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

Abstract

The 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 apparatus. [Solution] The focus motor of the present application includes a first pole plate, a second pole plate, a first hovering conductor plate, a second hovering conductor plate, a movable member holder, a conductor member, and a processing unit, wherein the first pole plate and the second pole plate are fixedly installed, the first hovering conductor plate is provided on a first surface of the movable member holder in the focusing direction, the second hovering conductor plate is provided on a second surface of the movable member holder away from the first surface, the first hovering conductor plate is connected to the second hovering conductor plate by a conductor member, the movable member holder is movable in the focusing direction, the first hovering conductor plate is installed opposite the first pole plate, the second hovering conductor plate is installed opposite the second pole plate, and a reference capacitance is formed between the first pole plate and the second pole plate, thereby further reducing the size of the focus motor and improving the accuracy of the closed-loop control of the focus motor.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application is filed based on and claims priority to a Chinese patent application having application number CN202410128714.4 and filing date January 30, 2024, the entire disclosure of which is hereby incorporated by reference into this application.

[0002] FIELD OF THEINVENTION The present embodiment relates 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 apparatus. [Background technology]

[0003] At present, the camera module in the imaging device usually adopts a closed-loop control method, which detects the real-time position of the mover holder in the focus motor during focusing, and adjusts the driving current for driving the lens according to the detected position of the mover holder, so that the mover holder can quickly reach the accurate focus position. In the related art, a method is used in which a transmitting plate and a receiving plate are arranged opposite to each other, and the transmitting plate is a mover plate, and the position between the transmitting plate and the receiving plate changes, which causes a change in the electric capacitance between the transmitting plate and the receiving plate, and the position detection of the optical focus motor is realized by the change in the electric capacitance.

[0004] However, in the related art, sufficient space must be reserved in advance for designing the transmitting and receiving plates in the focus motor, which requires a large space, which is disadvantageous for further reducing the size of the focus motor. In addition, a connecting line must be installed to realize capacitance detection, and the mover plate must constantly move to realize the closed-loop control of the focus motor, but the connecting line of the mover plate is disadvantageous to the movement of the mover plate, which limits the movement of the mover plate and affects the accuracy of the closed-loop control of the focus motor. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present embodiment is to provide a focus motor, a closed-loop control method for a focus motor, and an imaging apparatus that can further reduce the size of the focus motor and improve the accuracy of the closed-loop control of the focus motor. [Means for solving the problem]

[0006] In order to solve the above technical problems, an embodiment of the present application provides a focus motor, which includes a first electrode plate, a second electrode plate, a first hovering conductor plate, a second hovering conductor plate, a movable member holder, a conductor member, and a processing unit, wherein the first electrode plate and the second electrode plate are fixedly installed, the first hovering conductor plate is provided on a first surface of the movable member holder in a focusing direction, the second hovering conductor plate is provided on a second surface of the movable member holder away from the first surface, the first hovering conductor plate is connected to the second hovering conductor plate by the conductor member, the movable member holder is movable in the focusing direction, the first hovering conductor plate is installed opposite the first electrode plate, and the second hovering conductor plate is installed opposite the second electrode plate, a reference capacitance is formed between the first electrode plate and the second electrode plate, and the processing unit controls the movement of the movable member 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, the method including: acquiring the reference capacitance after the movable member holder moves in the focusing direction; determining whether the position of the movable member holder matches a target position based on a capacitance value of the reference capacitance; and if they do not match, controlling the movable member holder to move again in the focusing direction until it is determined that the position of the movable member holder matches the target position.

[0008] The present embodiment further provides an imaging device including a lens and the above-described focus motor for driving the lens.

[0009] In some embodiments, the focus motor further comprises a base, the base comprising a bottom plate and two side walls along the focusing direction, the first plate being fixedly mounted to one of the side walls and the second plate being fixedly mounted to the other side wall.

[0010] In some embodiments, the conductive member is disposed inside the armature holder.

[0011] In some embodiments, the first electrode plate and the second electrode plate are integrally molded with the base by insert injection molding, and the first hovering conductor plate and the second hovering conductor plate are integrally molded with the movable member holder by insert injection molding.

