Focus motor, closed-loop control method for focus motor, and imaging device

Abstract

Embodiments of the present application relate to the technical field of imaging, and disclose a focus motor, a closed-loop control method for a focus motor, and an imaging device. 【Solution means】The focus motor includes a first pole plate (10), a second pole plate (20), a hovering conductor plate (30), a mover holder (40), and a processing unit. The first pole plate (10) and the second pole plate (20) are fixedly installed and arranged perpendicular to the focusing direction. The hovering conductor plate (30) is installed opposite to the first pole plate (10) and the second pole plate (20) respectively. The hovering conductor plate (30) is provided on the mover holder (40). The mover holder (40) is movable in the focusing direction. The projection area between the hovering conductor plate (30) and the first pole plate (10), and the projection area between the hovering conductor plate (30) and the second pole plate (20) both change according to the movement of the mover holder (40). A reference capacitance is formed between the first pole plate (10) and the second pole plate (20). The processing unit controls the movement of the mover holder (40) in the focusing direction based on the reference capacitance.

Description

Technical Field

[0001] (Cross - reference to related applications) This application is filed based on a Chinese patent application with application number CN202410131895.6 and filing date January 30, 2024, and claims the priority of this Chinese patent application. The entire disclosure of this Chinese patent application is hereby incorporated herein by reference in its entirety.

[0002] (Field of the Invention) Embodiments of the present application relate to the technical field of imaging, and in particular, to a focus motor, a closed - loop control method for a focus motor, and an imaging device.

Background Art

[0003] Currently, the camera module in an imaging device usually detects the real - time position of the mover holder in the focus motor during focusing, and adjusts the drive current for driving the lens based on the detected position of the mover holder, so as to adopt a closed - loop control method that enables the mover holder to quickly reach the accurate focus position. In related technologies, a method is used in which a transmitting electrode plate and a receiving electrode plate are arranged opposite to each other. The transmitting electrode plate serves as the mover electrode plate, and its position relative to the receiving electrode plate changes, thereby causing a change in the capacitance between the transmitting electrode plate and the receiving electrode plate, and realizing the position detection of the optical focus motor through the change in capacitance.

[0004] However, in related technologies, it is necessary to reserve sufficient space in advance for designing the transmitting electrode plate and the receiving electrode plate in the focus motor. The requirement for space is high, which is disadvantageous for further reducing the size of the focus motor. Also, it is necessary to install connection wires to realize capacitance detection, and although the mover electrode plate moves constantly to realize the closed - loop control of the focus motor, the connection wires of the mover electrode plate are disadvantageous for the movement of the mover electrode plate, restricting the movement of the mover electrode plate and affecting the accuracy of the closed - loop control of the focus motor.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An embodiment of the present application aims to provide a focus motor, a closed-loop control method for a focus motor, and an imaging device that can further reduce the size of the focus motor and improve the accuracy of closed-loop control of the focus motor.

Means for Solving the Problems

[0006] To solve the above technical problems, an embodiment of the present application provides a focus motor, which includes a first pole plate, a second pole plate, a hovering conductor plate, a mover holder, and a processing unit. The first pole plate and the second pole plate are fixedly installed, and the first pole plate and the second pole plate are arranged perpendicular to the focusing direction. The hovering conductor plates are respectively installed opposite to the first pole plate and the second pole plate, and the hovering conductor plates are provided on the mover holder. The mover holder is movable in the focusing direction. The projection areas between the hovering conductor plate and the first pole plate and between the hovering conductor plate and the second pole plate both change according to the movement of the mover holder. A reference capacitance is formed between the first pole plate and the second pole plate, and the processing unit controls the movement of the mover holder in the focusing direction based on the reference capacitance.

[0007] An embodiment of the present application further provides a closed-loop control method for a focus motor applied to the processing unit of the above-mentioned focus motor. This method includes obtaining the reference capacitance after the mover holder moves in the focusing direction, determining whether the position of the mover holder coincides with the target position based on the capacitance value of the reference capacitance, and if not, controlling the mover holder to move again in the focusing direction until it is determined that the position of the mover holder coincides with the target position.

