A control method, related device and product for an SMA motor

Abstract

This application provides a control method, related apparatus, and product for an SMA motor, relating to the field of camera technology, aiming to extend the service life of the SMA motor. The SMA motor can drive a lens to move along a first direction and a second direction. The first direction is parallel to the lens's focusing direction, and the second direction intersects the first direction. The control method includes controlling the SMA motor to move a first stroke value along the first direction. It also includes receiving an instruction instructing the SMA motor to move a second stroke value along the second direction. If the first stroke value is equal to 0 and the second stroke value is greater than a first preset value, the SMA motor is controlled to move along the second direction by the first preset value. If the first stroke value is greater than 0 and the second stroke value is greater than a second preset value, the SMA motor is controlled to move along the second direction by the second preset value. The second preset value is less than the first preset value. This application, based on the motor's focusing stroke, limits the optical image stabilization stroke, avoiding over-driving of the SMA line and extending the motor's service life.

Description

Technical Field

[0001] This application relates to the field of camera technology, and in particular to a control method, related device and product for an SMA motor. Background Technology

[0002] Camera modules in various electronic devices are constantly being updated to meet the ever-increasing demands for image quality. For example, smartphones and tablets need to balance slimness and lightweight design with guaranteed image quality. Clearly, simply increasing sensor size and photosensitive area is insufficient to simultaneously address these requirements. Therefore, some electronic devices have adopted optical image stabilization (OIS) technology. By controlling lens movement, OIS compensates for device and lens shake, correcting optical axis misalignment. This prevents image blurring caused by device movement during camera module operation, effectively improving the image quality of electronic devices.

[0003] Shape memory alloy (SMA) motors offer numerous advantages, including high load capacity, small size, no magnetic interference, and low cost, making them widely used in camera modules of many electronic devices for lens control. They enable not only automatic focus (AF) but also excellent optical image stabilization (OIS) compensation. However, SMA motors use extremely fine SMA cables to drive the lens, and these cables are susceptible to damage from materials, manufacturing processes, and other factors. After a period of use, the SMA cables are prone to breakage, leading to motor failure and impacting the normal optical image stabilization and focusing functions of the electronic device.

[0004] Therefore, how to extend the service life of the SMA motor in the camera module is an urgent problem that technical personnel need to solve. Summary of the Invention

[0005] This application provides a control method, related device, and product for an SMA motor, with the main purpose of extending the service life of the SMA motor in a camera module.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, embodiments of this application provide a control method for a shape memory alloy (SMA) motor, wherein the SMA motor is configured to drive a lens to move along 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 includes: controlling the SMA motor to move a first stroke value along the first direction; receiving an instruction instructing the SMA motor to move a second stroke value along the second direction; controlling the SMA motor to move a first preset value along the second direction if the first stroke value is equal to 0 and the second stroke value is greater than a first preset value; and controlling the SMA motor to move a second preset value along the second direction if 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.

[0008] Through the above embodiments, the SMA motor can drive the lens to move along a first direction parallel to the lens's focusing direction to control lens focusing. The SMA motor can also drive the lens to move along a second direction intersecting the lens's focusing direction to control the lens for image stabilization compensation for instantaneous displacement. Furthermore, the movement of the SMA motor is achieved by contracting a portion of the SMA cable while it is energized and stretching the remaining portion while it is de-energized. When the first stroke value of the SMA motor moving along the first direction is 0, and the first preset value is the maximum distance at which the SMA motor can move along the second direction and the SMA cable is less prone to fatigue failure, then optical image stabilization compensation for 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. The second preset value is reduced compared to the first preset value. This not only ensures the effect of optical image stabilization compensation for the lens, but also avoids excessive stress (such as contractile stress or tensile stress) on the SMA line when the SMA motor moves in both the first and second directions, and also avoids excessive deformation (such as excessive contraction or stretching) of the SMA line, reducing the probability of SMA line breakage and effectively extending the service life of the SMA motor in the camera module.

[0009] In conjunction with the first aspect, in one possible implementation, the SMA motor includes a first SMA wire and a second SMA wire. The step of controlling the SMA motor to move along the second direction by a first preset value includes: 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 along the second direction by the first preset value. Thus, energizing at least two SMA wires in the SMA motor allows control of the SMA motor to move along the second direction.

[0010] The above-described step of controlling the SMA motor to move along the second direction by a second preset value includes: transmitting a third current to the first SMA line to control the first SMA line to contract; transmitting a fourth current to the second SMA line to control the second SMA line to contract, until the SMA motor moves along the second direction by a second preset value. Wherein, the first current is greater than the third current, or the second current is greater than the fourth current. In this implementation, when the first stroke value of the SMA motor moving along the first direction is greater than 0, the upper limit of the current threshold transmitted to at least one SMA line is reduced. If the instantaneous displacement of the lens exceeds the second preset value, the current transmitted to at least one SMA line is the reduced upper limit of the current threshold, thereby enabling the SMA motor to be controlled to move along the second direction by a second preset value.

[0011] In conjunction with the first aspect, in one possible implementation, if the first stroke value is a first stroke sub-value, the second preset value is also a first preset sub-value. If the first stroke value is a second stroke sub-value, the second preset value is also 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 value. In this implementation, the corresponding second preset value can be determined based on the magnitude of the first stroke value of the SMA motor moving along the first direction. As the first stroke value increases, the second preset value decreases accordingly, or in other words, the second preset value and the first stroke value have a negative correlation. Therefore, when the SMA motor moves along both the first and second directions, it is possible to avoid excessive tensile stress on the SMA cable and ensure the effectiveness of optical image stabilization compensation for the lens.

[0012] In conjunction with the first aspect, in one possible implementation, the second preset value and the first stroke value have an inverse linear relationship. Therefore, by making the second preset value change linearly based on the change in the first stroke value, it is possible to ensure that the tensile stress on the SMA line is within a reasonable range under different first stroke values, while also guaranteeing the effectiveness of optical image stabilization compensation for the lens, thus balancing the lifespan of the SMA motor and the effectiveness of optical image stabilization compensation for the lens.

[0013] In conjunction with the first aspect, in one possible implementation, the second preset value also includes a third preset sub-value. The first travel value is equal to the focus travel threshold, and the second travel value is greater than the third preset sub-value. The SMA motor is controlled to move along 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%. In this implementation, when the first travel value reaches its maximum, the tensile stress on the SMA line along the first direction is maximum. The third preset sub-value corresponding to this first travel value is the minimum value among the second preset values. This implementation sets the minimum value among the second preset values ​​to 40% to 70% of the first preset value, which can further balance the lifespan of the SMA motor and the effect of lens optical image stabilization compensation under extreme focusing conditions.

[0014] In conjunction with the first aspect, in one possible implementation, the first travel value is greater than 0, and the second travel value is greater than a second preset value. The step of controlling the SMA motor to move along the second direction by the second preset value includes: determining the focus travel range where the first travel value is greater than 0; determining the second preset value corresponding to the focus travel range; determining whether the second travel value is greater than the second preset value; and if the second travel value is greater than the second preset value, controlling the SMA motor to move along the second direction by the second preset value. In this implementation, when the first travel value is greater than 0, the focus travel range is determined, and the second preset value corresponding to the focus travel range is found from the preset correspondence between the focus travel range and the second preset value. The second preset value can be used as the image stabilization travel threshold under the current first travel value, controlling the SMA motor to move along the second direction by no more than the second preset value, thereby balancing the lifespan of the SMA motor and the effect of lens optical image stabilization compensation.