[0012] In some embodiments, the number of the second plates is two, and the two second plates are arranged along the focusing direction.

[0013] In some embodiments, during the process of the movement of the movable member holder, the facing area between the first hovering conductor plate and the first electrode plate remains unchanged, the facing area between the second hovering conductor plate and one of the second electrodes gradually decreases, and the facing area between the second hovering conductor plate and the other of the second electrodes gradually increases.

[0014] In some embodiments, the first hovering conductor plate and the second hovering conductor plate are made of stainless steel. Effect of the Invention

[0015] The technical solutions of the embodiments of the present application have at least the following advantages:

[0016] In the embodiment of the present application, the first and second plates are fixedly installed and are respectively installed opposite the first hovering conductor plate and the second hovering conductor plate, the first hovering conductor plate is connected to the second hovering conductor plate by a conductor member, and the capacitance between the first and second plates is changed by utilizing the jump bridge connection characteristics of the first and second hovering conductor plates for the capacitive signals. Compared with the related art, the spatial design of the first and second plates is more flexible, and the first and second plates can be installed in the vacant space of the focus motor. In addition, the distance between the first hovering conductor plate and the first plate, and the distance between the second hovering conductor plate and the second plate are shorter than the distance between the first and second plates in the related art, so that the impact of the installation of the first and second hovering conductor plates on the size of the focus motor is small, which is favorable for further reducing the size of the focus motor. In addition, the jump bridge connection characteristics of the first hovering conductor plate and the second hovering conductor plate can be realized without providing any other connecting lines, which eliminates the problem of increased complexity in the assembly process of the focus motor and local degradation of signal linearity due to the connecting lines of the mover pole plates, and improves the accuracy of the closed-loop control of the focus motor. [Brief description of the drawings]

[0017] One or more embodiments are illustratively illustrated by corresponding drawing figures, which illustrations are not intended to be limiting of the embodiments, in which identically numbered elements are shown as similar elements, and in which the drawing figures are not to be construed as limiting the scale unless otherwise specified. [Figure 1] FIG. 1 is a diagram showing the structure of a focus motor in the related art. [Diagram 2] FIG. 2 is a diagram showing a structure of a focus motor according to an embodiment of the present application. [Diagram 3] FIG. 3 is a diagram showing the principle of jump bridge connection characteristics of the first hovering conductor plate and the second hovering conductor plate according to an embodiment of the present application. [Figure 4] FIG. 4 is a graph showing change trends of two reference capacities according to one embodiment of the present application. [Diagram 5]FIG. 5 is a diagram showing a structure of a focus motor according to an embodiment of the present application. [Figure 6] FIG. 6 is a flowchart of a closed-loop control method for a focus motor according to an embodiment of the present application. [Figure 7] 7 is a flow chart illustrating a process for determining whether a target position is coincident with the target position according to one embodiment of the present application. One or more embodiments are illustratively illustrated by corresponding figures in the drawings, and these illustrative illustrations are not intended to be limiting of the embodiments, in which like reference numerals are used to denote similar elements, and in which the figures are not to scale unless otherwise specified. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In order to clarify the purpose, technical solution and advantages of the embodiments of the present application, the embodiments of the present application will be described in detail with reference to the drawings. However, those skilled in the art will understand that many technical details are proposed in the embodiments of the present application to allow the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution that the present application is intended to protect can be realized. The division of the following embodiments is for convenience and does not constitute any limitation on the specific embodiments of the present application, and the embodiments can be combined with each other for reference on the premise that there is no contradiction.

[0019] As shown in FIG. 1, the structure of a focus motor in the related art is shown. In the related art, the plate 1 and the plate 2 are the receiving plate, and the plate 3 is the transmitting plate, and the transmitting plate and the receiving plate are installed opposite to each other, and the transmitting plate 3 is a moving plate and moves along with the moving plate holder, thereby realizing the position detection of the optical focus motor. However, in order to realize accurate detection of the position of the focus motor, not only is it necessary to provide a dedicated space in the focus motor to install the transmitting plate 3 and the receiving plates 1 and 2, so that the transmitting plate 3 has sufficient movement space, but also a sufficient gap is required between the transmitting plate 3 and the receiving plates 1 and 2, which has a high requirement for space. Therefore, it is necessary to leave a sufficient space in advance to design the transmitting plate and the receiving plate in the focus motor, which makes it impossible to further reduce the size of the focus motor.