[0008] An imaging device including a lens and the above-described focus motor for driving the lens is further provided in an embodiment of the present application.

[0009] In some embodiments, the focus motor further includes a base, a magnet, and a coil. The base includes a bottom plate and two side walls along the focusing direction. The coil is provided on the two side walls of the base, the magnet is provided on both sides of the mover holder in the focusing direction, each coil is provided opposite to each magnet, and the mover holder is operated in the focusing direction by an electromagnetic force between the magnet and the coil.

[0010] In some embodiments, the first pole plate and the second pole plate are fixedly installed on the bottom plate, and the hovering conductor plate is provided on a surface of the mover holder close to the bottom plate.

[0011] In some embodiments, the first pole plate is fixedly installed on the bottom plate, the second pole plate is fixedly installed on one of the side walls, the hovering conductor plate includes a first conductor plate and a second conductor plate connected to the first conductor plate. The first conductor plate is provided on a surface of the mover holder close to the bottom plate, and the second conductor plate is provided on a surface of the mover holder close to the second pole plate.

[0012] In some embodiments, the first pole plate and the second pole plate are integrally formed with the base by insert injection molding, and the hovering conductor plate is integrally formed with the mover holder by insert injection molding.

[0013] In some embodiments, the number of the second pole plates is two, and the two second pole plates are arranged along the focusing direction.

[0014] In some embodiments, the material of the hovering conductor plate is stainless steel.

Advantages of the Invention

[0015] The technical solution according to the embodiment of the present application has at least the following advantages.

[0016] In the embodiment of the present application, by installing the first pole plate and the second pole plate so as to be fixedly arranged, the problem that the size of the focus motor is large due to the first pole plate and the second pole plate being arranged facing each other is solved. In this embodiment, the capacitance between the first pole plate and the second pole plate is changed by the jump bridge connection characteristic of the hovering conductor plate with respect to the capacitance signal. Since the distance between the hovering conductor plate and the first pole plate and the second pole plate is smaller than the distance between the first pole plate and the second pole plate in the related art, the influence of the installation of the hovering conductor plate on the size of the focus motor is small, which is advantageous for further reducing the size of the focus motor. In addition, the jump bridge connection characteristic of the hovering conductor plate can be realized without providing a connection line, which solves the problems of the complexity of the assembly process of the focus motor due to the connection line of the mover pole plate and the local signal linearity degradation, and can improve the accuracy of the closed-loop control of the focus motor.

Brief Description of the Drawings

[0017] One or more embodiments are exemplarily illustrated by the figures in the corresponding drawings. These exemplary descriptions do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. Unless otherwise specified, the figures in the drawings do not constitute scale limitations.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0018] In order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will describe each embodiment of the present application in detail with reference to the drawings. However, those skilled in the art can understand that in each embodiment of the present application, many technical details are proposed to enable readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, it is possible to implement the technical solutions that the present application intends to protect. The classification of the following embodiments is for convenience only and does not constitute any limitation to the specific embodiments of the present application. Each embodiment can be combined and referred to each other on the premise of non-contradiction.

[0019] As shown in FIG. 1, it is a diagram showing the structure of a focus motor in the related art. In the related art, pole plate 1 and pole plate 2 are used as receiving pole plates, pole plate 3 is used as a transmitting pole plate, the transmitting pole plate and the receiving pole plate are installed opposite to each other, and the transmitting pole plate 3 moves along with the mover holder as a mover pole plate to realize the position detection of the optical focus motor. However, in order to realize the accurate detection of the position of the focus motor, not only is it necessary to provide a dedicated space in the focus motor for installing the transmitting pole plate 3 and the receiving pole plates 1 and 2 so that the transmitting pole plate 3 has sufficient movement space, but also a sufficient interval is required between the transmitting pole plate 3 and the receiving pole plates 1 and 2, and the requirement for space is high. For this reason, it is necessary to reserve sufficient space in advance for designing the transmitting and receiving pole plates in the focus motor, making it impossible to further reduce the size of the focus motor.

