Shape memory alloy and camera device

Abstract

An embodiment discloses a shape memory alloy made of an alloy, wherein the alloy includes Ni, Ti, and A, and the A has an atomic ratio (at %) of 5 to 10.

Description

Shape memory alloys and camera devices

[0001] The present invention relates to a shape memory alloy and a camera device.

[0002] With the recent proliferation of high-resolution image sensors in smartphones, tablets, car cameras, and other compact electronic devices, demand is increasing for smaller, higher-powered actuators that precisely move the lenses within the camera. This demand is particularly critical for cameras that support autofocus (AF) and optical image stabilization (OIS).

[0003] Conventional camera devices primarily employ electromagnetic (e.g., voice coil motors, VCMs) or piezoelectric actuators. However, these have limitations in terms of thickness, noise, power consumption, and response speed. Consequently, active efforts are being made to utilize shape memory alloys (SMAs) as actuators.

[0004] SMA has the characteristic of changing its crystal structure and length according to changes in temperature. Specifically, when SMA is used as a driving wire, the heat generated by the current causes it to transform into a high-temperature phase (Austenite), shrinking its length. Upon cooling, it reverts to a low-temperature phase (Martensite), increasing its length. This repeated deformation can be used as a force to move the lens.

[0005] However, SMA actuators have the problem of being slow in the cooling section and having poor drive responsiveness.

[0006] The present invention provides a shape memory alloy and a camera device using the same, which can improve the transport speed and precision of a lens holder by reducing hysteresis and improving the cooling speed in a phase transformation section.

[0007] In addition, the embodiment can provide a shape memory alloy and a camera device that provide excellent stroke by implementing a stable crystal phase change through a ratio between a predetermined element A and an element of an alloy.

[0008] In addition, shape memory alloys and camera devices applicable to ultra-slim, ultra-small, and high-resolution cameras can be provided.

[0009] The problem to be solved in the embodiment is not limited to this, and it can be said that the purpose or effect that can be understood from the solution or implementation form of the problem described below is also included.

[0010] A shape memory alloy according to an embodiment is a shape memory alloy made of an alloy, wherein the alloy includes Ni, Ti and A, and the atomic ratio (at%) of A is 5 to 10.

[0011] The atomic ratio of the above Ni may be greater than the atomic ratio of the above A.

[0012] The atomic ratio of the above Ti may be greater than the atomic ratio of the above A.

[0013] The atomic ratio of the above Ti may be greater than the atomic ratio of the above Ni.

[0014] The crystal phase of the above shape memory alloy can be configured to change from B2 (body-centered cubic structure, BCC) to B19 (monoclinic crystal structure, Monoclinic) and B19'.

[0015] A may contain any one of copper (Cu), iron (Fe), cobalt (Co), aluminum (Al), tin (Sn), manganese (Mn), platinum (Pt), and palladium (Pd).

[0016] A camera device according to an embodiment comprises a housing; a lens holder disposed inside the housing; and a drive wire in contact with the housing and the lens holder, wherein the drive wire comprises an alloy of Ni, Ti, and A, wherein A has an atomic ratio (at%) of 5 to 10.

[0017] The above driving wire may include a first wire and a second wire.

[0018] The atomic ratio of A in the first wire may be different from the atomic ratio of A in the second wire.

[0019] The above first wire and second wire can cross each other.

[0020] According to an embodiment, the embodiment implements a shape memory alloy and a camera device using the same, which can improve the transport speed and precision of a lens holder by reducing hysteresis and improving the cooling speed in a phase transformation section.

[0021] In addition, the embodiment can realize a shape memory alloy and a camera device that provide excellent stroke by implementing a stable crystal phase change through a ratio between a predetermined element A and an element of an alloy.

[0022] The various advantageous and beneficial effects of the present invention are not limited to the above-described contents, and will be more easily understood in the course of explaining specific embodiments of the present invention.

