A device for detecting displacement using a magnet metal plating of a voice coil motor

Abstract

This invention discloses a device for detecting displacement using the metal plating of a voice coil motor's magnet. The device comprises: a drive motor including a permanent magnet and a drive coil, one of which is fixedly mounted, while the other is connected to a moving structure and moves synchronously with it; the surface of the permanent magnet has a metal plating; a control circuit module connected to the drive coil, configured to provide a drive signal to the drive coil and an excitation signal for generating eddy currents on the metal plating; and an inductance detection and position transformation module configured to detect the inductance signal of the drive coil and output the displacement state of the moving structure based on the inductance signal. Its advantages are: this method achieves accurate detection of the displacement state of the moving structure without requiring an additional displacement sensor inside the device, contributing to the miniaturization and integration of the device.

Description

Technical Field

[0001] This invention relates to the field of voice coil motor technology, specifically to a device for detecting displacement using the metal plating of the magnet of a voice coil motor, and particularly to a driving and displacement sensing structure applied to a small camera module, specifically to a small camera module based on the eddy current effect. Background Technology

[0002] A voice coil motor (VCPM) is a device that converts electrical energy into linear or finite-angle mechanical motion. Its core components include a coil and a permanent magnet. Its working principle relies on the interaction between the energized coil and the magnetic field of the permanent magnet, which drives the moving structure to produce displacement. Due to its advantages of simplified structure, miniaturization, and low power consumption, the VCPM is widely used in fields such as autofocus in mobile phone cameras, medical equipment, semiconductor manufacturing, and aerospace. However, in practical applications, devices using VCPMs still cannot meet the requirements for displacement detection.

[0003] For example, with the increasing demands for image quality from smartphones and smart wearable devices, cameras typically require precise driving and control during focusing, zooming, image stabilization, or module switching. Existing camera driving and control solutions usually require additional displacement sensors (such as Hall sensors) to provide displacement information for feedback control. However, this reliance on external displacement sensors brings several inconveniences: limited internal space within the camera module makes it difficult to integrate additional displacement sensors; the size, especially the thickness, of the camera module with integrated sensors increases, hindering its application in smartphones and smart wearable devices; the cost of camera modules with integrated sensors increases significantly; and the traditional structure has limited ability to sense the displacement state of the lens components, making fine control difficult. Therefore, improvements to existing displacement sensing solutions are needed.

[0004] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art. Summary of the Invention

[0005] Based on the aforementioned technical problems, the purpose of this invention is to provide a device for detecting displacement using the metal plating of the magnet of a voice coil motor. This device can sense the displacement state of a moving structure by making reasonable use of the internal metal structural components, i.e., the metal plating, without the need to add an additional displacement sensor inside.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: A device for detecting displacement using the metal plating of a voice coil motor's magnet, comprising: A drive motor comprising a permanent magnet and a drive coil, wherein one of the permanent magnet and the drive coil is fixedly disposed, and the other is connected to a moving structure and moves synchronously therewith, and the surface of the permanent magnet has a metal plating. A control circuit module connected to the drive coil, the control circuit module being configured to provide a drive signal to the drive coil and an excitation signal for generating eddy currents on the metal plating. An inductance detection and position transformation module is configured to detect the inductance signal of the drive coil and output the displacement state of the moving structure based on the inductance signal.

[0007] Optionally, the inductance detection and position transformation module is connected to the control circuit module, and the inductance detection and position transformation module is configured to output the displacement state of the moving structure to the control circuit module, and the control circuit module is configured to output a drive signal based on the displacement state of the moving structure.

[0008] Optionally, the control circuit module is configured to synchronously apply the drive signal and the excitation signal to the drive coil; Alternatively, the control circuit module is configured to continuously provide the excitation signal to the drive coil; Alternatively, the control circuit module is configured to provide the excitation signal to the drive coil at preset time intervals.

[0009] Optionally, the movable structure is a lens assembly.

[0010] Optionally, the driving signal is a low-frequency current signal.

[0011] Optionally, the excitation signal is an AC signal; Alternatively, the excitation signal may be a high-frequency AC signal.

[0012] Optionally, the frequency range of the excitation signal is 1MHz to 10MHz.

[0013] Optionally, the thickness of the metal coating ranges from 5 μm to 30 μm; Alternatively, the thickness of the metal coating may range from 10 μm to 20 μm.