[0020] In the related art, it is necessary to install connection lines to realize capacitance detection. To realize the closed-loop control of the focus motor, the mover pole plate moves constantly. However, due to the connection lines of the mover pole plate, not only is the assembly process complicated, but also the linearity of local signals may deteriorate depending on the positions of the connection lines, which affects the accuracy of the closed-loop control of the focus motor.

[0021] To solve the technical problems existing in the related art, such as the large size of the focus motor and the low accuracy of the closed-loop control of the focus motor, an embodiment of the present application relates to a focus motor, which includes a first pole plate, a second pole plate, a hovering conductor plate, a mover holder, and a processing unit. The first pole plate and the second pole plate are fixedly installed, and the first pole plate and the second pole plate are arranged perpendicular to the focusing direction. The hovering conductor plates are respectively installed opposite to the first pole plate and the second pole plate. The hovering conductor plates are provided on the mover holder, and the mover holder is movable in the focusing direction. The projection areas between the hovering conductor plate and the first pole plate and between the hovering conductor plate and the second pole plate both change according to the movement of the mover holder. A reference capacitance is formed between the first pole plate and the second pole plate. The processing unit controls the movement of the mover holder in the focusing direction based on the reference capacitance.

[0022] In this embodiment, the first electrode plate and the second electrode plate are fixedly installed and arranged perpendicular to the focusing direction. A hovering conductor plate is installed opposite to the first electrode plate and the second electrode plate. The hovering conductor plate can move in the focusing direction following the mover holder. As a result, the projection area between the hovering conductor plate and the first electrode plate and the projection area between the hovering conductor plate and the second electrode plate change. The capacitance between the projection areas of the first electrode plate and the second electrode plate changes under the influence of the jumping bridge connection characteristic of the hovering conductor plate. Thus, in the process of the hovering conductor plate moving along the mover holder, the capacitance between the first electrode plate and the second electrode plate shows a tendency of linear change. The processing unit determines the position of the mover holder based on the capacitance between the first electrode plate and the second electrode plate and controls the movement of the mover holder in the focusing direction to move the mover holder to the target position.

[0023] In this embodiment, by installing the first electrode plate and the second electrode plate in a fixed arrangement, the problem that the size of the focus motor is large due to the first electrode plate and the second electrode plate being arranged facing each other is solved. In this embodiment, the capacitance between the first electrode plate and the second electrode plate is changed by the jumping bridge connection characteristic of the hovering conductor plate with respect to the capacitance signal. Since the distance between the hovering conductor plate and the first electrode plate and the second electrode plate is smaller than the distance between the first electrode plate and the second electrode plate in the related art, the influence of the installation of the hovering conductor plate on the size of the focus motor is small, which is beneficial for further reducing the size of the focus motor. Also, the jumping bridge connection characteristic of the hovering conductor plate can be realized without providing a connection line, solving the problems of the complexity of the assembly process of the focus motor and the local signal linearity degradation caused by the connection line of the mover electrode plate, and improving the accuracy of the closed-loop control of the focus motor.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, each embodiment of this application will be described in detail below with reference to the drawings. However, those skilled in the art can understand that in each embodiment of this application, many technical details are proposed to help readers better understand this application. However, even without these technical details and various changes and modifications based on the following embodiments, it is still possible to implement the technical solution that this application intends to protect.

[0025] One embodiment of this application relates to a focus motor. The specific structure is shown in Figure 2. The focus motor includes a first pole plate 10, a second pole plate 20, a hovering conductor plate 30, a mover holder (not shown), and a processing unit (not shown).

[0026] Specifically, the first pole plate 10 and the second pole plate 20 are fixedly installed. The first pole plate 10 and the second pole plate 20 are arranged perpendicular to the focusing direction. The hovering conductor plate 30 is installed opposite to the first pole plate 10 and the second pole plate 20 respectively. The hovering conductor plate 30 is provided on the mover holder, and the mover holder is movable in the focusing direction. The projection areas between the hovering conductor plate 30 and the first pole plate 10, and between the hovering conductor plate 30 and the second pole plate both change according to the movement of the mover holder. A reference capacitance is formed between the first pole plate 10 and the second pole plate 20, and the processing unit controls the movement of the mover holder in the focusing direction based on the reference capacitance.

