Hollow two-dimensional piezoelectric flexible hinge platform

Abstract

A hollow two-dimensional piezoelectric flexible hinge platform disclosed by the present invention comprises a flexible hinge main body, a working platform located in the central area of the flexible hinge main body, a displacement amplification mechanism, a flexible hinge connecting rod and a cover plate assembly, the flexible hinge main body is arranged in a hollow frame type structure, and a through hole for light beam straight-through is formed in the center of the flexible hinge main body. The number of the displacement amplification mechanisms is two, the two displacement amplification mechanisms correspond to X-direction movement and Y-direction movement of the platform respectively, and each displacement amplification mechanism comprises a first lever amplification mechanism and a second lever amplification mechanism which are symmetrically arranged on the two opposite sides of the flexible hinge body. The first lever amplification mechanism and the second lever amplification mechanism are both connected with piezoelectric actuators. The invention relates to the technical field of mechanical precision displacement driving, and the platform has a highly compact integrated structure, excellent motion decoupling performance, a high-precision differential driving mode and good bearing capacity while the central clear aperture is ensured.

Description

Technical Field

[0001] This invention relates to the field of mechanical precision displacement driving technology, specifically a hollow two-dimensional piezoelectric flexible hinge platform for precision optical adjustment, laser processing, microscopic imaging and optical communication. Background Technology

[0002] In the fields of precision optical adjustment, laser processing, microscopic imaging and optical communication, the demand for two-dimensional precision motion platforms with a central light-passing aperture is becoming increasingly urgent. Such hollow two-dimensional piezoelectric flexible hinge platforms can provide an unobstructed straight path for beams or probes while achieving two-dimensional nanoscale positioning in X and Y dimensions, avoiding the obstruction of the optical path by traditional solid platforms, thus becoming a core component in optical path integration systems.

[0003] However, existing hollow two-dimensional piezoelectric flexible hinge platforms often face a series of mutually restrictive technical challenges in pursuing large light-transmitting apertures and high-performance indicators, mainly manifested in: 1. The contradiction between light aperture and structural compactness: In order to obtain a large light aperture, traditional designs often simply increase the overall size of the platform or use two one-dimensional platforms stacked in series, resulting in a bulky system structure, large size, and reduced natural frequency, making it difficult to integrate into space-constrained precision equipment.

[0004] 2. Motion coupling and accuracy loss: The two-dimensional motion of most platforms is achieved by the same flexible hinge base through flexible beams in different directions, which easily produces obvious parasitic motion coupling (i.e., X-axis motion is accompanied by unwanted Y-axis output, and vice versa). This coupling error seriously restricts the positioning accuracy and trajectory tracking accuracy of the platform.

[0005] 3. Limitations of the driving and amplification mechanism: In common designs, each dimension of motion is usually driven by a single piezoelectric actuator in conjunction with a single displacement amplification mechanism. This asymmetrical driving method is prone to causing inconsistent displacement on both sides of the output end, generating unnecessary deflection torque, which not only reduces the linearity of motion but also weakens the effective load capacity. In addition, there is an inherent contradiction between the amplification factor, stiffness, and stroke of a single amplification mechanism, which is difficult to balance.

[0006] 4. Insufficient load-bearing capacity and stiffness: The central opening inevitably weakens the overall stiffness of the structure. The traditional design with insufficient symmetry or a weak enlarged mechanism makes it less resistant to interference when subjected to eccentric loads or dynamic operation, and its load-bearing capacity is limited, affecting the stability and application range of the platform.

[0007] Therefore, improvements are needed to address the aforementioned issues. Summary of the Invention

[0008] In order to overcome the current technical defects, this invention provides a hollow two-dimensional piezoelectric flexible hinge platform. This platform has a highly compact integrated structure, excellent motion decoupling performance, high-precision differential drive method and good load-bearing capacity, while ensuring the central light-transmitting aperture.