[0015] In conjunction with the first aspect, in one possible implementation, the control method further includes: controlling the SMA motor to move the second stroke value along the second direction by the second stroke value when the first stroke value is greater than 0 and the second stroke value is not greater than a second preset value. In this implementation, by directly controlling the SMA motor to move the second stroke value along the second direction according to the received instruction, image stabilization compensation can be directly applied to the instantaneous displacement value of the SMA motor, thereby improving the optical image stabilization compensation effect of the lens.

[0016] In conjunction with the first aspect, in one possible implementation, the SMA motor is further configured to move the lens along a third direction, which intersects with the first direction. After controlling the SMA motor to move a first stroke value along the first direction, the control method further includes: receiving an instruction instructing the SMA motor to move a third stroke value along the third direction. If 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 along the third direction by the third preset value. If 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 along the third direction by the fourth preset value. The fourth preset value is less than the third preset value. In this implementation, the SMA motor can perform optical image stabilization compensation by moving along the second and third directions, and the image stabilization stroke thresholds of the SMA motor in both the second and third directions are related to the first stroke value of the SMA motor along the first direction. This not only improves the effectiveness of optical image stabilization compensation by the lens but also ensures the service life of the SMA motor.

[0017] Secondly, embodiments of this application provide a controller for an SMA motor, wherein the SMA motor is configured to drive a lens to move along 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 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 a first stroke value along the first direction. The signal receiving module is configured to receive an instruction instructing the SMA motor to move a second stroke value along the second direction. The second control module is configured to control the SMA motor to move a first preset value along the second direction 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 a second preset value along the second direction 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.

[0018] Thirdly, embodiments of this application provide a camera module, which includes a lens, an SMA motor, and a controller for the SMA motor in any of the above embodiments.

[0019] Fourthly, embodiments of this application provide an electronic device that includes a controller for an SMA motor as described in any of the foregoing embodiments or a camera module as described in any of the foregoing embodiments.

[0020] Fifthly, embodiments of this application provide an electronic device including a memory and a processor. The memory includes instructions. When the processor executes the instructions, the electronic device implements the control method described in any of the above embodiments.

[0021] Sixthly, embodiments of this application provide a computer-readable storage medium including a program or instructions that, when executed on a computer, implement the control method as described in any of the above embodiments.

[0022] In a seventh aspect, embodiments of this application provide a computer program product, which includes a computer program that, when executed by a processor, implements the control method described in any of the above embodiments.

[0023] Unless otherwise specified, the technical effects of any of the design methods in aspects two through seven can be found in the technical effects of different design methods in aspect one, and will not be repeated here.

[0024] Eighthly, embodiments of this application provide a testing method for SMA wires. The method includes: fixing one end of the SMA wire to be tested and connecting the other end to a free object. The SMA wire is then subjected to alternating energized and de-energized states until it breaks. The fatigue resistance of the SMA wire is positively correlated with the duration of the alternation between energized and de-energized states.

[0025] Through the above embodiments, tensile stress can be applied to the SMA wire under test by a free object alternately during the energized contraction and de-energized recovery processes. This not only simulates the scenario of tensile stress on the SMA wire when the SMA motor is in operation, but also quickly and effectively detects whether there are undesirable factors in the SMA wire that may lead to breakage, such as cracks and impurities. This helps to improve the fatigue resistance of the SMA wire and extend the service life of the SMA wire and the SMA motor.

[0026] In conjunction with the eighth aspect, in one possible implementation, the free object has a preset weight, which is positively correlated with the diameter of the SMA wire. Alternatively, the current passing through the SMA wire under test when energized is positively correlated with its diameter. Therefore, the current passing through the SMA wire under test and the preset weight of the free object can be reasonably determined based on its diameter. This not only simulates the real-world usage scenario of the SMA wire in an SMA motor but also allows for a more efficient acceleration of the SMA wire testing process by setting the current passing through the energized wire and the weight of the free object. This enables faster and more effective detection of factors that could lead to breakage in the SMA wire, thus improving testing efficiency.

[0027] Ninthly, embodiments of this application provide a testing method for SMA wires. The method includes: connecting one end of a first SMA wire to be tested to one end of a second SMA wire to be tested, fixing the other end of both the first and second SMA wires. Alternatingly energizing the first and second SMA wires until either the first or second SMA wire breaks. While the first SMA wire is energized, the second SMA wire is subjected to the tensile stress applied by the first SMA wire. While the second SMA wire is energized, the first SMA wire is subjected to the tensile stress applied by the second SMA wire. The fatigue resistance of the SMA wire is positively correlated with the duration of alternating energization between the first and second SMA wires.

[0028] Through the above embodiments, one of the first and second SMA wires under test is energized and shrinks while the other is de-energized and recovers. The first and second SMA wires under test are subjected to tensile stress on each other, which highly simulates the scenario of the SMA wire being subjected to tensile stress under the working state of the SMA motor. It can also quickly and effectively detect whether there are undesirable factors in the SMA wire that are prone to breakage, such as cracks and impurities, thereby helping to improve the fatigue resistance of the SMA wire and extend the service life of the SMA wire and the SMA motor.

[0029] In conjunction with aspect nine, in one possible implementation, when the first SMA line under test is energized, the reduced length of the first SMA line under test does not exceed the maximum recoverable deformation of both the first and second SMA lines under test. Alternatively, when the second SMA line under test is energized, the reduced length of the second SMA line under test does not exceed the maximum recoverable deformation of both the first and second SMA lines under test. Therefore, the magnitude of the current energizing the first and second SMA lines under test can be determined based on their maximum recoverable deformation, further improving the effectiveness of the test. Attached Figure Description

[0030] Figure 1 An exploded view of an electronic device provided in an embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the structure of a camera module provided in an embodiment of this application;

[0032] Figure 3 Some schematic diagrams of SMA line fractures provided in the embodiments of this application;

[0033] Figure 4 A schematic diagram of the fatigue life-strain energy density of an SMA wire provided in an embodiment of this application;

[0034] Figure 5 A schematic diagram of a manufacturing process for an SMA wire provided in an embodiment of this application;

[0035] Figure 6 This is a schematic diagram of a stroke threshold of an SMA motor provided in an embodiment of this application;

[0036] Figure 7 for Figure 6 A schematic diagram of a stroke value for an SMA motor provided in the illustrated embodiment;

[0037] Figure 8 A schematic diagram of the contraction strain of an SMA line provided in an embodiment of this application;

[0038] Figure 9 This is a schematic diagram illustrating the spatial range of movement of an SMA motor, provided in an embodiment of this application.

[0039] Figure 10 A schematic diagram of the planar range of movement of an SMA motor provided in an embodiment of this application;

[0040] Figure 11 A flowchart illustrating the steps of a control method for an SMA motor provided in this application embodiment;

[0041] Figure 12 for Figure 11 A schematic diagram of one stroke value of the SMA motor in the illustrated embodiment;

[0042] Figure 13 for Figure 11 A schematic diagram of a stroke threshold of the SMA motor in the illustrated embodiment.