[0027] It should be noted that the number of the second pole plates 20 in Figure 2 is set to 2. In actual applications, it may be set to 1 or more, specifically according to actual needs. It is not specifically limited in this embodiment. In the figure, only 2 second pole plates 20 are taken as an example for explanation.

[0028] In one embodiment, the first pole plate 10 is a transmitting pole plate, and the second pole plate 20 is a receiving pole plate. In another embodiment, the first pole plate 10 is a receiving pole plate, and the second pole plate 20 is a transmitting pole plate. Hereinafter, the first pole plate 10 is taken as the transmitting pole plate and the second pole plate 20 is taken as the receiving pole plate for illustrative description, but it does not limit the protection scope of this application.

[0029] Specifically, in the process of moving in the focusing direction following the mover holder, the projection area between the hovering conductor plate 30 and the first pole plate 10 and the projection area between the hovering conductor plate 30 and the second pole plate 20 change, and the capacitance between the projection areas of the first pole plate 10 and the second pole plate 20 changes under the influence of the jumping bridge connection characteristics of the hovering conductor plate 30. FIG. 3 is a diagram showing the principle of the jumping bridge connection characteristics of the hovering conductor plate 30 according to this embodiment. Here, when detecting the reference capacitance between the first pole plate 10 and the second pole plate 20, the first pole plate 10 and the second pole plate 20 are connected to the peripheral circuit, and the reference capacitance between the first pole plate 10 and the second pole plate 20 is measured by the charge transfer thereon. When a positive voltage signal is applied to the first pole plate 10, a large amount of positive charges are accumulated on the surface of the first pole plate 10, and negative charges are accumulated on the surface of the hovering conductor plate 30 corresponding to the first pole plate 10. Since there is no external circuit on the hovering conductor plate 30, the charge does not transfer, and since the charge of one hovering conductor plate 30 itself is conserved, the positive charges are accumulated on the other surface, that is, the surface close to the second pole plate. In this way, the surface on the second pole plate 20 side is affected by the positive charges of the hovering conductor plate 30, and negative charges are accumulated on the surface, thus achieving the capacitance effect between the two pole plates.

[0030] Therefore, due to the presence of the hovering conductor plate 30, the dielectric between the first electrode plate 10 and the second electrode plate 20 in the portion occupied by the hovering conductor plate 30 disappears, which is equivalent to reducing the distance between the first electrode plate 10 and the second electrode plate 20. From the capacitance calculation formula C = εS / 4πkd, where C is capacitance, ε is the dielectric constant of the dielectric, k is the electrostatic constant, S is the overlapping area of the two electrode plates, and d is the perpendicular distance between the two electrode plates, it can be seen that due to the presence of the hovering conductor plate 30, it is equivalent to reducing the distance d between the first electrode plate 10 and the second electrode plate 20. The capacitance between the hovering conductor plate 30 and a part of the first electrode plate 10 and a part of the second electrode plate 20 with a projection area increases. Thus, in the process of the hovering conductor plate 30 moving following the mover holder, the capacitance between the first electrode plate 10 and the second electrode plate 20 shows a tendency of linear change. As a result, the processing unit can more easily identify the position of the mover holder based on the linearly changing capacitance between the first electrode plate 10 and the second electrode plate 20, control the movement of the mover holder in the focusing direction, move the mover holder to the target position, and improve the accuracy of the closed-loop control of the focus motor.

[0031] Continuing to refer to FIG. 2, when the number of the second electrode plates 20 is set to two, the length of the first electrode plate 10 is greater than or equal to the lengths of the two second electrode plates 20. When there is a gap between the two second electrode plates 20, the length of the first electrode plate 10 is greater than or equal to the sum of the lengths of the two second electrode plates 20 and the gap. Here, the lengths of the first electrode plate 10 and the second electrode plates 20 are both the lengths in the focusing direction, the widths of the first electrode plate 10 and the second electrode plates 20 are the same, and the shapes and sizes of the two second electrode plates 20 are the same. In this case, in the process of moving in the focusing direction following the mover holder, the area of the projection region between the hovering conductor plate 30 and one of the second electrode plates 20 gradually decreases, and the area of the projection region between the hovering conductor plate 30 and the other second electrode plate 20 gradually increases. However, the area of the projection region between the hovering conductor plate 30 and the first electrode plate 10 does not change during the movement.

