SMA motor control method, related apparatus, and product

Abstract

Embodiments of the present application relate to the technical field of photographing, and provide an SMA motor control method, a related apparatus, and a product, aiming to prolong the service life of SMA motors. An SMA motor can drive a lens to move in a first direction and a second direction, the first direction being parallel to the focusing direction of the lens, and the second direction intersecting the first direction. The control method comprises: controlling an SMA motor to move in a first direction by a first stroke value; receiving an instruction instructing the SMA motor to move in a second direction by a second stroke value; if the first stroke value is equal to 0 and the second stroke value is greater than a first preset value, controlling the SMA motor to move in the second direction by the first preset value; and if the first stroke value is greater than 0 and the second stroke value is greater than a second preset value, controlling the SMA motor to move in the second direction by the second preset value, wherein the second preset value is less than the first preset value. According to the embodiments of the present application, on the basis of the focusing stroke of the motor, the stroke of optical image stabilization is limited, to avoid excessive driving of SMA wires, thereby prolonging the service life of the motor.

Description

A control method of an SMA motor, related devices and products

[0001] The present application claims priority to the Chinese patent application No. 202411255721.7, filed on September 6, 2024, and entitled "A control method of an SMA motor, related devices and products", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to the field of camera technology, in particular to a control method of an SMA motor, related devices and products. BACKGROUND

[0003] Camera modules of various electronic devices are constantly updated to meet the growing demand for camera quality of electronic devices. For example, electronic products such as smartphones and tablet computers need to consider the demand for thinness of the products, and also need to ensure the camera quality. Obviously, simply and roughly increasing the size and light-sensing area of the sensor cannot meet these demands. Therefore, some electronic devices introduce optical image stabilizer (OIS) technology, which controls the movement of the lens to compensate for the shaking of the device and the lens, thereby correcting the optical axis deviation. This can avoid image blur caused by device shaking during the operation of the camera module, and effectively improve the camera quality of the electronic device.

[0004] Shape memory alloy (SMA) motors have many advantages such as large load, small size, no magnetic interference and low cost, and are widely used in camera modules of many electronic devices to control the lens. Not only can the SMA motor complete automatic focus (AF), but also can achieve excellent optical image stabilize (OIS) compensation effect. However, the SMA motor uses very thin SMA wires to drive the lens, and the SMA wires are easily affected by factors such as material and process. After the SMA motor is used for a period of time, the SMA wires are prone to breakage, which causes the SMA motor to fail and affects the normal optical image stabilize and focus work of the electronic device.

[0005] Therefore, how to prolong the service life of the SMA motor in the camera module is a problem that needs to be solved by technical personnel. SUMMARY

[0006] Embodiments of the present application provide a control method of an SMA motor, related devices and products, which mainly aims to prolong the service life of the SMA motor in the camera module.

[0007] To achieve the above object, the embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, the embodiments of the present application provide a control method of a shape memory alloy (SMA) motor, wherein the SMA motor is configured to drive a lens to move in a first direction and a second direction. The first direction is parallel to a focusing direction of the lens, and the second direction intersects the focusing direction. The control method comprises: controlling the SMA motor to move in the first direction by a first stroke value. Receiving an instruction indicating that the SMA motor moves in the second direction by a second stroke value. When the first stroke value is equal to 0 and the second stroke value is greater than a first preset value, controlling the SMA motor to move in the second direction by the first preset value. When the first stroke value is greater than 0 and the second stroke value is greater than a second preset value, controlling the SMA motor to move in the second direction by the second preset value. The second preset value is less than the first preset value.

[0009] Through the above embodiments, the SMA motor can drive the lens to move in the first direction parallel to the focusing direction of the lens to control the focusing of the lens. The SMA motor can also drive the lens to move in the second direction intersecting the focusing direction of the lens to control the instantaneous displacement of the lens to perform optical image stabilization compensation. Moreover, the movement of the SMA motor is realized by the contraction of a part of SMA wires in the SMA motor in the energized state and the stretching of the remaining part of SMA wires in the de-energized state. When the first stroke value of the SMA motor moving in the first direction is 0, the first preset value is the maximum distance that the SMA motor can move in the second direction and the SMA wires are not prone to fatigue failure, so the optical image stabilization compensation of the lens can be maximized. When the first stroke value of the SMA motor moving in the first direction is greater than 0, the second preset value is the maximum distance that the SMA motor can move in the second direction, and the second preset value is reduced compared with the first preset value, which not only guarantees the effect of optical image stabilization compensation of the lens, but also avoids excessive stress (such as contraction stress or tensile stress) on the SMA wires and excessive deformation (such as excessive contraction or stretching) of the SMA wires when the SMA motor moves in the first direction and the second direction, thereby reducing the probability of SMA wire fracture and effectively prolonging the service life of the SMA motor in the camera module.

[0010] In combination with the first aspect, in a possible implementation manner, the SMA motor comprises a first SMA wire and a second SMA wire. The step of controlling the SMA motor to move in the second direction by the first preset value comprises: transmitting a first current to the first SMA wire to control the first SMA wire to contract. Transmitting a second current to the second SMA wire to control the second SMA wire to contract until the SMA motor moves in the second direction by the first preset value. In this way, at least two SMA wires in the SMA motor are energized, and the movement of the SMA motor in the second direction can be controlled.

[0011] The step of controlling the SMA motor to move a second preset value in the second direction includes: transmitting a third current to the first SMA wire to control the first SMA wire to contract; and transmitting a fourth current to the second SMA wire to control the second SMA wire to contract until the SMA motor moves the second preset value in the second direction. The first current is greater than the third current, or the second current is greater than the fourth current. In the implementation, when the first stroke value of the SMA motor moving in the first direction is greater than 0, the upper limit of the current threshold transmitted to the at least one SMA wire is reduced, and if the instantaneous displacement of the lens exceeds the second preset value, the current transmitted to the at least one SMA wire is the reduced current threshold, so that the SMA motor can be controlled to move the second preset value in the second direction.

[0012] With reference to the first aspect, in a possible implementation, the first stroke value is a first stroke sub-value, and the second preset value is a first preset sub-value. The first stroke value is a second stroke sub-value, and the second preset value is a second preset sub-value. The first stroke sub-value is greater than the second stroke sub-value, and the first preset sub-value is less than the second preset sub-value. In the implementation, the corresponding second preset value can be determined according to the first stroke value of the SMA motor moving in the first direction. As the first stroke value increases, the second preset value correspondingly decreases, or the second preset value and the first stroke value have a negative correlation, so that when the SMA motor moves in the first direction and the second direction, the tensile stress of the SMA wire can be prevented from being too large, and the optical anti-shake compensation effect on the lens can be ensured.

[0013] With reference to the first aspect, in a possible implementation, the second preset value and the first stroke value have an inverse linear relationship. In this way, the second preset value changes linearly based on the change of the first stroke value, so that the tensile stress of the SMA wire can be kept within a reasonable range and the optical anti-shake compensation effect on the lens can be ensured at different first stroke values, so as to balance the service life of the SMA motor and the optical anti-shake compensation effect on the lens.

[0014] With reference to the first aspect, in a possible implementation, the second preset value further includes a third preset sub-value. The first stroke value is equal to a focusing stroke threshold, and the second stroke value is greater than the third preset sub-value, and the SMA motor is controlled to move the third preset sub-value in the second direction. The ratio between the third preset sub-value and the first preset value is not less than 40% and not greater than 70%. In the implementation, when the first stroke value reaches the maximum, the tensile stress of the SMA wire in the first direction is the maximum, and the third preset sub-value corresponding to the first stroke value is the minimum in the second preset value. The minimum in the second preset value is set to 40% to 70% of the first preset value, so that the service life of the SMA motor and the optical anti-shake compensation effect on the lens can be balanced in the extreme focusing case.

[0015] With reference to the first aspect, in a possible implementation manner, the first stroke value is greater than 0, and the second stroke value is greater than a second preset value. The step of controlling the SMA motor to move in the second direction by the second preset value comprises: when the first stroke value is greater than 0, determining a focusing stroke interval in which the first stroke value is located; determining the second preset value corresponding to the focusing stroke interval; and judging whether the second stroke value is greater than the second preset value, and controlling the SMA motor to move in the second direction by the second preset value when the second stroke value is greater than the second preset value. In this implementation manner, when the first stroke value is greater than 0, the focusing stroke interval is determined, and the second preset value corresponding to the focusing stroke interval is found from the preset correspondence between the focusing stroke interval and the second preset value. The second preset value can be used as an anti-shake stroke threshold corresponding to the current first stroke value, and the stroke of the SMA motor controlled to move in the second direction does not exceed the second preset value, so that the service life of the SMA motor and the optical anti-shake compensation effect of the lens are both taken into account.

[0016] With reference to the first aspect, in a possible implementation manner, the control method further comprises: when the first stroke value is greater than 0 and the second stroke value is not greater than the second preset value, controlling the SMA motor to move in the second direction by the second stroke value. In this implementation manner, the SMA motor is directly controlled to move in the second direction by the second stroke value according to the received instruction, so that the instantaneous displacement value of the SMA motor can be directly compensated for anti-shake, and the optical anti-shake compensation effect of the lens is improved.

