Miniature double-stator ultrasonic motor for driving optical lens and excitation method

Abstract

The invention relates to a miniature double-stator ultrasonic motor for driving an optical lens and an excitation method. Two surfaces of a piezoelectric bimorph are respectively connected with an upper stator and a lower stator to excite a stator elastomer to vibrate so as to realize a driving function; the size of the whole machine is reduced by adopting the design that the bearing is built in and no shell is arranged, and the rotor grooves of the upper rotor assembly and the lower rotor assembly are matched with the boss structures of the rotating shaft and the shaft sleeve and rotate mutually to apply pre-pressure; according to the invention, a shell-free design is adopted, the structure is simple, the appearance is small and exquisite, the output of double stators is realized by utilizing a special driving mode of the piezoelectric bimorph, and the size of the motor can be further miniaturized while higher torque output is realized.

Description

Technical Field

[0001] The invention relates to a miniature double-stator ultrasonic motor for driving an optical lens and an excitation method, belonging to the field of ultrasonic motors. Background Art

[0002] Optical lens drive is mainly used to accurately control the position and movement of the optical lens, so as to realize functions such as auto focus and zoom. Therefore, the optical lens drive needs to have the characteristics of fast response, low noise, high resolution and precise positioning. Obviously, the traditional electromagnetic motor can no longer meet these characteristics, and the ultrasonic motor has obvious advantages; the ultrasonic motor uses the reverse piezoelectric effect of piezoelectric ceramics to make the stator vibrate through the action of the excitation voltage, and then realizes the conversion of electrical energy to mechanical energy through the friction between the stator and the rotor, so that the rotor rotates in a directional manner. Compared with traditional motors, it has the advantages of simple structure, low speed and high torque, fast response speed, and no interference from magnetic fields.

[0003] Existing multiple stator-rotor traveling wave ultrasonic motors for driving optical lenses are mostly of dual-stator-single-rotor or dual-stator-dual-rotor structures. Compared with single-stator micromotors, dual-stator ultrasonic motors can achieve greater torque output; for example, the invention with application number 201911145416.1 discloses a small frame-type controlled torque gyroscope driven by a dual-stator ultrasonic motor, including a frame, a momentum wheel, a high-speed motor, first to fourth bearings, a base, an encoder and a dual-stator ultrasonic motor; the frame includes a square frame and a shaft; the two ends of the momentum wheel rotating shaft are respectively connected to the square frame by bearings; the high-speed motor and the momentum wheel are coaxially arranged; through holes are provided at both ends of the base for the frame shaft to pass through; the frame shaft is connected to the through hole of the base through the bearing; the encoder is installed at one end of the base for measuring the rotation speed of the frame shaft; the rotor of the frame motor is connected to the other end of the frame shaft by a pin connector to drive the frame shaft to rotate. The aforementioned application uses a dual-stator ultrasonic motor, but due to the particularity of the optical lens, the ultrasonic motor needs to be miniaturized and have the characteristics of large torque output. Obviously, the aforementioned application has a shell structure, in which the shell is fixedly connected to the base with screws, and the pre-pressure is applied by directly pressing the bearing on the shell on the shoulder of the rotor or on the shoulder of the rotating shaft connected to the rotor, and the size of the pre-pressure is adjusted by changing the thickness of the adjustment gasket on the bearing and the shoulder, and miniaturization has not been achieved.

[0004] Therefore, it is necessary to design an ultrasonic motor for optical lens driving that can further miniaturize the motor size while achieving greater torque output. Summary of the invention

[0005] The present invention provides a miniature dual-stator ultrasonic motor and an excitation method for driving an optical lens. The motor adopts a housing-free design and utilizes a special driving method of a piezoelectric dual-chip to achieve dual-stator output. While achieving a greater torque output, the motor size can be further miniaturized.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A miniature dual-stator ultrasonic motor for driving an optical lens comprises a stator assembly and a rotor assembly, wherein the stator assembly comprises an upper stator, a lower stator and a piezoelectric dual-chip, the upper stator and the lower stator have the same structure, and the rotor assembly comprises an upper rotor assembly, a lower rotor assembly, a rotating shaft and a sleeve, the upper rotor assembly and the lower rotor assembly have the same structure; one end of the rotating shaft is defined as the top end, and the other end is defined as the bottom end, the upper rotor assembly, the upper stator, the piezoelectric dual-chip, the lower stator and the lower rotor assembly are coaxially arranged in sequence along the axial direction from the top end to the bottom end on the rotating shaft, the upper rotor assembly and the lower rotor assembly, the upper stator and the lower stator are symmetrically arranged relative to the piezoelectric dual-chip, and the bottom end of the rotating shaft is sleeved with a sleeve;