[0014] Optionally, the material used to prepare the metal coating includes at least one of nickel, copper, and zinc.

[0015] Optionally, the impedance range of the metal coating is 0.01Ω to 10Ω; Alternatively, the impedance range of the metal coating is 0.01Ω to 5Ω.

[0016] Compared with the prior art, the present invention has the following advantages: This invention discloses a device for detecting displacement using the metal plating of a voice coil motor's magnet. It integrates a permanent magnet, a drive coil, a control circuit module, and an inductance detection and position transformation module, reusing existing metal plating and drive coils. Based on the relationship between the eddy currents in the metal plating and the equivalent inductance of the drive coil, it achieves accurate detection of the displacement state of the displaced structure. This method eliminates the need for additional displacement sensing elements, helping to reduce the internal structural complexity and manufacturing cost of the device, while also improving the overall performance and integration of the device.

[0017] Furthermore, the moving structure is a lens assembly, and the corresponding device is a camera module. By making reasonable use of the metal structural components, i.e., the metal plating, inside the camera module, this invention can realize the perception of the displacement state of the lens assembly, thereby enabling feedback control of the camera module without adding additional sensors, so as to improve the overall performance of the camera module.

[0018] Furthermore, in this invention, the inductance detection and position transformation module is connected to the control circuit module. The inductance detection and position transformation module is configured to output the displacement state of the moving structure to the control circuit module, and the control circuit module is configured to output a drive signal based on the displacement state of the moving structure. Based on this method, closed-loop control of the moving structure drive can be achieved, which helps to improve the accuracy and precision of the drive adjustment. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings in the following description are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Figure 1 This is a schematic diagram of a device according to the present invention that uses the metal plating of the magnet of a voice coil motor to detect displacement; Figure 2 This is a simplified schematic diagram of a drive motor according to the present invention; Figure 3 This is a schematic diagram of the drive motor before and after driving according to the present invention; Figure 4 This is a schematic diagram comparing the superimposed signal of the driving signal and the excitation signal with a single driving signal according to the present invention. Detailed Implementation

[0020] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a device for detecting displacement using the metal plating of a voice coil motor's magnet. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clearly illustrate the embodiments of the invention. Please refer to the drawings for a clearer understanding of the objectives, features, and advantages of the invention. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes and to those skilled in the art, and are not intended to limit the implementation conditions of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed in the invention.

[0021] As discussed above, existing devices using voice coil motors still have significant room for improvement in displacement detection. Therefore, this invention provides a device that utilizes the metal plating of the magnet in a voice coil motor to detect displacement (see [link to related documentation]). Figure 1 This device utilizes its existing internal metal plating 23 and drive coil 22. Based on the relationship between the eddy current effect of the metal plating 23 and the equivalent inductance of the drive coil 22, it directly reflects the relative position change between the drive coil 22 and the permanent magnet 21. This allows for the simultaneous driving of the moving structure 10 and the sensing of its displacement state. This method achieves accurate sensing of the displacement state of the moving structure 10 without the need for an additional displacement sensor. It has a simple structure, is easy to integrate, and can meet the miniaturization requirements of devices (such as camera modules), while also ensuring the immediacy and reliability of the displacement state detection of the moving mechanism.

[0022] like Figures 1 to 3As shown, the device for detecting displacement using the metal plating of a voice coil motor's magnet according to the present invention includes a drive motor 20 (voice coil motor), a control circuit module 30, and an inductance detection and position transformation module 40. The drive motor 20 includes a permanent magnet 21 and a drive coil 22. One of the permanent magnet 21 and the drive coil 22 is fixedly disposed, while the other is connected to and moves synchronously with the moving structure 10. The surface of the permanent magnet 21 is provided with a corrosion-resistant metal plating 23, which is an integral part of the original structure of the permanent magnet 21. The control circuit module 30 is a voice coil motor drive and eddy current excitation module, electrically connected to the drive coil 22. The control circuit module 30 is configured to provide a drive signal to the drive coil 22 and an excitation signal for generating eddy currents on the metal plating 23. Under the action of the drive signal, the drive coil 22 can cause a change in the relative position between the permanent magnet 21 and the drive coil 22, thereby driving the moving structure 10 to move. The inductance detection and position transformation module 40 is configured to detect the inductance signal of the drive coil 22 and output the displacement state of the moving structure 10 based on the inductance signal.