[0020] In the related technology, a connecting line needs to be installed to realize capacitance detection, and the mover plate moves constantly to realize closed-loop control of the focus motor. However, the connecting line of the mover plate not only complicates the assembly process, but also may deteriorate the linearity of the local signal depending on the position of the connecting line, which affects the accuracy of the closed-loop control of the focus motor.

[0021] In order to solve the technical problems existing in the related art, that is, the size of the focus motor is large and the accuracy of the closed-loop control of the focus motor is low, one embodiment of the present application relates to a focus motor, which includes a first pole plate, a second pole plate, a first hovering conductor plate, a second hovering conductor plate, a mover holder, a conductor member, and a processing unit, the first pole plate and the second pole plate are fixedly installed, the first hovering conductor plate is provided on a first surface of the mover holder in a focusing direction, the second hovering conductor plate is provided on a second surface of the mover holder away from the first surface, the first hovering conductor plate is connected to the second hovering conductor plate by a conductor member, the mover holder is movable in the focusing direction, the first hovering conductor plate is installed opposite the first pole plate, the second hovering conductor plate is installed opposite the second pole plate, 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.

[0022] In this embodiment, the first electrode plate and the second electrode plate are fixedly installed, and the first hovering conductor plate and the second hovering conductor plate are installed opposite the first electrode plate and the second electrode plate. The first hovering conductor plate and the second hovering conductor plate are movable in the focusing direction following the mover holder, so that the projection area between the first hovering conductor plate and the first electrode plate and the projection area between the second hovering conductor plate and the second electrode plate change, and the capacitance between the projection area of ​​the first electrode plate and the projection area of ​​the second electrode plate becomes the first The capacitance between the first plate and the second plate changes due to the influence of the jump bridge connection characteristics of the hovering conductor plate and the second hovering conductor plate, so that in the process of the first hovering conductor plate and the second hovering conductor plate moving along the movable member holder, the capacitance between the first plate and the second plate shows a linear change trend, and the processing unit can determine the position of the movable member holder based on the capacitance between the first plate and the second plate, and control the movement of the movable member holder in the focusing direction to move the movable member holder to the target position.

[0023] In this embodiment, the first and second plates are fixedly installed and are respectively installed opposite the first hovering conductor plate and the second hovering conductor plate, and the first hovering conductor plate is connected to the second hovering conductor plate by a conductor member, and the capacitance between the first and second plates is changed by utilizing the jump bridge connection characteristics of the first and second hovering conductor plates for the capacitive signals. Compared with the related art, the spatial design of the first and second plates is more flexible, and the first and second plates can be installed in the vacant space of the focus motor. In addition, the distance between the first hovering conductor plate and the first plate, and the distance between the second hovering conductor plate and the second plate are shorter than the distance between the first and second plates in the related art, so that the impact of the installation of the first and second hovering conductor plates on the size of the focus motor is small, which is favorable for further reducing the size of the focus motor. In addition, the jump bridge connection characteristics of the first hovering conductor plate and the second hovering conductor plate can be realized without providing any other connecting lines, which eliminates the problem of increased complexity in the assembly process of the focus motor and local degradation of signal linearity due to the connecting lines of the mover pole plates, and improves the accuracy of the closed-loop control of the focus motor.

[0024] In order to clarify the purpose, technical solution and advantages of the embodiments of the present application, the embodiments of the present application will be described in detail with reference to the drawings. However, those skilled in the art will understand that many technical details are proposed in the embodiments of the present application to allow the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution that the present application is intended to protect can be realized.

[0025] One embodiment of the present application relates to a focus motor, the specific structure of which is shown in FIG. 2, where the focus motor includes a first pole plate 10, a second pole plate 20, a first hovering conductor plate 30, a second hovering conductor plate 40, a mover holder (not shown), a conductor member 50, and a processing unit (not shown).