[0043] Figure 14 for Figure 11 A schematic diagram of a stroke relationship of the SMA motor in the illustrated embodiment;

[0044] Figure 15 A structural block diagram of a controller for an SMA motor provided in an embodiment of this application;

[0045] Figure 16 A structural block diagram of an electronic device provided in an embodiment of this application;

[0046] Figure 17 This is a schematic diagram of a test scenario for an SMA line provided in an embodiment of this application;

[0047] Figure 18 for Figure 17 A flowchart illustrating the steps of a test method for an SMA line in the illustrated embodiment;

[0048] Figure 19 This is a schematic diagram of another test scenario for the SMA line provided in the embodiments of this application;

[0049] Figure 20 for Figure 19 A flowchart illustrating the steps of a test method for an SMA line in the illustrated embodiment.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1. Screen; 2. Mid-frame; 3. Back cover; 4. Motherboard; 5. Camera module; 51. Lens; 52. SMA motor; 100. Electronic device; 6. Application processor; 7. Gyroscope sensor; 500. SMA motor controller; 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 line; 5211. First SMA line under test; 5212. Second SMA line under test; 601. Free object. Detailed Implementation

[0052] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0053] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. "At least one" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, and c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. "a and / or b" includes the following three combinations: only a, only b, and a combination of a and b.

[0054] Furthermore, to facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" are not necessarily different. Additionally, in the embodiments of this application, words such as "exemplarily" or "for example" are used to indicate that something is being used as an example, illustration, or explanation.

[0055] In describing some embodiments, the term "connection" and its derivative expressions are used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0056] Furthermore, the architecture and scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of architecture and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0057] This application provides an electronic device including a camera module. This electronic device can be applied to various communication systems or protocols, such as Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Wideband-C Division Multiple Access (WCDMA), General Packet Radio Service (GPRS), and Long Term Evolution (LTE).

[0058] The aforementioned electronic devices include, but are not limited to, electronic devices in the fields 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, automotive products, wearable products, financial terminal products, communication products, and intelligent detection products. For example, the electronic device may include, but is not limited to, mobile phones, tablets, SLR cameras, camcorders, digital cameras, smart wearable products (e.g., smartwatches, smart bracelets), smart TVs, extended reality (XR) devices, inertial navigation systems, aerospace equipment, smart door locks, smart helmets, etc. The aforementioned XR devices include, for example, virtual reality (VR) devices, augmented reality (AR) devices, mixed reality (MR) devices, and robots.

[0059] The embodiments of this application do not limit the specific form of the above-described electronic device.

[0060] Figure 1 This is an exploded view of an electronic device provided in an embodiment of this application.

[0061] For ease of explanation, the following uses this electronic device as an example. Figure 1 The example shown is a mobile phone. Please refer to... Figure 1 The electronic device 100 is a mobile phone. The electronic device 100 may include a screen 1, a mid-frame 2, a back cover 3, a motherboard 4 fixed on the mid-frame 2, and a camera module 5. Among them, the motherboard 4 may be a printed circuit board (PCB).

[0062] Figure 1 This is merely an example illustrating one possible design of the electronic device 100; the actual shape, size, location, and construction of the components are not subject to change. Figure 1 Limitations. For example, in some examples, the camera module 5 can be located not only on the side of the back cover 3, but also on the side of the screen 1 of the electronic device 100.

[0063] Figure 2 This is a schematic diagram of the structure of a camera module provided in an embodiment of this application.

[0064] like Figure 2 As shown, this application embodiment provides a camera module 5, which includes a lens 51, an SMA motor 52, and a controller for the SMA motor. Exemplarily, the controller for the SMA motor can be a driver IC.

[0065] An SMA motor may include multiple shape memory alloy SMA wires 521. For example, an SMA motor may include, but is not limited to, four SMA wires 521 or eight SMA wires 521 (e.g., Figure 2 (As shown).

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

[0067] Therefore, the SMA motor 5 can be used to control the lens to achieve focusing and optical image stabilization compensation. For example, during the operation of the camera module, when the device containing the SMA motor 52 shakes 100μm in the second direction X, the SMA motor 52 can control the lens to move 100μm in the opposite direction of the second direction X to achieve optical image stabilization compensation and reduce image blur caused by device shaking.

[0068] Specifically, in some examples, a portion of the SMA line 521 in the SMA motor 52 retracts when energized, which can control the SMA motor 52 to move the lens 51. By utilizing the shape memory characteristics of the SMA line 521, multiple controls can be achieved.

[0069] Figure 3 Some fracture diagrams of the SMA line 521 provided in the embodiments of this application.

[0070] However, when the SMA motor 52 is energized, the alternating tension on the SMA wire 521 can easily lead to fatigue fracture of the SMA wire 521. Especially since SMA motors 52 generally use extremely fine SMA wires 521 to improve image stabilization and focusing speeds, such as SMA wires 521 with a diameter of only 25 or 30 μm, the SMA wire 521 is more prone to breakage during the manufacturing or use of these types of SMA motors 52. From the location of the SMA wire 521 breakage, the main types of breakage include root breakage (e.g.,...). Figure 3 (as shown at point A1) and the middle broken line (as shown) Figure 3 (As shown at point A2 in the middle).

[0071] Among them, the SMA wire 521 is fixed by the clamping of the clamps. Most wire breakage at the root is caused by improper clamping between the SMA wire 521 and the clamps. For example, excessive downward pressure from the clamps can damage the SMA wire 521, reducing its fatigue resistance. Alternatively, an excessively large exit angle from the clamps can cause stress concentration at the root of the SMA wire 521, exceeding the wire's fatigue resistance. Fatigue resistance, also known as fatigue strength, refers to an object's ability to withstand repeated stress.

[0072] To mitigate wire breakage at the root, in addition to optimizing the pressing process parameters, a C-angle or R-angle can be set at the wire exit position of the clamp, and a moderately hard adhesive can be applied to protect the weak part of the metal wire root and alleviate the problem of stress concentration.

[0073] Intermediate wire breakage is typically caused by factors such as unreasonable structural design of the SMA motor 52, unreasonable motion stroke design of the SMA motor 52, and poor material quality of the SMA wire 521. Unreasonable structural design of the SMA motor 52 refers to design gaps between its structural components, which can damage or jam the SMA wire 521 during assembly. To prevent this failure, the structural components around the SMA wire 521 can be designed with a nested, concave-convex structure to prevent the metal wire from slipping into the gaps.

[0074] The fatigue life of SMA wire 521 is related to stress (load) and strain (shrinkage rate). Under constant stress conditions, the fatigue life of SMA wire 521 decreases with increasing shrinkage rate. Under constant strain conditions, the fatigue life of SMA wire 521 decreases with increasing load.

[0075] Figure 4 This is a schematic diagram of the fatigue life-strain energy density of an SMA wire provided in an embodiment of this application.

[0076] like Figure 4 As shown, if the fatigue life of the SMA line is predicted using the Smith-Watson-Topper (SWT) model, then the fatigue life Nf of the SMA line is related to the strain energy density 2σ. max Eα (unit: MJ / m) 3 It has a negative exponential function relationship.

[0077] like Figure 4 As shown, the strain energy density 2σ max The larger Εα is, the shorter the fatigue life Nf of the SMA line. For example, under stresses of 80 MPa and 175 MPa, despite the different stress magnitudes, the above negative exponential function relationship can still be achieved. This is because the strain energy density Nf is equal to the product of stress and strain.

[0078] The reason why the fatigue life of SMA wire 521 exhibits the aforementioned functional relationship with strain energy density is that SMA wire 521 is not 100% pure at the microscopic level, but contains a certain amount of impurities. These impurities are called heterogeneous phase particles, generally carbides or oxides, which are formed during the smelting or high-temperature hot working of SMA wire 521. Since the hardness of heterogeneous phase particles is generally significantly higher than that of the metal matrix of SMA wire 521, when SMA wire 521 is subjected to shrinkage stress, the interface between these heterogeneous phase particles and the metal matrix becomes a stress or strain concentration point, causing microcracks to initiate at this concentration point. These microcracks propagate radially along the radial direction of SMA wire 521 until instantaneous fracture occurs. The greater the stress or strain, the faster the microcrack propagation rate, and the shorter the fatigue life of the wire.