[0032] Therefore, in the process of the hovering conductor plate 30 moving in the focusing direction following the mover holder, the reference capacitance between the first pole plate 10 and one of the second pole plates 20 gradually increases, and the reference capacitance between the first pole plate 10 and the other second pole plate 20 gradually decreases. The change trends of the two reference capacitances are shown in FIG. 4, where the horizontal axis is the distance that the mover holder moves in the focusing direction, the vertical axis is the capacitance value of the reference capacitance, curve A shows a tendency to decrease linearly, and curve B shows a tendency to increase linearly. In this embodiment, two second pole plates 20 are provided, and the capacitances that linearly change between the first pole plate 10 and the two second pole plates 20 respectively strengthen the robustness of the capacitance signal and further improve the accuracy of the closed-loop control of the focus motor. At the same time, in this embodiment, by controlling the mover holder to move to the target position according to the two formed reference capacitances, the influence of environmental factors on the acquired capacitance signal is easily offset, the moving position of the mover holder can be controlled more accurately, and the accuracy of the closed-loop control of the focus motor can be improved.

[0033] The above-mentioned focus motor may be an electromagnetic motor, a piezoelectric motor, or a shape memory alloy motor, but is not limited to these three types of motors. An electromagnetic motor is a motor that uses the electromagnetic force between a coil and a magnet as a driving force, a piezoelectric motor is a motor that uses the piezoelectric effect of ultrasonic piezoelectric ceramics as a driving force, and a shape memory alloy motor is a motor that uses the deformation characteristics of a memory metal as a driving force.

[0034] In this embodiment, the first electrode plate 10 and the second electrode plate 20 are fixedly arranged. The capacitance between the first electrode plate 10 and the second electrode plate 20 is changed by the jumping bridge connection characteristic of the hovering conductor plate 30 with respect to the capacitance signal. Since the distance between the hovering conductor plate and the first electrode plate and the second electrode plate is smaller than the distance between the first electrode plate and the second electrode plate in the related art, the installation of the hovering conductor plate 30 has little influence on the size of the focus motor, which is advantageous for further reducing the size of the focus motor. In addition, the jumping bridge connection characteristic of the hovering conductor plate 30 can be realized without providing a connection line, which solves the problems of the complexity of the assembly process of the focus motor and the local signal linearity degradation caused by the connection line of the mover electrode plate, and can improve the accuracy of the closed-loop control of the focus motor.

[0035] In one embodiment, the focus motor further includes a base, a magnet, and a coil. As shown in FIG. 5, which is a diagram showing the structure of the focus motor according to this embodiment, the focus motor includes a first electrode plate 10, a second electrode plate 20, a hovering conductor plate 30, a mover holder 40, a processing unit (not shown), a base 50, a magnet 60, and a coil 70.

[0036] Specifically, the base 50 includes a bottom plate 501 and two side walls 502 along the focusing direction. The coil 70 is provided on the two side walls 502 of the base 50. The magnet 60 is provided on both sides of the mover holder 40 in the focusing direction. Each coil 70 is provided opposite to each magnet 60. The mover holder 40 is operated in the focusing direction by the electromagnetic force between the magnet 60 and the coil 70.

[0037] In this embodiment, the specific connection method between the mover holder 40 and the base 50 is limited. The mover holder 40 of this embodiment is operated in the focusing direction by the electromagnetic force between the magnet 60 and the coil 70. The movable stroke of the mover holder 40 is large. In this embodiment, it can also serve as a motor with a large stroke.

[0038] In one embodiment, the first electrode plate 10 and the second electrode plate 20 are fixedly installed on the bottom plate 501, and the hovering conductor plate 30 is provided on the surface of the mover holder 40 close to the bottom plate 501.