[0023] like Figure 1 and Figure 3 As shown, during the detection process, the control circuit module 30 applies an excitation signal to the drive coil 22. Under the action of the excitation signal, the drive coil 22 forms an electromagnetic coupling with the metal plating layer 23 on the surface of the permanent magnet 21, thereby generating eddy currents on the metal plating layer 23 based on the excitation signal. These eddy currents will have a reverse effect on the electromagnetic characteristics of the drive coil 22 (e.g., the equivalent inductance of the drive coil 22). Since one of the permanent magnet 21 and the drive coil 22 is connected to the moving structure 10 and moves synchronously with it, the relative positions between the permanent magnet 21 and its metal plating layer 23 and the drive coil 22 will change as the moving structure 10 moves. This causes the intensity and distribution of the eddy currents induced in the metal plating layer 23 to change accordingly, thereby changing the effect of the eddy currents on the equivalent inductance of the drive coil 22. That is, when the relative position of the permanent magnet 21 and the drive coil 22 changes, the equivalent inductance of the drive coil 22 will also change, and there is a one-to-one correspondence between the equivalent inductance and the relative position. The inductance detection and position transformation module 40 detects the equivalent inductance signal of the drive coil 22, and outputs the real-time displacement state of the moving structure 10 based on the correspondence between the equivalent inductance signal and the displacement of the moving structure 10, thereby completing the accurate detection of the displacement of the moving structure 10.

[0024] As described above, this invention detects the displacement of the moving structure 10 based on the change in the equivalent inductance of the driving coil 22 caused by the eddy current in the metal plating 23 due to the relative position change of the permanent magnet and the driving coil 22. This method achieves displacement sensing of the moving structure 10 by reusing the original metal plating 23, driving coil 22, and control circuit module 30 on the surface of the permanent magnet 21. This method enables the driving coil 22 to simultaneously perform the dual functions of driving the moving structure 10 and sensing displacement in conjunction with the metal plating 23, eliminating the need for additional position sensors (such as Hall sensors) or independent detection coils as in traditional solutions. This significantly reduces the number of internal circuit components and signal crosstalk, simplifies the internal hardware structure and wiring complexity, reduces manufacturing costs, and effectively saves internal space. It meets the development needs of product miniaturization and high integration, and this displacement sensing solution is particularly suitable for integration into small devices (such as small camera modules). Meanwhile, this sensing mechanism directly reflects the true relative position between components, and has advantages such as high sensitivity, strong anti-interference ability, instant response, and insensitivity to environmental pollution. It can achieve accurate and stable sensing of 10 tiny displacements of moving structures.

[0025] like Figure 1 As shown, in some embodiments, the moving structure 10 is a lens assembly 11, and the corresponding device is a camera module (such as a camera module used in a mobile phone). Specifically, the lens assembly 11 is driven by a moving magnet method, and the permanent magnet 21 of the drive motor 20 is connected to the lens assembly 11 so as to move synchronously with the lens assembly 11; the drive coil 22 of the drive motor 20 is disposed on the periphery or below the lens assembly 11 so that the drive coil 22 drives the lens assembly 11 to move along the optical axis direction of the camera module under the action of the drive signal.

[0026] During the operation of the camera module, the control circuit module 30 outputs a drive signal to the drive coil 22. According to the principle of electromagnetic interaction, an electromagnetic force is generated between the drive coil 22, which carries the drive signal, and the permanent magnet 21. This electromagnetic force causes a change in the relative position between the drive coil 22 and the permanent magnet 21, thereby causing the permanent magnet 21 to move the lens assembly 11. The drive coil 22 can also form an electromagnetic coupling with the metal plating layer 23 on the surface of the permanent magnet 21 under the action of the excitation signal, so that the equivalent inductance of the drive coil 22 changes with the position of the lens assembly 11 / metal plating layer 23, thereby characterizing the displacement state or displacement trend of the lens assembly 11.