[0026] Specifically, the first electrode plate 10 and the second electrode plate 20 are fixedly installed, the first hovering conductor plate 30 is provided on a first surface in the focusing direction of the movable member holder, and the second hovering conductor plate 40 is provided on a second surface of the movable member holder away from the first surface, the first hovering conductor plate 30 is connected to the second hovering conductor plate 40 by a conductor member 50, the movable member holder is movable in the focusing direction, the first hovering conductor plate 30 is installed opposite the first electrode plate 10, and the second hovering conductor plate 40 is installed opposite the second electrode plate 20, a reference capacitance is formed between the first electrode plate 10 and the second electrode plate 20, and the processing unit controls the movement of the movable member holder in the focusing direction based on the reference capacitance.

[0027] In addition, the number of second electrodes 20 in FIG. 2 is set to two, and in actual applications, it may be set to one or more, specifically set according to actual needs, and is not specifically limited in this embodiment, and only two second electrodes 20 are illustrated as an example in the figure.

[0028] In one embodiment, the first plate 10 is a transmitting plate and the second plate 20 is a receiving plate. In another embodiment, the first plate 10 is a receiving plate and the second plate 20 is a transmitting plate. In the following, the first plate 10 is described as a transmitting plate and the second plate 20 is described as a receiving plate, but this does not limit the scope of protection of the present application.

[0029] Specifically, in the process of the first hovering conductor plate 30 and the second hovering conductor plate 40 moving in the focusing direction following the mover holder, the projection area between the first hovering conductor plate 30 and the first electrode plate 10 and the projection area between the second hovering conductor plate 40 and the second electrode plate 20 change, and the capacitance between the projection area of ​​the first electrode plate 10 and the projection area of ​​the second electrode plate 20 changes under the influence of the jump bridge connection characteristics of the first hovering conductor plate 30 and the second hovering conductor plate 40. Figure 3 is a diagram showing the principle of the jump bridge connection characteristics of the first hovering conductor plate 30 and the second hovering conductor plate 40 according to this embodiment, where, when detecting the reference capacitance between the first electrode plate 10 and the second electrode plate 20, the first electrode plate 10 and the second electrode plate 20 are connected to a peripheral circuit, and the reference capacitance between the first electrode plate 10 and the second electrode plate 20 is measured by charge transfer thereon. When a positive voltage signal is applied to the first plate 10, a large amount of positive charges are accumulated on the surface of the first plate 10, and a negative charge is accumulated on the surface of the first hovering conductor plate 30 corresponding to the first plate 10. The first hovering conductor plate 30 and the second hovering conductor plate 40 are connected by the conductor member 50, and the charges of the first hovering conductor plate 30 and the second hovering conductor plate 40 are kept constant, so that a positive charge is accumulated on the second hovering conductor plate 40, and the surface on the second plate 20 side is influenced by the positive charge of the second hovering conductor plate 40, and a negative charge is accumulated on the surface, thus achieving the capacitive effect between the two plates.

[0030] Therefore, due to the presence of the first hovering conductor plate 30 and the second hovering conductor plate 40, the dielectric of the space between the first electrode plate 10 and the second electrode plate 20 occupied by the first hovering conductor plate 30 and the second hovering conductor plate 40 is equivalent to disappearing, and the distance between the first electrode plate 10 and the second electrode plate 20 is shortened. Even if the distance between the first electrode plate 10 and the second electrode plate 20 becomes large, the actual distance is short. As can be seen from the capacitance calculation formula C=εS / 4πkd, where C is the capacitance, ε is the dielectric constant of the dielectric, k is the electrostatic force constant, S is the overlapping area of ​​the two electrodes, and d is the vertical distance between the two electrodes, due to the presence of the first hovering conductor plate 30 and the second hovering conductor plate 40, the dielectric of the first electrode plate 10 is eliminated. This corresponds to shortening the distance d between the electrode plate 10 and the second electrode plate 20, and the capacitance between a part of the first electrode plate 10 and a part of the second electrode plate 20 in the projection area becomes larger. As a result, in the process of the first hovering conductor plate 30 and the second hovering conductor plate 40 moving following the mover holder, the capacitance between the first electrode plate 10 and the second electrode plate 20 tends to change linearly, so that the processing unit can more easily identify the position of the mover holder based on the capacitance of linear change between the first electrode plate 10 and the second electrode plate 20, control the movement of the mover holder in the focusing direction, and move the mover holder to the target position, thereby improving the accuracy of the closed-loop control of the focus motor.

