High-precision lens focusing structure

Abstract

The utility model discloses a high accuracy lens focusing structure, including step motor, focusing screw rod, fixed bracket, feedback control assembly, fixed bracket includes bottom plate and the first bracket, second bracket of connecting in bottom plate both sides, feedback control assembly includes magnetic encoder, magnetic ring, the first end of focusing screw rod is through first bracket center with magnetic ring is connected, magnetic encoder is opposite interval setting with magnetic ring, the second end is through second bracket center with step motor transmission connection, and the outer periphery of focusing screw rod is equipped with focusing dial lever, and magnetic ring rotates with focusing screw rod and passes angle displacement information to magnetic encoder, realizes real -time detection of focusing position, the application will install magnetic ring in focusing screw rod end, and with magnetic encoder opposite setting makes the angle displacement that focusing dial lever corresponds in linear movement process can be real -time accurate collection, forms complete displacement closed -loop control, realizes the reverse compensation based on feedback signal, prevents the problem of false focus caused by step loss.

Description

Technical Field

[0001] This utility model relates to the field of imaging equipment technology, and in particular to a high-precision lens focusing structure. Background Technology

[0002] Currently, most imaging devices on the market, such as projectors and cameras, use stepper motors with external PI controllers as the zero-point control steps. Positioning control is achieved through a fixed step angle, enabling linear focusing movement of the lens module. This involves sending a preset number of pulses to the stepper motor to control its rotation angle, thereby calculating the lens displacement. However, due to limitations in the actual environment, such as changes in friction, load fluctuations, mechanical damping, and power supply fluctuations, the motor may experience "step loss," meaning the output shaft fails to complete the required angular displacement. This results in the lens module not reaching the correct position, leading to problems like out-of-focus or focusing failure. This affects image quality, especially in the fine focusing applications of projection equipment. Furthermore, it cannot effectively compensate for mechanical backlash and hysteresis, particularly the reverse positioning error caused by backlash during lever reversal, further exacerbating the insufficient focusing accuracy. As projection equipment becomes lighter and smaller, the complexity of its mechanical structure increases, placing higher demands on the control system. The linear adjustment method of traditional PI controllers is insufficient to meet the requirements of high precision and fast response.

[0003] On the other hand, existing focusing structures typically have many components, are not compact enough, and are cumbersome to install, failing to meet the space and structural requirements of modern projection equipment. Therefore, with the current trend towards lightweight, intelligent, and miniaturized projection equipment, traditional focusing structures are revealing increasing bottlenecks in control precision and response efficiency, unable to meet the higher requirements of next-generation high-performance projection products for the accuracy, stability, and reliability of autofocus systems.

[0004] Therefore, further research and development is needed to solve the technical problems existing in the above-mentioned existing technologies. Utility Model Content

[0005] Therefore, in order to solve the problems existing in the prior art, the purpose of this utility model is to provide a high-precision lens focusing structure.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A high-precision lens focusing structure includes a stepper motor, a focusing screw, a fixed bracket, and a feedback control component arranged coaxially in sequence. The fixed bracket includes a base plate and a first bracket and a second bracket connected to both sides of the base plate. The feedback control component includes a magnetic encoder and a magnetic ring. A first end of the focusing screw passes through the center of the first bracket and its end is connected to the magnetic ring. The magnetic encoder and the magnetic ring are spaced apart. A second end of the focusing screw passes through the center of the second bracket and is driven by the stepper motor. A focusing lever is sleeved on the outer periphery of the focusing screw. The focusing lever is located between the first bracket and the second bracket and can reciprocate along the focusing screw. The magnetic ring rotates with the focusing screw under the drive of the stepper motor and transmits angular displacement information to the magnetic encoder arranged at intervals in the form of magnetic field changes, thereby realizing real-time detection of the focusing position.

[0008] To further explain, the feedback control component includes a housing, which is mounted on the first bracket and covers the outer periphery of the magnetic encoder and the magnetic ring; the magnetic encoder is mounted on the inner wall of the housing via a circuit board and is spaced apart from the magnetic ring.

[0009] To further explain, the first end of the focusing screw is provided with a magnetic ring mounting part, the thickness of which is adapted to the thickness of the magnetic ring, and the magnetic ring is sleeved on the outer periphery of the magnetic ring mounting part and fixed.