[0027] As described above, the camera module utilizes the existing anti-corrosion metal coating 23 on the surface of the permanent magnet 21 to achieve displacement sensing of the lens assembly 11. This eliminates the need for introducing additional displacement sensing elements or structural modifications to the permanent magnet 21, reducing the structural complexity, manufacturing cost, and power consumption of the camera module, and contributing to improved overall performance and integration. Furthermore, due to the inherent characteristics of electromagnetic coupling sensing, the displacement sensing method utilizing the eddy current effect of the metal coating 23 offers numerous advantages, including high stability, insensitivity to environmental pollution, a wide operating temperature range, and a wide frequency response range. This can help improve the stability and reliability of the lens assembly 11's drive control, thereby enhancing the overall performance and consistency of the camera module. This displacement sensing method is particularly suitable for displacement measurement in high-resolution camera modules.

[0028] In some embodiments, the inductance detection and position transformation module 40 is connected to the control circuit module 30, the inductance detection and position transformation module 40 is configured to output the displacement state of the moving structure 10 to the control circuit module 30, and the control circuit module 30 is configured to output a drive signal based on the displacement state of the moving structure 10.

[0029] In practical applications, the inductance detection and position transformation module 40 feeds back the calculated real-time displacement state to the control circuit module 30. The control circuit module 30 compares the actual displacement state with the target position to dynamically and accurately adjust the drive signal delivered to the drive coil 22 (e.g., adjust the current magnitude or direction), thereby achieving high-precision closed-loop control of the lens assembly 11's displacement. Based on this method, a complete closed-loop control loop can be constructed for the camera module, significantly improving the positioning accuracy and motion stability of the camera module during autofocus or zoom. Furthermore, this method concentrates the generation of drive and excitation signals, as well as the reception of displacement states, within the control circuit module 30. This allows the "drive-displacement sensing-feedback adjustment" signal chain to be directly closed-loop within the control circuit module 30, eliminating the need to transmit displacement state data to external chips for cross-chip communication and processing. This effectively reduces signal transmission delay, avoids timing misalignment issues that may occur when multiple chips work together, significantly improves the accuracy and precision of drive adjustment, and thus enhances the response speed and stability of closed-loop control. Meanwhile, this internal closed-loop approach helps reduce complex communication routing, reduces interference with inductor detection, and reduces signal crosstalk between different lines, further simplifying the system hardware architecture and improving anti-interference capabilities.

[0030] In practical applications, the drive signal applied by the control circuit module 30 to the drive coil 22 is a low-frequency current signal, and the excitation signal is an AC signal (see [link to relevant documentation]). Figure 4During operation, the low-frequency current signal can generate a stable and strong electromagnetic force between the drive coil 22 and the permanent magnet 21 to meet the driving requirements of the lens assembly 11 for a large stroke and fast response; the AC signal can excite an alternating magnetic field and generate eddy currents on the metal plating layer 23 on the surface of the permanent magnet to affect the equivalent inductance of the drive coil 22, thereby realizing displacement sensing of the lens assembly 11.

[0031] As described above, by applying both a low-frequency current signal as the drive signal and an AC signal as the excitation signal to the same drive coil 22, the drive coil 22 can perform both driving and displacement sensing functions for the lens assembly 11. Because the low-frequency current signal and the AC signal have different frequency domains / bands, spectral aliasing and electromagnetic interference between the two signals can be effectively avoided, allowing the driving and detection functions of the lens assembly 11 to operate independently, in parallel, and stably on the same electrical path. This method satisfies the requirements of the driving stage for high current and high thrust, while ensuring the high sensitivity of the displacement detection stage to minute changes in inductance, avoiding functional conflicts between the two, and significantly improving overall reliability, detection accuracy, and response accuracy.

[0032] In some embodiments, the excitation signal is a high-frequency AC signal. In practical applications, the high-frequency AC signal has a high magnetic field change rate, which can excite stronger eddy currents on the metal coating 23 that are more sensitive to displacement changes. This makes the change in the equivalent inductance of the drive coil 22 more significant, greatly improving the sensitivity and resolution of displacement detection. This makes it easier for the inductance detection and position transformation module 40 to capture the minute displacement changes of the moving structure 10, which helps to achieve high-precision detection of the displacement of the lens assembly 11. At the same time, there is a significant frequency difference between the high-frequency AC signal as the excitation signal and the low-frequency current signal as the drive signal, which can effectively avoid mutual interference between the two signals.

[0033] Optionally, the frequency range of the excitation signal is 1MHz to 10MHz. Based on this range, it can meet the high-frequency signal requirement of displacement detection based on the eddy current effect, while avoiding problems such as high-frequency radiation loss that may be caused by using excessively high frequencies, thus balancing the accuracy of displacement detection with the requirements of low power consumption and high energy utilization in practical applications.