[0017] With reference to the first aspect, in a possible implementation manner, the SMA motor is further configured to be capable of driving the lens to move in a third direction, and the third direction intersects the first direction. After the step of controlling the SMA motor to move in the first direction by the first stroke value, the control method further comprises: receiving an instruction indicating that the SMA motor moves in the third direction by a third stroke value. When the first stroke value is equal to 0 and the third stroke value is greater than a third preset value, the SMA motor is controlled to move in the third direction by the third preset value. When the first stroke value is greater than 0 and the third stroke value is greater than a fourth preset value, the SMA motor is controlled to move in the third direction by the fourth preset value. The fourth preset value is less than the third preset value. In this implementation manner, the SMA motor can move in the second direction and the third direction for optical anti-shake compensation, and the anti-shake stroke thresholds of the SMA motor in the second direction and the third direction are both related to the first stroke value of the SMA motor in the first direction, so that the optical anti-shake compensation effect of the lens is improved, and the service life of the SMA motor is guaranteed.

[0018] In a second aspect, the embodiments of the present application provide a controller of an SMA motor, wherein the SMA motor is configured to drive a lens to move in a first direction and a second direction. The first direction is parallel to a focusing direction of the lens, and the second direction intersects the first direction. The controller includes a first control module, a signal receiving module, and a second control module. The first control module is configured to control the SMA motor to move in the first direction by a first stroke value. The signal receiving module is configured to receive an instruction indicating that the SMA motor moves in the second direction by a second stroke value. The second control module is configured to control the SMA motor to move in the second direction by a first preset value when the first stroke value is equal to 0 and the second stroke value is greater than a first preset value. The second control module is further configured to control the SMA motor to move in the second direction by a second preset value when the first stroke value is greater than 0 and the second stroke value is greater than a second preset value. The second preset value is less than the first preset value.

[0019] In a third aspect, the embodiments of the present application provide a camera module, which includes a lens, an SMA motor, and the controller of the SMA motor according to any one of the above embodiments.

[0020] In a fourth aspect, the embodiments of the present application provide an electronic device, which includes the controller of the SMA motor according to any one of the above embodiments or the camera module according to any one of the above embodiments.

[0021] In a fifth aspect, the embodiments of the present application provide an electronic device, which includes a memory and a processor. The memory includes instructions. When the processor executes the instructions, the electronic device implements the control method according to any one of the above embodiments.

[0022] In a sixth aspect, the embodiments of the present application provide a computer-readable storage medium, which includes a program or instructions. When the program or instructions are run on a computer, the control method according to any one of the above embodiments is implemented.

[0023] In a seventh aspect, the embodiments of the present application provide a computer program product, which includes a computer program. When the computer program is executed by a processor, the control method according to any one of the above embodiments is implemented.

[0024] The technical effects brought by any one of the second aspect to the seventh aspect can be referred to the technical effects brought by different design manners in the first aspect, and details are not described herein.

[0025] In an eighth aspect, an embodiment of the present application provides a test method of the SMA wire, the test method comprising: fixing one end of a to-be-tested SMA wire and connecting the other end of the to-be-tested SMA wire with a free object. Alternating the to-be-tested SMA wire between an energized state and a de-energized state until the to-be-tested SMA wire is broken. The fatigue resistance of the SMA wire is positively correlated with the time length of the alternating between the energized state and the de-energized state.

[0026] Through the above embodiment, the free object can be used to alternately apply tensile stress to the to-be-tested SMA wire in the process of the SMA wire being energized to contract and in the process of the SMA wire being de-energized to recover. Not only the scenario that the SMA wire is subjected to tensile stress in the working state of the SMA motor is simulated, but also whether there is a bad factor, such as a crack, impurity, etc., that is easy to cause the SMA wire to be broken can be quickly and effectively detected. Therefore, the fatigue resistance of the SMA wire can be improved, and the service life of the SMA wire and the SMA motor can be prolonged.

[0027] In combination with the eighth aspect, in a possible implementation manner, the free object has a preset weight, and the preset weight of the free object is positively correlated with the wire diameter of the SMA wire. Alternatively, the current value passed by the to-be-tested SMA wire in the energized state is positively correlated with the wire diameter of the to-be-tested SMA wire. In this way, the current value passed by the to-be-tested SMA wire in the energized state and the preset weight of the free object can be reasonably determined according to the wire diameter of the to-be-tested SMA wire. Not only the real use scenario of the SMA wire in the SMA motor can be simulated, but also the test process of the SMA wire can be appropriately accelerated by setting the current value passed by the to-be-tested SMA wire in the energized state and the weight of the free object. Whether there is a bad factor, such as a crack, impurity, etc., that is easy to cause the SMA wire to be broken can be more quickly and effectively detected, and the test efficiency can be improved.

[0028] In a ninth aspect, an embodiment of the present application provides a test method of the SMA wire, the test method comprising: connecting one end of a first to-be-tested SMA wire with one end of a second to-be-tested SMA wire, fixing the other end of the first to-be-tested SMA wire, and fixing the other end of the second to-be-tested SMA wire. Alternating the first to-be-tested SMA wire and the second to-be-tested SMA wire to be energized until the first to-be-tested SMA wire or the second to-be-tested SMA wire is broken. In the state that the first to-be-tested SMA wire is energized, the second to-be-tested SMA wire is subjected to tensile stress applied by the first to-be-tested SMA wire. In the state that the second to-be-tested SMA wire is energized, the first to-be-tested SMA wire is subjected to tensile stress applied by the second to-be-tested SMA wire. The fatigue resistance of the SMA wire is positively correlated with the time length of the alternating of the first to-be-tested SMA wire and the second to-be-tested SMA wire to be energized.

[0029] Through the above embodiment, one of the first SMA wire to be tested and the second SMA wire to be tested is powered to contract, the other is powered off to recover, and the first SMA wire to be tested and the second SMA wire to be tested apply tensile stress to each other, which highly simulates the scene that the SMA wire is subjected to tensile stress in the working state of the SMA motor, and can quickly and effectively detect whether there is a bad factor in the SMA wire that is easy to cause fracture, such as a crack, impurities, and the like, thereby helping to improve the fatigue resistance of the SMA wire, and prolong the service life of the SMA wire and the SMA motor.

[0030] In combination with the ninth aspect, in a possible implementation manner, in a state that the first SMA wire to be tested is powered, the length of the first SMA wire to be tested that is reduced does not exceed the maximum recoverable deformation of the first SMA wire to be tested and the maximum recoverable deformation of the second SMA wire to be tested. Alternatively, in a state that the second SMA wire to be tested is powered, the length of the second SMA wire to be tested that is reduced does not exceed the maximum recoverable deformation of the first SMA wire to be tested and the maximum recoverable deformation of the second SMA wire to be tested. In this way, the current size of the first SMA wire to be tested and the second SMA wire to be tested can be determined based on the maximum recoverable deformation of the first SMA wire to be tested and the maximum recoverable deformation of the second SMA wire to be tested, and the effectiveness of the test is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is an exploded schematic diagram of an electronic device according to an embodiment of the present application;

[0032] FIG. 2 is a structural schematic diagram of a camera module according to an embodiment of the present application;

[0033] FIG. 3 is a schematic diagram of some fractures of an SMA wire according to an embodiment of the present application;

[0034] FIG. 4 is a schematic diagram of a fatigue life-strain energy density of an SMA wire according to an embodiment of the present application;

[0035] FIG. 5 is a schematic diagram of a manufacturing process flow of an SMA wire according to an embodiment of the present application;

[0036] FIG. 6 is a schematic diagram of a stroke threshold of an SMA motor according to an embodiment of the present application;

[0037] FIG. 7 is a schematic diagram of a stroke value of the SMA motor according to the embodiment shown in FIG. 6;

[0038] FIG. 8 is a schematic diagram of a contraction strain of an SMA wire according to an embodiment of the present application;

[0039] FIG. 9 is a schematic diagram of a space range of movement of an SMA motor according to an embodiment of the present application;

[0040] FIG. 10 is a schematic diagram of a planar range of movement of an SMA motor according to an embodiment of the present application;

[0041] FIG. 11 is a flowchart of a method of controlling an SMA motor according to an embodiment of the present application;

[0042] FIG. 12 is a schematic diagram of a stroke value of an SMA motor according to an embodiment of the present application;

[0043] FIG. 13 is a schematic diagram of a stroke threshold of an SMA motor according to an embodiment of the present application;

[0044] FIG. 14 is a schematic diagram of a stroke relationship of an SMA motor according to an embodiment of the present application;

[0045] FIG. 15 is a block diagram of a controller of an SMA motor according to an embodiment of the present application;

[0046] FIG. 16 is a block diagram of an electronic device according to an embodiment of the present application;

[0047] FIG. 17 is a schematic diagram of a test scenario of an SMA wire according to an embodiment of the present application;

[0048] FIG. 18 is a flowchart of a method of testing an SMA wire according to an embodiment of the present application;

[0049] FIG. 19 is a schematic diagram of another test scenario of an SMA wire according to an embodiment of the present application;

[0050] FIG. 20 is a flowchart of a method of testing an SMA wire according to an embodiment of the present application.

[0051] Reference Signs Description: 1, screen; 2, middle frame; 3, back shell; 4, mainboard; 5, camera module; 51, lens; 52, SMA motor; 100, electronic device; 6, application processor; 7, gyroscope sensor; 500, controller of SMA motor; 501, first control module; 502, signal receiving module; 503, second control module; 504, gyroscope filtering module; 505, first processing module; 506, second processing module; 521, SMA wire; 5211, first SMA wire to be tested; 5212, second SMA wire to be tested; 601, free object. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be described below with reference to the drawings.