[0039] Specifically, regarding the installation of the first electrode plate 10 and the second electrode plate 20 on the base 50 respectively, the first electrode plate 10 and the second electrode plate 20 can be directly attached to the corresponding areas on the base 50 and connected to the connection wires inside the motor to achieve conduction. Or, insert injection molding in which metal parts are incorporated into plastic parts can be used for direct injection molding to save the motor assembly process. Or, by laser direct shaping technology, electroplating can be activated by using laser engraving on the surface of a part of the plastic part, endowing the electroplated area with conductivity, and realizing the processing of the electrode plate in the corresponding area of the base 50.

[0040] In one embodiment, the first electrode plate 10 and the second electrode plate 20 are integrally formed with the base 50 by insert injection molding, and the hovering conductor plate 30 is integrally formed with the mover holder 40 by insert injection molding.

[0041] In the related art, for a certain motor with a large stroke, in order to realize control for stable movement, the mover holder does not use a conductive metal elastic sheet, and always uses a non-conductive ball or rail bar to realize the sliding connection between the mover holder and the housing. In the related art, since the mover pole plate is installed on the mover holder and a connection wire needs to be installed for power supply as the mover holder moves, it is very difficult to supply power to the mover pole plate of the large-stroke motor with a ball or rail bar installed in the related art. Therefore, in this embodiment, the transmitting pole plate and the receiving pole plate can be installed on the fixed base 50 where electrical connection can be easily realized, and the corresponding hovering conductor plate 30 can be installed on the mover holder 40. The hovering conductor plate 30 can realize the detection of the capacitive mover position without requiring an electrical connection structure, can realize the focusing closed-loop control, and can also be applied to a large-stroke motor with a ball or rail bar installed. Therefore, the mover holder 40 of this embodiment can be slidably connected to the housing using a ball or rail bar in order to realize control for stable movement. Note that the housing of this embodiment is a metal housing, which is installed outside the base, and a ball or rail bar is installed on the metal housing to realize the sliding connection between the mover holder 40 and the metal housing.

[0042] In one embodiment, the first pole plate 10 is fixedly installed on the bottom plate 501, the second pole plate 20 is fixedly installed on one side wall 502, the hovering conductor plate 30 includes a first conductor plate and a second conductor plate connected to the first conductor plate. The first conductor plate is provided on the surface of the mover holder 40 close to the bottom plate 501, and the second conductor plate is provided on the surface of the mover holder 40 close to the second pole plate 20. As shown in FIG. 6, which is a diagram showing the structure of the focus motor of this embodiment, here, the first pole plate 10 and the second pole plate 20 are perpendicular to each other and are respectively provided on the bottom plate 501 and one side wall 502. On the other hand, the hovering conductor plate 30 has an L-shaped structure, includes a first conductor plate and a second conductor plate connected to the first conductor plate. The first conductor plate is installed opposite to the first pole plate 10, and the second conductor plate is installed opposite to the second pole plate 20. Accordingly, the first conductor plate is installed on the surface of the mover holder 40 close to the bottom plate 501, and the second conductor plate is installed on the surface of the mover holder 40 close to the second pole plate 20.

[0043] In this embodiment, another method of installing the first pole plate 10 and the second pole plate 20 on the base 50 is provided. By installing the first pole plate 10 and the second pole plate 20 on two adjacent angled surfaces, the same position detection function is realized.

[0044] In one embodiment, the material of the hovering conductor plate 30 is stainless steel. In other embodiments, the hovering conductor plate 30 may be made of other metal materials, such as copper, aluminum, and other materials that can realize the conductor function.

[0045] The classification of the above components is for the convenience of description. During implementation, they can be integrated into one component or divided into several components. As long as they include the same logical relationship, they are all within the protection scope of this patent.

[0046] Another embodiment of the present application relates to a closed-loop control method for a focus motor applied to the above-mentioned focus motor. As shown in FIG. 7, the closed-loop control method for the focus motor includes the following steps.