[0034] like Figure 4As shown, the control circuit module 30 can be configured to synchronously apply the driving signal and excitation signal to the same driving coil 22, i.e., driving and displacement detection are synchronized. During operation, the driving signal of the driving coil 22 causes an electromagnetic force between the driving coil 22 and the permanent magnet 21 to drive the lens assembly 11 to move. At the same time, the excitation signal of the driving coil 22 excites eddy currents on the metal plating layer 23 on the surface of the permanent magnet 21 to affect the equivalent inductance of the driving coil 22, so that the inductance detection and position transformation module 40 can detect the change in the equivalent inductance of the driving coil 22 caused by the change in relative position.

[0035] Based on this method, the displacement state of the lens assembly 11 can be continuously acquired throughout its entire motion cycle, enabling real-time continuous monitoring of the lens assembly 11's displacement. Furthermore, this method eliminates the need for an additional synchronization triggering mechanism, helping to ensure the immediacy and reliability of displacement detection. This, in turn, guarantees the dynamic response speed and position tracking accuracy of the closed-loop control for driving and monitoring the lens assembly 11. This method is particularly suitable for the synchronous driving and displacement measurement of high-resolution mobile phone camera modules. In addition, the synchronous application of signals from the control circuit module 30 to the drive coil 22 simplifies the logical complexity of timing control, eliminating the need for frequent switching between driving and detection, thus improving overall work efficiency and control consistency.

[0036] It should be noted that the application methods of the driving signal and the excitation signal are not limited to those described above. In other embodiments, other forms may also be used, and the present invention does not impose any limitations on them. For example, in some embodiments, the application of the driving signal and the excitation signal is not synchronized. For instance, the control circuit module 30 applies a driving signal to the driving coil 22 in the first time period to drive the lens assembly 11 to move. In the second time period (e.g., during the intermittent or stopped movement of the lens assembly 11), the output of the driving signal is stopped and an excitation signal is applied for inductance detection, thereby obtaining the displacement state of the lens assembly 11. Based on this method, the driving signal and the excitation signal can be isolated in the time domain, effectively avoiding the influence of the driving signal on the excitation signal and the displacement detection based on the eddy current effect, which helps to improve the accuracy of displacement measurement. In addition, the time-division multiplexing of the driving coil 22 reduces the instantaneous peak power consumption of the entire device, which helps to alleviate the power supply pressure and internal thermal management.

[0037] On the other hand, in practical applications, the timing of applying the excitation signal can be set without using the driving signal as a reference; that is, the excitation signal application strategy is independent of the state of the driving signal. Based on this, the complex linkage judgment and switching logic with the state of the driving signal can be eliminated, which helps to ensure the operational stability of the detection process.

[0038] For example, in some embodiments, the control circuit module 30 is configured to continuously provide the excitation signal to the drive coil 22 throughout the entire working cycle, so that the drive coil 22 always maintains an electromagnetic coupling state with the metal plating layer 23 on the surface of the permanent magnet 21, continuously exciting eddy currents. Regardless of whether the lens assembly 11 is in a rapid movement phase or a stationary holding phase, the inductance detection and position transformation module 40 can continuously acquire the equivalent inductance signal of the drive coil 22, thereby outputting the displacement state of the lens assembly 11 in real time. Based on this method, the position feedback of the lens assembly 11 can be acquired in real time, realizing continuous monitoring of the displacement of the lens assembly 11, ensuring the dynamic response speed and position tracking accuracy of the closed-loop control of the lens assembly 11's motion. This method is particularly suitable for application scenarios that require high-frequency dynamic adjustment or extremely high position stability requirements (such as continuous autofocus or active image stabilization processes of camera modules). In addition, the method of continuously applying the excitation signal eliminates the switching logic and state waiting time of signal start and stop, making the hardware operation state of the detection link more stable and ensuring the continuity and consistency of displacement sensing data.