[0053] In the description of the embodiments of the present application, "a plurality of" means two or more than two, unless otherwise specified. "At least one" or similar expressions mean any combination of the items, including a single item or any combination of multiple items. For example, at least one of a, b and c can represent a, b, c, a-b, a-c, b-c or a-b-c, where a, b and c can be a single item or multiple items. "A and / or b" includes the following three combinations: only a, only b, and a combination of a and b.

[0054] In addition, in order to facilitate the clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, "first", "second" and the like are used to distinguish the same items or similar items with basically the same function and role. Those skilled in the art can understand that "first", "second" and the like do not limit the quantity and execution order, and "first", "second" and the like do not necessarily mean different. At the same time, in the embodiments of the present application, "exemplarily" or "for example" and the like are used to represent as an example, illustration or explanation.

[0055] In the description of some embodiments, "connection" and its derivatives are used. The term "connection" should be understood broadly, for example, "connection" can be fixed connection, or detachable connection, or integral; can be directly connected, or indirectly connected through intermediate medium. In addition, the use of "based on" means openness and inclusiveness, because the process, step, calculation or other action "based on" one or more described conditions or values can be based on additional conditions or values beyond the described values in practice.

[0056] In addition, the architecture and scenarios described in the embodiments of the present application are used to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those skilled in the art can know that, with the evolution of architecture and the appearance of new scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0057] Embodiments of the present application provide an electronic device, which includes a camera module. The electronic device can be applied to various communication systems or communication protocols, such as global system of mobile communication (GSM), code division multiple access (CDMA) system, wideband-C division multiple access wireless (WCDMA), general packet radio service (GPRS), long term evolution (LTE), and the like.

[0058] The electronic device described above includes, but is not limited to, electronic devices in the field of information technology (IT) and communication technology (CT), and can be applied to various scenarios. These electronic devices include, for example, consumer products, home products, vehicle-mounted products, wearable products, financial terminal products, communication products, intelligent detection products. Exemplarily, the electronic device can include, but is not limited to, a mobile phone, a tablet computer, a single-lens reflex camera, a video camera, a digital camera, a smart wearable product (for example, a smart watch, a smart bracelet), a smart television, an extended reality (XR) device, an inertial navigation device, an aerospace device, a smart door lock, a smart helmet, and the like. The XR device described above is, for example, a virtual reality (VR) device, an augmented reality (AR) device, or a mixed reality (MR) device, or a robot.

[0059] Embodiments of the present application do not limit the specific form of the electronic device described above.

[0060] FIG. 1 is an exploded schematic diagram of an electronic device provided by embodiments of the present application.

[0061] For the convenience of description, the following is an example of taking the electronic device as a mobile phone shown in FIG. 1. Please refer to FIG. 1, the electronic device 100 is a mobile phone. The electronic device 100 can include a screen 1, a middle frame 2, a back shell 3, a mainboard 4 fixed on the middle frame 2, and a camera module 5. The mainboard 4 can be a printed circuit board (PCB).

[0062] FIG. 1 only shows one design of the electronic device 100 by way of example, and the actual shape, actual size, actual position, and actual structure of each component are not limited by FIG. 1. For example, in some examples, the camera module 5 can be disposed on the side of the screen 1 of the electronic device 100 as well as on the side of the back cover 3.

[0063] FIG. 2 is a structural schematic diagram of a camera module provided in an embodiment of the present application.

[0064] As shown in FIG. 2, the present application provides a camera module 5, which includes a lens 51, an SMA motor 52, and a controller of the SMA motor. The controller of the SMA motor can be a driver IC by way of example.

[0065] The SMA motor can include a plurality of SMA wires 521. By way of example, the SMA motor can include, but is not limited to, four SMA wires 521 or eight SMA wires 521 (as shown in FIG. 2).

[0066] In some optional embodiments, the controller of the SMA motor is configured to control the SMA motor to drive the lens to move along a focusing direction of the lens (e.g., a first direction Z) and to control the SMA motor to drive the lens to move along a direction intersecting the focusing direction of the lens (e.g., a second direction X or a third direction Y). By way of example, the controller of the SMA motor is configured to control the SMA motor to drive the lens to move along the focusing direction of the lens and a direction perpendicular to the focusing direction of the lens.

[0067] Thus, the SMA motor 5 can be used to control the lens to achieve focusing and optical image stabilization compensation. For example, during the working process of the camera module, when the device in which the SMA motor 52 is located shakes 100 μm in the second direction X, the SMA motor 52 can control the lens to move 100 μm in the opposite direction of the second direction X, thereby achieving optical image stabilization compensation and reducing image blur caused by the shaking of the device.

[0068] Specifically, in some examples, a part of the SMA wires 521 in the SMA motor 52 contract in the energized state, and the SMA motor 52 can be controlled to drive the lens 51 to move. The shape memory characteristics of the SMA wires 521 can be used to achieve multiple controls.

[0069] FIG. 3 is a schematic diagram of some fractures of the SMA wire 521 provided in an embodiment of the present application.

[0070] However, when the SMA motor 52 is energized to move, the alternating tension on the SMA wire 521 is prone to cause fatigue fracture of the SMA wire 521. Especially, in order to improve the anti-shake speed and focusing speed, the SMA motor 52 generally adopts a very thin SMA wire 521, for example, an SMA wire 521 with a diameter of only 25 or 30 um. In the manufacturing process or use process of such SMA motor 52, the SMA wire 521 is more prone to fracture. From the position of the SMA wire 521 fracture, the fracture mainly includes root breakage (as shown in A1 in FIG. 3) and middle breakage (as shown in A2 in FIG. 3).

[0071] Among them, the root breakage is mostly caused by improper pressing of the SMA wire 521 by the clamp. For example, the SMA wire 521 is pressed and injured by excessive pressing force of the clamp, so that the fatigue resistance of the SMA wire 521 decreases. For another example, the SMA wire 521 has a stress concentration at the root due to excessive wire exit angle of the clamp, which exceeds the fatigue resistance of the wire. Among them, the fatigue resistance, also known as fatigue strength, can refer to the ability of an object to withstand repeated stress.

[0072] In order to alleviate the root breakage, in addition to optimizing the pressing process parameters, a C angle or R angle can be arranged at the wire exit position of the clamp, and a glue with moderate hardness can be applied to protect the weak part of the metal wire and alleviate the stress concentration problem.

[0073] The middle breakage is usually caused by unreasonable structural design of the SMA motor 52, unreasonable movement stroke design of the SMA motor 52, and poor material quality of the SMA wire 521. Among them, the unreasonable structural design of the SMA motor 52 means that the SMA wire 521 is pinched or stuck in the assembly process of the SMA motor 52 due to the design gap between the structural parts of the SMA motor 52. In order to prevent such failure, the structural parts around the SMA wire 521 can be designed as a concave-convex nested structure to prevent the metal wire from falling into the gap.

[0074] The fatigue life of the SMA wire 521 is related to the stress (load) and strain (contraction rate). Under constant stress conditions, as the contraction rate increases, the fatigue life of the SMA wire 521 decreases accordingly. Under constant strain conditions, as the load increases, the fatigue life of the SMA wire 521 decreases accordingly.

[0075] FIG. 4 is a fatigue life-strain energy density diagram of an SMA wire provided by an embodiment of the present application.

[0076] As shown in FIG. 4, if the fatigue life of the SMA wire is predicted by a (smith-watson-topper, SWT) model, the fatigue life Nf of the SMA wire has a negative exponential function relationship with the strain energy density 2σmaxΕα(unit: MJ / m3).

[0077] As shown in FIG. 4, the greater the strain energy density 2σmaxΕα, the shorter the fatigue life Nf of the SMA wire. For example, under stresses of 80 MPa and 175 MPa, although the stress sizes are different, the regression of the above-mentioned negative exponential function relationship can be achieved. This is because the strain energy density Nf is equal to the product of stress and strain.

[0078] The above-mentioned function relationship between the fatigue life of the SMA wire 521 and the strain energy density is because the SMA wire 521 is not 100% pure in a microcosmic sense, but contains a certain amount of impurities. These impurities are called heterogeneous phase particles, which are generally carbides or oxides, and are formed during smelting or high-temperature hot processing of the SMA wire 521. Since the hardness of the heterogeneous phase particles is generally significantly higher than that of the metal matrix of the SMA wire 521, when the SMA wire 521 is contracted under stress, the interface between the heterogeneous phase particles and the metal matrix will become a stress or strain concentration point, causing micro-cracks to occur at the concentration point, and the micro-cracks will expand along the radial direction of the SMA wire 521 until instantaneous fracture occurs. The greater the stress or strain, the faster the micro-cracks expand, and the shorter the fatigue life of the wire.

[0079] FIG. 5 is a schematic diagram of a manufacturing process flow of the SMA wire 521 provided by the embodiments of the present application.

[0080] As shown in FIG. 5, the manufacturing of the SMA wire 521 can specifically include the following steps:

[0081] Step S21, smelting.

[0082] Step S22, hot extrusion.

[0083] Step S23, rolling.

[0084] Step S24, wire drawing.

[0085] Step S25, interpass annealing.

[0086] Step S26, determining the final deformation amount.

[0087] Step S27, final heat-treatment.

[0088] Step S28, training.

[0089] Step S29, manufacturing a plating layer.