[0079] Figure 5 This is a schematic diagram of a manufacturing process for the SMA line 521 provided in an embodiment of this application.

[0080] like Figure 5 As shown, the fabrication of SMA line 521 may specifically include the following steps:

[0081] Step S21: Smelting.

[0082] Step S22: Hot extrusion.

[0083] Step S23: Rolling.

[0084] Step S24, drawing fibers.

[0085] Step S25: Interpass annealing.

[0086] Step S26: Determine the final deformation amount.

[0087] Step S27: Final heat treatment.

[0088] Step S28, Training.

[0089] Step S29: Create the coating.

[0090] As can be seen, smelting, as the first step in the production of SMA 521 wire, plays a crucial role in the purity of the SMA 521 material. Although the smelting process of SMA 521 is constantly improving, it is still difficult to achieve a level of 100% purity, so the presence of heterogeneous phase particles in SMA 521 wire is often unavoidable.

[0091] Figure 6 This is a schematic diagram of a stroke threshold of an SMA motor provided in an embodiment of this application.

[0092] This application provides a control method for an SMA motor, wherein the SMA motor 52 can be applied to a camera module 5. For example... Figure 6 As shown, this control method mainly restricts the movement of the SMA motor 52 along the second direction X or the third direction Y. In other words, the movement of the SMA motor 52 along the second direction X or the third direction Y has an OIS limit T1. The OIS limit T1 can be the maximum travel distance that the SMA motor 52 can move along the stabilization direction. For example, the OIS limit T1 can be 100 μm, and the stabilization direction can be a direction intersecting with or even perpendicular to the focusing direction of the lens 51.

[0093] like Figure 6 As shown, 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 telephoto position SF can be the position of the SMA motor 52 when the camera module is at its maximum focal length. The near-focal position SN can be the position of the SMA motor 52 when the camera module is at its minimum focal length.

[0094] AF1 and AF2 can be the focus travel thresholds of the SMA motor 52.

[0095] Among them, the second direction X and the third direction Y can be directions that intersect or are perpendicular to the first direction Z, and the first direction Z can be the focusing direction of the lens 51.

[0096] Through the above embodiments, excessive movement of the SMA motor 52 along the image stabilization direction can be avoided to a certain extent, thereby reducing the excessive strain energy density on the SMA line 521 and lowering the risk of breakage of the SMA line 521. If the SMA motor 52 has a large stroke value in both the focusing and image stabilization directions, the contraction / extension of the SMA line 521 will be superimposed in both directions, which will still increase the risk of breakage of the SMA line 521 and shorten the service life of the SMA motor 52. For example, as... Figure 6 As shown, the focusing travel value of SMA motor 52 along the first direction Z is D1, the image stabilization travel value of SMA motor 52 along the second direction X is D2, and the actual travel value of SMA motor 52 is D3. D3 is the sum of D1 and D2. D3 is significantly increased compared to D1 or D2, which requires SMA line 521 to be contracted more significantly, which can easily cause SMA line 521 to break and fail, reducing the service life of SMA motor 52 in camera module 5.

[0097] Figure 7 for Figure 6 The illustrated embodiment provides a schematic diagram of one stroke value for an SMA motor.

[0098] like Figure 7 As shown, at the same time t, the SMA motor 52 has the corresponding image stabilization travel code value OIS-C and focus travel code value AF-C.

[0099] Among them, the image stabilization travel code value OIS-C can be regarded as the travel value of the SMA motor 52 for optical image stabilization compensation. For example, the image stabilization travel code value OIS-C can be regarded as the first image stabilization travel value OIS-A along the second direction X, or it can be the second image stabilization travel value OIS-B along the third direction Y.

[0100] like Figure 7 As shown, the focus travel code value AF-C can be regarded as the travel value of the SMA motor 52 driving the lens 51 to focus. For example, the focus travel code value AF-C can be regarded as the travel value along the first direction Z.

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

[0102] Specifically, OIS-C generally does not exceed the range of the SMA motor 52's image stabilization travel threshold T1. AF-C generally does not exceed the range of the SMA motor 52's focus travel threshold T2.

[0103] Figure 8This is a schematic diagram of the contraction strain of an SMA line provided in an embodiment of this application.

[0104] Taking the eight-line SMA motor as an example, all eight SMA lines are angled pull lines, and each SMA line can participate in the movement of the SMA motor in the focusing direction and the image stabilization direction by contraction.

[0105] like Figure 8 As shown, with the current value and shrinkage strain of the SMA line fixed, the stroke of the OIS along the second direction X or the second direction Y continuously decreases as the AF stroke along the first direction Z increases.

[0106] like Figure 8 As shown, the length of the SMA wire after contraction is L*(1-R). Here, L is the length of the SMA wire in the de-energized state, or its original length. R is the maximum contraction strain rate of the SMA wire, which can be artificially limited by setting the magnitude of the current flowing into the SMA wire.

[0107] Figure 9 This is a schematic diagram illustrating the spatial range of movement of an SMA motor, provided in an embodiment of this application.

[0108] like Figure 9 As shown, for example, SMA motor 52 is an eight-wire SMA motor. With the maximum contraction of each SMA wire 521 fixed, from a spatial perspective, the envelope of the motion trajectory of the eight-wire SMA motor can form a symmetrical octahedral structure.

[0109] Figure 10 This is a schematic diagram of the planar range of movement of an SMA motor 52 provided in an embodiment of this application.

[0110] like Figure 10 As shown, the above octahedral structure, when projected onto the XZ plane or YZ plane, forms a rhombus.

[0111] In view of this, this application provides a control method for 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 lens 51 to focus. 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 perform image stabilization compensation for instantaneous displacement.

[0112] Figure 11A flowchart illustrating the steps of a control method for an SMA motor 52 provided in this application embodiment.

[0113] like Figure 11 As shown, the above control method specifically includes the following steps:

[0114] Step S31: Control the SMA motor 52 to move a first stroke value along the first direction.

[0115] In some alternative embodiments, a focus control signal may be received from the application processor (AP) 6. This focus control signal may include an instruction to move the SMA motor 52 along a first direction by a first stroke value. For example, if the lens 51 needs to focus in the near-focal length, the application processor 6 AP may send a focus control signal to the controller of the SMA motor 52. This focus control signal may include an instruction to move the SMA motor 52 along the near-focal direction of the lens 51.

[0116] Taking a mobile phone as an example, the application processor 6AP can obtain a focus indication signal through the phone's screen touch sensor and generate a focus control signal accordingly. Similarly, taking a camera as an example, the application processor 6AP can obtain a focus indication signal through the camera's focus button and generate a focus control signal accordingly.

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

[0118] In some optional embodiments, the lens 51 can return to its initial position each time it needs to refocus. The first travel value can refer to the distance between the initial position and the focusing position. For example, the initial position of the lens 51 can refer to the position of the SMA motor 52 when it is powered off.

[0119] In some optional embodiments, the initial position of the lens 51 can be set in the mid-to-long focal length of the lens 51, and the first direction can be from the mid-to-long focal length of the lens 51 toward the long focal length, or the first direction can be from the mid-to-long focal length of the lens 51 toward the short focal length.

[0120] Step S32: Receive an instruction to move the SMA motor 52 along the second direction by a second stroke value.

