -X direction, referred to as the lower first arm 261 and the lower third arm 263. Another pair of non-adjacent arms deforms along the +Y or -Y direction, referred to as 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 sheathed with sapphire sleeves 23. Each sapphire sleeve 23 abuts against 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 about an auxiliary vertical axis perpendicular to the surface of the lower piezoelectric cross 26 and passing through its center. An outwardly extending diamond-shaped piece is provided between each of 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 formed on the opposing end surfaces of the two fixing blocks 11. The diamond-shaped piece is clamped in the diamond-shaped grooves 111 to securely mount the lower piezoelectric cross 26 on the base 1.

[0048] 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 by 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, the two ends of the spring sheet 13 can be synchronously raised or lowered by synchronously tightening the bolts at both ends of the spring sheet 13, thereby changing the pressure of the spring sheet 13 on the upper piezoelectric cross 25. The sample holder 241 also includes a clearance hole 2411 to provide rolling space for the ball 14. When the upper piezoelectric cross 25 and the lower piezoelectric cross 26 slide relative to each other, the ball 14 moves within the clearance hole 2411, preventing it from escaping the coverage of the spring sheet 13. The upper piezoelectric cross 25, relying on its own elasticity and the downward pressure of the spring sheet 13, achieves point contact with the lower piezoelectric cross 26 in four directions, exerting four equal positive pressures on the lower piezoelectric cross 26.

[0049] The base 1 can be processed with structures such as long grooves and holes to facilitate the lead-out of electrode wires and facilitate the integrated and modular production of two-dimensional piezoelectric motors.

[0050] The spring sheet 13 applies pressure to the rolling ball 14, pressing the upper piezoelectric cross 25 against the lower piezoelectric cross 26. However, it is difficult for the four arms of the upper and lower piezoelectric crosses 25, 26 to simultaneously and accurately contact each other. The upper and lower piezoelectric crosses 25, 26 are made of a piezoelectric material that is only a few tenths of a millimeter thick. Therefore, when the spring sheet 13 and rolling ball 14 are used to press the upper piezoelectric cross 25 against the lower piezoelectric cross 26, it is difficult for the four arms of the upper and lower piezoelectric crosses 25, 26 to simultaneously and accurately contact each other. Ball 231 is positioned at the two-dimensional center of the upper piezoelectric cross 25. Because each piezoelectric stack 22 consists of only two layers, it maintains elasticity and allows for vertical deformation. Therefore, ball 14 automatically distributes vertical force to the four arms, similar to the seesaw principle. This automatically equalizes the positive pressure from spring sheet 13 applied to the four arms of the lower piezoelectric cross 26, ensuring four-point contact. Consequently, when the four arms of the upper piezoelectric cross 25 deform, the frictional forces they experience are also automatically equalized.

[0051] 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.

[0052] As can be seen, while maintaining basic displacement capability, stacking the upper and lower piezoelectric crosses 25 and 26 using fewer layers of piezoelectric material not only reduces the weight of the moving structure but also lowers the minimum operating voltage of the motor, enriching its use cases. Furthermore, the structure is simple, assembly is easy, and operating and maintenance costs are reduced.

[0053] 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, and 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.

[0054] 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:

[0055] During operation, the upper second arm 252 and the upper fourth arm 254 are first simultaneously extended, contracted, or in their original length. Next, the upper first arm 251 remains extended to its longest state, while the upper third arm 253 remains contracted to its shortest state. Subsequently, the upper first arm 251 and the upper third arm 253 simultaneously deform in the opposite direction, until the upper first arm 251 contracts to its shortest state and the upper third arm 253 extends to its longest state. During this process, the upper second arm 252 and the upper fourth arm 254 simultaneously perform periodic expansion and contraction deformation movements toward each other at a high frequency. Also during this process, synchronously, the lower second arm 262 and the lower fourth arm 264 of the lower piezoelectric cross 26 perform periodic expansion and contraction deformation movements toward each other at a high frequency relative to the upper piezoelectric cross 25.