[0008] The piezoelectric bimorph comprises a first piezoelectric sheet, a second piezoelectric sheet, an intermediate layer and a PCB board, wherein the first piezoelectric sheet and the second piezoelectric sheet are symmetrically arranged on both sides of the intermediate layer, the surface of the first piezoelectric sheet relative to the top end of the rotating shaft is pasted to the upper stator, the bottom surface of the second piezoelectric sheet relative to the bottom end of the rotating shaft is pasted to the lower stator, the circumferential outer ring of the intermediate layer is connected to the PCB board, and there is a gap between the PCB board and the lower rotor assembly;

[0009] By applying a voltage with a time difference of π / 2 to the middle layer, the electric field signal is transmitted to the first piezoelectric sheet and the second piezoelectric sheet, so that the piezoelectric bimorph generates mechanical movement to excite the stator assembly to vibrate, and the sleeve and the shaft cooperate to rotate with each other to apply pre-pressure, thereby driving the motor to rotate;

[0010] Furthermore, the intermediate layer includes a flexible printed circuit board, and the first piezoelectric sheet and the second piezoelectric sheet are symmetrically arranged on both sides of the flexible printed circuit board;

[0011] Furthermore, the intermediate layer includes a plastic layer and two flexible printed boards, one flexible printed board is respectively bonded to the two end surfaces of the plastic layer, a first piezoelectric sheet is arranged on the flexible printed board located on the upper end surface of the plastic layer, and a second piezoelectric sheet is arranged on the flexible printed board located on the lower end surface of the plastic layer;

[0012] Furthermore, it also includes a fixing assembly, which is placed along the axial direction of the rotating shaft at the inner diameter of the piezoelectric bimorph;

[0013] The fixing assembly includes a non-elastic material and a bearing, and the bearing is sleeved on the rotating shaft, that is, the rotating shaft is fixed by the inner ring of the bearing;

[0014] The non-elastic material is a ring-shaped structure, and is filled between the outer diameter of the bearing, the inner diameter of the upper stator and the inner diameter of the lower stator;

[0015] Furthermore, the lower rotor assembly includes a lower rotor and a friction material, wherein the lower rotor is an annular structure made of a flexible material, and the portion of the lower rotor relative to the top of the rotating shaft is defined as the lower layer, and the lower layer friction material is pasted on the lower layer boss and then placed on the lower stator teeth;

[0016] The upper rotor assembly has the same structure as the lower rotor assembly, that is, the upper friction material is also pasted on the lower boss of the upper rotor and then placed on the upper stator teeth;

[0017] Furthermore, a boss structure is provided at the top of the rotating shaft, a thread is arranged on the outside of the bottom end of the rotating shaft, a boss structure is provided at the open end of the sleeve, a thread is arranged inside the sleeve, and the thread of the rotating shaft matches the thread of the sleeve;

[0018] A rotor groove is arranged at the center of the upper rotor and the lower rotor, the boss structure at the top end of the rotating shaft is fixed to the rotor groove of the upper rotor, and the boss structure of the shaft sleeve is fixed to the rotor groove of the lower rotor;

[0019] Furthermore, the first piezoelectric sheet and the second piezoelectric sheet are both annular structures, and the surface of the first piezoelectric sheet and the second piezoelectric sheet relative to the flexible printed circuit board is defined as the front surface, and the A phase, the ground wire and the B phase are arranged in sequence along the circumference of the front surface of the annular structure; wherein the A phase and the B phase are both composed of a forward polarized piezoelectric ceramic sheet and a reverse polarized piezoelectric ceramic sheet, and the forward polarized piezoelectric ceramic sheet and the reverse polarized piezoelectric ceramic sheet are placed alternately;

[0020] The polarization directions of the A phase and the B phase of the first piezoelectric sheet are the same as the polarization directions of the A phase and the B phase of the second piezoelectric sheet;

[0021] The front ground wire and the back ground wire of the first piezoelectric sheet and the second piezoelectric sheet are connected by plating conductive material on the outer diameter edges corresponding to the first piezoelectric sheet and the second piezoelectric sheet;

[0022] When the first piezoelectric sheet and the second piezoelectric sheet are mounted on both sides of the flexible printed circuit board, the A phase of the first piezoelectric sheet is connected to the B phase of the second piezoelectric sheet to form the A phase of the piezoelectric bimorph, and the B phase of the first piezoelectric sheet is connected to the A phase of the second piezoelectric sheet to form the B phase of the piezoelectric bimorph;

[0023] Furthermore, the two sides of the flexible printed circuit board are respectively the front side and the back side, and the front side and the back side have the same structure, and are both divided into a conductive area of ​​the flexible printed circuit board, a non-conductive area of ​​the flexible printed circuit board, and a wiring hole of the flexible printed circuit board.