[0121] In some optional embodiments, taking an electronic device 100 equipped with a gyroscope sensor (Gyro) 7 as an example, the gyroscope sensor 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. Exemplarily, 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 the X, Y, and Z directions, and the angular displacement data can include the angle of deflection of the electronic device 100. For example, the X, Y, and Z coordinate values ​​of the linear displacement data are (2500 μm, 0 μm, 3000 μm), where the 3000 μm displacement along the direction parallel to the first direction Z can be compensated by the focusing algorithm, and the 2500 μm displacement along the direction parallel to the second direction X requires optical image stabilization compensation, for example, controlling the SMA motor 52 to move the lens 51 100 μm along the second direction X to achieve optical image stabilization compensation. For example, the electronic device 100 deflects by 30° horizontally and 15° vertically. The angular displacement data and linear displacement data can also be fused and calculated, and compensation can be applied to the fused data.

[0122] The displacement data of the electronic device 100 can be regarded as the displacement data of the SMA motor 52. The displacement data of the SMA motor 52 can be used to instruct the SMA motor 52 to move along the second direction in order to perform anti-shake compensation on the displacement of the SMA motor 52.

[0123] Step S33: When the first stroke value is equal to 0 and the second stroke value is greater than the first preset value, control the SMA motor 52 to move along the second direction by the first preset value.

[0124] In some optional embodiments, the first preset value may be a stroke threshold for the SMA motor 52 to move in the second direction when the first stroke value is equal to 0. Alternatively, the first preset value may be the anti-shake stroke threshold 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 200μm, and the first preset value is 100μm.

[0126] The first preset value can be determined by the preset rated stroke of the SMA motor 52. For example, the first preset value can be 1 / 4 of the preset 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 along the second direction by the second stroke value. This allows for direct optical image stabilization compensation based on the instructions transmitted by the gyroscope sensor 7. For example, if the gyroscope sensor 7 indicates that the second stroke value of the SMA motor 52 moving along the second direction is 80 μm, the first preset value is 100 μm, and the second stroke value is not greater than the first preset value, then the SMA motor 52 is controlled to move along the second direction by 80 μm.

[0128] In this embodiment of the application, step S33 may further include: when the first stroke value is greater than 0 and the second stroke value is greater than the second preset value, controlling the SMA motor 52 to move along the second direction by the second preset value.

[0129] In some optional embodiments, the second preset value may be a stroke threshold for the SMA motor 52 to move in the second direction when the first stroke value is greater than 0. Alternatively, the second preset value may be the anti-shake stroke threshold of the SMA motor 52 when 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 this embodiment, 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] Figure 12 for Figure 11 A schematic diagram of one stroke value for the SMA motor 52 in the illustrated embodiment.

[0133] like Figure 12 As shown, if the focus travel value AF-C is greater than 0, the corresponding image stabilization travel value OIS-C is smaller and does not exceed the second preset value P2. If the focus travel value AF-C is 0 or close to 0, the corresponding image stabilization travel value OIS-C is larger and does not exceed the first preset value P1.

[0134] In some optional embodiments, instructions instructing the SMA motor 52 to move a first stroke value along a first direction and instructions instructing the SMA motor 52 to move a second stroke value along a second direction can be received simultaneously. Therefore, in some optional embodiments, steps S31 and S33 can be executed simultaneously, or steps S31 and S35 can be executed simultaneously, thereby simultaneously achieving focusing and image stabilization of the lens 51.

[0135] In some alternative embodiments, step S31 can be performed first, followed by step S33 or step S35, so that the optical image stabilization compensation of the lens 51 is performed after the lens 51 has finished focusing.

[0136] Through the above embodiments, when the first stroke value of the SMA motor 52 moving along the first direction is 0, the first preset value P1 is the maximum distance at which the SMA motor 52 can move along the second direction and the SMA line 521 is not prone to fatigue failure, thus maximizing optical image stabilization compensation for the lens 51. When the first stroke value of the SMA motor 52 moving along the first direction is greater than 0, the second preset value P2 is the maximum distance that the SMA motor 52 can move along the second direction. The second preset value P2 is reduced compared to the first preset value P1, which not only ensures the effect of optical image stabilization compensation for the lens 51, but also avoids excessive stress on the SMA line 521 and excessive deformation of the SMA line 521 when the SMA motor 52 moves along both the first and second directions, effectively extending the service life of the SMA motor 52 in the camera module 5.

[0137] In some optional embodiments, step S34 may be performed before step S33 above. Step S34 may specifically include:

[0138] Step S341: Determine whether the first stroke value is equal to 0.

[0139] Step S342: If the first stroke value is equal to 0, determine whether the second stroke value is greater than the first preset value.

[0140] Step S343: If the first stroke value is greater than 0, determine whether the second stroke value is greater than the second preset value.

[0141] In some optional implementations, step S343 may further include:

[0142] Step S3431: The first stroke value is greater than 0, and the focus stroke range in which the first stroke value is located is determined.

[0143] In some examples, the focus travel threshold is 500μm, and the focus travel is divided into five ranges: (0, 100μm], (100μm, 200μm], (200μm, 300μm], (300μm, 400μm], and (400μm, 500μm).

[0144] For example, if the first travel value is 180μm, then the focus travel range within the first travel value is (100μm, 200μm).

[0145] Step S3432: Determine the second preset value corresponding to the focus travel range.

[0146] Among them, multiple preset relationships between the focus travel range and the second preset value can be established in advance, so that the second preset value corresponding to the focus travel range can be obtained by looking up a table.

[0147] In some examples, the second preset value can gradually decrease as the value of the focus travel range increases. For example, the preset relationships between the focus travel range and the second preset value are as follows: focus travel range (0, 100 μm) and second preset value 90 μm, focus travel range (100, 200) and second preset value 80 μm, (200, 300) and second preset value 70 μm, focus travel range (300, 400) and second preset value 60 μm, and focus travel range (400, 500) and second preset value 50 μm.

[0148] For example, the second preset value corresponding to the focus travel range (100μm, 200μm) is 80μm.

[0149] Step S3433: Determine whether the second stroke value is greater than the second preset value.

[0150] For example, if the first stroke value is 180μm and the second stroke value is 200μm, then the second stroke value is greater than the second preset value.

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

[0152] Through the above embodiments, when the first travel value is greater than 0, the focus travel range is determined, and the second preset value corresponding to the focus travel range is found from the preset correspondence between the focus travel range and the second preset value. The second preset value can be used as the image stabilization travel threshold under the current first travel value, so as to control the travel of the SMA motor 52 moving in the second direction to not exceed the second preset value, thereby taking into account both the life of the SMA motor 52 and the effect of optical image stabilization compensation of the lens 51.

[0153] In some alternative implementations, in addition to obtaining the second preset value corresponding to the first travel value by looking up a table, a functional relationship between the first travel value and the second preset value can be established in advance, thereby directly determining the second preset value corresponding to the first travel value.

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

[0155] In some optional implementations, step S35 may further include:

[0156] 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 line 521 to control the first SMA line 521 to contract.

[0157] 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 line 521 to control the second SMA line 521 to contract until the SMA motor 52 moves along the second direction by the second preset value.

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

[0159] Therefore, by energizing at least two SMA lines 521 in the SMA motor 52, the SMA motor 52 can be controlled to move along 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.

[0160] In some alternative embodiments, step S33 may further include:

[0161] 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 line 521 to control the first SMA line 521 to contract.

[0162] Step S334: When the first stroke value is greater than 0 and the second stroke value is greater than the first preset value, a second current is transmitted to the second SMA line 521 to control the second SMA line 521 to contract until the SMA motor 52 moves along the second direction by the first preset value.

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

[0164] Therefore, by energizing at least two SMA lines 521 in the SMA motor 52, the SMA motor 52 can be controlled to move along 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.

