Camera actuator

Abstract

The present invention relates to a camera actuator and, more specifically, to a camera actuator comprising: a magnet unit in which multiple magnets are formed in a Halbach array; and a yoke in contact with the lower surface, the left surface, and the right surface of the magnet unit. In order to solve the above technical problem, the yoke may be formed of a ferromagnetic material.

Description

Camera actuator

[0001] The present invention relates to a camera actuator, and more specifically, to a camera actuator comprising a magnet assembly including a magnet portion in which a plurality of magnets are formed in a Halbach arrangement and a yoke that contacts the lower surface and left and right sides of the magnet portion.

[0002] The actuator used in a camera module is a driving device that moves the lens to the optimal focus position to achieve sharp image quality by magnifying or reducing the subject during shooting. As smartphone camera modules evolve, they are now used as common mobile components.

[0003] Voice coil motor (VCM) actuators utilize coils and electromagnets to implement lens movement. In the VCM method, the magnetic force (magnetic flux density) of the magnet determines the driving force of the actuator; therefore, a magnet with strong magnetic force is an essential and important component.

[0004] Figure 1 is an exploded perspective view showing an actuator of a camera module.

[0005] The actuator of the camera module performs a focusing operation to enlarge or reduce the subject and focus by varying the position of the lens assembly (200) to adjust the distance between the image sensor and the lens.

[0006] Referring to FIG. 1, a coil portion (1700) is mounted on the housing (1100) of an actuator, and a magnet assembly (100) is installed facing the coil portion (1700).

[0007] When current flows through the coil portion (1700) located within the magnetic field formed by the magnet assembly (100), a Lorentz force is generated, and the magnet assembly (100) is driven.

[0008] As the magnitude of the magnetic field radiated in the direction of the coil portion (1700) increases, the driving force of the magnet assembly (100) increases, and thus the driving force of the lens assembly (200) fixed to the magnet assembly (100) also increases. At this time, the magnetic field radiated in the opposite direction to the direction of the coil portion (1700) may cause interference with the operation of other magnets or other electronic components.

[0009] As such, appropriate amplification or shielding according to the radiation direction of the magnetic field of the magnet assembly (100) is important for the performance of the actuator.

[0010] The driving force (F) applied to the magnet assembly (100) is obtained according to the following formula.

[0011] F (driving force) = B (magnetic force) × I (current) × L (coil length)

[0012] That is, the driving force (F) is proportional to the magnitude (I) of the current applied to the coil section (1700), the length (L) of the coil section (1700), and the magnetic force (B) of the magnet assembly (100).

[0013] In line with the increasing performance requirements of camera modules in recent years, the lens assembly (200) may include multiple lens assemblies, and as the size of the image sensor increases, the actuator requires a greater driving force.

[0014] In order to increase the current applied to the coil section (1700), power consumption increases, and in order to increase the length of the coil section (1700), the coil section (1700) becomes larger, so the size of the camera module must be increased. Therefore, the most desirable method to increase the driving force is to increase the magnetic force while maintaining the size of the magnet assembly (100).

[0015] However, as the magnetic force of the magnet increases, there is a concern about magnetic interference between magnets or between actuators, so magnetic field control technology is required that considers not only magnetic field amplification in the direction where a large magnetic field is needed but also magnetic field shielding in the direction where a magnetic field is not needed.

[0016] FIG. 2 is a drawing showing a conventional magnet assembly, where (a) is a perspective view, (b) is a plan view, and (c) is a front view.

[0017] Referring to FIG. 2, the device includes a rectangular magnet part (1400) having an upper surface and a lower surface with different polarities, and a yoke (1800) in contact with the lower surface of the magnet part (1400), wherein the yoke (1800) is formed of a magnetic material.

[0018] When a yoke (1800) is formed using a magnetic material at the bottom of the magnet part (1400), the magnetic flux density in the direction where the yoke (1800) is not attached increases, and the magnetic flux density in the direction where the yoke (1800) is attached decreases. For example, the yoke (1800) is formed using SUS430, a type of stainless steel. SUS430 is a ferritic stainless steel that contains chromium (Cr) and possesses magnetism, so it is widely used as a material for forming the yoke (1800).