[0090] It can be seen that smelting as the first step of the process flow for making SMA wire 521 plays a crucial role in the material purity of SMA wire 521. Although the smelting process of SMA wire 521 is constantly improving, it is still difficult to reach the level of 100% purity, so the presence of heterogeneous phase particles in SMA wire 521 is often inevitable.

[0091] FIG. 6 is a schematic diagram of a stroke threshold of an SMA motor according to an embodiment of the present application.

[0092] An embodiment of the present application provides a control method of an SMA motor 52, which can be applied to a camera module 5. As shown in FIG. 6, the control method mainly limits the movement of the SMA motor 52 in the second direction X or the third direction Y, or in other words, the movement of the SMA motor 52 in the second direction X or the third direction Y has an anti-shake stroke threshold (OIS limit) T1. Wherein the anti-shake stroke threshold T1 can be the maximum stroke value that the SMA motor 52 can move in the anti-shake direction. Exemplarily, the anti-shake stroke threshold T1 can be 100 pm, and the anti-shake direction can be a direction intersecting or even perpendicular to the focusing direction of the lens 51.

[0093] As shown in FIG. 6, the initial position O can be the position of the SMA motor 52 when the camera module is not working or the SMA motor 52 is powered off. The far focus segment position SF can be the position of the SMA motor 52 when the camera module is at the maximum focal length. The near focus segment position SN can be the position of the SMA motor 52 when the camera module is at the minimum focal length.

[0094] AF1 and AF2 can be the focusing stroke threshold of the SMA motor 52.

[0095] Wherein the second direction X and the third direction Y can be a direction intersecting or even perpendicular to the first direction Z, and the first direction Z can be the focusing direction of the lens 51.

[0096] By the above embodiment, the SMA motor 52 can be prevented from moving excessively in the anti-shake direction, and the strain energy density of the SMA wire 521 can be reduced, thereby reducing the risk of breakage of the SMA wire 521. If the SMA motor 52 has a large stroke value in the focusing direction and the anti-shake direction, the contraction / extension range of the SMA wire 521 is in a superimposed state in the two directions, and the risk of breakage of the SMA wire 521 is still increased, and the service life of the SMA motor 52 is shortened. For example, as shown in FIG. 6, the focusing stroke value of the SMA motor 52 in the first direction Z is D1, the anti-shake stroke value of the SMA motor 52 in the second direction X is D2, and the actual stroke value of the SMA motor 52 is D3, which is the equivalent superimposed value of D1 and D2. D3 is greatly increased compared with D1 or D2, so that the SMA wire 521 needs to be contracted by a larger range, which is easy to cause the breakage of the SMA wire 521, and reduces the service life of the SMA motor 52 in the camera module 5.

[0097] FIG. 7 is a stroke value diagram of the SMA motor provided in the embodiment shown in FIG. 6.

[0098] As shown in FIG. 7, at the same time t, the SMA motor 52 has a corresponding anti-shake stroke code value OIS-C and a focusing stroke code value AF-C.

[0099] The anti-shake stroke code value OIS-C can be regarded as the stroke value of the SMA motor 52 for optical anti-shake compensation, for example, the anti-shake stroke code value OIS-C can be regarded as the first anti-shake stroke value OIS-A in the second direction X, or can be the second anti-shake stroke value OIS-B in the third direction Y.

[0100] As shown in FIG. 7, the focusing stroke code value AF-C can be regarded as the stroke value of the SMA motor 52 for focusing the lens 51, for example, the focusing stroke code value AF-C can be regarded as the stroke value in the first direction Z.

[0101] In this embodiment, the anti-shake stroke threshold range T1 of the SMA motor 52 is fixed.

[0102] The OIS-C is substantially not more than the range of the anti-shake stroke threshold T1 of the SMA motor 52. The AF-C is substantially not more than the range of the focusing stroke threshold T2 of the SMA motor 52.

[0103] FIG. 8 is a contraction strain diagram of the SMA wire provided in the embodiment of the application.

[0104] Taking an eight-wire SMA motor as an example, the eight SMA wires are all inclined wires, and each SMA wire can participate in the movement of the SMA motor in the focusing direction and the anti-shake direction by contraction.

[0105] As shown in FIG. 8, in the case that the current value of the SMA wire is fixed and the shrinkage strain is fixed, the stroke of the OIS along the second direction X or the second direction Y is constantly reduced as the AF stroke along the first direction Z increases.

[0106] As shown in FIG. 8, the length of the SMA wire after shrinkage is L*(1-R). Wherein, L is the length of the SMA wire in the state of power-off, or the original wire length. R is the maximum shrinkage strain rate of the SMA wire, which can be artificially limited by setting the size of the current flowing in the SMA wire.

[0107] FIG. 9 is a schematic diagram of a spatial range of movement of the SMA motor according to an embodiment of the present application.

[0108] As shown in FIG. 9, for example, the SMA motor 52 is an eight-wire SMA motor, and in the case that the maximum shrinkage amount of each SMA wire 521 is fixed, the envelope of the movement trajectory of the eight-wire SMA motor can form a symmetrical octahedral structure in space.

[0109] FIG. 10 is a schematic diagram of a planar range of movement of the SMA motor 52 according to an embodiment of the present application.

[0110] As shown in FIG. 10, the above-mentioned octahedral structure projected onto the XZ plane or the YZ plane is a rhombus.

[0111] In view of this, the present application provides a control method of a shape memory alloy (SMA) motor 52, wherein the SMA motor 52 is configured to drive a lens 51 to move along a first direction and a second direction. The first direction is parallel to the focusing direction of the lens 51, and the second direction intersects the first direction. For example, the second direction is perpendicular to the first direction. Thus, the SMA motor 52 can drive the lens 51 to move along the first direction parallel to the focusing direction of the lens 51 to control the focusing of the lens 51. The SMA motor 52 can also drive the lens 51 to move along the second direction intersecting the focusing direction of the lens 51 to control the lens 51 to compensate for the instantaneous displacement.

[0112] FIG. 11 is a step flowchart of a control method of the SMA motor 52 according to an embodiment of the present application.

[0113] As shown in FIG. 11, the above-mentioned control method specifically includes the following steps:

[0114] Step S31, control the SMA motor 52 to move along the first direction by a first stroke value.

[0115] In some alternative embodiments, the focus control signal can be received from an adjunct processor (AP) 6, and the focus control signal can include an instruction indicating the SMA motor 52 to move a first stroke value in a first direction. For example, if the lens 51 needs to be focused at the near focus section, the adjunct processor 6AP can issue a focus control signal to the controller of the SMA motor 52, and the focus control signal can include an instruction indicating the SMA motor 52 to move in the near focus direction of the lens 51.

[0116] For example, if the electronic device 100 is a mobile phone, the adjunct processor 6AP can obtain a signal indicating the focus through the screen touch sensor of the mobile phone, and generate the focus control signal accordingly. For example, if the electronic device 100 is a camera, the adjunct processor 6AP can obtain a signal indicating the focus through the focus case of the camera, and generate the focus control signal accordingly.

[0117] For example, the SMA motor 52 is controlled to move a first stroke value 180 μm in the focus direction of the lens 51.

[0118] In some alternative embodiments, the lens 51 can be returned to the initial position each time it needs to be refocused, and the first stroke value can refer to the distance value between the initial position and the focus position. For example, the initial position of the lens 51 can refer to the position of the SMA motor 52 in the power-off state.

[0119] In some alternative embodiments, the initial position of the lens 51 can be set at the mid-tele focus section of the lens 51, the first direction can be the direction of the mid-tele focus section of the lens 51 towards the tele focus section, and the first direction can also be the direction of the mid-tele focus section of the lens 51 towards the near focus section.

[0120] Step S32, receiving an instruction indicating the SMA motor 52 to move a second stroke value in a second direction.

[0121] In some optional embodiments, taking the electronic device 100 provided with a gyroscope 7 as an example, the gyroscope 7 can monitor the shaking of the electronic device 100 in real time, and send the displacement data of the electronic device 100 to the controller of the SMA motor 52. For example, the displacement data of the electronic device 100 can include linear displacement data and angular displacement data. For example, the linear displacement data can include coordinate data in XYZ three directions, and the angular displacement data can include the angle of deflection of the electronic device 100. For example, the XYZ coordinate values of the linear displacement data are (2500 μm, 0 μm, 3000 μm), wherein the 3000 μm of displacement along the direction parallel to the first direction Z can be compensated by the focusing algorithm, and the 2500 μm of displacement along the direction parallel to the second direction X needs to be compensated by optical image stabilization, for example, the SMA motor 52 drives the lens 51 to move 100 μm along the second direction X to realize optical image stabilization compensation. For another example, the angle of deflection of the electronic device 100 is 30° along the horizontal direction and 15° along the vertical direction. The angular displacement data and the linear displacement data can also be fused and calculated, and the fused and calculated data can be compensated.

[0122] For example, the displacement data of the electronic device 100 can be regarded as the displacement data of the SMA motor 52, and the displacement data of the SMA motor 52 can be used to indicate the movement of the SMA motor 52 along the second direction to compensate for the displacement of the SMA motor 52.

[0123] In step S33, the first stroke value is equal to 0, and the second stroke value is greater than the first preset value, and the SMA motor 52 is controlled to move along the second direction by the first preset value.

[0124] In some optional embodiments, the first preset value can be a stroke threshold value of the SMA motor 52 moving along the second direction when the first stroke value is equal to 0. Alternatively, the first preset value can be a stabilization stroke threshold value of the SMA motor 52 when the first stroke value is equal to 0.