[0024] The conductive area of ​​the flexible printed circuit board on the front side includes the A-phase conductive area on the front side of the flexible printed circuit board, the B-phase conductive area on the front side of the flexible printed circuit board, and the ground conductive area on the front side of the flexible printed circuit board. The conductive area of ​​the flexible printed circuit board on the back side includes the A-phase conductive area on the back side of the flexible printed circuit board, the B-phase conductive area on the back side of the flexible printed circuit board, and the ground conductive area on the back side of the flexible printed circuit board.

[0025] The flexible printed circuit board wiring holes on the front and back sides include the flexible printed circuit board A-phase wiring hole, the flexible printed circuit board B-phase wiring hole and the flexible printed circuit board ground wire wiring hole;

[0026] Conductivity between the A-phase conductive area on the front side of the flexible printed board and the A-phase conductive area on the back side of the flexible printed board is achieved by plating conductive materials on the A-phase wiring holes of the flexible printed board on the front side and the back side, and between the B-phase conductive area on the front side of the flexible printed board and the B-phase conductive area on the back side of the flexible printed board is achieved by plating conductive materials on the B-phase wiring holes of the flexible printed board on the front side and the back side, and between the ground wire conductive area on the front side of the flexible printed board and the ground wire conductive area on the back side of the flexible printed board is achieved by plating conductive materials on the ground wire wiring holes of the flexible printed board on the front side and the back side;

[0027] In the piezoelectric bimorph, the ground wire of the first piezoelectric sheet and the ground wire of the second piezoelectric sheet are respectively pasted in the ground wire conductive areas of the conductive areas on both sides of the matching flexible printed circuit board, and the ground wires are aligned;

[0028] The excitation method of the miniature dual-stator ultrasonic motor driven by the optical lens is as follows: the ground wire wiring hole of the flexible printed circuit board is connected separately, the electrical signal is divided into two phases, a sin(ωt) signal is applied to the A-phase wiring hole of the flexible printed circuit board, and a sin(ωt+π / 2) signal is applied to the B-phase wiring hole of the flexible printed circuit board. At this time, the two-phase signals differ by π / 2; when the two-phase signals differ by -π / 2, the rotation direction of the motor changes.

[0029] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The micro dual-stator ultrasonic motor for driving an optical lens provided by the present invention adopts a piezoelectric dual-chip, which is to place the first piezoelectric sheet and the second piezoelectric sheet symmetrically on both sides of the flexible printed circuit board in a face-to-face manner, and realize the driving function by exciting the vibration of the stator elastic body. Compared with the prior art that uses the elastic body between two ceramic sheets for vibration work, the new design reduces the energy transmission link, the energy loss is relatively small, and the energy utilization rate of the entire driving system is improved; at the same time, the additional elastic structure in the middle is reduced, making the entire driving structure more compact, which is convenient for the miniaturization design of the equipment;

[0031] 2. The miniature dual-stator ultrasonic motor for optical lens driving provided by the present invention has a housing-free design, and the filling material is located between the outer diameter of the bearing and the inner diameter of the stator. In some devices with special requirements for space layout, the positions of the components can be arranged more flexibly, and the internal components can be configured more reasonably according to the actual space requirements and functional requirements, thereby improving the space utilization rate inside the device;

[0032] 3. The present invention provides a miniature dual-stator ultrasonic motor for driving an optical lens, wherein the boss structure at the top of the rotating shaft is fixed to the rotor groove of the upper rotor, and the boss structure of the sleeve is fixed to the rotor groove of the lower rotor. The sleeve and the rotating shaft cooperate to rotate with each other to apply pre-pressure, thereby providing a new pressurization method for a miniature motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0034] Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment provided by the present invention;

[0035] Figure 2 It is a schematic diagram of a structural cross-section of a preferred embodiment provided by the present invention;

[0036] Figure 3 It is a top view of the structure of a preferred embodiment provided by the present invention;

[0037] Figure 4 It is a schematic diagram of the structure of the intermediate layer of a preferred embodiment provided by the present invention;

[0038] Figure 5 It is a schematic diagram of a first piezoelectric sheet according to a preferred embodiment of the present invention;

[0039] Figure 6 It is a schematic diagram of a second piezoelectric sheet according to a preferred embodiment of the present invention;

[0040] Figure 7 It is a schematic diagram of ground connection between the front and back sides of the first piezoelectric sheet in a preferred embodiment of the present invention;

[0041] Figure 8 It is a schematic diagram of a flexible printed circuit board according to a preferred embodiment of the present invention;

[0042] Fig. 9 It is a schematic diagram of the relative position of the piezoelectric bimorph according to the preferred embodiment of the present invention;

[0043] Fig.10 It is a schematic diagram of the bearing installation of the preferred embodiment provided by the present invention;

[0044] Fig.11It is a schematic diagram of the structure of a rotor assembly according to a preferred embodiment of the present invention;

[0045] Fig.12 It is a schematic diagram of a pre-pressure application method of a preferred embodiment provided by the present invention;

[0046] Fig.13 It is a schematic diagram of the electrical excitation method of the preferred embodiment provided by the present invention.