[0031] Continuing to refer to FIG. 2, when the number of second pole plates 20 is set to two, in the process in which the first hovering conductor plate 30 and the second hovering conductor plate 40 move in the focusing direction following the mover holder, the facing area between the first hovering conductor plate 30 and the first pole plate 10 remains unchanged, the facing area between the second hovering conductor plate 40 and one of the second pole plates 20 gradually decreases, and the facing area between the second hovering conductor plate 40 and the other second pole plate 20 gradually increases.

[0032] Therefore, in the process of the first hovering conductor plate 30 and the second hovering conductor plate 40 moving in the focusing direction following the mover holder, the reference capacitance between the first electrode plate 10 and one of the second electrode plates 20 gradually increases, and the reference capacitance between the first electrode plate 10 and the other of the second electrode plates 20 gradually decreases, and the change trends of the two reference capacitances are shown in Figure 4, where the horizontal axis is the distance the mover holder moves in the focusing direction, and the vertical axis is the capacitance value of the reference capacitance, where curve A shows a linear decrease trend, and curve B shows a linear increase trend. In this embodiment, two second electrode plates 20 are provided, and the capacitance between the first electrode plate 10 and the two second electrode plates 20 changes linearly, respectively, to enhance 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, the movable piece holder is controlled to move to a target position using the two reference capacitances formed, which makes it easier to offset the influence of environmental factors on the acquired capacitance signal, and the position of the movable piece holder movement can be controlled more precisely, thereby improving the accuracy of the closed-loop control of the focus motor.

[0033] 2, in the process of the first hovering conductor plate 30 and the second hovering conductor plate 40 moving in the focusing direction following the mover holder, in order to ensure that the facing area between the first hovering conductor plate 30 and the first electrode plate 10 does not change, the length of the first hovering conductor plate 30 must be greater than or equal to the sum of the length of the first electrode plate 10 and the maximum stroke of the mover holder, and the width of the first hovering conductor plate 30 may be greater than or equal to the width of the first electrode plate 10, where the length of the first hovering conductor plate 30 and the length of the first electrode plate 10 are both lengths in the focusing direction. As a result, no matter how the first hovering conductor plate 30 moves, the first hovering conductor plate 30 can completely cover the first electrode plate 10, and the facing area between the first hovering conductor plate 30 and the first electrode plate 10 can not be changed.

[0034] In addition, the first electrode plate 10 and the second hovering conductor plate 40 have the same shape and size, the width of the second electrode plate 20 is greater than or equal to the width of the second hovering conductor plate 40, and the two second electrode plates 20 have the same size and shape, and here, the width of the second electrode plate 20 and the width of the second hovering conductor plate 40 are both widths perpendicular to the focusing direction. As a result, during the movement of the mover holder, the sum of the area of ​​the first electrode plate 10 affected by the jump bridge connection characteristics and the area of ​​the two second electrode plates 20 affected by the jump bridge connection characteristics is the same, which is equivalent to the first hovering conductor plate 30 and the second hovering conductor plate 40 only shortening the distance between the first electrode plate 10 and the second electrode plate 20. This process is completely equivalent to there being no space between the first electrode plate 10 and the second electrode plate 20, which allows the first electrode plate 10 and the second electrode plate 20 to be installed without being restricted by space, and allows the first electrode plate 10 and the second electrode plate 20 to be installed farther away, thereby improving the space utilization rate of the focus motor.

[0035] The focus motor described above 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 of 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 memory metals as a driving force.