[0125] For example, the first stroke value is equal to 0, the second stroke value is 200 μm, and the first preset value is 100 μm.

[0126] For example, the first preset value can be determined according to the rated stroke of the SMA motor 52. For example, the first preset value can be 1 / 4 of the rated maximum stroke of the SMA motor 52.

[0127] In some optional embodiments, if the first stroke value is 0 and the second stroke value is not greater than the first preset value, the SMA motor 52 is controlled to move in the second direction by the second stroke value. Thus, the optical anti-shake compensation can be directly performed according to the instruction transmitted by the gyroscope sensor 7. For example, the gyroscope sensor 7 indicates that the SMA motor 52 moves in the second direction by a second stroke value of 80 μm, and the first preset value is 100 μm. If the second stroke value is not greater than the first preset value, the SMA motor 52 is controlled to move in the second direction by 80 μm.

[0128] In the embodiments of the present application, the step S33 can further include: if the first stroke value is greater than 0 and the second stroke value is greater than the second preset value, the SMA motor 52 is controlled to move in the second direction by the second preset value.

[0129] In some optional embodiments, the second preset value can be a stroke threshold value of the SMA motor 52 in the state that the first stroke value is greater than 0 and the SMA motor 52 moves in the second direction. In other words, the second preset value can be an anti-shake stroke threshold value of the SMA motor 52 in the state that the first stroke value is greater than 0.

[0130] For example, the first stroke value is 180 μm, the second stroke value is 200 μm, and the second preset value is 80 μm.

[0131] In the embodiments of the present application, the second preset value is less than the first preset value. For example, the second preset value is 80 μm, and the first preset value is 100 μm.

[0132] FIG. 12 is a stroke value diagram of the SMA motor 52 in the embodiment shown in FIG. 11.

[0133] As shown in FIG. 12, if the focusing stroke value AF-C is greater than 0, the corresponding anti-shake stroke value OIS-C is relatively small and does not exceed the second preset value P2. If the focusing stroke value AF-C is 0 or close to 0, the corresponding anti-shake stroke value OIS-C is relatively large and does not exceed the first preset value P1.

[0134] In some optional embodiments, the instruction indicating that the SMA motor 52 moves in the first direction by the first stroke value and the instruction indicating that the SMA motor 52 moves in the second direction by the second stroke value can be received synchronously. Thus, in some optional embodiments, the above-mentioned step S31 and step S33 can be executed synchronously, or the step S31 and step S35 can be executed synchronously, so as to synchronously realize the focusing and anti-shake of the lens 51.

[0135] In yet some optional embodiments, the above-mentioned step S31 can be executed first, and then the step S33 or step S35 is executed, so as to execute the optical anti-shake compensation of the lens 51 after the focusing of the lens 51 is completed.

[0136] By the above embodiment, in a case that the first stroke value of the SMA motor 52 moving in the first direction is 0, the first preset value P1 is the maximum distance that the SMA motor 52 can move in the second direction and the SMA wire 521 is not prone to fatigue failure, so that the optical anti-shake compensation of the lens 51 can be maximized. In a case that the first stroke value of the SMA motor 52 moving in the first direction is greater than 0, the second preset value P2 is the maximum distance that the SMA motor 52 can move in the second direction, and the second preset value P2 is reduced compared with the first preset value P1, which not only guarantees the effect of optical anti-shake compensation of the lens 51, but also avoids excessive stress on the SMA wire 521 and excessive deformation of the SMA wire 521 in a case that the SMA motor 52 moves in the first direction and the second direction, thereby effectively prolonging the service life of the SMA motor 52 in the camera module 5.

[0137] In some optional embodiments, the above step S33 can further perform step S34, and the step S34 can specifically include:

[0138] Step S341, judging whether the first stroke value is equal to 0.

[0139] Step S342, in a case that the first stroke value is equal to 0, judging whether the second stroke value is greater than the first preset value.

[0140] Step S343, in a case that the first stroke value is greater than 0, judging whether the second stroke value is greater than the second preset value.

[0141] In some optional embodiments, the above step S343 can further include:

[0142] Step S3431, in a case that the first stroke value is greater than 0, determining the focus stroke interval in which the first stroke value is located.

[0143] In some examples, the focus stroke threshold is 500 μm, and five focus stroke intervals are divided, which are (0, 100 μm], (100 μm, 200 μm], (200 μm, 300 μm], (300 μm, 400 μm], (400 μm, 500 μm].

[0144] For example, the first stroke value is 180 μm, and the focus stroke interval in which the first stroke value is located is (100 μm, 200 μm].

[0145] Step S3432, determining the second preset value corresponding to the focus stroke interval.

[0146] Wherein, a plurality of preset relationships between the focus stroke interval and the second preset value can be established in advance, so as to obtain the second preset value corresponding to the focus stroke interval by using a lookup table.

[0147] In some examples, the second preset value can gradually decrease as the value of the focusing stroke interval increases. For example, the preset relationship between the focusing stroke interval and the second preset value is as follows: the focusing stroke interval (0, 100 pm] corresponds to the second preset value 90 pm, the focusing stroke interval (100, 200] corresponds to the second preset value 80 pm, the focusing stroke interval (200, 300] corresponds to the second preset value 70 pm, the focusing stroke interval (300, 400] corresponds to the second preset value 60 pm, and the focusing stroke interval (400, 500] corresponds to the second preset value 50 pm.

[0148] For example, the focusing stroke interval (100 pm, 200 pm] corresponds to the second preset value 80 pm.

[0149] In step S3433, it is determined whether the second stroke value is greater than the second preset value.

[0150] For example, the first stroke value is 180 pm, and the second stroke value is 200 pm. In this case, the second stroke value is greater than the second preset value.

[0151] In some optional embodiments, in the above step S33, the first stroke value is 180 pm, the second stroke value is 200 pm, the second stroke value is greater than the second preset value, and the SMA motor 52 is controlled to move in the second direction by the second preset value 80 pm corresponding to the focusing stroke interval (100 pm, 200 pm].

[0152] In the above embodiments, when the first stroke value is greater than 0, the focusing stroke interval is determined, and the second preset value corresponding to the focusing stroke interval is found from the preset corresponding relationship between the focusing stroke interval and the second preset value. The second preset value can be used as the anti-shake stroke threshold under the current first stroke value, so that the stroke of the SMA motor 52 moving in the second direction does not exceed the second preset value, thereby balancing the service life of the SMA motor 52 and the optical anti-shake compensation effect of the lens 51.

[0153] In some optional embodiments, in addition to obtaining the second preset value corresponding to the first stroke value by using the look-up table, a function relationship between the first stroke value and the second preset value can be established in advance, so that the second preset value corresponding to the first stroke value can be directly determined.

[0154] In some optional embodiments, the SMA motor 52 includes a first SMA wire 521 and a second SMA wire 521. By transmitting a current to the first SMA wire 521 and the second SMA wire 521, or in other words, by transmitting a current to at least two SMA wires 521 in the SMA motor 52, the SMA motor 52 can be controlled to drive the lens 51 to move.

[0155] In some optional embodiments, the above step S35 can further include:

[0156] In step S331, when the first stroke value is greater than 0 and the second stroke value is greater than the second preset value, a third current is transmitted to the first SMA wire 521 to control the first SMA wire 521 to contract.

[0157] In step S332, when the first stroke value is greater than 0 and the second stroke value is greater than the second preset value, a fourth current is transmitted to the second SMA wire 521 to control the second SMA wire 521 to contract until the SMA motor 52 moves the second preset value in the second direction.

[0158] In some examples, the execution order of step S331 and step S332 can be exchanged, or step S331 and step S332 can be executed synchronously.

[0159] Therefore, by energizing at least two SMA wires 521 in the SMA motor 52, the SMA motor 52 can be controlled to move the second preset value in the second direction when the first stroke value is greater than 0 and the second stroke value is greater than the second preset value.

[0160] In yet some optional embodiments, the above step S33 can further include:

[0161] In step S333, when the first stroke value is equal to 0 and the second stroke value is greater than the first preset value, the first current is transmitted to the first SMA wire 521 to control the first SMA wire 521 to contract.

[0162] In step S334, when the first stroke value is greater than 0 and the second stroke value is greater than the first preset value, the second current is transmitted to the second SMA wire 521 to control the second SMA wire 521 to contract until the SMA motor 52 moves the first preset value in the second direction.

[0163] In some examples, the execution order of step S333 and step S334 can be exchanged, or step S333 and step S334 can be executed synchronously.

[0164] Therefore, by energizing at least two SMA wires 521 in the SMA motor 52, the SMA motor 52 can be controlled to move the first preset value in the second direction when the first stroke value is equal to 0 and the second stroke value is greater than the first preset value.

[0165] In the above embodiments, the first current is greater than the third current, and / or the second current is greater than the fourth current.

[0166] According to the above embodiment, in the case that the first stroke value of the SMA motor 52 moving in the first direction is greater than 0, compared with the case that the first stroke value of the SMA motor 52 moving in the first direction is equal to 0, the upper limit of the current threshold transmitted to the at least one SMA wire 521 is reduced, and if the instantaneous displacement of the lens 51 exceeds the second preset value, the current transmitted to the at least one SMA wire 521 is the reduced current threshold upper limit, so that the SMA motor 52 can be controlled to move in the second direction by the second preset value, and the second preset value is less than the first preset value.