[0019] As the yoke (1800) absorbs magnetic field lines, it shields the magnetic force in the direction to which the yoke (1800) is attached and amplifies the magnetic force in the direction not to which the yoke (1800) is attached.

[0020] However, the magnetic field at the edge portion of the magnet part (1400) where the magnetic flux density is concentrated cannot be controlled, and there are limitations to shielding and amplification due to the low saturation magnetic flux density of stainless steel, SUS430.

[0021] It is necessary to develop technology that can provide a camera actuator capable of increasing the driving force for moving the lens by improving these problems and amplifying the magnetic flux in areas requiring strong magnetic flux.

[0022] The technical problem that the present invention aims to solve is to provide a camera actuator capable of moving a lens with a strong driving force by forming a magnet assembly that maintains the size of a conventional magnet assembly, amplifies the magnetic flux in areas where strong magnetic flux is required, and shields the magnetic flux in areas where it is not required to be lower.

[0023] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0024] A camera actuator of the present invention for solving the above technical problem comprises a housing, a first lens assembly and a second lens assembly that move along the optical axis direction within the housing, a first magnet assembly and a second magnet assembly respectively disposed on the first lens assembly and the second lens assembly, and a coil portion that drives the magnet assembly, wherein the first magnet assembly and the second magnet assembly comprise a magnet portion formed by arranging a plurality of magnets in a Halbach arrangement and a yoke that contacts at least a portion of the lower surface and side surface of the magnet portion, and the yoke is formed of a ferromagnetic material.

[0025] In some embodiments of the present invention, the yoke may include a flat plate in contact with the lower surface of the magnet part and a reinforcing part in contact with the side of the magnet part, and the upper end of the reinforcing part may be characterized by coinciding with the upper surface of the magnet part.

[0026] In some embodiments of the present invention, the yoke may be formed of a CoFe alloy.

[0027] In some embodiments of the present invention, the content of Co in the CoFe alloy may be 27% or more by weight.

[0028] In some embodiments of the present invention, the yoke may be formed of pure iron.

[0029] In some embodiments of the present invention, the carbon content of the pure iron may be 0.02% or less by weight.

[0030] In some embodiments of the present invention, the yoke may be formed of iron containing Si.

[0031] In some embodiments of the present invention, the content of Si may be 3% or less by weight.

[0032] In some embodiments of the present invention, one or more of the magnets may be characterized by having polarity divided diagonally.

[0033] According to the camera actuator of the present invention, a magnet assembly is included in which a magnet portion is formed by a Halbach arrangement of magnets and the structure and material of a yoke attached to the magnet portion are modified. This allows the magnetic field at the edge portion of the magnet portion to be reduced, the magnetic flux in areas requiring strong magnetic flux to be amplified, and the magnetic flux in areas not requiring strong magnetic flux to be shielded at a lower level. Therefore, the camera actuator can drive multiple lens modules with a stronger driving force using the same current and coil of the same size. Furthermore, despite the increased magnetic force of the magnet portion, magnetic interference that causes interference with the operation of other magnets or other components can be prevented due to the improved shielding rate.

[0034] Figure 1 is an exploded perspective view showing an actuator of a camera module.

[0035] Figure 2 is a drawing showing a conventional magnet assembly.

[0036] Figure 3 is a diagram showing the magnetic flux of the magnet part of the Halbach array.

[0037] Figure 4 is a diagram showing the amplification rate of the magnet part of the Halbach array.

[0038] Figure 5 is a diagram showing the shielding rate of the magnet part of the Halbach array.

[0039] FIG. 6 is a drawing showing a yoke according to one embodiment of the present invention.

[0040] Figure 7 is a diagram showing the magnetic field strength of the magnet part.

[0041] Figure 8 is a diagram showing the magnetic flux density by shielding material of the yoke.

[0042] FIG. 9 is a diagram showing the distribution of magnetic flux density with a yoke applied according to one embodiment of the present invention.

[0043] FIG. 10 is a drawing showing a magnet assembly according to one embodiment of the present invention.

[0044] FIG. 11 is a perspective view of a camera actuator according to one embodiment of the present invention.

[0045] Figure 12 is a cross-sectional view cut along BB' in Figure 11.

[0046] FIG. 13 is a perspective view showing the driving components of the actuator according to FIG. 11.