[0023] Figure 1 is a schematic diagram of a camera module according to an embodiment of the present invention;

[0024] Figure 2 is a configuration diagram of a camera module according to an embodiment;

[0025] Figure 3 is an example of a lens holder and a driving unit in a camera module.

[0026] Figure 4 is an example explaining driving by a driving unit in a camera module.

[0027] Figure 5 is another example explaining driving by a driving unit in a camera module.

[0028] Fig. 6 is a drawing showing the configuration of a drive wire according to an embodiment;

[0029] Figure 7 is a drawing showing the configuration changes of the drive wires of comparative examples and examples at high and low temperatures.

[0030] Figure 8 is a drawing showing the configuration of the drive wire of the comparative example and embodiment.

[0031] Figure 9 is a drawing showing the stroke according to the temperature of the driving wire of the comparative example and the embodiment.

[0032] Figure 10 is a drawing showing the stroke according to the current of the driving wire of the comparative example and the embodiment.

[0033] Figure 11 is a drawing showing the change in hysteresis and stroke according to the content of A in the driving wire.

[0034] FIG. 12 is a diagram illustrating an electronic device including a camera device according to an embodiment.

[0035] The present invention can be modified in various ways and has various embodiments, and specific embodiments are illustrated and described in the drawings. However, this is not to be construed as a specific embodiment of the present invention.

[0036] It is not intended to be limited to the embodiments, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0037] Terms that include ordinal numbers, such as "second," "first," etc., may be used to describe various components, but the components are not limited by the terms. The terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a second component may be referred to as "first component," and similarly, a first component may also be referred to as "second component." The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0038] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0039] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0041] Hereinafter, embodiments will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or corresponding components are given the same reference numbers, and redundant descriptions thereof will be omitted.

[0042] Figure 1 is a schematic diagram of a camera module according to an embodiment of the present invention.

[0043] Referring to FIG. 1, a camera module (1000) according to an embodiment of the present invention may include a fixed part (G1), a moving part (G2), a first driving part (M1), a second driving part (M2), a third driving part (M3), and a control part (CL).

[0044] The fixed part (G1) may include a fixed component in the camera module (1000). That is, the fixed part (G1) may be composed of components that do not move due to autofocus (AF) and optical image stabilization (OIS). In particular, in the present invention, the fixed part (G1) may be composed of components that do not move due to optical image stabilization (OIS).

[0045] For example, the fixed part (G1) may include at least one of a housing, a base, and a cover in the camera module (1000) according to the embodiment. In addition, as described above, the fixed part (G1) may be a concept that includes all components that do not move due to auto-focusing and optical image stabilization (OIS).

[0046] The moving unit (G2) may include a component that moves in the camera module (1000). That is, the moving unit (G2) may be composed of a component that moves by optical image stabilization (OIS). In particular, in the present invention, the moving unit (G2) may be composed of a component that moves by performing OIS. Accordingly, in an embodiment, the moving unit (G2) may move axially in a direction perpendicular to the optical axis direction or may move in one direction on a plane perpendicular to the optical axis direction. Accordingly, the moving unit (G2) may include a component that moves except for the movement in the optical axis direction. In other words, the moving unit (G2) may include a component that axially moves (or tilts) in a direction perpendicular to the optical axis direction. For example, the moving unit (G2) may include at least one of a lens unit, a lens module, and an image sensor in the camera module (1000) according to the embodiment. In addition, as described above, the moving unit (G2) may be a concept that includes all components that move by auto-focusing or optical image stabilization.

[0047] The first driving unit (M1) to the third driving unit (M3) are connected to the fixed unit (G1) and can drive the moving unit (G2) to move relative to the fixed unit (G1). At this time, the first driving unit (M1) to the third driving unit (M3) can move the moving unit (G2) in the direction of the optical axis or in a direction perpendicular to the direction of the optical axis. Here, the movement includes tilting with respect to the corresponding axis.