[0167] In some optional embodiments, the first stroke value includes a first stroke sub-value and a second stroke sub-value. The second preset value includes a first preset sub-value and a second preset sub-value.

[0168] If the first stroke value is the first stroke sub-value, the second preset value is the first preset sub-value. If the first stroke value is the second stroke sub-value, the second preset value is the second preset sub-value. The first stroke sub-value is greater than the second stroke sub-value, and the first preset sub-value is less than the second preset sub-value.

[0169] The first stroke sub-value is greater than the second stroke sub-value, and the first preset sub-value is less than the second preset sub-value.

[0170] For example, the first stroke sub-value is 180 μm, the second stroke sub-value is 280 μm, the first preset sub-value is 80 μm, and the second preset sub-value is 70 μm.

[0171] According to the above embodiment, the corresponding second preset value can be determined according to the size of the first stroke value of the SMA motor 52 moving in the first direction. As the first stroke value increases, the second preset value correspondingly decreases, or in other words, the second preset value and the first stroke value have a negative correlation, so that in the case that the SMA motor 52 moves in the first direction and the second direction, the SMA wire 521 can be prevented from being subjected to excessive tensile stress, and the effect of optical anti-shake compensation on the lens 51 can be ensured.

[0172] FIG. 13 is a stroke threshold diagram of the SMA motor 52 in the embodiment shown in FIG. 11.

[0173] As shown in FIG. 13, in some optional embodiments, the second preset value N1 and the first stroke value M1 have an inverse linear relationship.

[0174] For example, the distance between the initial position O of the lens 51 and the far focus segment position SF of the lens 51 can not be equal to the distance between the initial position O of the lens 51 and the near focus segment position SN of the lens 51. Correspondingly, in the case that the focusing stroke threshold changes, the second preset value corresponding to each first stroke value can also change.

[0175] In some examples, the first preset value is 100 μm. The distance between the initial position of the lens 51 and the near focus position of the lens 51 is a first focus stroke threshold, the first focus stroke threshold is 500 μm, the second preset value is 50 μm in the case that the first stroke value is 500 μm, and the second preset value is linearly and negatively related to the first stroke value.

[0176] In yet some examples, the first preset value is 100 μm. The distance between the initial position of the lens 51 and the far focus position of the lens 51 is a second focus stroke threshold, the second focus stroke threshold is 200 μm, the second preset value is 80 μm in the case that the first stroke value is 200 μm, and the second preset value is linearly and negatively related to the first stroke value.

[0177] Through the embodiment, the second preset value is linearly changed based on the change of the first stroke value, which can further enable the SMA wire 521 to be in a reasonable range of tensile stress and guarantee the optical anti-shake compensation effect of the lens 51 at different first stroke values, so as to balance the service life of the SMA motor 52 and the optical anti-shake compensation effect of the lens 51.

[0178] As shown in FIG. 13, the commonly used lens 51 focus position in shooting is the middle-far focus position O, and the middle-far focus position of the lens 51 can be set at the position in the power-off state of the SMA motor 52. Thus, a larger anti-shake compensation can be obtained in most shooting scenes, achieving better user experience. For the camera near focus scene such as mobile phone code scanning and face unlocking, the stroke value of the SMA motor 52 in the focusing direction is larger, and correspondingly, the stroke value of the SMA motor 52 in the direction intersecting with the focusing direction for optical anti-shake compensation decreases under the violent shaking of the electronic device 100, so as to avoid excessive contraction or stretching of the SMA wire 521, prolonging the service life of the SMA motor 52. Compared with the middle focus position and far focus position shooting scene such as shooting people and scenery, the requirement for the quality of the photographed image is lower in the camera near focus scene such as mobile phone code scanning and face unlocking, and the compensation effect of the optical anti-shake is weakened, which has little effect on the user experience. Thus, the above embodiment can balance the user experience and the service life of the SMA motor 52.

[0179] FIG. 14 is a stroke relationship diagram of the SMA motor 52 in the embodiment shown in FIG. 11.

[0180] As shown in FIG. 14, if the focusing stroke is represented by the target code value in the focusing direction, and the target code value in the focusing direction takes the end position of the close-up section or the end position of the telephoto section of the lens 51 as the zero point of the code value (for example, the target code value in the focusing direction is about 2000, which corresponds to the initial position of the lens 51 in practice), the anti-shake stroke threshold value and the target code value in the focusing direction can present a linear relationship of first increasing and then decreasing.

[0181] In some optional embodiments, the second preset value further includes a third preset sub-value. The above step S33 further includes:

[0182] In step S335, the first stroke value is equal to the focusing stroke threshold value, and the second stroke value is greater than the third preset sub-value. The SMA motor 52 is controlled to move in the second direction by the third preset sub-value. The ratio between the third preset sub-value and the first preset value is not less than 40% and not greater than 70%.

[0183] Exemplarily, the ratio between the third preset sub-value and the first preset value can be, but is not limited to, one of the following: 40%, 50%, 55%, 60%, and 70%. For example, the third preset sub-value is 50 μm, and the first preset value is 100 μm.

[0184] Through the above embodiments, in the case that the first stroke value reaches the maximum, the tensile stress that the SMA wire 521 receives in the first direction is the maximum, and the third preset sub-value corresponding to the first stroke value is the minimum in the second preset value. The above embodiments set the minimum in the second preset value to 40%-70% of the first preset value, which can further take into account the service life of the SMA motor 52 and the optical anti-shake compensation effect of the lens 51 in the extreme focusing case.

[0185] In some optional embodiments, the above control method can further include:

[0186] In step S35, if the first stroke value is greater than 0, and the second stroke value is not greater than the second preset value, the SMA motor 52 is controlled to move in the second direction by the second stroke value.

[0187] Exemplarily, if the first stroke value is 200 μm, the second stroke value is 30 μm, and the second preset value is 60 μm, the first stroke value is greater than 0, and the second stroke value is not greater than the second preset value. The SMA motor 52 is controlled to move in the second direction by 30 μm.

[0188] Through this embodiment, the SMA motor 52 is directly controlled to move in the second direction by the second stroke value based on the received instruction, which can directly compensate the instantaneous displacement value of the SMA motor 52, and improve the optical anti-shake compensation effect of the lens 51.

[0189] In some optional embodiments, the SMA motor 52 is further configured to drive the lens 51 to move in a third direction intersecting the first direction. After step S31, the following steps can be further included:

[0190] Step S36, receiving an instruction indicating the SMA motor 52 to move in the third direction by a third stroke value.

[0191] Step S37, when the first stroke value is equal to 0 and the third stroke value is greater than a third preset value, controlling the SMA motor 52 to move in the third direction by the third preset value. When the first stroke value is greater than 0 and the third stroke value is greater than a fourth preset value, controlling the SMA motor 52 to move in the third direction by the fourth preset value. The fourth preset value is less than the third preset value.

[0192] The execution of the steps in the above embodiments can refer to the steps of controlling the SMA motor 52 to move in the second direction, and thus the details will not be repeated.

[0193] In the embodiments of the present application, the steps S36-S37 and the steps S32-S33 can be executed synchronously, or the execution order of the steps S36-S37 and the steps S32-S33 can be exchanged.

[0194] Through the above embodiments, the SMA motor 52 can move in the second direction and the third direction to compensate for optical anti-shake, and the anti-shake stroke threshold of the SMA motor 52 in the second direction and the third direction is related to the first stroke value of the SMA motor 52 in the first direction, thereby not only improving the effect of the lens 51 to compensate for optical anti-shake, but also guaranteeing the service life of the SMA motor 52.

[0195] FIG. 15 is a structural block diagram of a controller of the SMA motor 52 according to an embodiment of the present application.

[0196] The embodiments of the present application provide a controller of the SMA motor 52, wherein the SMA motor 52 is configured to drive the lens 51 to move in a first direction and a second direction. The first direction is parallel to the focusing direction of the lens 51, and the second direction intersects the first direction.

[0197] As shown in FIG. 15, the controller includes a first control module 501, a signal receiving module 502, and a second control module 503.

[0198] The first control module 501 is configured to control the SMA motor 52 to move in the first direction by a first stroke value.

[0199] The signal receiving module 502 is configured to receive an instruction indicating the SMA motor 52 to move in the second direction by a second stroke value.

[0200] The second control module 503 is configured to control the SMA motor 52 to move in the second direction by a first preset value when the first stroke value is equal to 0 and the second stroke value is greater than the first preset value.

[0201] The second control module 503 is further configured to control the SMA motor 52 to move in the second direction by a second preset value when the first stroke value is greater than 0 and the second stroke value is greater than the second preset value. The second preset value is less than the first preset value.

[0202] FIG. 16 is a structural block diagram of an electronic device 100 provided in an embodiment of the present application.

[0203] As shown in FIG. 16, in some optional embodiments, the controller of the SMA motor 52 can further include a gyro filter module 504, a first processing module 505, and a second processing module 506.

[0204] In some optional embodiments, the gyro filter module 504 is configured to receive an instruction of the gyro sensor 7 indicating that the SMA motor 52 moves in the second direction by a second stroke value. The gyro filter module 504 can further filter the instruction of the gyro sensor 7 indicating that the SMA motor 52 moves in the second direction by the second stroke value.