[0056] Because when the upper second arm 252 and the upper fourth arm 254 deform toward each other, the two sliding friction forces along their lengths cancel each other out, reducing the sliding friction perpendicular to their lengths to a negligible level. The upper first arm 251 and the upper third arm 253 deform in the same direction, subjecting the upper piezoelectric cross 25 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 static friction to reach a stage where they experience minimal dynamic friction. This results in a higher starting voltage and asymmetric amplification of the tiny friction forces, leading to coupling of degrees of freedom and even stalling of movement at certain locations. Therefore, the lower piezoelectric cross 26 is used to cause the upper and lower piezoelectric cross arms to move in antiphase. As a result, the upper piezoelectric cross 25 will inevitably overcome static friction and move, thus experiencing minimal dynamic friction. Eventually, the sum of the maximum static friction forces acting on the second and fourth upper arms 252, 254 becomes greater than the sum of the dynamic friction forces acting on the second and fourth upper arms 252, 254. This causes the center of the upper piezoelectric cross 25 to move a certain distance relative to the base 1. Then, the first upper arm 251 stretches and deforms to its longest length, while the other three arms remain stationary. Finally, the third upper arm 253 contracts and deforms to its shortest length, while the other three arms remain stationary. During this process, only one arm deforms at a time, and the sum of the static friction forces acting on the other three arms far exceeds the sliding friction forces acting on a single arm. Therefore, the center position of the upper piezoelectric cross 25 relative to the base 1 remains unchanged during this process. At this point, the upper piezoelectric cross 25 has made one step in the +X direction. The motion control process is repeated to achieve movement in the +X direction. Because the upper piezoelectric cross 25 is symmetrical in all four directions, the motor can achieve stepping in all four directions according to the aforementioned principle. It should be noted that during the aforementioned stepping process, when the upper first arm 251 and the upper third arm 253 simultaneously complete their opposite deformation, the upper second arm 252 and the upper fourth arm 254 should have completed at least half a cycle of their opposite motion; otherwise, the motor's operating efficiency will be reduced or even inoperable. This is because if the upper first arm 251 and the upper third arm 253 have been contracting or extending for some time, while the upper second arm 252 and the upper fourth arm 254 are still stationary, then during this time, the upper first arm 251 and the upper third arm 253 will need to overcome the static friction between the upper second arm 252 and the upper fourth arm 254, as well as the lower second arm 262 and the lower fourth arm 264, in order to operate. 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 weak connections will form at the microscopic level of the contact surface, and the kinetic friction in the +X direction should also be reduced. The above analysis is also valid for the stepping motion of the motor in all four directions.

[0057] Following the above stepping process, steps in other directions can be completed. The maximum displacement in each direction is combined to form a square area, and the two-dimensional piezoelectric motor can move arbitrarily within this square area.

[0058] like Figures 7 to 9 As shown, the two-dimensional piezoelectric motor of the present invention can also be used to make a corresponding scanning probe microscope, specifically 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.

[0059] 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 robot and transferred to the slide bar 34. At the same time, the robot 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 solely by gravity.

[0060] 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 a series of scanning probe microscope family functions such as STM, AFM, MFM, PFM, etc.

[0061] 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. It can serve as a window for the interaction between light and matter, provide a path for light to irradiate the sample, 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.

[0062] The two-dimensional piezoelectric motor is screwed to the outer frame 3 via the base 1. An inertial piezoelectric motor assembly 38 is also mounted within the outer frame 3. This inertial piezoelectric motor assembly 38 drives the slide 34 up and down along the Z-axis. A scanner assembly 37 is mounted at the lower end of the slide 34, and a probe holder 33 within the scanner assembly 37 is mounted with a probe. During scanning, the two-dimensional piezoelectric motor drives the sample to be tested to move along the XY plane, while the inertial piezoelectric motor assembly 38 drives the slide 34 to push the scanner assembly 37, which is fixed to the slide 34, in the Z-axis direction. The scanner assembly 37 then scans the sample to be tested via the probe on the probe holder 33.

[0063] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion, 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 in the upper piezoelectric cross (25) and the lower piezoelectric cross (26) can be deformed along the length direction of each arm itself, and a space is formed between the upper and lower corresponding arms of the upper piezoelectric cross (25) and the lower piezoelectric cross (26). A single-point contact is formed so that four-point horizontal contact is 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 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 in contact with each other through the 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 opposite motion according to claim 1, characterized in that: A ball (231) is fixedly mounted on the bottom of each telescopic end of the upper piezoelectric cross (25), and each ball (231) is pressed tightly against the corresponding arm of the lower piezoelectric cross (26) below it to form the single-point contact.

3. A two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion according to claim 2, characterized in that: The center of the rolling ball (14), the centroid of the upper piezoelectric cross (25), the centroid of the lower piezoelectric cross (26) and the centroid 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 opposite motion 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. The two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion 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 opposite motion according to claim 5, characterized in that: The sample holder (24) includes a sample holder (241) fixedly mounted on the upper piezoelectric cross (25), and a horizontally arranged 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 opposite motion 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. The two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion 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 sphere (231) is fixed to the bottom of the sapphire sleeve (23) above it.

9. The two-dimensional piezoelectric motor based on the principle of reducing friction by opposite motion 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 opposite motion as claimed in claim 9, characterized in that: A one-step walk along the +X direction is achieved by following the 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 upper third 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, and at the same time, the upper third arm (253) extends 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 reverse 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 its shortest position, while the upper third arm (253) is extended to its longest position, 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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