Piezoelectric diaphragm with variable optical aperture

Abstract

The invention discloses a piezoelectric diaphragm with a variable optical aperture, which comprises a shell, an annular rotor and a blade group arranged on the upper surface of the rotor, a variable aperture is formed in the middle of the blade group, and when the rotor rotates forwards or reversely, the aperture becomes larger or smaller. The ring-shaped stator is propped against the lower part of the rotor; the ring-shaped piezoelectric ceramic is fixed with the stator; the integral structure of the diaphragm can be mounted in the shell in an axial symmetry manner to form a cylindrical structure, and compared with an irregular structure in the prior art, the axial symmetry structure is convenient to mount and high in universality.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a variable aperture diaphragm. Background Art

[0002] Optical imaging technology has placed extremely high demands on imaging technology in extreme environment exploration, such as in the aerospace field, deep-sea and polar scientific research fields. However, traditional optical imaging systems often have many limitations when facing complex and changing environments. Extreme environments put the resolution, dynamic range, anti-interference ability and adaptability of imaging systems to the test. Traditional optical imaging systems usually use a fixed aperture diaphragm. Although this design can meet the imaging needs in conventional environments to a certain extent, it cannot flexibly adjust the light flux according to different lighting conditions and scene requirements, resulting in overexposure in strong light environments and too dark images in low light environments, seriously affecting the imaging quality and the accuracy of information acquisition.

[0003] In the prior art, the paper "Design of a High-Precision Aperture Diaphragm Driven by a Single-Phase Piezoelectric Motor" (Cao Teng, Li Xiaoniu, Wang Boquan, et al.; China Mechanical Engineering, Vol. 33, No. 20, pp. 39, 72, 73) discloses a technical solution for an aperture structure that uses a piezoelectric motor as a driver to change the aperture size. This solution utilizes a piezoelectric stator in contact with a moving coil, generating high-speed, high-frequency friction on the moving coil, which in turn rotates the blade assembly inward or outward to change the aperture size. While this solution provides a compact, lightweight, and high-precision single-phase driven piezoelectric aperture diaphragm, its overall structure is irregular, occupying space adjacent to the blade assembly. This requires separate design of assembly space and coordination for the entire diaphragm structure when used in conjunction with other components, as well as adjustment of assembly tolerances for both the moving coil and the piezoelectric stator. These factors result in high application requirements for the diaphragm in this solution, making installation inconvenient. Summary of the Invention

[0004] Purpose of the invention: To solve the above problems, the present invention provides a piezoelectric variable optical aperture diaphragm to solve the problem of irregular diaphragm structure in the prior art causing inconvenience in installation.

[0005] Technical solution: To achieve the above-mentioned purpose, the piezoelectric variable optical aperture diaphragm provided by the present invention can adopt the following technical solution:

[0006] A piezoelectric variable optical aperture diaphragm includes a housing, an annular rotor, and a blade assembly mounted on the upper surface of the rotor. A variable aperture is formed in the middle of the blade assembly. When the rotor rotates forward or reverse, the aperture increases or decreases. The diaphragm also includes an annular stator abutting against the bottom of the rotor and an annular piezoelectric ceramic fixed to the stator. The outer diameters of the rotor, stator, and piezoelectric ceramic are equal and all are mounted in the housing, which is cylindrical.

[0007] Furthermore, the shell includes a base and a cover body, the base is annular, the cover body includes a circular upper cover and a side wall extending downward from the outer periphery of the upper cover, the bottom of the side wall is fixed to the base, and a receiving space is formed between the base and the cover body.

[0008] Furthermore, a butterfly spring is provided between the base and the lower surface of the piezoelectric ceramic, and the butterfly spring abuts against the lower surface of the piezoelectric ceramic to form an upward pre-tightening force on the piezoelectric ceramic.

[0009] Furthermore, the stator includes a circular stator ring and a plurality of driving teeth with triangular or trapezoidal cross-sections located on the upper surface of the stator ring, and the plurality of driving teeth are evenly arranged around the outer circumference of the stator ring and are located within the diameter range of the stator ring. There is a gap between adjacent driving teeth, the outer height of the driving teeth is greater than the inner height, and the top of the driving teeth is a pointed end and abuts against the rotor.