[0205] The second processing module 506 can be configured to receive an instruction of the application processor 6 indicating that the SMA motor 52 moves in the first direction by a first stroke value. The second processing module 506 can further be configured to transmit the instruction of the application processor 6 indicating that the SMA motor 52 moves in the first direction by the first stroke value to the gyro filter module 504. The second processing module 506 can further be configured to process the instruction of the application processor 6 indicating that the SMA motor 52 moves in the first direction by the first stroke value. For example, after determining that the SMA motor 52 can move in the first direction by the first stroke value, the second processing module 506 transmits the processed instruction to the first control module 501. For example, the processed instruction can make the first control module 501 first control the SMA motor 52 to return the lens 51 to the initial position, and then move in the first direction by the first stroke value.

[0206] The first processing module 505 can further be configured to receive the first stroke value and the second stroke value at the same time transmitted by the gyro filter module 504, and determine the stroke value of the SMA motor 52 in the second direction based on the first stroke value and the second stroke value, and transmit a control instruction to the second control module 503.

[0207] As shown in FIG. 16, the present application further provides an electronic device 100, which includes the controller of the SMA motor 52 in any of the above embodiments.

[0208] As shown in FIG. 16, the electronic device 100 can further include an application processor 6 and a gyroscope sensor 7.

[0209] The embodiments of the present application further provide a camera module 5, which includes the controller of the SMA motor 52 in any of the above embodiments.

[0210] The embodiments of the present application further provide an electronic device 100, which includes the camera module 5 in any of the above embodiments.

[0211] The embodiments of the present application further provide another electronic device 100, which includes a memory and a processor. The memory includes instructions. When the processor executes the instructions, the electronic device 100 implements the control method in any of the above embodiments.

[0212] The embodiments of the present application further provide a computer-readable storage medium, which includes a program or instructions. When the program or instructions are run on a computer, the control method in any of the above embodiments is implemented.

[0213] The embodiments of the present application further provide a computer program product, which includes a computer program. When the computer program is executed by a processor, the control method in any of the above embodiments is implemented.

[0214] Generally, after the manufacturing process of the SMA wire 521 is determined, the fatigue life data of the manufactured SMA wire 521 needs to be collected, and then the SMA motor 52 and the control logic of the SMA motor 52 are designed based on the life times of the SMA wire 521 in various use scenarios, to prevent the problem of over-driving the SMA wire 521 and causing the SMA wire 521 to break prematurely.

[0215] In the related art, in addition to tracking the fatigue life in the later period, the early detection mainly includes visual detection of impurity particles of the SMA wire 521 and visual detection of longitudinal cracks on the surface of the SMA wire 521.

[0216] The visual detection of the impurity particles of the SMA wire 521 mainly includes focused ion beam (FIB) section observation, to visually detect whether there are impurity particles in the longitudinal section of the SMA wire 521. The visual detection of the longitudinal cracks on the surface of the SMA wire 521 needs to remove the surface insulating coating of the SMA wire 521, and then the observation is performed by a scanning electron microscope (SEM) or by FIB section observation.

[0217] Obviously, the above method is time-consuming and laborious, and can only selectively detect part of the section or part of the surface of the SMA wire 521. For example, the surface longitudinal crack usually appears segmentally on the SMA wire 521 in a range of hundreds of meters or even thousands of meters, and the above method is difficult to exclude the early fracture hidden danger in the SMA wire 521 one by one.

[0218] Therefore, it is urgent to solve the problem that the fatigue resistance of the SMA wire 521 cannot be early mass detected.

[0219] FIG. 17 is a schematic diagram of a test scene of the SMA wire 521 provided by an embodiment of the present application. FIG. 18 is a step flowchart of a test method of the SMA wire 521 provided by an embodiment of the present application.

[0220] As shown in FIGS. 17 and 18, in view of this, the present embodiment further provides a test method of the SMA wire 521, which specifically includes the following steps:

[0221] Step S61, one end of the SMA wire 521 to be tested is fixed, and the other end is connected with a free object 601.

[0222] The free object 601 can have a preset density and weight. For example, the material of the free object 601 can include at least one of iron and copper.

[0223] In some optional embodiments, the SMA wire 521 to be tested can be fixed by a metal clamp, and the free object 601 can be fixed and connected by another metal clamp. The two metal clamps are connected with the positive and negative poles of the power supply through wires, and can form a power supply loop system.

[0224] For example, the weight of the free object 601 can be 50g.

[0225] Step S62, alternating the SMA wire 521 to be tested between the power-on state and the power-off state until the SMA wire 521 to be tested is broken.

[0226] In some optional embodiments, the SMA wire 521 to be tested can be alternated between the power-on state and the power-off state by alternately controlling the opening and closing of the switch in the power supply loop system in the above step S61. Wherein, the SMA wire 521 to be tested is contracted in the power-on state and is restored in the power-off state. Correspondingly, the free object 601 can produce up and down reciprocating motion, thereby realizing the fatigue life test of the SMA wire 521.

[0227] In the present embodiment, the fatigue resistance of the SMA wire 521 is positively correlated with the length of time of the power-on state and the power-off state alternation.

[0228] In some optional embodiments, the length of time that the SMA wire 521 is powered on and the length of time that the SMA wire 521 is powered off can be the same or different.

[0229] For example, one test cycle of the SMA wire 521 being powered on and off is 2s, and the duty cycle of the SMA wire 521 being powered on is 0.4. In one alternating cycle, the length of time that the SMA wire 521 is powered on can be 0.8s, and the length of time that the SMA wire 521 is powered off can be 1.2s.

[0230] Through the above embodiments, the free object 601 can be used to alternately apply tensile stress to the SMA wire 521 under test during the process of the SMA wire 521 being powered on and contracted and the process of the SMA wire 521 being powered off and returned. Not only is the scenario simulated in which the SMA wire 521 is subjected to tensile stress in the working state of the SMA motor 52, but it is also possible to quickly and effectively detect whether there are adverse factors in the SMA wire 521 that are prone to cause breakage, such as cracks, impurities, etc., thereby helping to improve the fatigue resistance of the SMA wire 521 and prolong the service life of the SMA wire 521 and the SMA motor 52.

[0231] In some optional embodiments, the free object 601 has a preset weight, and the preset weight of the free object 601 is positively correlated with the wire diameter of the SMA wire 521. Alternatively, the current value passed by the SMA wire 521 under test in the powered-on state is positively correlated with the wire diameter of the SMA wire 521 under test.

[0232] Through the above embodiments, the current value passed by the SMA wire 521 under test in the powered-on state and the preset weight of the free object 601 can be reasonably determined according to the wire diameter of the SMA wire 521 under test. Not only can the real use scenario of the SMA wire 521 in the SMA motor 52 be simulated, but the test process of the SMA wire 521 can also be appropriately accelerated using the setting of the current value passed by the SMA wire 521 under test in the powered-on state and the weight of the free object 601, and it is possible to more quickly and effectively detect whether there are adverse factors in the SMA wire 521 that are prone to cause breakage, thereby improving the test efficiency.

[0233] For example, a SMA wire 521 with a diameter of 30 μm and a length of 200 mm is tested. An exemplary test method is also provided by the embodiments of the present application, in which the cross-sectional area of the SMA wire 521 to be tested is about 706.9 mm2, the weight of the free object 601 is 50 g, the maximum tensile stress to which the SMA wire 521 to be tested is subjected is about 707 MPa, the resistivity of the SMA wire 521 to be tested is 9.00E-04 Ω·m, the total resistance of the SMA wire 521 to be tested is about 254.6 Ω, the material phase transition temperature of the SMA wire 521 to be tested is about 128.9 °C, the test frequency of the on-off and power-off of the SMA wire 521 to be tested is 0.5, one test cycle of the on-off and power-off of the SMA wire 521 to be tested is 2 s, the duty cycle of the power-on time of the SMA wire 521 to be tested is 0.4, the voltage applied to the two ends of the SMA wire 521 to be tested is 25 V, the peak current in the SMA wire 521 to be tested is about 98.2 mA, and the maximum shrinkage of the SMA wire 521 to be tested is 2.1%, and the maximum stroke value of the free object 601 is 4.2 mm.

[0234] The duty cycle of the power-on time refers to the ratio between the time length of the power-on state and the cycle length in one cycle of alternation between the power-on state and the power-off state.

[0235] FIG. 19 is a schematic diagram of another test scenario of the SMA wire 521 provided by the embodiments of the present application. FIG. 20 is a step flowchart of a test method of the SMA wire 521 in the embodiment shown in FIG. 19.

[0236] As shown in FIGS. 19 and 20, the embodiments of the present application also provide another test method of the SMA wire 521, which comprises:

[0237] In step S71, one end of a first SMA wire 5211 to be tested and one end of a second SMA wire 5212 to be tested are connected, the other end of the first SMA wire 5211 to be tested is fixed, and the other end of the second SMA wire 5212 to be tested is fixed.

[0238] In some optional embodiments, the distance between the fixed two ends of the first SMA wire 5211 to be tested and the second SMA wire 5212 to be tested can be equal to the sum of the lengths of the first SMA wire 5211 to be tested in the power-off state and the second SMA wire 5212 to be tested in the power-off state.

[0239] In step S72, the first SMA wire 5211 to be tested and the second SMA wire 5212 to be tested are alternately powered on until the first SMA wire 5211 to be tested or the second SMA wire 5212 to be tested is broken.

[0240] In the embodiment, in the state that the first SMA wire 5211 is powered, the second SMA wire 5212 is subjected to the tensile stress applied by the first SMA wire 5211.