[0036] In this embodiment, the first electrode plate 10 and the second electrode plate 20 are fixedly installed and are respectively installed opposite the first hovering conductor plate 30 and the second hovering conductor plate 40. The first hovering conductor plate 30 is connected to the second hovering conductor plate 40 by a conductor member 50. The capacitance between the first electrode plate 10 and the second electrode plate 20 is changed by utilizing the jump bridge connection characteristics of the first hovering conductor plate 30 and the second hovering conductor plate 40 for the capacitance signal. Compared with the related art, the spatial setting of the first electrode plate 10 and the second electrode plate 20 is simplified. The flexibility of the system is high, the first electrode plate 10 and the second electrode plate 20 can be installed in the free space in the focus motor, and the distance between the first hovering conductor plate 30 and the first electrode plate 10, and the distance between the second hovering conductor plate 40 and the second electrode plate 20 are shorter than the distance between the first electrode plate 10 and the second electrode plate 20 in the related art, so that the impact on the size of the focus motor caused by the installation of the first hovering conductor plate 30 and the second hovering conductor plate 40 is small, which is favorable for further reduction in the size of the focus motor. In addition, the jump bridge connection characteristics of the first hovering conductor plate 30 and the second hovering conductor plate 40 can be realized without providing other connection lines, which can solve the problems of increased complexity in the assembly process of the focus motor and local signal linearity deterioration caused by the connection lines of the mover electrode plates, and can improve the accuracy of the closed-loop control of the focus motor.

[0037] In one embodiment, the conductor member 50 is installed inside the mover holder. In this embodiment, the first hovering conductor plate 30 is connected to the second hovering conductor plate 40 by the conductor member 50, the first hovering conductor plate 30 is provided on a first surface in the focusing direction of the mover holder, and the second hovering conductor plate 40 is provided on a second surface away from the first surface of the mover holder. By providing the conductor member 50 inside the mover holder, the occupancy of the focus motor volume is saved, which is advantageous for further reducing the size of the focus motor. In another embodiment, the conductor member 50 may be provided outside the mover holder, for example, the first hovering conductor plate 30 and the second hovering conductor plate 40 can be connected by a coil provided around the mover holder.

[0038] In one embodiment, the focus motor further includes a base, as shown in FIG. 5, which is a diagram showing the structure of the focus motor in this embodiment, and the focus motor includes a first pole plate 10, a second pole plate 20, a first hovering conductor plate 30, a second hovering conductor plate 40, a mover holder 60, a conductor member (not shown), a processing unit (not shown), and a base (not shown).

[0039] Specifically, the base comprises a bottom plate and two side walls 70 along the focusing direction, the first electrode plate 10 is fixedly installed on one of the side walls 70, the second electrode plate 20 is fixedly installed on the other side wall 70, the first hovering conductor plate 30 is provided on a first surface of the movable member holder 60 in the focusing direction, the second hovering conductor plate 40 is provided on a second surface away from the first surface of the movable member holder 60, the first hovering conductor plate 30 is connected to the second hovering conductor plate 40 by a conductor member, the movable member holder 60 is movable in the focusing direction, the first hovering conductor plate 30 is installed opposite the first electrode plate 10, and the second hovering conductor plate 40 is installed opposite the second electrode plate 20.

[0040] In this embodiment, the specific installation form between the first electrode plate 10, the second electrode plate 20 and the base is limited, and the first electrode plate 10 and the second electrode plate 20 in this embodiment are respectively installed on two side walls 70, which can reduce the occupation of the electrodes in the volume of the focus motor and further improve the space utilization rate of the focus motor.

[0041] Specifically, with regard to providing the first electrode plate 10 and the second electrode plate 20 on the two side walls 70 of the base, respectively, the first electrode plate 10 and the second electrode plate 20 can be directly attached to the corresponding areas of the side walls 70, and the first electrode plate 10 and the second electrode plate 20 can be connected to the connecting lines inside the motor for electrical conduction; alternatively, insert injection molding can be used to incorporate metal parts into plastic parts, thereby directly performing injection molding, thereby saving the assembly process of the motor; or laser direct molding technology can be used to activate electroplating on some surfaces of the plastic parts using laser engraving, so that the electroplated areas have electrical conductivity, and then the electrode plates can be processed on the corresponding areas of the base.

[0042] In one embodiment, the first electrode plate 10 and the second electrode plate 20 are integrally molded with the base by insert injection molding, and the first hovering conductor plate 30 and the second hovering conductor plate 40 are integrally molded with the movable member holder 60 by insert injection molding.