[0009] The technical solution adopted by this invention is as follows: The hollow two-dimensional piezoelectric flexible hinge platform provided by this solution includes a flexible hinge body, a working platform located in the central area of ​​the flexible hinge body, a displacement amplification mechanism, a flexible hinge connecting rod, and a cover plate assembly. The flexible hinge body is configured with a hollow frame structure, and a through hole for direct beam passage is formed in the center of the flexible hinge body. The displacement amplification mechanism is provided in two sets, which correspond to the X-axis and Y-axis movements of the platform, respectively. Each set of displacement amplification mechanisms includes two lever amplification mechanisms, namely lever amplification mechanism one and lever amplification mechanism two, symmetrically arranged on opposite sides of the flexible hinge body. Piezoelectric actuators are connected to lever amplification mechanism one and lever amplification mechanism two. One end of the flexible hinge connecting rod is fixedly connected to the output end of the corresponding lever amplification mechanism one and lever amplification mechanism two, and the other end of the flexible hinge connecting rod is connected to the working platform. The cover plate assembly is composed of an upper cover plate, a lower cover plate, and a side wall cover plate, and is used to encapsulate and protect the platform.

[0010] Preferably, the lever amplification mechanism one and the lever amplification mechanism two are equipped with a compression spring preload mechanism, which is used to apply axial preload to the piezoelectric actuator to keep it in the optimal working state.

[0011] Preferably, the two symmetrically arranged lever amplification mechanisms one and two in the same direction of motion constitute a differential drive mode. Its core working mechanism is to use the central flexible hinge inside the mechanism as the rotation fulcrum to amplify the small input displacement of the piezoelectric ceramic. In this process, the parasitic displacement perpendicular to the output direction caused by the rotation of the fulcrum is the main source of error. Through symmetrical arrangement, the parasitic displacements generated by the two mechanisms are opposite in direction and equal in magnitude, so that they cancel each other out when output to the working platform, generating a pure one-dimensional translational output.

[0012] Preferably, the flexible hinge connecting rod is provided with a flexible hinge structure as a second decoupling mechanism. This flexible hinge structure further counteracts the displacement component from the non-motion direction through its own purposeful deformation.

[0013] Preferably, the flexible hinge structure can adopt different configurations such as elliptical, circular or beam-shaped to adapt to different load and stroke requirements.

[0014] Preferably, the flexible hinge connecting rod is pressed and fixed to the working platform by a screw plug.

[0015] Preferably, the cover plate assembly includes an upper cover plate, a lower cover plate, and a plurality of side wall cover plates, at least one of which is a wire outlet side wall cover plate for leading out the wires of the piezoelectric actuator.

[0016] The beneficial effects achieved by the present invention using the above structure are as follows: This invention, through its integrated hollow flexible hinge design, maximizes the central light-transmitting aperture while maintaining a highly compact overall structure. By configuring symmetrical dual piezoelectric actuators and dual lever amplification mechanisms for each dimension of motion, a differential drive and primary motion decoupling mechanism is formed, effectively suppressing parasitic motion coupling and improving motion linearity, accuracy, and load capacity. The dedicated hinge structure on the flexible hinge connecting rod provides secondary decoupling protection, further ensuring the high independence of two-dimensional motion. The built-in compression spring preload mechanism ensures the stability and lifespan of the piezoelectric ceramic operation. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is an isometric view of the hollow two-dimensional piezoelectric flexible hinge platform of the present invention. Figure 2 An exploded view of the hollow two-dimensional piezoelectric flexible hinge platform of the present invention; Figure 3 This is an enlarged schematic diagram of the hollow two-dimensional piezoelectric flexible hinge platform of the present invention; Figure 4 This is a schematic diagram of the assembly of the lever amplification mechanism and the working platform of the present invention; Figure 5 This is a schematic diagram of the motion direction components of the present invention; Figure 6 This is a simulation result diagram of the motion direction and coupling error direction of the present invention; Figure 7 This is a schematic diagram of the working curves of the piezoelectric actuator of the present invention under no-load and low spring stiffness load conditions. Figure 8 This is a schematic diagram of the working curves of the piezoelectric actuator of the present invention under no-load and constant mass load conditions; Figure 9 This is a schematic diagram illustrating the decoupling working principle of the flexible hinge connecting rod of the present invention; Figure 10 The diagram shows different types of flexible hinge structure connecting rods of the present invention.

[0018] Among them, 1. upper cover plate; 2. outlet end side wall cover plate; 3. lever amplification mechanism one; 4. flexible hinge connecting rod; 5. side wall cover plate; 6. lower cover plate; 7. lever amplification mechanism two; 8. pre-tightening block. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0021] Example 1 like Figures 1 to 10 As shown, this embodiment provides a specific structure of a hollow two-dimensional piezoelectric flexible hinge platform. The flexible hinge body is an integrally formed hollow frame with a light-transmitting hole at the center. Mounting grooves are machined on its four sides. Two lever amplification mechanisms 1-3 are symmetrically mounted in the opposite grooves in the X direction using screws. Two lever amplification mechanisms 2-7 are symmetrically mounted in the opposite grooves in the Y direction. Each lever amplification mechanism contains a piezoelectric actuator, which typically consists of a piezoelectric ceramic stack and a spring preload mechanism. Specifically, the spring of lever amplification mechanism 1-3 is internally located within it; while the spring of lever amplification mechanism 2-7 is placed in an independent preload block 8, and the preload block 8 applies an axial preload force to the piezoelectric actuator.