[0047] In the figure: 1 is a stator assembly;

[0048] 11 is an upper stator, 12 is a lower stator;

[0049] 13 is a piezoelectric bimorph, 131 is a first piezoelectric sheet, 131a is the front of the first piezoelectric sheet; 131b is the back of the first piezoelectric sheet, 131c is the ground of the first piezoelectric sheet, 132 is a second piezoelectric sheet, 132a is the front of the second piezoelectric sheet, 132b is the back of the second piezoelectric sheet, 132c is the ground of the second piezoelectric sheet, 133 is an intermediate layer, 1331 is a non-conductive area of ​​a flexible printed board, 1332 is a conductive area of ​​a flexible printed board on the front, 1332a is a conductive area of ​​a phase A on the front of the flexible printed board, 1332b is a conductive area of ​​a flexible printed board on the front, The B-phase conductive area on the front side of the board, 1332c is the ground conductive area on the front side of the flexible printed board, 1333 is the wiring hole of the flexible printed board, 1333a is the wiring hole of the A-phase of the flexible printed board, 1333b is the wiring hole of the B-phase of the flexible printed board, 1333c is the ground wiring hole of the flexible printed board, 1334 is the conductive area of ​​the flexible printed board on the reverse side, 1334a is the A-phase conductive area on the back side of the flexible printed board, 1334b is the B-phase conductive area on the back side of the flexible printed board, 1334c is the ground conductive area on the back side of the flexible printed board, and 134 is the PCB board;

[0050] 14 is a fixing component, 141 is a non-elastic material, and 142 is a bearing;

[0051] 2 is a rotor assembly;

[0052] 21 is an upper rotor assembly, 211 is an upper rotor, 212 is an upper friction material, 213 is a rotor groove, 22 is a lower rotor assembly, 221 is a lower rotor, 222 is a lower friction material; 23 is a rotating shaft, 231 is a boss structure at the top of the rotating shaft, 24 is a shaft sleeve, and 241 is a boss structure of the shaft sleeve. DETAILED DESCRIPTION

[0053] The present invention will now be described in further detail with reference to the accompanying drawings. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and "first", "second", etc. do not indicate the importance of the components, and therefore cannot be understood as a limitation on the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution by example, and do not limit the scope of protection of the present invention.

[0054] As described in the background technology, the optical lens drive needs to meet the characteristics of fast response, low noise, high resolution and precise positioning. The existing structure of the dual-stator ultrasonic motor is limited by the optical lens and cannot balance the needs of large torque output and structural miniaturization. Therefore, in order to solve the above problems, the present application provides a miniature dual-stator ultrasonic motor for optical lens drive, which utilizes the two surfaces of the piezoelectric dual chip to connect with the two stators to excite the vibration of the stator elastomer to achieve the driving function; adopts a design with built-in bearings and no housing to reduce the size of the whole machine; utilizes the groove of the rotor structure to cooperate with the boss of the rotating shaft and the sleeve, and rotates with each other to achieve the application of pre-pressure; finally achieves the purpose of simple structure and compact appearance, and meets the precision driving requirements of the optical lens.

[0055] like Figure 1 As shown in FIG. 1 , it is a schematic diagram of the overall structure of a miniature dual-stator ultrasonic motor for driving an optical lens provided by the present application, including a stator component 1 and a rotor component 2, and its specific internal structure is analyzed, as shown in FIG. Figure 2 As shown, the stator assembly includes an upper stator 11, a lower stator 12 and a piezoelectric dual chip 13, and the upper stator and the lower stator have the same structure. The rotor assembly includes an upper rotor assembly 21, a lower rotor assembly 22, a rotating shaft 23 and a sleeve 24, and the upper rotor assembly and the lower rotor assembly have the same structure. One end of the rotating shaft is defined as the top end, and the other end is defined as the bottom end. The upper rotor assembly, the upper stator, the piezoelectric dual chip, the lower stator and the lower rotor assembly are coaxially arranged in sequence along the axial direction from the top end to the bottom end of the rotating shaft. The upper rotor assembly and the lower rotor assembly, the upper stator and the lower stator are symmetrically arranged relative to the piezoelectric dual chip, and the bottom end of the rotating shaft is sleeved with a sleeve.