[0010] Furthermore, the rotor includes a circular rotor ring and several driving parts located on the lower surface of the rotor ring. The driving parts are evenly distributed around the outer circumference of the rotor ring and are located within the diameter range of the rotor ring. There are gaps between adjacent driving parts. The driving parts are rectangular or rectangular variants with arc-shaped outer walls. The lower surface of the driving parts abuts against the tips of the driving teeth.

[0011] Furthermore, the structure and size of each driving tooth are the same, and the length and size of each driving portion are the same.

[0012] Beneficial effects: Compared with the prior art, the present invention adopts a structure in which the blade group, rotor, and stator are all arranged in a circular ring shape and stacked up and down. The outer diameters of the rotor, stator, and piezoelectric ceramics are equal, so that the overall structure can be installed in an axially symmetrical manner in the outer shell to form a structure with a cylindrical appearance. Compared with the irregular structure in the prior art, the axially symmetrical structure is easy to install and has strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a three-dimensional exploded view of the piezoelectric variable optical aperture diaphragm of the present invention.

[0014] Figure 2 Schematic diagram of the first contact structure between the stator and the rotor.

[0015] Figure 3 Schematic diagram of the second contact structure between the stator and the rotor. DETAILED DESCRIPTION

[0016] See also Figure 1 As shown, the present invention provides a piezoelectric variable optical aperture diaphragm, comprising a housing, a rotor 3, a blade group 2 mounted on the upper surface of the rotor 3, a circular stator 4 abutting against the bottom of the rotor 3, and a circular piezoelectric ceramic 5 fixed to the stator 4. The piezoelectric ceramic 5, the stator 4, the rotor 3, and the blade group 2 are coaxially stacked from bottom to top. A variable aperture is formed in the middle of the blade group 2, and the aperture becomes larger or smaller when the rotor rotates forward or reversely. The blade group 2 includes a number of blades with the same structure. The upper surface of the rotor 3 is provided with a rotating shaft 33 that cooperates with the rotor 3, and each blade is provided with an axial hole that cooperates with the rotating shaft 33. The structure of the rotor 3 and the blades is the same as the structure of the rotor and blades in the document "Design of High-Precision Aperture Diaphragm Driven by Single-Phase Piezoelectric Motor" cited in the background technology, and will not be repeated here.

[0017] The rotor 3, stator 4, and piezoelectric ceramic 5 have equal outer diameters and are all mounted within the housing. The housing is generally flat and cylindrical, comprising a base 7 and a cover 1. The base 7 is annular, and the cover 1 comprises a disc-shaped upper cover 11 and a sidewall 12 extending downward from the periphery of the upper cover 11. The bottom of the sidewall 12 is fixed to the base 7, forming a receiving space between the base 7 and the cover 1 for accommodating the rotor 3, stator 4, and piezoelectric ceramic 5. A butterfly spring 6 is provided between the base 7 and the lower surface of the piezoelectric ceramic 5. The butterfly spring 6 abuts against the lower surface of the piezoelectric ceramic 5 to form an upward preload force on the piezoelectric ceramic 5, enabling the stator 4 to tightly abut against the rotor 3.

[0018] During operation, the aperture applies an AC voltage of a certain frequency to the piezoelectric ceramic 5. Leveraging the inverse piezoelectric effect, the piezoelectric ceramic 5 converts electrical energy into mechanical energy, causing the stator 4 to generate high-frequency periodic microscopic vibrations. This microscopic deformation is amplified through mechanical resonance of the vibrating body. The contact friction between the stator 4 and the rotor 3 converts the stator 4's microscopic vibrations into macroscopic rotations of the rotor 3, thereby driving the blades to move synchronously and varying the degree of blade overlap, thereby achieving dynamic adjustment of the aperture, either widening or narrowing it. The piezoelectric ceramic 5 is excited using a single-phase asymmetric excitation, applying a single-phase voltage signal diagonally to the four positively polarized electrode regions on either side of the stator. The excitation frequency is close to the natural frequency of the vibration mode. The elliptical trajectory excited by this method is affected by the excitation frequency and voltage amplitude, and bidirectional drive is achieved by varying the excitation region. The specific principle of converting the stator 4's microscopic vibrations into the rotor 3's macroscopic rotation is similar to the principle of converting the stator's microscopic vibrations into the rotor's macroscopic rotation proposed in the background document "Design of a High-Precision Aperture Aperture Diaphragm Driven by a Single-Phase Piezoelectric Motor," and will not be further elaborated here.