[0022] One end of the flexible hinge connecting rod 4 passes through the output hole of the corresponding lever amplification mechanism and is fixedly connected. The other end of the flexible hinge connecting rod 4 extends into the working platform and is located in the mounting hole of the movable part at the center of the flexible hinge body. It is then pressed and fixed by a screw plug, thereby transmitting the output displacement of the lever amplification mechanism to the working platform.

[0023] To achieve sealing and protection, the outlet end side wall cover 2 and the ordinary side wall cover 5 are installed on the side of the flexible hinge body with screws to close the mounting groove. The outlet end side wall cover 2 has a wire hole, and the upper cover 1 and the lower cover 6 are installed on the upper and lower surfaces of the body with screws.

[0024] like Figure 5As shown, the working process and decoupling principle are as follows: When the working platform needs to be driven to move along the X direction, the two symmetrical piezoelectric actuators in the X direction are controlled to extend synchronously. Each lever amplification mechanism 3 uses its internal central flexible hinge as the fulcrum to amplify the lever, generating an effective driving displacement (F output) along the X direction and a parasitic displacement (F coupling) perpendicular to the X direction caused by the rotation of the lever. Since the two mechanisms are symmetrically arranged, the parasitic displacements F coupling 1 and F coupling 2 generated by them are opposite in direction. When these two displacements are transmitted to the common working platform through the flexible hinge connecting rod 4, the components in the Y direction cancel each other out, thereby outputting a pure X-direction translation. The Y-direction motion principle is the same and is realized by the symmetrical lever amplification mechanism 7. This symmetrical differential drive design suppresses the parasitic coupling inside the single-dimensional motion from the mechanism.

[0025] like Figure 9 As shown, to further ensure motion decoupling, the flexible hinge connecting rod 4 is designed with a specific flexible hinge structure. When the connecting rod transmits displacement, the flexible hinge on it can undergo targeted deformation, allowing and absorbing any residual small displacement components perpendicular to the main motion direction. This serves as a second layer of protection, minimizing motion coupling error between the X and Y directions.

[0026] like Figure 6 As shown, the above structure was optimized and verified using simulation software such as COMSOL Multiphysics. The simulation results showed that after adopting the symmetrical dual mechanism and decoupling design of the present invention, the output displacement in the motion direction (such as the X direction) was stable, while the coupling error in the other direction (Y direction) was suppressed to an extremely low level, verifying the effectiveness of the present solution in motion decoupling.

[0027] Example 2 like Figure 7 and Figure 8 As shown, this embodiment focuses on explaining the working mechanism and advantages of the spring preload mechanism. Both lever amplification mechanism 1 (3) and lever amplification mechanism 2 (7) integrate springs to apply a continuous axial preload force to the piezoelectric actuator. The output force direction of the spring is opposite to the output displacement direction of the lever amplification mechanism, thereby achieving preload on the piezoelectric ceramic.

[0028] Preload is crucial to the performance of piezoelectric ceramics. Here, ΔLFS is the free travel, FBlock is the resistance force, kA is the piezoelectric actuator stiffness, and kL is the load (here, the preload spring) stiffness. Appropriate preload (achieved by selecting a suitable spring stiffness kL) can achieve the following effects: Ensure that the piezoelectric ceramic is always under pressure during operation to avoid damage due to stretching; Eliminating the gap between the piezoelectric ceramic and the driving structure improves the linearity and response speed of displacement transmission and reduces motion hysteresis; This allows the piezoelectric ceramic to operate in its optimal linearity region, improving the stability and accuracy of the output displacement.

[0029] Pre-tensioning is achieved through a built-in compression spring, resulting in a simple and reliable structure that eliminates the need for complex external adjustment mechanisms. This ensures that the piezoelectric actuator remains in optimal working condition for extended periods, thereby improving the stability and lifespan of the entire platform.