[0056] As the most outstanding innovation of this application, the piezoelectric dual-chip design is adopted, in which the two surfaces of the piezoelectric dual-chip are interconnected with the metal elastomer to excite the vibration of the stator elastomer and realize the driving function. This driving method reduces the link of the additional elastomer in the middle, making the entire driving structure more compact. Compared with the traditional piezoelectric dual crystal structure that uses the elastomer between two ceramic sheets for vibration, it has more advantages in space utilization. Secondly, the new design directly uses the piezoelectric dual-chip and the metal elastomer to connect to each other to excite the vibration of the stator elastomer, which reduces the energy transfer link and the energy loss is relatively small. At the same time, through the direct connection between the piezoelectric dual-chip and the metal elastomer, the frequency, amplitude and other parameters of the vibration can be better controlled.

[0057] Regarding the specific structure of the piezoelectric bimorph, Figure 3 As shown, it includes a first piezoelectric sheet 131, a second piezoelectric sheet 132, an intermediate layer 133 and a PCB board 134. The first piezoelectric sheet and the second piezoelectric sheet are symmetrically arranged on both sides of the intermediate layer. The surface of the first piezoelectric sheet relative to the top of the rotating shaft is pasted to the upper stator, and the bottom surface of the second piezoelectric sheet relative to the bottom of the rotating shaft is pasted to the lower stator. The PCB board is connected to the circumferential outer ring of the intermediate layer, and there is a gap between the PCB board and the lower rotor assembly. The gap left here not only plays a conductive role, but also can support the micro motor. There are two design methods for the intermediate layer here. In the first method, the intermediate layer is a flexible printed circuit board. The second structure is also an innovation of the present application. The intermediate layer includes a plastic layer and two flexible printed circuit boards. A flexible printed circuit board is respectively attached to the two end faces of the plastic layer. The first piezoelectric sheet is arranged on the flexible printed circuit board located on the upper end face of the plastic layer, and the second piezoelectric sheet is arranged on the flexible printed circuit board located on the lower end face of the plastic layer. That is, Figure 4 As shown, a plastic layer of a certain thickness is arranged in the middle of the piezoelectric dual chip, which can isolate the vibration between the first piezoelectric sheet and the second piezoelectric sheet on both sides, so that the vibrations of the upper stator and the lower stator do not interfere with each other, thereby achieving the effect of amplitude amplification.

[0058] Figure 5-Figure 6 As shown, the first piezoelectric sheet and the second piezoelectric sheet are both annular structures, and the surface of the first piezoelectric sheet and the second piezoelectric sheet relative to the flexible printed circuit board is defined as the front surface, and the A phase, the ground wire and the B phase are arranged in sequence along the front circumference of the annular structure; wherein the A phase and the B phase are both composed of a forward polarized piezoelectric ceramic sheet and a reverse polarized piezoelectric ceramic sheet, and the forward polarized piezoelectric ceramic sheet and the reverse polarized piezoelectric ceramic sheet are placed alternately. The polarization directions of the A phase and the B phase of the first piezoelectric sheet are the same as those of the A phase and the B phase of the second piezoelectric sheet; the connection between the front ground wire and the reverse ground wire of the first piezoelectric sheet and the second piezoelectric sheet is achieved by plating a conductive material on the outer diameter edge corresponding to the first piezoelectric sheet and the second piezoelectric sheet, and correspondingly, Figure 5The first piezoelectric sheet front surface 131a and the first piezoelectric sheet back surface 131b are structured, and the first piezoelectric sheet ground wire 131c is provided on the front and back surfaces. Figure 6 The second piezoelectric sheet is structured by a front side 132a of the second piezoelectric sheet and a back side 132b of the second piezoelectric sheet, and a second piezoelectric sheet ground line 132c is provided on the front side and the back side. Figure 7 Taking the first piezoelectric sheet as an example, the ground connection between the front and back surfaces of the first piezoelectric sheet is achieved by plating a conductive material on the corresponding outer diameter edge.

[0059] In the piezoelectric bimorph structure, Fig. 9 As shown, when the first piezoelectric sheet and the second piezoelectric sheet are installed on both sides of the flexible printed circuit board, the first piezoelectric sheet and the second piezoelectric sheet are placed face to face, that is, the A phase of the first piezoelectric sheet is connected to the B phase of the second piezoelectric sheet to form the A phase of the piezoelectric bimorph, and the B phase of the first piezoelectric sheet is connected to the A phase of the second piezoelectric sheet to form the B phase of the piezoelectric bimorph. In the piezoelectric bimorph, the ground wire of the first piezoelectric sheet and the ground wire of the second piezoelectric sheet are respectively pasted in the ground wire conductive area of ​​the conductive area on both sides of the flexible printed circuit board, and the ground wires are aligned. The ground wire is set in the overall structure of the piezoelectric bimorph, which is convenient for integrated design and wiring.