[0048] For example, the first driving unit (M1) and the second driving unit (M2) can move the moving unit (G2) in a direction perpendicular to the optical axis. And the third driving unit (M3) can move the moving unit (G2) in parallel along the optical axis. And the third driving unit (M3) can be included in the first driving unit (M1). In other words, the first driving unit (M1) can move the moving unit (G2) in a direction along the optical axis or perpendicular to the optical axis.

[0049] In the embodiment below, the moving part (G2) can move in the same direction by the first driving part (M1) and the second driving part (M2).

[0050] In addition, according to the embodiment, the first driving unit (M1) and the second driving unit (M2) can perform shake prevention by moving the moving unit (G2) in a direction perpendicular to the optical axis, and the third driving unit (M3) can perform auto focusing by moving the moving unit (G2) along the optical axis.

[0051] In addition, for example, the first driving unit (M1) to the third driving unit (M3) may include various actuators. For example, the plurality of driving units may include a voice coil motor (VCM) actuator, an actuator driven by piezoelectric power, a MEMS actuator driven by electrostatic capacitance, an ultrasonic motor (USM), a step motor, etc. In particular, at least one of the plurality of driving units may be formed of a shape memory alloy (SMA) actuator.

[0052] SMA has the property of returning to its original shape due to heat generation when current is applied, and the contractile force generated at this time is used to drive the moving part.

[0053] For example, the first driving unit (M1) and / or the second driving unit (M2) may perform a function of minutely moving the image sensor (600) in the horizontal (X, Y) direction by including an SMA wire. Such precise control performance of the SMA is advantageous in improving optical image stabilization (OIS) performance during high-resolution shooting.

[0054] Additionally, the third driving unit (M3) can perform autofocusing (AF) by moving the lens assembly (300) in the optical axis direction (Z-axis) based on the SMA.

[0055] SMA is designed in the form of a wire and can contract when current is applied, inducing linear motion.

[0056] Therefore, the driving unit employing SMA can achieve precise control while reducing the driving range, and can satisfy both the requirements of module miniaturization and low power consumption.

[0057] The control unit (CL) controls the driving characteristics of the SMA by adjusting the magnitude, duration, waveform, etc. of the current applied to each driving unit. In addition, the control unit (CL) may include a feedback circuit combined with a temperature sensor, thereby ensuring repeatability and stability of the SMA. The control unit (CL) may individually control the direction, intensity, amplitude, etc. of the current supplied to drive the first to third driving units (M1) to M3. Control signals for controlling the movement or driving of the first to third driving units (M1) to M3 may be received from an external device (e.g., a terminal, a smartphone, etc.). For example, the camera module according to the embodiment may be mounted in various electronic devices, and the first to third driving units (M1) to M3 may be controlled through the control unit (CL) arranged inside or outside the camera module in the electronic device. The control unit can control the first driving unit (M1) to the third driving unit (M3) to perform an anti-shake function or an auto-focusing function. Furthermore, the control unit can perform auto-focus feedback control and / or shake correction feedback control for the lens driving device.

[0058] FIG. 2 is a configuration diagram of a camera module according to an embodiment, FIG. 3 is an example of a lens holder and a driving unit in a camera module, FIG. 4 is an example explaining driving by a driving unit in a camera module, and FIG. 5 is another example explaining driving by a driving unit in a camera module.

[0059] Referring to FIG. 2, a camera module according to an embodiment may include a housing (100), a lens unit including a lens holder (200) and a lens assembly (300), an elastic member (400), a base (500), an image sensor (600), a first driving unit (M1), a second driving unit (M2), and a third driving unit (M3).

[0060] The housing (100) can be placed on the outside of the camera module. The housing (100) has an outer structure and can protect components placed inside from external impacts, foreign substances, and electromagnetic waves.

[0061] The lens holder (200) is located inside the housing (100) and can support and align the lens assembly (300).

[0062] The lens assembly (300) may be composed of a plurality of fixed lenses and movable lenses. The lens assembly (300) may be movable, thereby implementing autofocusing and / or image stabilization.