[0010] To further explain, a guide rod is provided on one side of the focusing screw, and the two ends of the guide rod are fixed to the first bracket and the second bracket respectively; the central axis of the guide rod and the central axis of the focusing screw are located in the same plane; a guide hole adapted to the guide rod is provided on one side of the focusing lever, and the lever is slidably connected to the guide rod through the guide hole.

[0011] Further explanation: The stepper motor includes a front housing, a rear housing, and a stator assembly and a rotor assembly disposed between the front housing and the rear housing; the rotor assembly includes a cylindrical magnet sleeved on the outer periphery of the focusing screw and driving the focusing screw to rotate; the stator assembly includes a winding frame sleeved on the outer periphery of the cylindrical magnet and a coil wound on the outer periphery of the winding frame; when the coil is energized, it drives the cylindrical magnet to drive the focusing screw to rotate.

[0012] To further explain, the winding frame has winding portions at both ends for mounting the coil. The front end housing and the rear end housing are respectively provided with mounting portions that engage with the winding portions at their ends facing the winding frame, and are respectively mounted at both ends of the winding frame through the cooperation of the mounting portions with the winding portions. The outer side of the rear end housing is provided with a fixed end cover. The end of the focusing screw is rotatably connected to the center of the fixed end cover through a bearing.

[0013] To further explain, the second end of the focusing screw is fitted with a pressure spring and a washer, which are sequentially positioned between the bearing and the columnar magnet. The pressure spring has elastic abutment portions on both sides that protrude towards and abut against the washer, and the middle portion of the pressure spring arches towards and abuts against the bearing. A washer and a bearing are also provided at the connection between the first end of the focusing screw and the fixed support plate.

[0014] To further explain, the fixing bracket is integrally bent from a metal plate, and the cross-sections of the first bracket, the second bracket, and the base plate are U-shaped or inverted C-shaped.

[0015] To further explain, the focusing structure also includes an SMT circuit board, which is electrically connected to the stepper motor and the magnetic encoder respectively.

[0016] To further clarify, the magnetic encoder is a magnetic angle sensor of model MT6701.

[0017] Compared with the prior art, the beneficial effects of this utility model are at least in the following aspects:

[0018] 1) This utility model installs a magnetic ring at the end of the focusing screw and sets it opposite to the magnetic encoder, so that the angular displacement corresponding to the linear movement of the focusing lever can be accurately collected in real time, forming a complete displacement closed-loop control. This not only effectively prevents loss of synchronization and false focus caused by load disturbance, friction change and other factors, but also realizes reverse compensation based on feedback signal, effectively preventing false focus caused by loss of synchronization, and ensuring image clarity and focusing reliability.

[0019] Furthermore, this invention achieves error compensation through magnetic feedback, eliminating the need for complex mechanical compensation structures and simplifying system design.

[0020] 2) Furthermore, this utility model places the magnetic encoder and stepper motor at opposite ends of the focusing screw, coaxially mounted on both sides of the fixed bracket along the same central axis. This not only results in a symmetrical and compact structural layout but also effectively utilizes the axial space of the focusing assembly, avoiding detection errors or rotational offsets in traditional focusing structures and improving the overall transmission accuracy. Simultaneously, it maximizes the use of the structural axial space, eliminating the need for stacking or offset installation, which facilitates product miniaturization. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the high-precision lens focusing structure of the preferred embodiment of this utility model;

[0022] Figure 2 This is a schematic diagram of the overall structure of the high-precision lens focusing structure of the preferred embodiment of this utility model from another angle.

[0023] Figure 3 This is an exploded view of the overall structure of the high-precision lens focusing structure according to a preferred embodiment of the present invention.

[0024] Figure 4 This is a top view of the overall structure of the high-precision lens focusing structure of the preferred embodiment of this utility model;

[0025] Figure 5 for Figure 4 Schematic diagram of the cross-sectional structure along the AA direction.