[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] Through the above embodiments, when the first stroke value of the SMA motor 52 moving along the first direction is greater than 0, compared to when the first stroke value of the SMA motor 52 moving along the first direction is equal to 0, the upper limit of the current threshold transmitted to at least one SMA line 521 is reduced. If the instantaneous displacement of the lens 51 exceeds the second preset value, the current transmitted to at least one SMA line 521 is the reduced upper limit of the current threshold, thereby enabling the SMA motor 52 to move along the second direction by a 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 travel value is the first travel sub-value, the second preset value is the first preset sub-value. If the first travel value is the second travel sub-value, the second preset value is the second preset sub-value. The first travel sub-value is greater than the second travel sub-value, and the first preset sub-value is less than the second preset value.

[0169] Among them, 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 180μm, the second stroke sub-value is 280μm, the first preset sub-value is 80μm, and the second preset sub-value is 70μm.

[0171] Through the above embodiments, a corresponding second preset value can be determined based on the magnitude of the first stroke value of the SMA motor 52 moving along the first direction. As the first stroke value increases, the second preset value decreases accordingly, or in other words, the second preset value and the first stroke value have a negative correlation. Thus, when the SMA motor 52 moves along both the first and second directions, it is possible to avoid excessive tensile stress on the SMA line 521 and also to ensure the effectiveness of optical image stabilization compensation for the lens 51.

[0172] Figure 13 for Figure 11 A schematic diagram of a stroke threshold of the SMA motor 52 in the illustrated embodiment.

[0173] like Figure 13 As shown, 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 lens 51 and the telephoto position SF of lens 51 may not be equal to the distance between the initial position O of lens 51 and the near-focal position SN of lens 51. Accordingly, when the focusing travel threshold changes, the second preset value corresponding to each first travel value may also change.

[0175] In some examples, the first preset value is 100 μm. The distance between the initial position of lens 51 and the near-focal position of lens 51 is the first focusing travel threshold, which is 500 μm. When the first travel value is 500 μm, the second preset value is 50 μm. The second preset value is linearly negatively correlated with the first travel value.

[0176] In some other examples, the first preset value is 100 μm. The distance between the initial position of lens 51 and the telephoto position of lens 51 is the second focusing travel threshold, which is 200 μm. When the first travel value is 200 μm, the second preset value is 80 μm. The second preset value and the first travel value are linearly negatively correlated.

[0177] By making the second preset value change linearly based on the change of the first stroke value, it is possible to ensure that the tensile stress on the SMA line 521 is within a reasonable range under different first stroke values, while also ensuring the effect of optical image stabilization compensation for the lens 51, thereby taking into account both the lifespan of the SMA motor 52 and the effect of optical image stabilization compensation for the lens 51.

[0178] like Figure 13 As shown, the commonly used focal length of lens 51 during shooting is the mid-to-telephoto range O. The mid-to-telephoto position of lens 51 can be set to the position where the SMA motor 52 is powered off. This allows for greater image stabilization compensation in most shooting scenarios, resulting in a better user experience. However, in close-focus shooting scenarios such as mobile phone scanning and face unlocking, the travel value of the SMA motor 52 along the focusing direction is larger. Under severe shaking of the electronic device 100, corresponding to the travel value along the focusing direction, the travel value of the SMA motor 52 for optical image stabilization compensation in the direction intersecting the focusing direction decreases. This avoids excessive contraction or stretching of the SMA line 521, extending the lifespan of the SMA motor 52. Compared to mid-to-telephoto shooting scenarios such as portraits and landscapes, the image quality requirements are lower in close-focus shooting scenarios like mobile phone scanning and face unlocking, so a slight reduction in optical image stabilization compensation has little impact on the user experience. Therefore, the above embodiment cleverly balances user experience and the lifespan of the SMA motor 52.

[0179] Figure 14 for Figure 11A schematic diagram of the stroke relationship of the SMA motor 52 in the illustrated embodiment.

[0180] like Figure 14 As shown, if the focusing travel is represented by the target code value in the focusing direction, and the target code value in the focusing direction is taken as the zero point of the code value at the end point of the near focal length or the end point of the far focal length of the lens 51 (for example, when the target code value in the focusing direction is about 2000, it corresponds to the actual initial position of the lens 51), then the image stabilization travel threshold 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. Step S33 above also includes:

[0182] Step S335: The first travel value is equal to the focus travel threshold, and the second travel value is greater than the third preset sub-value. Control the SMA motor 52 to move the third preset sub-value along 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%.

[0183] For example, 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%, or 70%. For example, the third preset sub-value is 50 μm and the first preset value is 100 μm.

[0184] Through the above embodiments, when the first travel value reaches its maximum, the tensile stress on the SMA line 521 along the first direction is the maximum. The third preset sub-value corresponding to the first travel value is the minimum value among the second preset values. The above embodiments set the minimum value among the second preset values ​​to 40% to 70% of the first preset value, which can further balance the lifespan of the SMA motor 52 and the optical image stabilization compensation effect of the lens 51 under extreme focusing conditions.

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

[0186] Step S35: If the first stroke value is greater than 0 and the second stroke value is not greater than the second preset value, control the SMA motor 52 to move the second stroke value along the second direction.

[0187] For example, if the first stroke value is 200μm, the second stroke value is 30μm, and the second preset value is 60μm, then 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 30μm along the second direction.

[0188] Through this embodiment, the SMA motor 52 is directly controlled to move a second stroke value along the second direction based on the received command, and the instantaneous displacement value of the SMA motor 52 can be directly compensated for to improve the optical image stabilization compensation effect of the lens 51.

[0189] In some optional embodiments, the SMA motor 52 is also configured to move the lens 51 along a third direction, which intersects the first direction. Following step S31 above, the following steps may also be included:

[0190] Step S36: Receive an instruction to move the SMA motor 52 along a third direction by a third stroke value.

[0191] Step S37: If the first stroke value is equal to 0 and the third stroke value is greater than the third preset value, control the SMA motor 52 to move the third preset value along the third direction. If the first stroke value is greater than 0 and the third stroke value is greater than the fourth preset value, control the SMA motor 52 to move the fourth preset value along the third direction. If the fourth preset value is less than the third preset value.

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

[0193] In the embodiments of this application, steps S36 to S37 and steps S32 to S33 can be executed simultaneously, or the execution order of steps S36 to S37 and steps S32 to S33 can be interchanged.

[0194] Through the above embodiments, the SMA motor 52 can move along the second direction and the third direction to perform optical image stabilization compensation, and the image stabilization travel threshold of the SMA motor 52 in the second direction and the third direction is related to the first travel value of the SMA motor 52 along the first direction. This not only improves the effect of optical image stabilization compensation of the lens 51, but also ensures the service life of the SMA motor 52.

[0195] Figure 15 This is a structural block diagram of a controller for an SMA motor 52 provided in an embodiment of this application.

[0196] This application provides a controller for an 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.

[0197] like Figure 15 As shown, 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 a first stroke value along a first direction.

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

[0200] The second control module 503 is configured to control the SMA motor 52 to move along the second direction by the 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 along 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.

[0202] Figure 16 This is a structural block diagram of an electronic device 100 provided in an embodiment of this application.

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

[0204] In some alternative implementations, the gyroscope filtering module 504 is used to receive a command from the gyroscope sensor 7 instructing the SMA motor 52 to move a second stroke value along a second direction. The gyroscope filtering module 504 can also filter the command from the gyroscope sensor 7 instructing the SMA motor 52 to move a second stroke value along a second direction.