[0063] The elastic member (400) can be connected to the fixed part and the movable part. The elastic member (400) can provide buffering and restoring force between each component. In other words, the elastic member (400) can perform the function of absorbing shock.

[0064] The base (500) is located at the bottom of the camera device and can support the housing (100) and the image sensor (600), etc.

[0065] The image sensor (600) is a core component that converts an optical signal into an electrical signal and can be implemented as a CCD, CMOS, etc. For example, the image sensor (600) can be any one of a CCD (charge coupled device), MOS (metal oxide semi-conductor), CPD, and CID.

[0066] The substrate (not shown) may be a printed circuit board. The substrate (not shown) may be electrically connected to a control unit (not shown) of the mobile terminal.

[0067] Each driving unit can be positioned between a fixed unit and a moving unit. This is described below based on the drawing.

[0068] The first driving unit (M1) may be positioned between the housing (100) and the base (500) or between the lens assembly (300) and the base (500). The first driving unit (M1) performs optical image stabilization (OIS) by moving a moving unit (e.g., lens assembly) in a direction perpendicular to the optical axis (X, Y axes). As an embodiment, a shape memory alloy (SMA)-based wire actuator may be applied as the first driving unit (M1).

[0069] This first driving unit (M1) can move the housing or lens unit by contracting the SMA when current is applied. In particular, micro-movement of the moving unit can be implemented by the first driving unit (M1).

[0070] The second driving unit (M2) may be arranged between the housing (100) and the image sensor (600). The second driving unit (M2) may move a moving unit (e.g., an image sensor). For example, the second driving unit (M2) may precisely move the image sensor (600) in the direction perpendicular to the optical axis (X, Y) to improve high-resolution shooting and shake correction performance. In particular, an SMA may be applied to the second driving unit (M2). Accordingly, highly precise movement of the moving unit is possible, and high responsiveness and repeatability can be secured.

[0071] The third driving unit (M3) is positioned between the lens assembly (300) and the housing (100) and can move the lens assembly in the optical axis direction (Z-axis). The third driving unit (M3) can move the moving unit. For example, the third driving unit (M3) can move the lens assembly (300) in the optical axis direction to perform autofocusing (AF). An SMA-based wire actuator can be applied to the third driving unit (M3).

[0072] That is, in the embodiment, the first driving unit (M1) to the third driving unit (M3) may include SMA-based driving wires.

[0073] Referring further to FIGS. 3 to 5, the moving part, which is the lens holder (200), can be moved by the driving part. With reference to FIG. 2, the lens holder (200) can be moved by the first driving part (M1) and / or the third driving part (M3).

[0074] The first driving unit (M1) and / or the third driving unit (M3) may be formed of a first driving wire. The length of the first driving wire may decrease or increase depending on the applied current. The first driving unit (M1) and / or the third driving unit (M3) may be formed of a second driving wire. The length of the second driving wire may decrease or increase depending on the applied current.

[0075] By means of the first drive wire, the lens holder (200) can move in a direction perpendicular to the optical axis (e.g., in the Z-axis direction and / or the Y-axis direction). By means of the second drive wire, the lens holder (200) can move along the optical axis (e.g., in the X-axis direction).

[0076] As an example, a force (F1, F2) that moves the lens holder (200) in a direction perpendicular to the optical axis direction (X-axis direction) can be generated by the first drive wire. As a result, hand shake correction can be performed.

[0077] Additionally, the driving force (F3, F4) by the second driving wire can move the lens holder (200) in the direction of the optical axis. As a result, auto-focusing can be performed.

[0078] The first drive wire and the second drive wire can be connected to the moving part and the fixed part. For example, one end of the first drive wire and the second drive wire can be in contact with the moving part, and the other end can be in contact with the fixed part. For example, the first drive wire and the second drive wire can be in contact with the lens holder. In addition, the first drive wire and the second drive wire can be in contact with the housing. The first drive wire and the second drive wire can also move the lens holder (200) in the direction of the optical axis and in the direction perpendicular to the optical axis.