[0039] In other embodiments, the control circuit module 30 is configured to intermittently provide the excitation signal to the drive coil 22 at preset time intervals. This effectively reduces the average power consumption of the entire device, decreases the thermal load on the drive coil 22 and control circuit module 30, and helps extend the device's battery life. This method is particularly suitable for power-sensitive portable electronic devices (such as camera modules in smartphones). In practical applications, by reasonably setting the preset time interval, the application time of the excitation signal can be staggered from potential interference sources within the system, avoiding mutual interference between signals and improving the accuracy of single detection. Furthermore, the time interval can be adaptively adjusted according to different movement stages of the lens assembly 11 (e.g., shortening the time interval for intensive monitoring during rapid startup and lengthening the time interval when the lens assembly 11 is stationary), thereby achieving a dynamic optimal balance between performance and overall power consumption while ensuring the reliability of displacement detection.

[0040] In practical applications, the metal plating layer 23 on the surface of the permanent magnet 21 is made of at least one of nickel, copper, and zinc. In some embodiments, the metal plating layer 23 adopts a "nickel-copper-nickel" three-layer composite plating structure. Based on this approach, the intermediate copper layer is wrapped by two nickel layers, which prevents copper oxidation and helps ensure the long-term durability of the metal plating layer 23. Simultaneously, the manufacturing cost of this structure is relatively low. On the other hand, since copper has excellent conductivity, using it as an intermediate layer provides a low-resistance flow path for the generation of eddy currents, allowing the excitation signal to generate stronger eddy currents on the metal plating layer 23 that are more sensitive to displacement changes, thereby improving the sensitivity and resolution of displacement detection.

[0041] Optionally, the overall impedance range of the metal coating 23 is 0.01Ω to 10Ω. Within this impedance range, according to the eddy current detection principle, the smaller the impedance of the metal coating 23 (i.e., the higher the conductivity of the material), the greater the intensity of the eddy currents generated within the metal coating 23 under the same excitation signal. Stronger eddy currents have a more significant reverse effect on the equivalent inductance of the drive coil 22. This characteristic allows a small displacement change in the lens assembly 11 to cause a significant change in the equivalent inductance of the drive coil 22 (i.e., a large displacement-inductance rate). Based on this, the inductance detection and position transformation module 40 can more easily capture and distinguish the small displacement changes of the moving structure 10, thereby significantly improving the sensitivity and resolution of displacement detection and ensuring high accuracy. Furthermore, the smaller impedance allows for a larger inductance feedback with only a smaller excitation signal, effectively reducing the power required for the excitation signal and thus reducing overall power consumption, contributing to improved overall energy efficiency. Preferably, the overall impedance range of the metal coating 23 is 0.01Ω to 5Ω, so as to further improve the sensitivity and resolution of displacement detection, meet the application requirements of extremely high precision displacement measurement, and at the same time, the smaller impedance further reduces the power consumption of the system, which is especially suitable for long-term stable operation of power-sensitive portable electronic devices such as smartphones.

[0042] In practical applications, the thickness of the metal coating 23 can range from 5 μm to 30 μm. If the thickness of the metal coating 23 is less than 5 μm, the effective eddy current channel within the metal coating 23 is smaller, resulting in a weaker eddy current intensity excited by the same intensity excitation signal. This leads to a smaller displacement-inductance change rate, causing a significant reduction in the sensitivity and resolution of displacement detection. In addition, the corrosion resistance of a thinner metal coating 23 is also weaker. If the thickness of the metal coating 23 is greater than 30 μm, it will significantly increase the weight of the permanent magnet 21, increase the dynamic load, and lead to a decrease in motion flexibility and an increase in power consumption. At the same time, an excessively thick metal coating 23 will have a certain shielding effect on the main magnetic field of the permanent magnet 21 itself, reducing the magnetic flux exerted by the permanent magnet 21 on the outside, weakening the electromagnetic driving force between the drive coil 22 and the permanent magnet 21, and affecting the overall driving performance. Based on the 5μm~30μm thickness range of this invention, not only can the metal coating 23 have sufficient physical thickness to form a reliable anti-corrosion effect, but it can also provide a suitable flow path range for the generation of eddy currents, ensuring a high displacement-inductance change rate, thereby maintaining high sensitivity and high resolution displacement detection performance. Simultaneously, this thickness range can effectively avoid excessive shielding and overloading of the magnetic field of the permanent magnet 21, preventing improper attenuation of the electromagnetic driving force. Preferably, the thickness range of the metal coating 23 is 10μm~20μm to further optimize the balance between anti-corrosion performance, displacement detection performance, and driving performance.