[0047] Step 101: After the mover holder moves in the focusing direction, obtain the reference capacitance.

[0048] Step 102: Based on the capacitance value of the reference capacitance, determine whether the position of the mover holder coincides with the target position.

[0049] If they do not coincide, proceed to step 103, and control to continue moving the mover holder by increasing or decreasing the output drive current or drive voltage, return to step 101. After the mover holder moves in the focusing direction, obtain the reference capacitance between the first electrode plate and the second electrode plate, and repeat the determination in step 102 until it is determined that the position of the mover holder coincides with the target position, and then proceed to step 104 to complete the movement of the mover holder.

[0050] Step 103: Control to continue moving the mover holder by increasing or decreasing the output drive current or drive voltage.

[0051] Step 104: Complete the movement of the mover holder.

[0052] In one embodiment, step 102, that is, based on the capacitance value of the reference capacitance, determining whether the position of the mover holder coincides with the target position, its specific sub-steps are shown in FIG. 8, and specifically include the following sub-steps.

[0053] Step 201: Receive the target position required for the movement of the mover holder transmitted from the host.

[0054] Step 202: Based on the correspondence relationship between the pre-stored positions and capacitance values, determine the capacitance value corresponding to the target position as the target capacitance value.

[0055] Step 203: Based on the capacitance value of the reference capacitance and the target capacitance value, determine whether the position of the mover holder coincides with the target position.

[0056] Specifically, when the number of the second electrode plates is two, when controlling the movement of the mover holder in the focusing direction using the reference capacitances of the first electrode plate and the second electrode plates, it is possible to determine whether the mover holder coincides with the target position by the following method. In the first method, if the two acquired reference capacitances are respectively the same as the two capacitances between the first electrode plate and the two second electrode plates acquired when the focus motor is at the target position during the pre-adjustment process, the mover holder coincides with the target position. In the second method, a difference operation is performed on the two acquired reference capacitances, and if the calculated difference value is the same as the difference value of the two capacitances between the first electrode plate and the two second electrode plates acquired when the focus motor is at the target position during the pre-adjustment process, the mover holder coincides with the target position. Note that after performing the difference operation, the difference value can be amplified to increase the robustness of the capacitance signal and make the control of the focus motor more sensitive. In the third method, a calibration value is calculated from the two above-mentioned reference capacitances and the two capacitance values between the first electrode plate and the two second electrode plates when the mover holder is at the bottom of the focus motor. To cancel the influence of environmental factors on the two reference capacitances, the difference value of the two reference capacitances is calibrated based on this calibration value, and the calibrated difference value is compared with the difference value of the two reference capacitances when the focus motor is at the target position during the pre-adjustment process. If the two are the same, the mover holder coincides with the target position.

[0057] Specifically, the closed-loop control is realized by a processing unit, and the processing unit includes a capacitance detection circuit, an analysis and calculation circuit, and a control output circuit. Here, the capacitance detection circuit is used to detect the reference capacitance between the first electrode plate and the second electrode plate. The analysis and calculation circuit is used to determine whether to move the mover based on the acquired reference capacitance and the drive current or drive voltage required for the movement. The control output circuit is used to output the calculated drive current or drive voltage to the motor to control the movement of the mover holder of the motor.

[0058] Specifically, after controlling the movement of the mover holder of the motor, the mover holder after the movement changes the reference capacitance between the first and second pole plates again, and the processing unit performs analysis and calculation based on the capacitance signal after the change again until the current position of the mover holder coincides with the target position, and completes the control of the motor.

[0059] Specifically, the correspondence between the position and the capacitance value pre-stored in step 202 can be established in the following manner. First, move the mover holder to the bottom of the focus motor, and then move the mover holder step by step at a preset interval. And record the capacitance value of the reference capacitance after each movement and the distance between the mover holder after each movement and the bottom plate of the focus motor. The correspondence between the distance between the mover holder and the bottom plate after each movement and the capacitance value of the reference capacitance is taken as the correspondence between the position and the capacitance value.