[0047] FIG. 14 is a diagram showing the thrust of an actuator according to one embodiment of the present invention.

[0048] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0049] "And / or" includes each of the mentioned items and all combinations of one or more.

[0050] The terms used herein are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprising" and / or "comprising" does not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0051] Furthermore, throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly" or "electrically connected" with other members or elements interposed between them.

[0052] Additionally, throughout the specification, the description that each layer (film), region, pattern, or structure is formed "on" or "under" the substrate, each layer (film), region, pad, or pattern includes both direct formation and formation through another layer. The criteria for "on" or "under" each layer are described based on the drawings.

[0053] Furthermore, expressions such as 'first, second,' etc., are used solely to distinguish multiple compositions and do not limit the order or other characteristics between the compositions.

[0054] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0055] Hereinafter, a magnet assembly according to an embodiment of the present invention will be described with reference to the drawings.

[0056] In the magnet assembly of FIGS. 3 to 10, the positive direction of the Z-axis is set to the upward direction and the negative direction to the downward direction, the positive direction of the X-axis is set to the right and the negative direction to the left, and the negative direction of the Y-axis is set to the forward direction and the positive direction to the rear.

[0057] This explains how the magnetic flux of a magnet section formed by arranging multiple magnets in a Halbach array is amplified and shielded.

[0058] FIG. 3 is a diagram showing the magnetic flux of the magnet portion of a Halbach array, (a) a conventional magnet formed with one rod magnet (1419), (b) a magnet portion (1400) formed by rotating it 90 degrees in a Halbach array in the present invention, and (c) a magnet portion (1400) formed by arranging it in a Halbach array so that the polarity is divided diagonally in the present invention, each showing the distribution of magnetic flux density.

[0059] Referring to FIG. 3 (b) and (c), a Halbach arrangement can be formed by arranging a plurality of magnets (1411 to 1415) in a first direction (e.g., the x-axis of FIG. 3) so that the magnets (1411 to 1415) are rotated counterclockwise (or clockwise) along the first direction. Additionally, the upper surface of each magnet (1411 to 1415) can be arranged such that the polarity (S, N) is the same as the upper surface of any one of the magnets (1411 to 1415) adjacent in the first direction. Furthermore, the lower surface of each magnet (1411 to 1415) is characterized by being arranged such that the polarity (S, N) is different from the lower surface of any one of the magnets (1411 to 1415) adjacent in the first direction. In this case, if the upper surface or the lower surface includes two polarities, the upper surface or the lower surface may refer to a portion of the area that contacts another magnet in the first direction.

[0060] To explain using the case of FIG. 3(b) as an example, the N pole is located on the upper surface of the third magnet (1413), and the N pole is located in the same area on the upper surface of the second magnet (1412) adjacent to one side of the third magnet (1413) that is in contact with the upper surface of the third magnet (1413). At the same time, the N pole is located in the same area on the upper surface of the fourth magnet (1414) adjacent to the other side of the third magnet (1413) that is in contact with the upper surface of the third magnet (1413). Therefore, the second to fourth magnets (1412 to 1414) can be formed in a shape where N poles are gathered on the upper surface and arranged in a Halbach arrangement.

[0061] Referring to FIG. 3, the polarity of the magnets (1411 to 1415) can be indicated by arrows, with the tail end of the arrow indicating the N pole and the head end indicating the S pole. In the case of FIG. 3 (b), the first magnet (1411) and the fifth magnet (1415) are magnetized in one direction of the z-axis, the second magnet (1412) is magnetized in the other direction of the x-axis, the third magnet (1413) is magnetized in the other direction of the z-axis, and the fourth magnet (1414) is magnetized in one direction of the x-axis, thereby maintaining the Hal Hag arrangement.

[0062] In the case of Fig. 3(c), the first magnet (1411) and the fifth magnet (1415) are magnetized in one direction of the z-axis, the second magnet (1412) is magnetized in the other direction dividing the x-axis and z-axis in half, the third magnet (1413) is magnetized in the other direction of the z-axis, and the fourth magnet (1414) is magnetized in one direction dividing the x-axis and z-axis in half, so that they can be arranged in a Halbach array.