[0060] Regarding the flexible printed circuit board, the two sides of the flexible printed circuit board are defined as the front side and the back side, and the front side and the back side have the same structure, and are divided into a flexible printed circuit board conductive area, a flexible printed circuit board non-conductive area 1331 and a flexible printed circuit board wiring hole 1333. Figure 8 As shown, the flexible printed board conductive area 1332 on the front side includes the flexible printed board front A-phase conductive area 1332a, the flexible printed board front B-phase conductive area 1332b, and the flexible printed board front ground conductive area 1332c, and the flexible printed board conductive area 1334 on the back side includes the flexible printed board back A-phase conductive area 1334a, the flexible printed board back B-phase conductive area 1334b, and the flexible printed board back ground conductive area 1334c. The flexible printed board wiring holes on the front and back sides include the flexible printed board A-phase wiring hole 1333a, the flexible printed board B-phase wiring hole 1333b, and the flexible printed board ground wiring hole 1333c.

[0061] Conductivity between the A-phase conductive area on the front side of the flexible printed board and the A-phase conductive area on the back side of the flexible printed board is achieved by plating conductive material on the A-phase wiring holes of the flexible printed board on the front and back sides. Similarly, conductivity between the B-phase conductive area on the front side of the flexible printed board and the B-phase conductive area on the back side of the flexible printed board is achieved by plating conductive material on the B-phase wiring holes of the flexible printed board on the front and back sides. Conductivity between the ground wire conductive area on the front side of the flexible printed board and the ground wire conductive area on the back side of the flexible printed board is achieved by plating conductive material on the ground wire wiring holes of the flexible printed board on the front and back sides.

[0062] The upper rotor assembly and the lower rotor assembly of the present application adopt the same structural design. The following rotor assembly is taken as an example, including a lower rotor 221 and a friction material. The lower rotor is an annular structure made of a flexible material. The part of the lower rotor relative to the top of the rotating shaft is defined as the lower layer. The lower friction material 222 is pasted on the lower boss and then placed on the lower stator teeth. Since the upper rotor assembly has the same structure as the lower rotor assembly, the upper friction material 212 is also pasted on the lower boss of the upper rotor 211 and then placed on the upper stator teeth.

[0063] Since the present application adopts a housing-free design, a fixing component 14 is also provided in the micro dual-stator ultrasonic motor, which is placed along the axial direction of the rotating shaft at the inner diameter of the piezoelectric dual-chip. The fixing component includes a non-elastic material 141 and a bearing 142, and the bearing sleeve is arranged on the rotating shaft, that is, the rotating shaft is fixed by the inner ring of the bearing; Fig.10 As shown, the non-elastic material is a circular ring structure, which is filled between the outer diameter of the bearing, the inner diameter of the upper stator and the inner diameter of the lower stator, and is placed in the axial center position of the entire piezoelectric dual chip.

[0064] In the micro dual-stator ultrasonic motor, the piezoelectric dual-chip generates mechanical motion to excite the stator assembly to vibrate. Regarding the pressurization method, the present application provides a new concept for the micro motor. The pre-pressure is applied by the sleeve and the rotating shaft rotating in cooperation with each other, thereby driving the motor to rotate. Specifically, Fig.12 As shown, a boss structure is provided at the top of the rotating shaft, a thread is arranged on the outside of the bottom end of the rotating shaft, a boss structure is provided at the open end of the sleeve, a thread is arranged inside the sleeve, and the thread of the rotating shaft matches the thread of the sleeve; Fig.11 As shown, a rotor groove 213 is provided at the center of the upper rotor and the lower rotor, a boss structure 231 at the top of the rotating shaft is fixed to the rotor groove of the upper rotor, and a boss structure 241 of the sleeve is fixed to the rotor groove of the lower rotor.