[0079] Additionally, the first drive wire and the second drive wire may include multiple wires. For example, the first drive wire may include a first wire and a second wire. The first wire and the second wire may be positioned to intersect each other. For example, the first wire and the second wire may be positioned adjacent to the same side among the multiple sides of the lens holder (200).

[0080] Furthermore, the first wire and the second wire may include an alloy of Ni, Ti, and A as described below. At this time, A may have an atomic ratio (at%) of 5 to 10. At this time, the atomic ratio (at%) of A of the first wire and the atomic ratio (at%) of A of the second wire may be different from each other. The atomic ratio (at%) may be equal to the atomic percentage.

[0081] By this configuration, the driving speed of the first wire and the driving speed of the second wire can be different from each other. The difference in the A element ratio of the first wire and the second wire can control the driving speed and precision, thereby simultaneously implementing fast responsiveness and high accuracy. For example, a wire with a high A element ratio can provide fast driving speed, and a wire with a low A element ratio can provide precise position control. For example, one of the first wire and the second wire can have a fast driving speed. And the other of the first wire and the second wire can have a slow driving speed. In this case, the moving part (e.g., the lens holder) can be moved quickly by a desired moving distance through one of the first wire and the second wire. And the moving part (e.g., the lens holder) can be moved more precisely through the other of the first wire and the second wire. Through these first wires and the second wire, both fast responsiveness and improved accuracy can be provided in autofocusing and / or image stabilization.

[0082] As another example, the first and second wires may be provided to implement different functions. For example, a first wire with a high A atomic ratio (e.g., 8 to 10 at%) may provide a fast driving speed and be applied to optical image stabilization (OIS), while a second wire with a low A atomic ratio (e.g., 5 to 7 at%) may provide precise position control and be applied to autofocus (AF).

[0083] FIG. 6 is a drawing showing the configuration of a drive wire according to an embodiment, FIG. 7 is a drawing showing changes in the configuration of a drive wire of a comparative example and an embodiment at high and low temperatures, and FIG. 8 is a drawing showing the configuration of a drive wire of a comparative example and an embodiment.

[0084] Referring to FIGS. 6 to 8, the drive wire (WI) may correspond to a drive unit, which is a driving means for precisely moving the lens of a camera device. Furthermore, the drive wire (WI) may be formed of a shape memory alloy (SMA). Accordingly, as described above, the drive wire (WI) can contract or restore in a certain direction by thermal stimulation.

[0085] According to an embodiment, the shape memory alloy of the drive wire (WI) may include an alloy containing nickel (Ni), titanium (Ti), and A elements. Furthermore, the drive wire (WI) may be a multi-element alloy to which Li, Be, Mg, Sc, Zn, Ga, Ag, In, Tb, etc. are additionally added.

[0086] And in the embodiment, element A can be at least one of copper (Cu), iron (Fe), cobalt (Co), aluminum (Al), tin (Sn), manganese (Mn), platinum (Pt), and palladium (Pd). For example, Cu can increase lattice stability, and Fe can provide additional magnetic properties.

[0087] Copper (Cu), iron (Fe), cobalt (Co), aluminum (Al), tin (Sn), manganese (Mn), platinum (Pt), and palladium (Pd) can be substituted for Ni in Ti-Ni.

[0088] More specifically, referring to Fig. 7(a), the shape memory alloy made of Ti-Ni as a comparative example maintains a B2 structure, which is a body-centered cubic structure, at high temperatures, but transitions to a B19′ structure, which is a monoclinic structure, at low temperatures. In the case of the comparative example, it undergoes a transformation process into an intermediate phase (R phase) or a B19′ structure at low temperatures.

[0089] These direct phase transformations can cause structurally abrupt crystal lattice (crystal phase) changes and large volume changes. Furthermore, these changes, i.e., the phase transformation process, can induce significant internal stress and energy loss. Furthermore, these rapid phase transformations can ultimately increase hysteresis and degrade response consistency and control precision during repeated operation.