[0026] In the picture:

[0027] 1. Stepper motor; 11. Front housing; 12. Rear housing; 13. Stator assembly; 131. Winding frame; 1311. Winding section; 132. Wire coil; 14. Rotor assembly; 141. Columnar magnet; 15. Mounting section; 16. Fixed end cover; 17. Bearing; 18. Pressing spring; 181. Elastic abutment section; 19. Gasket; 2. Focusing screw; 21. First end; 211. Magnetic ring mounting section; 22. Second end; 3. Fixed bracket; 31. Base plate; 32. First bracket; 33. Second bracket; 4. Feedback control assembly; 41. Magnetic encoder; 42. Magnetic ring; 43. Housing; 5. Focusing lever; 51. Guide hole; 6. Guide rod; 7. SMT circuit board. Detailed Implementation

[0028] To facilitate understanding of this utility model, the technical solution and advantages of the utility model will be further described in detail below with reference to the accompanying drawings and embodiments. The specific structure and features of this utility model are illustrated by way of example and should not constitute any limitation on this utility model. Furthermore, any of the technical features mentioned below (including implicit or disclosed features), as well as any technical features directly shown or implied in the figures, can be arbitrarily combined or deleted among these technical features to form other embodiments that may not be directly or indirectly mentioned in this utility model. The accompanying drawings show preferred embodiments of this utility model. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein.

[0029] In the description of this utility model, unless otherwise stated, all components used are conventional components in the prior art.

[0030] like Figure 1-5As shown, this utility model provides a high-precision lens focusing structure, including a stepper motor 1, a focusing screw 2, a fixed bracket 3, and a feedback control component 4 arranged coaxially in sequence. The fixed bracket 3 includes a base plate 31 and a first bracket 32 ​​and a second bracket 33 connected to both sides of the base plate 31. The fixed bracket 3 is integrally bent from a metal plate, and the cross-sections of the first bracket 32, the second bracket 33, and the base plate 31 are U-shaped or inverted C-shaped. The feedback control component 4 includes a magnetic encoder 41 and a magnetic ring 42. In this embodiment, the magnetic encoder 41 is a magnetic angle sensor of model MT6701. In addition, the focusing structure also includes an SMT circuit board 7, which is electrically connected to the stepper motor 1 and the magnetic encoder 41 respectively.

[0031] The first end 21 of the focusing screw 2 passes through the center of the first bracket 32 ​​and its end is connected to the magnetic ring 42. The magnetic encoder 41 and the magnetic ring 42 are arranged at intervals relative to each other. Specifically, the first end 21 of the focusing screw 2 is provided with a magnetic ring mounting part 211, the thickness of which is adapted to the thickness of the magnetic ring 42. The magnetic ring 42 is sleeved on the outer periphery of the magnetic ring mounting part 211 and fixed. This design ensures that the magnetic ring 42 and the focusing screw 2 are coaxially and stably installed, avoiding rotational eccentricity, improving the accuracy of the magnetic encoder in acquiring angular displacement, and simplifying the assembly process while improving the structural compactness and reliability.

[0032] The second end 22 of the focusing screw 2 passes through the center of the second bracket 33 and is connected to the stepper motor 1 for transmission. A focusing lever 5 is sleeved on the outer periphery of the focusing screw 2. The focusing lever 5 is located between the first bracket 32 ​​and the second bracket 33 and can reciprocate along the focusing screw 2. The magnetic ring 42 rotates with the focusing screw 2 under the drive of the stepper motor 1 and transmits the angular displacement information to the magnetic encoder 41 set at relative intervals in the form of magnetic field change, thereby realizing the real-time detection of the focusing position.

[0033] In this embodiment, the MT6701 magnetic angle sensor is directly connected to the focusing screw to form a high-resolution position feedback system. The rotational position signal is transmitted through the magnetic ring, and the actual position of the focusing lever is read in real time by the encoder.

[0034] Furthermore, by installing a magnetic ring at the end of the focusing screw and setting it opposite to the magnetic encoder, the angular displacement corresponding to the linear movement of the focusing lever can be accurately acquired in real time, forming a complete displacement closed-loop control. This not only effectively prevents loss of synchronization and false focus caused by factors such as load disturbance and friction changes, but also enables reverse compensation based on feedback signals, effectively preventing false focus problems caused by loss of synchronization and ensuring image clarity and focusing reliability.

[0035] Furthermore, this invention achieves error compensation through magnetic feedback, eliminating the need for complex mechanical compensation structures and simplifying system design.

[0036] Optionally, the feedback control component 4 includes a housing 43, which is mounted on the first bracket 32 ​​and covers the outer periphery of the magnetic encoder 41 and the magnetic ring 42. The magnetic encoder 41 is mounted on the inner wall of the housing 43 via a circuit board and is spaced apart from the magnetic ring 42. Mounting the magnetic encoder, circuit board, and housing as an independent packaged module on the bracket facilitates the formation of a standardized and modular structural unit, simplifies the overall assembly process, and facilitates maintenance or component replacement.