[0019] In actual practice, since the friction force generated between the stator 4 and the rotor 3 needs to be adjusted, if a face-to-face friction method is directly adopted, it is difficult to adjust the friction force by structural changes. Therefore, in this embodiment, two methods are used to design the contact structure between the stator 4 and the rotor 3.

[0020] The first one is: Figure 2 As shown, the stator 4 includes an annular stator ring 41 and a plurality of driving teeth 42 with triangular cross-sections located on the upper surface of the stator ring 41. The driving teeth 42 are evenly distributed around the outer circumference of the stator ring 41 and are located within the diameter of the stator ring 41. There is a gap between adjacent driving teeth 42. The outer height of the driving teeth 42 is greater than the inner height, and the top of the driving teeth is a pointed tip. The rotor 3 includes an annular rotor ring 31 and a plurality of driving portions 32 located on the lower surface of the rotor ring 31. The driving portions 32 are evenly distributed around the outer circumference of the rotor ring and are located within the diameter of the rotor ring 31. There is a gap between adjacent driving portions 32. The driving portions 32 are rectangular or rectangular with curved outer walls. The lower surface of the driving portion 32 abuts against the tips of the driving teeth 42. By adjusting the gaps between the drive teeth 42 and / or the gaps between the drive parts 32, combined with adjusting the preload force generated by the disc springs 6, the contact area between all the drive teeth 42 and all the drive parts 32 can be selected during the design verification phase to adjust the preset friction force. The gaps between the drive teeth 42 are smaller than the length of the drive parts 32, and the gaps between the drive parts 32 are smaller than the length of the drive teeth 42. This ensures that the contact between the drive teeth 42 and the drive parts 32 is limited to upper and lower surface contact, without cross-interference.

[0021] The second type is: Figure 3 As shown, the driving teeth 42 with a triangular cross-section in the first method are modified into driving teeth 42 with a trapezoidal cross-section. The principle is the same as in the first method. By adjusting the gaps between the driving teeth 42 and / or the gaps between the driving parts 32, and then adjusting the preload force generated by the butterfly spring 6, the contact area between all driving teeth 42 and all driving parts 32 can be selected in the design verification stage to adjust the preset friction force.

[0022] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A piezoelectric variable optical aperture diaphragm comprising a housing, an annular rotor, and a blade assembly mounted on the upper surface of the rotor, wherein a variable aperture is formed between the blade assembly. When the rotor rotates forward or reverse, the aperture increases or decreases. The invention is characterized in that: It also includes an annular stator resting against the bottom of the rotor and an annular piezoelectric ceramic fixed to the stator. The outer diameters of the rotor, stator and piezoelectric ceramic are equal and all are installed in a cylindrical shell.

2. The piezoelectric variable optical aperture diaphragm according to claim 1, characterized in that: The shell includes a base and a cover. The base is annular. The cover includes a circular upper cover and a side wall extending downward from the outer periphery of the upper cover. The bottom of the side wall is fixed to the base, and a receiving space is formed between the base and the cover.

3. The piezoelectric variable optical aperture diaphragm according to claim 2, characterized in that: A butterfly spring is provided between the base and the lower surface of the piezoelectric ceramic. The butterfly spring abuts against the lower surface of the piezoelectric ceramic to form an upward pre-tightening force on the piezoelectric ceramic.

4. The piezoelectric variable optical aperture diaphragm according to claim 1, characterized in that: The stator includes a circular stator ring and a plurality of driving teeth with triangular or trapezoidal cross sections located on the upper surface of the stator ring. The plurality of driving teeth are evenly arranged around the outer circumference of the stator ring and are located within the diameter range of the stator ring. There is a gap between adjacent driving teeth, the outer height of the driving teeth is greater than the inner height, and the top of the driving teeth is a pointed end and abuts against the rotor.

5. The piezoelectric variable optical aperture diaphragm according to claim 4, characterized in that: The rotor includes a circular rotor ring and several driving parts located on the lower surface of the rotor ring. The driving parts are evenly distributed around the outer circumference of the rotor ring and are located within the diameter range of the rotor ring. There is a gap between adjacent driving parts. The driving part is a rectangular parallelepiped or a rectangular parallelepiped variant with an arc-shaped outer wall. The lower surface of the driving part abuts against the tip of the driving tooth.

6. The piezoelectric variable optical aperture diaphragm according to claim 5, characterized in that: The structure and size of each driving tooth are the same, and the length and size of each driving part are the same.

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