[0065] In this application, in addition to the innovative design of the miniature dual-stator ultrasonic motor, it is also necessary to combine the application and control of its electric field to achieve a greater output while satisfying the miniaturization of the motor. Therefore, the excitation method of the ultrasonic motor is also particularly important. This application applies a voltage with a time difference of π / 2 to the flexible printed circuit board to transmit the electric field signal to the first piezoelectric sheet and the second piezoelectric sheet, so that the piezoelectric dual chip generates mechanical movement to excite the stator assembly to vibrate and drive the motor to rotate. Fig.13 As shown in the figure, the ground wire connection hole of the flexible printed circuit board is connected separately, and the electrical signal is divided into two phases. The sin(ωt) signal is applied to the A-phase connection hole of the flexible printed circuit board, and the sin(ωt+π / 2) signal is applied to the B-phase connection hole of the flexible printed circuit board. At this time, the two-phase signals differ by π / 2, and grounding is performed at the ground wire connection hole of the flexible printed circuit board. The two phases are combined to realize the rotation of the ultrasonic motor. When the two-phase signals differ by -π / 2, the rotation direction of the motor changes.

[0066] In summary, the present invention provides a miniature dual-stator ultrasonic motor and excitation method for driving an optical lens, which utilizes the two surfaces of a piezoelectric dual chip to be connected to an upper stator and a lower stator respectively, so as to excite the vibration of the stator elastic body and realize the driving function; adopts a design with built-in bearings and no housing to reduce the size of the whole machine, and utilizes the rotor grooves of the upper rotor assembly and the lower rotor assembly to cooperate with the boss structure of the rotating shaft and the sleeve, and rotates with each other to realize the application of pre-pressure; the present invention adopts a housing-free design, has a simple structure and a compact appearance, and utilizes the special driving method of the piezoelectric dual chip to realize the output of the dual stators, which can further miniaturize the size of the motor while realizing a larger torque output.

[0067] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0068] The meaning of "and / or" described in this application means that the situations where each exists alone or both exist at the same time are included.

[0069] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0070] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A miniature dual-stator ultrasonic motor for driving an optical lens, characterized in that: It comprises a stator assembly and a rotor assembly, wherein the stator assembly comprises an upper stator, a lower stator and a piezoelectric bimorph, the upper stator and the lower stator have the same structure, the rotor assembly comprises an upper rotor assembly, a lower rotor assembly, a rotating shaft and a sleeve, and the upper rotor assembly and the lower rotor assembly have the same structure; one end of the rotating shaft is defined as the top end, and the other end thereof is defined as the bottom end, and the upper rotor assembly, the upper stator, the piezoelectric bimorph, the lower stator and the lower rotor assembly are coaxially arranged in sequence along the axial direction from the top end to the bottom end on the rotating shaft, the upper rotor assembly and the lower rotor assembly, the upper stator and the lower stator are symmetrically arranged relative to the piezoelectric bimorph, and the bottom end of the rotating shaft is sleeved with a sleeve; The piezoelectric bimorph comprises a first piezoelectric sheet, a second piezoelectric sheet, an intermediate layer and a PCB board, wherein the first piezoelectric sheet and the second piezoelectric sheet are symmetrically arranged on both sides of the intermediate layer, the surface of the first piezoelectric sheet relative to the top end of the rotating shaft is pasted to the upper stator, the bottom surface of the second piezoelectric sheet relative to the bottom end of the rotating shaft is pasted to the lower stator, the circumferential outer ring of the intermediate layer is connected to the PCB board, and there is a gap between the PCB board and the lower rotor assembly; By applying a voltage with a time difference of π / 2 to the middle layer, the electric field signal is transmitted to the first piezoelectric film and the second piezoelectric film, so that the piezoelectric dual chip generates mechanical movement to stimulate the vibration of the stator assembly, and the sleeve and the shaft rotate with each other to apply pre-pressure, thereby driving the motor to rotate.

2. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 1, characterized in that: The middle layer comprises a flexible printed board, and the first piezoelectric sheet and the second piezoelectric sheet are symmetrically arranged on both sides of the flexible printed board.

3. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 1, characterized in that: The middle layer includes a plastic layer and two flexible printed boards. A flexible printed board is respectively attached to the two end surfaces of the plastic layer. A first piezoelectric sheet is arranged on the flexible printed board located on the upper end surface of the plastic layer, and a second piezoelectric sheet is arranged on the flexible printed board located on the lower end surface of the plastic layer.

4. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 1, characterized in that: Also included is a fixing assembly, which is placed along the axial direction of the rotating shaft at the inner diameter of the piezoelectric bimorph; The fixing assembly includes a non-elastic material and a bearing, and the bearing is sleeved on the rotating shaft, that is, the rotating shaft is fixed by the inner ring of the bearing; The non-elastic material is a ring-shaped structure and is filled between the outer diameter of the bearing, the inner diameter of the upper stator and the inner diameter of the lower stator.

5. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 1, characterized in that: The lower rotor assembly includes a lower rotor and a friction material. The lower rotor is an annular structure made of a flexible material. The portion of the lower rotor relative to the top of the rotating shaft is defined as the lower layer. The lower friction material is pasted on the lower boss and then placed on the lower stator teeth. The upper rotor assembly has the same structure as the lower rotor assembly, that is, the upper friction material is also pasted on the lower boss of the upper rotor and then placed on the upper stator teeth.

6. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 1, characterized in that: The top of the rotating shaft is provided with a boss structure, the bottom of the rotating shaft is provided with threads on the outside, the open end of the sleeve is provided with a boss structure, the inside of the sleeve is provided with threads, and the threads of the rotating shaft match the threads of the sleeve; A rotor groove is arranged at the center of the upper rotor and the lower rotor, the boss structure at the top end of the rotating shaft is fixed to the rotor groove of the upper rotor, and the boss structure of the shaft sleeve is fixed to the rotor groove of the lower rotor.

7. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 1, characterized in that: The first piezoelectric sheet and the second piezoelectric sheet are both annular structures, and the surface of the first piezoelectric sheet and the second piezoelectric sheet relative to the flexible printed circuit board is defined as the front surface, and the A phase, the ground wire and the B phase are arranged in sequence along the circumference of the front surface of the annular structure; wherein the A phase and the B phase are both composed of a forward polarized piezoelectric ceramic sheet and a reverse polarized piezoelectric ceramic sheet, and the forward polarized piezoelectric ceramic sheet and the reverse polarized piezoelectric ceramic sheet are placed alternately; The polarization directions of the A phase and the B phase of the first piezoelectric sheet are the same as the polarization directions of the A phase and the B phase of the second piezoelectric sheet; The front ground wire and the back ground wire of the first piezoelectric sheet and the second piezoelectric sheet are connected by plating conductive material on the outer diameter edges corresponding to the first piezoelectric sheet and the second piezoelectric sheet; When the first piezoelectric sheet and the second piezoelectric sheet are installed on both sides of the middle layer, the phase A of the first piezoelectric sheet is connected to the phase B of the second piezoelectric sheet to form the phase A of the piezoelectric dual chip, and the phase B of the first piezoelectric sheet is connected to the phase A of the second piezoelectric sheet to form the phase B of the piezoelectric dual chip.

8. The miniature dual-stator ultrasonic motor for driving an optical lens according to claim 2 or 3, characterized in that: The two sides of the flexible printed circuit board are the front side and the back side respectively. The front side and the back side have the same structure, and are divided into the conductive area of ​​the flexible printed circuit board, the non-conductive area of ​​the flexible printed circuit board, and the wiring holes of the flexible printed circuit board. The conductive area of ​​the flexible printed circuit board on the front side includes the A-phase conductive area on the front side of the flexible printed circuit board, the B-phase conductive area on the front side of the flexible printed circuit board, and the ground conductive area on the front side of the flexible printed circuit board. The conductive area of ​​the flexible printed circuit board on the back side includes the A-phase conductive area on the back side of the flexible printed circuit board, the B-phase conductive area on the back side of the flexible printed circuit board, and the ground conductive area on the back side of the flexible printed circuit board. The flexible printed circuit board wiring holes on the front and back sides include the flexible printed circuit board A-phase wiring hole, the flexible printed circuit board B-phase wiring hole and the flexible printed circuit board ground wire wiring hole; Conductivity between the A-phase conductive area on the front side of the flexible printed board and the A-phase conductive area on the back side of the flexible printed board is achieved by plating conductive materials on the A-phase wiring holes of the flexible printed board on the front side and the back side, and between the B-phase conductive area on the front side of the flexible printed board and the B-phase conductive area on the back side of the flexible printed board is achieved by plating conductive materials on the B-phase wiring holes of the flexible printed board on the front side and the back side, and between the ground wire conductive area on the front side of the flexible printed board and the ground wire conductive area on the back side of the flexible printed board is achieved by plating conductive materials on the ground wire wiring holes of the flexible printed board on the front side and the back side; In the piezoelectric bimorph, the ground wire of the first piezoelectric sheet and the ground wire of the second piezoelectric sheet are respectively pasted in the ground wire conductive areas of the conductive areas on both sides of the matching flexible printed circuit board, and the ground wires are aligned.

9. The excitation method of the miniature dual-stator ultrasonic motor for driving an optical lens according to claim 8, characterized in that: The ground wire connection hole of the flexible printed circuit board is connected separately, and the electrical signal is divided into two phases. A sin(ωt) signal is applied to the A-phase connection hole of the flexible printed circuit board, and a sin(ωt+π / 2) signal is applied to the B-phase connection hole of the flexible printed circuit board. At this time, the two-phase signals differ by π / 2; when the two-phase signals differ by -π / 2, the rotation direction of the motor changes.

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