[0205] The second processing module 506 can be used to receive an instruction from the application processor 6 instructing the SMA motor 52 to move a first stroke value along the first direction. The second processing module 506 can also be used to transmit the instruction from the application processor 6 instructing the SMA motor 52 to move the first stroke value along the first direction to the gyroscope filtering module 504. The second processing module 506 can also process the instruction from the application processor 6 instructing the SMA motor 52 to move the first stroke value along the first direction. For example, after determining that the SMA motor 52 can move the first stroke value along the first direction, the second processing module 506 transmits the processed instruction to the first control module 501. For example, the processed instruction can cause the first control module 501 to first control the SMA motor 52 to drive the lens 51 back to its initial position, and then move the first stroke value along the first direction.

[0206] The first processing module 505 can also be used to receive the first stroke value and the second stroke value transmitted by the gyroscope filter module 504 at the same time, and based on the first stroke value and the second stroke value, determine the stroke value of the SMA motor 52 along the second direction, and transmit the control command to the second control module 503.

[0207] like Figure 16 As shown, this application embodiment also provides an electronic device 100, which includes a controller for the SMA motor 52 in any of the above embodiments.

[0208] like Figure 16 As shown, the electronic device 100 may also include an application processor 6 and a gyroscope sensor 7.

[0209] This application embodiment also provides a camera module 5, which includes a controller for the SMA motor 52 in any of the above embodiments.

[0210] This application also provides an electronic device 100, which includes the camera module 5 in any of the above embodiments.

[0211] This application also provides 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 causes the electronic device 100 to implement the control method in any of the above embodiments.

[0212] This application also provides a computer-readable storage medium that includes a program or instructions that, when executed on a computer, implement the control method as described in any of the above embodiments.

[0213] This application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the control method in any of the above embodiments.

[0214] Generally, after the manufacturing process of SMA line 521 is determined, it is also necessary to collect fatigue life data of the manufactured SMA line 521. Based on the required number of life cycles of SMA line 521 under various usage scenarios, the SMA motor 52 and the control logic of SMA motor 52 are designed to prevent the problem of premature breakage and failure of SMA line 521 due to excessive driving.

[0215] In addition to tracking the fatigue life in the later stages, the monitoring methods for the life of SMA line 521 in related technologies mainly include visual inspection of impurity particles in SMA line 521 by cross-section and visual inspection of longitudinal cracks on the surface of SMA line 521.

[0216] The visual inspection of impurity particles in SMA line 521 mainly involves observing the longitudinal sections of the SMA line 521 using focused ion beam (FIB) slicing to visually detect the presence of impurity particles. Visual inspection of longitudinal surface cracks in SMA line 521 requires removing the surface insulating coating and observing the cracks using a scanning electron microscope (SEM) or FIB slicing.

[0217] Obviously, the above methods are time-consuming and labor-intensive, and can only selectively detect a portion of the cross-section or surface of the SMA line 521. Taking longitudinal surface cracks as an example, they usually appear in sections within a range of several hundred meters or even thousands of meters on the SMA line 521, making it difficult for the above methods to eliminate early fracture risks in the SMA line 521 one by one.

[0218] Therefore, it is urgent to solve the problem of the difficulty in conducting early, large-scale testing of the fatigue resistance of SMA line 521.

[0219] Figure 17 This is a schematic diagram of a test scenario for the SMA line 521 provided in an embodiment of this application. Figure 18 A flowchart illustrating the steps of a test method for an SMA line 521 provided in this application embodiment.

[0220] like Figure 17 and Figure 18 As shown, in view of this, this application embodiment also provides a test method for SMA line 521, which specifically includes the following steps:

[0221] Step S61: Fix one end of the SMA wire 521 to be tested and connect the other end to the free object 601.

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

[0223] In some alternative embodiments, the SMA wire 521 to be tested can be fixed by one metal clamp, and the free object 601 of the SMA wire 521 to be tested can be fixedly connected by another metal clamp. The two metal clamps are respectively connected to the positive and negative terminals of the power supply through wires, which can form a power circuit system.

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

[0225] Step S62 involves alternating between a powered-on state and a powered-off state on the SMA line 521 until the SMA line 521 breaks.

[0226] In some optional embodiments, by alternately controlling the opening and closing of the switches in the power circuit system in step S61 above, the SMA wire 521 under test can be alternated between an energized state and an de-energized state. Specifically, the SMA wire 521 under test contracts when energized and recovers when de-energized. Correspondingly, the free object 601 can generate up-and-down reciprocating motion, thereby achieving fatigue life testing of the SMA wire 521.

[0227] In the embodiments of this application, the fatigue resistance of the SMA wire 521 is positively correlated with the duration of alternation between energized and de-energized states.

[0228] In some alternative embodiments, the duration of energizing and de-energizing the test SMA line 521 can be the same or different.

[0229] For example, a test cycle for switching the SMA line 521 on and off is 2 seconds. The duty cycle for the SMA line 521 on is 0.4. In one alternating cycle, the duration of the on state can be 0.8 seconds, and the duration of the off state can be 1.2 seconds.

[0230] Through the above embodiments, a free object 601 can be used to alternately apply tensile stress to the SMA wire 521 under test during the energized contraction and de-energized recovery processes. This not only simulates the scenario where the SMA wire 521 is subjected to tensile stress while the SMA motor 52 is in operation, but also quickly and effectively detects whether there are any undesirable factors in the SMA wire 521 that may lead to breakage, such as cracks or impurities. This helps to improve the fatigue resistance of the SMA wire 521 and extend the service life of both the SMA wire 521 and the SMA motor 52.

[0231] In some alternative embodiments, the free object 601 has a preset weight, which is positively correlated with the wire diameter of the SMA wire 521. Alternatively, the current passing through the SMA wire 521 under test when energized is positively correlated with the wire diameter of the SMA wire 521 under test.

[0232] Through the above embodiments, the current value passing through the SMA wire 521 under test 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. This can not only simulate the real usage scenario of the SMA wire 521 in the SMA motor 52, but also accelerate the testing process of the SMA wire 521 by setting the current value passing through the SMA wire 521 under test and the weight of the free object 601 under test, thus more quickly and effectively detecting whether there are any undesirable factors in the SMA wire 521 that may lead to breakage, thereby improving testing efficiency.

[0233] Taking the testing of an SMA wire 521 with a diameter of 30 μm and a length of 200 mm as an example, this application embodiment also provides an exemplary testing method, wherein the cross-sectional area of ​​the SMA wire 521 to be tested is approximately 706.9 mm², the weight of the free object 601 is 50 g, the maximum tensile stress on the SMA wire 521 to be tested is approximately 707 MPa, the resistivity of the SMA wire 521 to be tested is 9.00 E-04 Ω·m, the total resistance of the SMA wire 521 to be tested is approximately 254.6 Ω, and the material phase transition temperature of the SMA wire 521 to be tested is approximately 128.9 °C. The test frequency for switching on and off the SMA line 521 under test is 0.5 seconds. One test cycle for switching on and off the SMA line 521 under test is 2 seconds. The duty cycle for the energized time of the SMA line 521 under test is 0.4 seconds. The voltage applied across the SMA line 521 under test is 25V. The peak current in the SMA line 521 under test is approximately 98.2mA. The maximum contraction rate of the SMA line 521 under test is 2.1%. The maximum travel of the free object 601 is 4.2mm.

[0234] The duty cycle of the energizing time refers to the ratio between the duration of the energizing state and the duration of the cycle during one period of alternation between the energizing and de-energizing states.

[0235] Figure 19 This is a schematic diagram of another test scenario for the SMA line 521 provided in the embodiments of this application. Figure 20 for Figure 19 A flowchart illustrating the steps of a test method for the SMA line 521 in the illustrated embodiment.