[0090] In contrast, as illustrated in Fig. 7(b), the shape memory alloy of Ti-Ni-Cu, to which element A (copper (Cu)) is applied as an example, can undergo a phase transformation process more gradually than in the comparative example. In other words, copper (Cu) can increase the local stability of the crystal structure by being selectively substituted within the crystal lattice of the shape memory alloy. In other words, it can be seen that the addition of element A (e.g., Cu) replaces the Ni site to increase the local stability within the crystal lattice, and induces a multi-stage phase transformation from B2 →→ to lower the phase transformation energy barrier, thereby dispersing the lattice distortion and volume change to reduce hysteresis. Specifically, as illustrated, the crystal phase or crystal structure can change to the B2 structure (body-centered cubic structure) at high temperatures, and to the B19 or B19' structure (monoclinic crystal structure) at low temperatures. That is, the shape memory alloy according to the embodiment can be configured so that the crystal phase changes from B2 (body-centered cubic, BCC) to B19 (monoclinic) and B19'. In addition, a multi-stage phase transformation can be induced in which the B2 structure transitions to the intermediate B19 structure and finally to the B19' structure during the phase transformation. In this way, in the shape memory alloy according to the embodiment, this step-by-step phase transformation path (B2 →→) can distribute the structural distortion and volume change required for the phase transformation, thereby lowering the overall phase transformation energy barrier. As a result, the shape memory alloy according to the embodiment can have reduced hysteresis. In other words, the phase transformation path can be simplified, thereby increasing the driving efficiency and reducing the hysteresis. Accordingly, the driving wire to which the shape memory alloy is applied can provide repeatable phase transformation characteristics within a narrower temperature range. That is, at high temperatures, it can return to its original length by a restoring force, and at low temperatures, it can be quickly shortened without external stress.

[0091] Furthermore, in shape memory alloys containing copper (Cu), the volume change during phase transformation is relatively small and the continuity of the crystal structure is ensured, allowing for the maintenance of shape resilience and response precision even during repeated thermal cycles. Furthermore, internal stress generated during operation is alleviated, reducing material fatigue and extending the overall operating life.

[0092] Thus, the drive wire according to the embodiment can improve lens alignment accuracy and the stability of the image stabilization function in a camera device. In other words, the shape memory alloy-based drive wire according to the embodiment can be advantageously applied to a camera device that requires precise position control and repetitive deformation recovery.

[0093] Fig. 9 is a drawing showing the stroke according to the temperature of the driving wire of the comparative example and the embodiment, Fig. 10 is a drawing showing the stroke according to the current of the driving wire of the comparative example and the embodiment, and Fig. 11 is a drawing showing the change in hysteresis and stroke according to the content of A in the driving wire.

[0094] Referring to Fig. 9, as described above, the phase transformation and deformation characteristics exhibited by the wires of the Ti-Ni alloy (comparative example) and the Ti-Ni-Cu alloy (example) upon heating and cooling are shown based on the stroke (Y-axis) according to the temperature (X-axis).

[0095] More specifically, in the comparative example, the Ti-Ni shape memory alloy wire can have a phase transformation between the austenite phase and the martensite phase according to a temperature change. In particular, the wire according to the comparative example can have an increased stroke while transforming from the austenite phase to the martensite phase when cooled, and can be restored to its original shape by returning from the martensite phase to the austenite phase when heated again. In this change, the temperature ranges at which the phase transformation starts are different for each heating and cooling process, which causes hysteresis, and the comparative example can have a greater hysteresis than the embodiment. For example, the hysteresis can be expressed as the temperature difference between point a (where transformation starts when heated) and point b (where transformation starts when cooling), and it can be seen that the hysteresis in the comparative example is significantly greater than that in the embodiment.