[0030] The approximate displacement of the actuator under load is expressed by the following formula:

[0031] In this case, the stroke decreases slightly because the force applied by the spring acts on the piezoelectric device, causing "self-compression" and reducing the overall stroke of the actuator. If stroke and force are considered as complementary properties of the piezoelectric actuator, it can be seen that the low-stiffness spring produces a displacement close to the free stroke, but the effective force is much smaller than the resisting force; the high-stiffness spring (kL>>kA) has the opposite performance. The effective force is then given by the following formula:

[0032] If a constant mass is applied as a load to the actuator, then the force (m) applied to the actuator... g) Independent of travel distance, its working curve is as follows: Figure 8 As shown. A constant mass force shifts the actuator's operating point, but because the force is constant, the operating curve is similar to that of an unloaded actuator, and the stroke remains close to the free stroke. A constant physical load only shifts the zero point by providing initial compression and maintains the same stroke range.

[0033] In addition, the flexible hinge connecting rod serves as a second decoupling mechanism. Its flexible hinge acts as a deformation fulcrum, which can further absorb and offset displacement components in non-primary motion directions through targeted elastic deformation, thereby improving the overall motion purity.

[0034] Example 3 like Figure 10 As shown, this embodiment illustrates an alternative to the flexible hinge connecting rod. For the flexible hinge connecting rod 4, which achieves a second level of decoupling, the structural form of its key component—the flexible hinge—can be selected and replaced according to specific application requirements. For example: Circular flexible hinge: fixed rotation center, high motion accuracy, suitable for short stroke and high precision applications; Elliptical flexible hinges: offer a greater range of flexible deformation than circular hinges, suitable for medium strokes; Beam-type flexible hinge: It has a simple structure, is easy to manufacture, and can provide greater flexibility in a specific direction. It is suitable for scenarios with special requirements for decoupling in a specific direction.

[0035] Users can select a suitable flexible hinge structure to install on the connecting rod based on the platform's required load capacity, output displacement stroke, and accuracy specifications. This modular design enhances the platform's applicability and flexibility.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, material, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, material, or apparatus.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hollow two-dimensional piezoelectric flexible hinge platform, characterized in that, include: The flexible hinge body has a hollow frame structure with a through hole in the center for direct beam passage; the working platform is located in the central area of ​​the flexible hinge body; the displacement amplification mechanism has two sets, corresponding to the X and Y directions of the platform respectively; each set of displacement amplification mechanism includes two lever amplification mechanisms symmetrically arranged on opposite sides of the flexible hinge body, forming a differential drive mode to achieve motion decoupling in this dimension; the flexible hinge connecting rod (4) is used to connect the displacement amplification mechanism and the working platform; the cover plate assembly is used to encapsulate and protect the platform; wherein, each set of displacement amplification mechanisms includes two lever amplification mechanisms symmetrically arranged on opposite sides of the flexible hinge body, and each lever amplification mechanism is connected to a piezoelectric actuator.

2. The hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: The lever amplification mechanism includes a lever amplification mechanism one (3) and a lever amplification mechanism two (7). Both the lever amplification mechanism one (3) and the lever amplification mechanism two (7) are provided with a spring preload mechanism for applying axial preload force to the piezoelectric actuator. The spring preload mechanism of at least one lever amplification mechanism is installed and adjusted by a preload block (8).

3. The hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: Two symmetrically arranged lever amplification mechanisms in the same direction of motion constitute a differential drive mode, and the parasitic displacements caused by the rotation of the levers cancel each other out when output to the working platform.

4. The hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: The flexible hinge connecting rod (4) is provided with a flexible hinge structure as a secondary decoupling mechanism to further counteract the displacement component from the non-motion direction.

5. A hollow two-dimensional piezoelectric flexible hinge platform according to claim 4, characterized in that: The flexible hinge structure is a circular, elliptical, or beam-shaped flexible hinge.

6. The hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: The flexible hinge connecting rod (4) is pressed and fixed to the working platform by a screw plug.

7. The hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: The cover plate assembly includes an upper cover plate (1), a lower cover plate (6), and multiple side wall cover plates (5), wherein at least one side wall cover plate (5) is a wire outlet side wall cover plate (2), which is provided with a lead hole for leading out the wire of the piezoelectric actuator.

8. The hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: The flexible hinge body is a one-piece molded structure.

9. A hollow two-dimensional piezoelectric flexible hinge platform according to claim 1, characterized in that: The piezoelectric actuator is a piezoelectric ceramic stack.

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