[0060] The division of the steps of each of the above methods is for the convenience of description. When implemented, it can be integrated into one step or divided into several steps. As long as the same logical relationship is included, all are within the protection scope of this patent. Whether in an algorithm or in a process, adding unimportant modifications or introducing unimportant designs, but the core designs that do not change the algorithm or process are all within the protection scope of this patent.

[0061] Another embodiment of the present application relates to an imaging device including a lens and the above-described focus motor for driving the lens.

[0062] In the imaging device according to the embodiment of the present application, compared with the related art, since the focus motor according to the above embodiment is provided, the same technical effects as those of the above embodiment can be achieved, and the description is omitted here.

[0063] Those skilled in the art can understand that each of the above embodiments is a specific example for implementing the present invention, but in actual applications, various changes can be made to the form and details without departing from the spirit and scope of the present application.

Claims

1. A focusing motor comprising a first electrode plate, a second electrode plate, a hovering conductor plate, a mover holder, and a processing unit, wherein the first electrode plate and the second electrode plate are fixedly installed, and the first electrode plate and the second electrode plate are arranged perpendicular to the focusing direction, the hovering conductor plates are respectively installed opposite to the first electrode plate and the second electrode plate, the hovering conductor plates are provided on the mover holder, the mover holder is movable in the focusing direction, and the projection areas between the hovering conductor plates and the first electrode plate and between the hovering conductor plates and the second electrode plate both change according to the movement of the mover holder, a reference capacitance is formed between the first electrode plate and the second electrode plate, and the processing unit controls the movement of the mover holder in the focusing direction based on the reference capacitance, characterized in that it is a focusing motor.

2. The focusing motor further comprises a base, a magnet, and a coil, the base comprises a bottom plate and two side walls along the focusing direction, the coils are provided on the two side walls of the base, the magnets are provided on both sides of the mover holder in the focusing direction, and each coil is provided opposite to each magnet, the mover holder is operated in the focusing direction by the electromagnetic force between the magnet and the coil, characterized in that it is the focusing motor according to claim 1.

3. The first electrode plate and the second electrode plate are fixedly installed on the bottom plate, and the hovering conductor plate is provided on the surface of the mover holder close to the bottom plate, characterized in that it is the focusing motor according to claim 2.

4. The first electrode plate is fixedly installed on the bottom plate, and the second electrode plate is fixedly installed on one of the side walls, the hovering conductor plate comprises a first conductor plate and a second conductor plate connected to the first conductor plate, the first conductor plate is provided on the surface of the mover holder close to the bottom plate, and the second conductor plate is provided on the surface of the mover holder close to the second electrode plate, characterized in that it is the focusing motor according to claim 2.

5. The first electrode plate and the second electrode plate are integrally formed with the base by insert injection molding, and the hovering conductor plate is integrally formed with the mover holder by insert injection molding, characterized in that it is the focusing motor according to claim 3 or 4.

6. The number of the second plates is two, and the two second plates are arranged along the focusing direction. The focus motor according to any one of claims 1 to 4, characterized in that.

7. The material of the hovering conductor plate is stainless steel. The focus motor according to any one of claims 1 to 4, characterized in that.

8. A closed-loop control method for a focus motor applied to the processing unit of the focus motor according to any one of claims 1 to 7, comprising: After the mover holder moves in the focusing direction, obtaining the reference capacitance; Based on the capacitance value of the reference capacitance, determining whether the position of the mover holder coincides with the target position; If they do not coincide, controlling the mover holder to move again in the focusing direction until it is determined that the position of the mover holder coincides with the target position. A closed-loop control method for a focus motor, characterized in that.

9. Determining whether the position of the mover holder coincides with the target position based on the capacitance value of the reference capacitance includes: Based on the correspondence relationship between the pre-stored position and capacitance value, determining the capacitance value corresponding to the target position as the target capacitance value; Based on the capacitance value of the reference capacitance and the target capacitance value, determining whether the position of the mover holder coincides with the target position. The closed-loop control method for a focus motor according to claim 8, characterized in that.

10. An imaging device comprising a lens and the focus motor according to any one of claims 1 to 7 for driving the lens. Characterized in that.

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