[0096] In contrast, in the embodiment, it can be seen that the wire of the Ti-Ni-Cu shape memory alloy has a narrower phase transformation temperature range under similar temperature change conditions as the comparative example. As mentioned above, the property improvement can be realized by adding an A element, such as copper (Cu). For example, copper (Cu) can alleviate lattice distortion during the B2 → transformation process by replacing the Ni site in the Ti-Ni lattice, and reduce volume change and energy loss during the phase transformation. Therefore, in the case of the wire according to the embodiment, the phase transformation temperatures during cooling and heating are formed close to each other, so that the hysteresis can be significantly reduced compared to the comparative example. As shown, the temperature difference between points a and b is very small, and this shows that the phase transformation in the wire according to the embodiment occurs more stably within a constant temperature range. Consequently, the wire based on the shape memory alloy according to the embodiment can provide repeatable characteristics of a stroke that are maintained consistently, and can provide improved thermal response sensitivity and enhanced control precision.

[0097] As a result, the Ti-Ni wire corresponding to the comparative example exhibits relatively large hysteresis, resulting in low control responsiveness, while the Ti-Ni-Cu wire corresponding to the exemplary embodiment exhibits reduced hysteresis, enabling fast and precise operation. Therefore, the wire of the exemplary embodiment can be easily applied to modules requiring high driving precision, such as camera lens position control or image stabilization mechanisms.

[0098] Referring to Fig. 10, Fig. 10(a) shows the stroke characteristics (X-axis represents current, Y-axis represents stroke) of a Ti-Ni shape memory alloy wire as a comparative example. In the comparative example, it can be seen that the wire gradually deforms as the current increases, and tends to reach the maximum stroke after reaching a certain current. Furthermore, in the comparative example, it can be seen that the stroke paths when the current is applied and removed are different, and this forms a clear hysteresis. That is, the comparative example can have greater hysteresis than Examples 1 and 2.

[0099] Figure 10(b) shows the characteristics of a Ti-Ni-Cu shape memory alloy wire with 5% Cu, which is Example 1. In the case of Example 1, the overall stroke change pattern is similar to that of the comparative example, but the hysteresis width can be significantly reduced compared to the comparative example. That is, in the case of Example 1, it can be seen that the path difference when the current increases and decreases is reduced, enabling more precise and consistent stroke control.

[0100] Fig. 10(c) shows the characteristics of the Ti-Ni-Cu shape memory alloy wire with 7% Cu, which is Example 2. In the case of Example 2, the characteristics are further improved in stroke and hysteresis. In particular, the stroke response according to the current is very linear, and the hysteresis is reduced to a level where it is almost non-existent. That is, it can be seen that the increase in the amount of copper (Cu) added in Example 2 further improves the lattice stability and minimizes lattice distortion and energy consumption during phase transformation. In addition, since the stroke of the wire is maintained constant under a set current condition, it can be seen that the driving performance optimized for precise control can also be secured.

[0101] Furthermore, referring to Fig. 11, changes in hysteresis and stroke can be seen according to changes in the atomic ratio (at%) of copper (Cu) in the shape memory alloy of the wire. In the embodiment, the content (atomic ratio) of A can be 5 at% to 10 at%. Hereinafter, the content of Cu will be described.

[0102] Specifically, as shown, when the Cu content is between approximately 5 at% and 10 at%, hysteresis gradually decreases, while the stroke tends to increase. In particular, when the Cu content is around 7.5 at%, the stroke is the largest, and the hysteresis remains stable, demonstrating excellent driving characteristics. On the other hand, when the Cu content exceeds 10 at%, the hysteresis remains at a low level, but the stroke tends to decrease again.

[0103] These results demonstrate that when designing the composition of a shape memory alloy, the optimal balance of hysteresis and stroke characteristics can be achieved when the atomic ratio of element A is within the range of 5 to 10 at%, particularly around 7.5 at%. Furthermore, as hysteresis decreases, energy loss during actuation decreases and response speeds can be improved. Simultaneously, increased stroke allows for greater actuation deformation, further improving wire usability.