[0043] It is understood that in the device of the present invention that uses the metal coating of the magnet of the voice coil motor to detect displacement, the driving method of the moving structure 10 is not limited to the above-mentioned method, but may be other methods. The present invention does not limit this, that is, the technical solution of the present invention has strong versatility and application adaptability, and is not constrained by the driving method of the moving structure 10. Taking a camera module as an example, in some embodiments, the lens assembly 11 of the camera module adopts a moving coil driving method. The driving coil 22 of the driving motor 20 is connected to the lens assembly 11, and the permanent magnet 21 of the driving motor 20 is fixedly set (e.g., fixed on the base). Under the action of the driving signal, the driving coil 22 can change the relative position between the driving coil 22 and the permanent magnet 21 / metal coating 23, thereby causing the driving coil 22 to drive the lens assembly 11 to move. On the other hand, the moving structure 10 is not limited to the above-mentioned lens assembly 11. In other embodiments, it may be other structures, and the present invention does not limit this.

[0044] In summary, the device for detecting displacement using the metal plating of a voice coil motor magnet of the present invention combines a permanent magnet 21, a drive coil 22, a control circuit module 30, and an inductance detection and position transformation module 40. Based on the eddy current effect of the inherent metal plating 23 of the permanent magnet 21, the drive coil 22 has both driving and displacement detection functions in coordination with the metal plating 23. By utilizing the relationship between the eddy current of the metal plating 23 and the equivalent inductance of the drive coil 22, accurate detection of the displacement state of the displacement structure can be achieved. This method eliminates the need for introducing additional displacement sensing elements or modifying the internal structure of the device, helping to reduce the internal structural complexity and manufacturing cost of the device, while also improving the overall performance and integration of the device.

[0045] Furthermore, the moving structure 10 is a lens assembly 11, and the corresponding device is a camera module. By making reasonable use of the metal structural components, namely the metal plating layer 23, inside the camera module, the present invention can realize the sensing of the displacement state of the lens assembly 11, thereby enabling feedback control of the camera module without adding additional sensors, so as to improve the overall performance of the camera module.

[0046] Furthermore, in this invention, the inductance detection and position transformation module 40 is connected to the control circuit module 30. The inductance detection and position transformation module 40 is configured to output the displacement state of the moving structure 10 to the control circuit module 30, and the control circuit module 30 is configured to output a drive signal based on the displacement state of the moving structure 10. Based on this method, closed-loop control of the moving structure 10 can be achieved, which helps to improve the accuracy and precision of drive adjustment.

[0047] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, 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 a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0048] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0049] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0051] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A device for detecting displacement using the metal plating of a voice coil motor's magnet, characterized in that, Include: A drive motor comprising a permanent magnet and a drive coil, wherein one of the permanent magnet and the drive coil is fixedly disposed, and the other is connected to a moving structure and moves synchronously therewith, and the surface of the permanent magnet has a metal plating. A control circuit module connected to the drive coil, the control circuit module being configured to provide a drive signal to the drive coil and an excitation signal for generating eddy currents on the metal plating. An inductance detection and position transformation module is configured to detect the inductance signal of the drive coil and output the displacement state of the moving structure based on the inductance signal.

2. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The inductance detection and position transformation module is connected to the control circuit module. The inductance detection and position transformation module is configured to output the displacement state of the moving structure to the control circuit module. The control circuit module is configured to output a drive signal based on the displacement state of the moving structure.

3. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The control circuit module is configured to synchronously apply the driving signal and the excitation signal to the driving coil; Alternatively, the control circuit module is configured to continuously provide the excitation signal to the drive coil; Alternatively, the control circuit module is configured to provide the excitation signal to the drive coil at preset time intervals.

4. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The movable structure is a lens assembly.

5. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The driving signal is a low-frequency current signal.

6. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The excitation signal is an AC signal; Alternatively, the excitation signal may be a high-frequency AC signal.

7. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The frequency range of the excitation signal is 1MHz to 10MHz.

8. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The thickness of the metal coating ranges from 5 μm to 30 μm; Alternatively, the thickness of the metal coating may range from 10 μm to 20 μm.

9. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The materials used to prepare the metal coating include at least one of nickel, copper, and zinc.

10. The device for detecting displacement using the metal plating of the magnet of a voice coil motor as described in claim 1, characterized in that, The impedance range of the metal coating is 0.01Ω to 10Ω; Alternatively, the impedance range of the metal coating is 0.01Ω to 5Ω.

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