[0236] like Figure 19 and Figure 20 As shown in the embodiments of this application, another test method for SMA line 521 is also provided, the test method including:

[0237] Step S71: Connect one end of the first SMA line to be tested 5211 to one end of the second SMA line to be tested 5212, fix the other end of the first SMA line to be tested 5211, and fix the other end of the second SMA line to be tested 5212.

[0238] In some alternative embodiments, the distance between the fixed ends of the first SMA line 5211 and the second SMA line 5212 under test can be equal to the sum of the lengths of the first SMA line 5211 under power-off state and the second SMA line 5212 under power-off state.

[0239] In step S72, the first SMA line 5211 and the second SMA line 5212 to be tested are alternately energized until the first SMA line 5211 or the second SMA line 5212 to be tested breaks.

[0240] In this embodiment of the application, when the first SMA line 5211 to be tested is energized, the second SMA line 5212 to be tested is subjected to tensile stress applied by the first SMA line 5211 to be tested.

[0241] In this embodiment, when the second SMA wire 5212 is energized, the first SMA wire 5211 is subjected to tensile stress applied by the second SMA wire 5212. The fatigue resistance of the SMA wire 521 is positively correlated with the duration of alternating energization between the first and second SMA wires 5211 and 5212.

[0242] Through the above embodiments, one of the first SMA wire 5211 and the second SMA wire 5212 under test is energized and shrinks, while the other is de-energized and recovers. The first SMA wire 5211 and the second SMA wire 5212 under test apply tensile stress to each other, which highly simulates the scenario where the SMA wire 521 is subjected to tensile stress when the SMA motor 52 is working. It can also quickly and effectively detect whether there are undesirable factors in the SMA wire 521 that are prone to breakage, such as cracks and impurities, thereby helping to improve the fatigue resistance of the SMA wire 521 and extend the service life of the SMA wire 521 and the SMA motor 52.

[0243] In some optional embodiments, the magnitude of the current in the SMA line 521 under test (including the first SMA line 5211 and the second SMA line 5212 under test) under energized conditions can be positively correlated with the diameter of the SMA line 521 and also positively correlated with the material phase transition temperature of the SMA line 521.

[0244] In some alternative embodiments, the duty cycle of the energizing time of the SMA line 521 under test can be positively correlated with the diameter of the SMA line 521 and also positively correlated with the material phase transition temperature of the SMA line 521.

[0245] In some optional embodiments, when the first SMA line 5211 to be tested is energized, the length of the first SMA line 5211 to be tested is reduced to no more than the maximum recoverable deformation of the first SMA line 5211 to be tested and the maximum recoverable deformation of the second SMA line 5212 to be tested.

[0246] In some optional embodiments, when the second SMA line 5212 is energized, the length of the second SMA line 5212 reduced does not exceed the maximum recoverable deformation of the first SMA line 5211 and the maximum recoverable deformation of the second SMA line 5212.

[0247] Through the above embodiments, the magnitude of the current energized by the first SMA line 5211 and the second SMA line 5212 under test can be determined based on the maximum recoverable deformation of the first SMA line 5211 and the maximum recoverable deformation of the second SMA line 5212 under test, thereby further improving the effectiveness of the test.

[0248] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A control method for a shape memory alloy (SMA) motor, characterized in that, The SMA motor is configured to move the lens along 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 includes: Control the SMA motor to move a first stroke value along the first direction; Receive an instruction instructing the SMA motor to move a second stroke value along the second direction; If the first stroke value is equal to 0 and the second stroke value is greater than the first preset value, the SMA motor is controlled to move along the second direction by the first preset value. If the first stroke value is greater than 0 and the second stroke value is greater than the second preset value, the SMA motor is controlled to move along the second direction by the second preset value; if the second preset value is less than the first preset value; if the first preset value is less than the maximum distance the SMA motor can move along the second direction without the SMA line failing.

2. The control method for the SMA motor according to claim 1, characterized in that, The SMA line includes a first SMA line and a second SMA line; The step of controlling the SMA motor to move along the second direction by the first preset value includes: A first current is transmitted to the first SMA line to control the contraction of the first SMA line; A second current is transmitted to the second SMA line to control the second SMA line to contract until the SMA motor moves the first preset value along the second direction; The step of controlling the SMA motor to move along the second direction by the second preset value includes: A third current is transmitted to the first SMA line to control the contraction of the first SMA line; A fourth current is transmitted to the second SMA line to control the second SMA line to contract until the SMA motor moves the second preset value along the second direction. Wherein, the first current is greater than the third current, or the second current is greater than the fourth current.

3. The control method for the SMA motor according to claim 1 or 2, characterized in that, If the first travel value is a first travel sub-value, the second preset value is a first preset sub-value; if the first travel value is a second travel sub-value, the second preset value is a second preset 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. The control method for an SMA motor according to any one of claims 1 to 3, characterized in that, The second preset value and the first travel value have an inverse linear relationship.

5. The control method for an SMA motor according to any one of claims 1 to 4, characterized in that, The second preset value also includes a third preset sub-value; The first travel value is equal to the focus travel threshold, and the second travel value is greater than the third preset sub-value, so the SMA motor is controlled to move the third preset sub-value along 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%.

6. The control method for an SMA motor according to any one of claims 1 to 5, characterized in that, The step of controlling the SMA motor to move along 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 includes: If the first travel value is greater than 0, the focus travel range in which the first travel value is located is determined; Determine the second preset value corresponding to the focusing travel range; Determine whether the second stroke value is greater than the second preset value. If the second stroke value is greater than the second preset value, control the SMA motor to move along the second direction by the second preset value.

7. The control method for an SMA motor according to any one of claims 1 to 6, characterized in that, The control method further includes: 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 is controlled to move along the second direction by the second stroke value.

8. The control method for an SMA motor according to any one of claims 1 to 7, characterized in that, The SMA motor is also configured to move the lens along a third direction; the third direction intersects the first direction. After the step of controlling the SMA motor to move a first stroke value along the first direction, the control method further includes: Receive an instruction instructing the SMA motor to move a third stroke value along the third direction; If the first stroke value is equal to 0 and the third stroke value is greater than the third preset value, the SMA motor is controlled to move along the third direction by the third preset value; If the first stroke value is greater than 0 and the third stroke value is greater than the fourth preset value, the SMA motor is controlled to move along the third direction by the fourth preset value; if the fourth preset value is less than the third preset value.

9. A control device for an SMA motor, characterized in that, The SMA motor is configured to move the lens along 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 includes: The first control module is configured to control the SMA motor to move a first stroke value along the first direction; The signal receiving module is configured to receive an instruction instructing the SMA motor to move a second stroke value along the second direction; The second control module is configured to control the SMA motor to move along the second direction by the first preset value when the first stroke value is equal to 0 and the second stroke value is greater than the first preset value; the second control module is also configured to control the SMA motor to move along the second direction by the 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; the first preset value is less than the maximum distance that the SMA motor can move along the second direction without the SMA line failing.

10. A camera module, characterized in that, It includes a lens, an SMA motor, and a control device for the SMA motor as described in claim 9.

11. An electronic device, characterized in that, Includes the control device for the SMA motor as described in claim 9 or the camera module as described in claim 10.

12. An electronic device, characterized in that, include: Memory, including instructions; A processor, when executing the instructions, causes the electronic device to implement the control method as described in any one of claims 1 to 8.

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

14. A computer program product, characterized in that, It includes a computer program that, when executed by a processor, implements the control method as described in any one of claims 1 to 8.

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