[0241] In the embodiment, in the state that the second SMA wire 5212 is powered, the first SMA wire 5211 is subjected to the tensile stress applied by the second SMA wire 5212. The fatigue resistance of the SMA wire 521 is positively correlated with the time length of the first SMA wire 5211 and the second SMA wire 5212 being powered alternately.

[0242] Through the above embodiment, one of the first SMA wire 5211 and the second SMA wire 5212 is powered to contract, and the other is powered off to recover, and the first SMA wire 5211 and the second SMA wire 5212 apply tensile stress to each other, which highly simulates the scenario that the SMA wire 521 is subjected to tensile stress in the working state of the SMA motor 52, and can quickly and effectively detect whether there is a bad factor in the SMA wire 521 that is easy to cause fracture, such as crack, impurity, etc., thereby helping to improve the fatigue resistance of the SMA wire 521 and prolong the service life of the SMA wire 521 and the SMA motor 52.

[0243] In some optional embodiments, the current size of the above-mentioned SMA wire 521 (including the first SMA wire 5211 and the second SMA wire 5212) in the powered state can be positively correlated with the diameter of the SMA wire 521, and can also be positively correlated with the material phase transition temperature of the SMA wire 521.

[0244] In some optional embodiments, the duty cycle of the power-on time of the above-mentioned SMA wire 521 can be positively correlated with the diameter of the SMA wire 521, and can also be positively correlated with the material phase transition temperature of the SMA wire 521.

[0245] In some optional embodiments, in the state that the first SMA wire 5211 is powered, the length of the first SMA wire 5211 reduced does not exceed the maximum recoverable deformation of the first SMA wire 5211 and the maximum recoverable deformation of the second SMA wire 5212.

[0246] In some optional embodiments, in the state that the second SMA wire 5212 is powered, the length of the second SMA wire 5212 reduced does not exceed the maximum recoverable deformation of the first SMA wire 5211 and the maximum recoverable deformation of the second SMA wire 5212.

[0247] Through the above embodiment, the current size of the first SMA wire 5211 and the second SMA wire 5212 can be determined based on the maximum recoverable deformation of the first SMA wire 5211 and the maximum recoverable deformation of the second SMA wire 5212, and the effectiveness of the test is further improved.

[0248] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art within the technical range disclosed in the present application, thinks of the change or the replacement, should be covered in the protection scope of the present application.

Claims

1. A control method of a shape memory alloy (SMA) motor, characterized by, The SMA motor is configured to drive the lens to move in a first direction and a second direction; the first direction is parallel to the focusing direction of the lens, and the second direction intersects the first direction; The control method comprises: controlling the SMA motor to move in the first direction by a first stroke value; receiving an instruction indicating that the SMA motor moves in the second direction by a second stroke value; when the first stroke value is equal to 0 and the second stroke value is greater than a first preset value, controlling the SMA motor to move in the second direction by the first preset value; when the first stroke value is greater than 0 and the second stroke value is greater than a second preset value, controlling the SMA motor to move in the second direction by the second preset value; the second preset value is less than the first preset value.

2. The control method of an SMA motor according to claim 1, characterized in that, The SMA motor comprises a first SMA wire and a second SMA wire; The step of controlling the SMA motor to move in the second direction by the first preset value comprises: transmitting a first current to the first SMA wire to control the first SMA wire to contract; transmitting a second current to the second SMA wire to control the second SMA wire to contract until the SMA motor moves in the second direction by the first preset value; The step of controlling the SMA motor to move in the second direction by the second preset value comprises: transmitting a third current to the first SMA wire to control the first SMA wire to contract; transmitting a fourth current to the second SMA wire to control the second SMA wire to contract until the SMA motor moves in the second direction by the second preset value; wherein the first current is greater than the third current, or the second current is greater than the fourth current.

3. The control method of the SMA motor according to claim 1 or 2, wherein, when the first stroke value is a first stroke sub-value, the second preset value is a first preset sub-value; when the first stroke value is a second stroke sub-value, the second preset value is a second preset sub-value; the first stroke sub-value is greater than the second stroke sub-value, and the first preset sub-value is less than the second preset sub-value.

4. A method of controlling an SMA motor according to any one of claims 1 to 3, characterized in that, The second preset value has an inverse linear relationship with the first stroke value.

5. A method of controlling an SMA motor according to any one of claims 1 to 4, characterized in that, The second preset value further comprises a third preset sub-value; when the first stroke value is equal to a focusing stroke threshold value and the second stroke value is greater than the third preset sub-value, controlling the SMA motor to move in the second direction by the third preset sub-value; the ratio between the third preset sub-value and the first preset value is not less than 40% and not greater than 70%.

6. The control method of an SMA motor according to any one of claims 1 to 5, characterized in that, when the first stroke value is greater than 0 and the second stroke value is greater than a second preset value, the step of controlling the SMA motor to move in the second direction by the second preset value comprises: when the first stroke value is greater than 0, determining a focusing stroke interval in which the first stroke value is located; determining the second preset value corresponding to the focusing stroke interval; judging whether the second stroke value is greater than the second preset value, and in the case that the second stroke value is greater than the second preset value, controlling the SMA motor to move in the second direction by the second preset value.

7. The control method of an SMA motor according to any one of claims 1 to 6, characterized in that, The control method further comprises: the first stroke value is greater than 0, and the second stroke value is not greater than the second preset value, the SMA motor is controlled to move the second stroke value in the second direction.

8. The control method of an SMA motor according to any one of claims 1 to 7, characterized in that, the SMA motor is further configured to drive the lens to move in a third direction; the third direction intersects the first direction; after the step of controlling the SMA motor to move a first stroke value in the first direction, the control method further comprises: receiving an instruction indicating that the SMA motor moves a third stroke value in the third direction; the first stroke value is equal to 0, and the third stroke value is greater than a third preset value, the SMA motor is controlled to move the third preset value in the third direction; the first stroke value is greater than 0, and the third stroke value is greater than a fourth preset value, the SMA motor is controlled to move the fourth preset value in the third direction; the fourth preset value is less than the third preset value.

9. A control device of an SMA motor, characterized by the SMA motor is configured to drive the lens to move in a first direction and a second direction; the first direction is parallel to the focusing direction of the lens, and the second direction intersects the first direction; the control device comprises: a first control module configured to control the SMA motor to move a first stroke value in the first direction; a signal receiving module configured to receive an instruction indicating that the SMA motor moves a second stroke value in the second direction; a second control module configured to, in the case that the first stroke value is equal to 0 and the second stroke value is greater than a first preset value, control the SMA motor to move the first preset value in the second direction; the second control module is further configured to, in the case that the first stroke value is greater than 0 and the second stroke value is greater than a second preset value, control the SMA motor to move the second preset value in the second direction; the second preset value is less than the first preset value.

10. An image capture module, comprising: a control device of the SMA motor as claimed in claim 9, or a camera module as claimed in claim 10.

11. An electronic device, comprising: a control device of the SMA motor as claimed in claim 9, or a camera module as claimed in claim 10.

12. An electronic device, comprising: comprises: a memory comprising instructions; a processor, when the processor executes the instructions, causes the electronic device to implement the control method as claimed in any one of claims 1-8.

13. A computer-readable storage medium, characterized in that, comprises a program or instructions, when the program or instructions are run on a computer, implement the control method as claimed in any one of claims 1-8.

14. A computer program product, characterised in that, comprises a computer program, when the computer program is executed by a processor, implement the control method as claimed in any one of claims 1-8.

15. A method of testing an SMA wire, characterized by, the test method comprises: one end of the SMA wire to be tested is fixed, and the other end is connected with a free object; the SMA wire to be tested is alternated between the energized state and the de-energized state until the SMA wire to be tested is broken; wherein the fatigue resistance of the SMA wire is positively correlated with the length of time of alternation between the energized state and the de-energized state.

16. The test method of the SMA wire according to claim 15, wherein the free object has a preset weight, and the preset weight of the free object is positively correlated with the diameter of the SMA wire; or ​ The current value passed through the SMA wire to be tested in the energized state is positively correlated with the wire diameter of the SMA wire to be tested.

17. A method of testing an SMA wire, characterized by, The test method comprises: connecting one end of a first SMA wire to be tested with one end of a second SMA wire to be tested, the other end of the first SMA wire to be tested being fixed, and the other end of the second SMA wire to be tested being fixed; energizing the first SMA wire to be tested and the second SMA wire to be tested alternately until the first SMA wire to be tested or the second SMA wire to be tested is broken; wherein, in the state that the first SMA wire to be tested is energized, the second SMA wire to be tested is subjected to tensile stress applied by the first SMA wire to be tested; or in the state that the second SMA wire to be tested is energized, the first SMA wire to be tested is subjected to tensile stress applied by the second SMA wire to be tested; the fatigue resistance of the SMA wire is positively correlated with the time length of the first SMA wire to be tested and the second SMA wire to be tested being energized alternately.

18. The test method of the SMA wire according to claim 17, wherein, in the state that the first SMA wire to be tested is energized, the reduced length of the first SMA wire to be tested does not exceed the maximum recoverable deformation of the first SMA wire to be tested and the maximum recoverable deformation of the second SMA wire to be tested; or, in the state that the second SMA wire to be tested is energized, the reduced length of the second SMA wire to be tested does not exceed the maximum recoverable deformation of the first SMA wire to be tested and the maximum recoverable deformation of the second SMA wire to be tested.

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