[0043] In one embodiment, the first hovering conductor plate 30 and the second hovering conductor plate 40 are made of stainless steel. In other embodiments, the first hovering conductor plate 30 and the second hovering conductor plate 40 may be made of other metals, such as copper, aluminum, and other materials that can achieve a conductor function.

[0044] The above classification of each component is for convenience of explanation, and when implemented, they may be integrated into one component or divided into several components, and as long as they contain the same logical relationship, they all fall within the scope of protection of this patent.

[0045] Another embodiment of the present application relates to a closed-loop control method for a focus motor applied to the above-mentioned focus motor, and as shown in FIG. 6, the closed-loop control method for a focus motor includes the following steps:

[0046] Step 101: After the mover holder moves in the focusing direction, a reference capacitance is obtained.

[0047] Step 102: It is determined whether the position of the mover holder coincides with the target position based on the capacitance value of the reference capacitance.

[0048] If they do not match, proceed to step 103, where the output drive current or drive voltage is increased or decreased to control the moving member holder to continue moving, then return to step 101, and after the moving member holder has moved in the focusing direction, a reference capacitance between the first and second plates is obtained, and the judgment of step 102 is repeated until it is determined that the position of the moving member holder matches the target position, and then proceed to step 104 to complete the movement of the moving member holder.

[0049] In step 103, the output driving current or driving voltage is increased or decreased to control the moving piece holder to continue to move.

[0050] Step 104, the movement of the mover holder is completed.

[0051] In one embodiment, step 102, i.e., determining whether the position of the mover holder coincides with the target position based on the capacitance value of the reference capacitance, has specific sub-steps shown in FIG. 7, and specifically includes the following sub-steps:

[0052] In step 201, a target position required for moving the mover holder is received from the host.

[0053] In step 202, a capacitance value corresponding to a target position is determined as a target capacitance value based on a correspondence relationship between positions and capacitance values ​​stored in advance.

[0054] In step 203, it is determined whether the position of the mover holder coincides with the target position based on the capacitance value of the reference capacitance and the target capacitance value.

[0055] Specifically, when the number of second plates is two, when the movement of the mover holder in the focusing direction is controlled using the reference capacitances of the first plate and the second plate, it can be determined whether the mover holder coincides with the target position by the following method. In the first method, if the two acquired reference capacitances are equal to the two capacitances between the first plate and the two second plates acquired when the focus motor is located at the target position in the pre-adjustment process, the mover holder coincides with the target position. In the second method, a difference calculation is performed on the two acquired reference capacitances, and if the calculated difference value is equal to the difference value between the two capacitances between the first plate and the two second plates acquired when the focus motor is located at the target position in the pre-adjustment process, the mover holder coincides with the target position. In addition, after the difference calculation, the difference value is amplified to increase the robustness of the capacitance signal, and the focus motor can be controlled more sensitively. In the third method, a calibration value is calculated from the two reference capacitances mentioned above and the two capacitance values ​​between the first plate and the two second plates when the movable member holder is located at the bottom of the focus motor. In order to offset 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. The difference value after calibration is compared with the difference value of the two reference capacitances when the focus motor is located at the target position during the pre-adjustment process. If the two are the same, the movable member holder is aligned with the target position.

[0056] Specifically, the closed-loop control is realized by a processing unit, which includes a capacitance detection circuit, an analysis and calculation circuit, and a control output circuit, where the capacitance detection circuit is used to detect a reference capacitance between the first plate and the second plate, the analysis and calculation circuit is used to determine whether to move the armature and the driving current or driving voltage required for the movement according to the acquired reference capacitance, and the control output circuit is used to output the calculated driving current or driving voltage to the motor to control the armature holder of the motor to move.

[0057] Specifically, after controlling the motor's rotor holder to move, the rotor holder after movement again changes the reference capacitance between the first and second pole plates, and the processing unit again performs analytical calculations based on the changed capacitance signal until the current position and target position of the rotor holder match, thereby completing the control of the motor.

[0058] Specifically, the correspondence between the positions and the capacitance values ​​stored in advance in step 202 can be established in the following manner: First, move the mover holder to the bottom of the focus motor, then move the mover holder step by step at a preset interval, and record the capacitance value of the reference capacitance after each step and the distance between the mover holder and the bottom plate of the focus motor after each step, and the correspondence between the distance between the mover holder and the bottom plate after each step and the capacitance value of the reference capacitance is set as the correspondence between the positions and the capacitance values.