[0037] Optionally, a guide rod 6 is provided on one side of the focusing screw 2, and the two ends of the guide rod 6 are fixed to the first bracket 32 ​​and the second bracket 33 respectively; the central axis of the guide rod 6 is located in the same plane as the central axis of the focusing screw 2; a guide hole 51 adapted to the guide rod 6 is provided on one side of the focusing lever 5, and the lever is slidably connected to the guide rod 6 through the guide hole. In this embodiment, by providing a guide rod 6 arranged coplanarly with the focusing screw 2 on one side, a stable linear guide mechanism is constructed, enabling the focusing lever 5 to slide smoothly along a fixed trajectory during movement. The focusing lever 5 is slidably connected to the guide rod 6 through its guide hole 51, which not only restricts the movement direction of the lever and effectively prevents lateral shaking, tilting, and jamming, but also ensures that the lever achieves highly repeatable and smooth linear displacement under the rotation of the focusing screw. While improving the smoothness of the focusing process, it also significantly enhances the positioning accuracy and operational reliability of the system.

[0038] Optionally, the stepper motor 1 includes a front housing 11, a rear housing 12, and a stator assembly 13 and a rotor assembly 14 disposed between the front housing 11 and the rear housing 12. The rotor assembly 14 includes a cylindrical magnet 141 sleeved on the outer periphery of the focusing screw 2 and driving the focusing screw 2 to rotate. The stator assembly 13 includes a winding frame 131 sleeved on the outer periphery of the cylindrical magnet 141 and a coil 132 wound on the outer periphery of the winding frame 131. When the coil 132 is energized, it drives the cylindrical magnet 141 to drive the focusing screw 2 to rotate. In this embodiment, after being energized, the coil generates a magnetic field, driving the cylindrical magnet to rotate, thereby driving the focusing screw to achieve precise rotation. The torque response is fast and the control is sensitive, which is beneficial for achieving small-step fine adjustment.

[0039] Optionally, the winding frame 131 has winding portions 1311 at both ends for mounting the coil 132. The front housing 11 and the rear housing 12 are respectively provided with mounting portions 15 at one end facing the winding frame 131, which engage with the winding portions 1311. They are respectively mounted at both ends of the winding frame 131 through the cooperation of the mounting portions 15 with the winding portions 1311. In this way, the winding portions at both ends of the winding frame can be quickly assembled and the accuracy of the coil installation position can be ensured through the engagement of the mounting portions with the housing. At the same time, the stability of the winding under stress is improved, and displacement due to vibration or thermal expansion and contraction is avoided.

[0040] A fixed end cap 16 is provided on the outer side of the rear housing 12; the end of the focusing screw 2 is rotatably connected to the fixed end cap 16 via a bearing 17. Furthermore, a pressure spring 18 and a gasket 19 are sleeved on the end of the focusing screw 2, and the pressure spring 18 and gasket 19 are sequentially disposed between the bearing 17 and the columnar magnet 141; the pressure spring 18 has elastic abutment portions 181 on both sides protruding towards and abutting against the gasket 19, and the middle part of the pressure spring 18 arches towards the bearing 17 and abuts against the bearing 17. The pressure spring and gasket are located between the columnar magnet and the bearing, forming an elastic pressing structure. The arched middle part of the spring against the bearing helps absorb small axial clearances and mechanical vibrations during rotation, prevents axial movement, improves rotational stability, and reduces noise.

[0041] It should be noted that this utility model also includes other components and elements that fulfill the operational functions of the focusing structure, such as the main control system for drive control, the power supply module, the signal processing circuit for focusing position detection and feedback processing, the interface circuit for communication with the main equipment, etc., all of which are conventional components necessary for realizing the functions of the focusing system. The innovation of this utility model does not involve structural improvements or functional changes to the above-mentioned components, and therefore will not be elaborated upon here.

[0042] The operation of this invention is as follows: Upon receiving a focusing command from the main control system, the stepper motor coil is energized, driving the cylindrical magnet inside it to rotate, thereby rotating the focusing screw. The rotation of the focusing screw causes the focusing lever outside it to move along the thread, realizing the position adjustment of the lens module. At the same time, the magnetic ring fixed at one end of the focusing screw rotates synchronously with it. The magnetic encoder senses the changes in the magnetic field generated by the rotation of the magnetic ring in real time, realizing precise position control and error compensation.