[0104] Therefore, in this embodiment, by increasing the atomic ratio of element A to 5 at% to 10 at%, the driving performance of the shape memory alloy wire can be optimized.

[0105] Furthermore, in the embodiment, the atomic ratio of Ti may be greater than the atomic ratio of A. Furthermore, the atomic ratio of Ti may be greater than the atomic ratio of Ni. That is, the alloy composition may be configured to contain more nickel (Ni) than element A. As a result, the crystal structure stability and phase transformation characteristics of the alloy can be more effectively maintained.

[0106] Additionally, the atomic ratio of titanium (Ti) in the alloy may be greater than that of element A. Titanium can function as a primary structural element in the lattice structure. That is, titanium plays a key role in the crystal phase transition between martensite and austenite. Therefore, a stable crystal phase transition can be achieved only when element A is substituted in small amounts while maintaining a sufficient titanium content. This ensures excellent stroke performance.

[0107] FIG. 12 is a diagram illustrating an electronic device including a camera device according to an embodiment.

[0108] Referring to FIG. 12, the electronic device may be any one of a mobile phone, a cell phone, a smart phone, a portable communication device, a portable smart device, a digital camera, a laptop computer, a digital broadcasting terminal, a PDA (Personal Digital Assistant), a PMP (Portable Multimedia Player), and a navigation device. However, the type of electronic device is not limited thereto, and any device for taking videos or photos may be included in the electronic device.

[0109] An electronic device may include a body (1). The body (1) may form the exterior of the electronic device. The body (1) may accommodate a camera device (1000). A display (2) may be arranged on one side of the body (1). For example, the display (2) and the camera device (1000) may be arranged on one side of the body (1), and a camera device (1000) may be additionally arranged on the other side of the body (1) (a side located opposite the one side).

[0110] The electronic device may include a display (2). The display (2) may be arranged on one side of the main body (1). The display (2) may output an image captured by the camera device (1000).

[0111] The electronic device may include a camera device (1000). The camera device (1000) may be placed in the main body (1). At least a portion of the camera device (1000) may be accommodated inside the main body (1). The camera device (1000) may be provided in multiple units. The camera device (1000) may include a dual camera device. The camera device (1000) may be placed on one side of the main body (1) and the other side of the main body (1). The camera device (1000) may capture an image of a subject.

[0112] Although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be construed as being included within the scope of the present invention defined in the appended claims.

Claims

1. In a shape memory alloy made of an alloy, The above alloy contains Ni, Ti and A, The above A is a shape memory alloy having an atomic ratio (at%) of 5 to 10.

2. In paragraph 1, A shape memory alloy in which the atomic ratio of Ni is greater than the atomic ratio of A.

3. In paragraph 1, A shape memory alloy in which the atomic ratio of the above Ti is greater than the atomic ratio of the above A.

4. In paragraph 1, A shape memory alloy in which the atomic ratio of the above Ti is greater than the atomic ratio of the above Ni.

5. In paragraph 1, A shape memory alloy configured such that the crystal phase of the above shape memory alloy changes from B2 (body-centered cubic structure, BCC) to B19 (monoclinic crystal structure, Monoclinic) and B19'.

6. In paragraph 1, The above A is a shape memory alloy containing any one of copper (Cu), iron (Fe), cobalt (Co), aluminum (Al), tin (Sn), manganese (Mn), platinum (Pt), and palladium (Pd).

7. Housing; a lens holder disposed inside the housing; and including a driving wire in contact with the housing and the lens holder; The above driving wire comprises an alloy of Ni, Ti and A, The above A is a camera device having an atomic ratio (at%) of 5 to 10.

8. In paragraph 7, A camera device wherein the above drive wire includes a first wire and a second wire.

9. In paragraph 8, A camera device wherein the atomic ratio of A in the first wire is different from the atomic ratio of A in the second wire.

10. In paragraph 8, A camera device in which the first wire and the second wire intersect each other.

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