[0059] The division of steps in each method above is for convenience of explanation, and they can be integrated into one step or divided into several steps in realization, and as long as they contain the same logical relationship, they are all within the scope of protection of this patent. In both algorithms and processes, adding non-significant modifications or introducing non-significant designs, but not changing the core design of the algorithm or process, are all within the scope of protection of this patent.

[0060] Another embodiment of the present application relates to an imaging device including a lens and the above-described focus motor for driving the lens.

[0061] Compared to the related art, the imaging device according to the present embodiment is provided with a focus motor according to the above-mentioned embodiment, and therefore can achieve the same technical effects as those of the above-mentioned embodiment, so a description thereof will be omitted here.

[0062] Those skilled in the art will understand that the above embodiments are specific examples for implementing the present invention, but in practical applications, various changes in form and details may be made without departing from the spirit and scope of the present application.

Claims

1. A focus motor, comprising: The movable body includes a first electrode plate, a second electrode plate, a first hovering conductor plate, a second hovering conductor plate, a mover holder, a conductor member, and a processing unit; the first electrode plate and the second electrode plate are fixedly installed, the first hovering conductor plate is provided on a first surface of the movable member holder in a focusing direction, the second hovering conductor plate is provided on a second surface of the movable member holder away from the first surface, the first hovering conductor plate is connected to the second hovering conductor plate by the conductor member, and the movable member holder is movable in the focusing direction; The first hovering conductor plate is disposed opposite the first electrode plate, and the second hovering conductor plate is disposed opposite the second electrode plate; A reference capacitance is formed between the first plate and the second plate, and the processing unit controls the movement of the mover holder in the focusing direction based on the reference capacitance; The focus motor further comprises a base; The base includes a bottom plate and two side walls along the focusing direction, the first plate is fixed to one of the side walls, and the second plate is fixed to the other side wall; The number of the second plates is two, and the two second plates are arranged along the focusing direction; The length of the first hovering conductor plate is equal to or greater than the sum of the length of the first electrode plate and the maximum stroke of the movable member holder, the width of the first hovering conductor plate is equal to or greater than the width of the first electrode plate, the length of the first hovering conductor plate and the length of the first electrode plate are both lengths in the focusing direction, and in the process of the movable member holder moving, the facing area between the first hovering conductor plate and the first electrode plate remains unchanged, the facing area between the second hovering conductor plate and one of the second electrodes gradually decreases, and the facing area between the second hovering conductor plate and the other of the second electrodes gradually increases. A focus motor characterized by:

2. The conductive member is disposed inside the movable piece holder.

2. The focus motor according to claim 1 .

3. the first electrode plate and the second electrode plate are integrally molded with the base by insert injection molding, and the first hovering conductor plate and the second hovering conductor plate are integrally molded with the mover holder by insert injection molding.

2. The focus motor according to claim 1 .

4. The first hovering conductor plate and the second hovering conductor plate are made of stainless steel.

4. The focus motor according to claim 1, wherein the first and second electrodes are arranged in a first direction.

5. A method for closed-loop control of a focus motor, which is applied to the processing unit of the focus motor according to any one of claims 1 to 4, comprising: acquiring the reference capacitance after the mover holder moves in the focusing direction; determining whether the position of the mover holder coincides with a target position based on a capacitance value of the reference capacitance; If they do not match, controlling the movable piece holder to move again in the focusing direction until it is determined that the position of the movable piece holder and the target position match.

23. A method for closed-loop control of a focus motor comprising:

6. Determining whether the position of the mover holder coincides with a target position based on a capacitance value of the reference capacitance includes: determining a capacitance value corresponding to the target position as a target capacitance value based on a correspondence relationship between positions and capacitance values ​​stored in advance; and determining whether or not the position of the movable piece holder coincides with the target position based on a capacitance value of the reference capacitance and the target capacitance value.

6. The method for closed-loop control of a focus motor according to claim 5.

7. A lens and a focus motor according to any one of claims 1 to 4 for driving the lens.

1. An imaging device comprising:

Images