[0043] Through this magnetic feedback mechanism, the system can dynamically correct position errors caused by load changes, gap hysteresis, or stepper motor step loss, avoiding the problem of false focus during the focusing process and greatly improving focusing accuracy, response speed, and system stability.

[0044] The above embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of protection of the present utility model. For those skilled in the art, it will be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A high-precision lens focusing structure, characterized in that, The device includes a stepper motor, a focusing screw, a fixed bracket, and a feedback control component arranged coaxially in sequence. The fixed bracket includes a base plate and a first bracket and a second bracket connected to both sides of the base plate. The feedback control component includes a magnetic encoder and a magnetic ring. The first end of the focusing screw passes through the center of the first bracket, and its end is connected to the magnetic ring. The magnetic encoder and the magnetic ring are spaced apart. The second end of the focusing screw passes through the center of the second bracket and is driven by the stepper motor. A focusing lever is sleeved on the outer periphery of the focusing screw. The focusing lever is located between the first bracket and the second bracket and can reciprocate along the focusing screw. The magnetic ring rotates with the focusing screw under the drive of the stepper motor and transmits angular displacement information to the magnetic encoder arranged at intervals, thereby realizing real-time detection of the focusing position.

2. The high-precision lens focusing structure as described in claim 1, characterized in that, The feedback control component includes a housing mounted on the first bracket and covering the outer periphery of the magnetic encoder and magnetic ring. The magnetic encoder is mounted on the inner wall of the housing via a circuit board and is spaced apart from the magnetic ring.

3. The high-precision lens focusing structure as described in claim 2, characterized in that, The first end of the focusing screw is provided with a magnetic ring mounting part, the magnetic ring mounting part is adapted to the thickness of the magnetic ring, and the magnetic ring is sleeved on the outer periphery of the magnetic ring mounting part and fixed.

4. The high-precision lens focusing structure as described in claim 3, characterized in that, The focusing screw has a guide rod on one side, and the two ends of the guide rod are fixed to the first bracket and the second bracket respectively; the central axis of the guide rod and the central axis of the focusing screw are located in the same plane; the focusing lever has a guide hole on one side that matches the guide rod, and is slidably connected to the guide rod through the guide hole.

5. The high-precision lens focusing structure as described in claim 3, characterized in that, The stepper motor includes a front housing, a rear housing, and a stator assembly and a rotor assembly disposed between the front housing and the rear housing; the rotor assembly includes a cylindrical magnet sleeved on the outer periphery of the focusing screw and driving the focusing screw to rotate; the stator assembly includes a winding frame sleeved on the outer periphery of the cylindrical magnet and a coil wound on the outer periphery of the winding frame; when the coil is energized, it drives the cylindrical magnet to drive the focusing screw to rotate.

6. The high-precision lens focusing structure as described in claim 5, characterized in that, The winding frame has winding portions at both ends for mounting the coil. The front and rear housings are respectively provided with mounting portions that engage with the winding portions at their ends facing the winding frame, and are respectively mounted at both ends of the winding frame through the cooperation of the mounting portions with the winding portions. The outer side of the rear housing is provided with a fixed end cover. The end of the focusing screw is rotatably connected to the center of the fixed end cover through a bearing.

7. The high-precision lens focusing structure as described in claim 6, characterized in that, The end of the focusing screw is fitted with a pressing spring and a gasket, which are sequentially arranged between the bearing and the columnar magnet. The pressing spring has elastic abutment portions on both sides that protrude toward the gasket and abut against it. The middle part of the pressing spring arches toward the bearing and abuts against it.

8. The high-precision lens focusing structure as described in claim 7, characterized in that, The fixed bracket is integrally bent from a metal plate, and the cross-sections of the first bracket, the second bracket, and the base plate are U-shaped or inverted C-shaped.

9. The high-precision lens focusing structure as described in claim 1, characterized in that, The focusing structure also includes an SMT circuit board, which is electrically connected to the stepper motor and the magnetic encoder respectively.

10. The high-precision lens focusing structure as described in claim 1, characterized in that, The magnetic encoder is a magnetic angle sensor of model MT6701.

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