[0063] When comparing the magnet section (1400), formed by arranging multiple magnets in a Halbach array as described above, with a conventional rod magnet (1419), it can be confirmed that the magnetic field at the top of the magnet section (1400) is amplified and the magnetic field at the bottom is reduced. The magnetic field at the top can be increased by the same amount as the magnetic field at the bottom is reduced.

[0064] In this way, magnetic flux can be amplified and shielded by a magnet part (1400) formed with a Halbach array of magnets.

[0065] Meanwhile, although it has been illustrated and described that five magnets (1411 to 1415) form the magnet portion (1400), the present disclosure is not limited thereto. Specifically, the magnet portion (1400) may include fewer or more magnets than five.

[0066] Referring to FIG. 3(a), the magnetic field strength distribution of a conventional rod magnet (1419) is shown to be distributed in equal size on the upper and lower surfaces of the rod magnet (1419).

[0067] Referring to FIG. 3(b), the magnetic field strength distribution of the magnet section (1400), formed by arranging the first magnet (1411) to the fifth magnet (1415) by rotating them 90 degrees each, is shown to be distributed with a larger size on the upper surface and a smaller size on the lower surface. However, it shows that it is not flat due to a large difference in amplification.

[0068] Referring to FIG. 3(c), the magnetic field strength distribution of the magnet section (1400) can be observed by rotating the first magnet (1411) to the fifth magnet (1415) to form a Halbach array, while arranging the second magnet (1412) and the fourth magnet (1414) so ​​that their polarities are divided diagonally. As in FIG. 3(b), the magnetic field strength distribution is distributed with a larger magnitude on the upper surface of the magnet section (1400) and with a smaller magnitude on the lower surface. However, the difference in amplification is not large, and it exhibits flatter characteristics.

[0069] Figure 4 is a diagram showing the amplification rate of a magnet section formed by a Halbach array, where the horizontal axis represents the length in the horizontal direction (X-axis direction) where the magnet section is installed in mm, and the vertical axis represents the magnetic flux density measured in mT at a position spaced 5 mm upward (positive Z-axis direction) from the magnet section.

[0070] At this time, the dotted line represents the case of a conventional rod magnet (1419), the solid line represents the magnetic flux density of a magnet part (1400) rotated by 90 degrees, and the dotted line represents the magnetic flux density of a magnet part (1400) in which the polarity is divided diagonally.

[0071] Referring to FIG. 4, it can be seen that the magnetic flux density is amplified more significantly in the case of a magnet part (1400) rotated by 90 degrees (solid line) or a magnet part (1400) with polarity divided diagonally (dotted line) compared to the case formed by a conventional rod magnet (1419).

[0072] However, it can be seen that in the case of the magnet part (1400) in which the polarity is divided diagonally (dotted line), the maximum amplification is lower than in the case of the magnet part (1400) rotated by 90 degrees (solid line), and instead, the difference between the maximum amplification and the minimum amplification is reduced, resulting in a flat amplification. Such a flat amplification is advantageous for enabling the actuator to be driven with a constant thrust during the operating range.

[0073] Figure 5 is a diagram showing the shielding rate of a magnet section formed by a Halbach array, where the horizontal axis represents the length in the horizontal direction (X-axis direction) where the magnet section is installed in mm, and the vertical axis represents the magnetic flux density measured in mT at a position spaced 5 mm downward (negative Z-axis direction) from the magnet section.

[0074] At this time, the dotted line represents the case of a conventional single rod magnet (1419), the solid line represents the magnet part (1400) rotated by 90 degrees, and the dotted line represents the magnetic flux density in the case of a magnet part (1400) in which the polarity is divided diagonally.

[0075] Referring to FIG. 5, it can be seen that the magnetic flux density is reduced more in the case of a magnet part (1400) rotated by 90 degrees (solid line) or a magnet part (1400) with polarity divided diagonally (dotted line) than in the case of a conventional rod magnet (1419) (dotted line), and thus the shielding effect is greater than that of a conventional rod magnet (1419).

[0076] When compared to the shielding rate of the case where a yoke (1800) is formed with a steel shielding material (SU 430) on a rod magnet (1419) as in the case of (a) of FIG. 3, where a stainless steel shielding material (SUS 430) with a thickness of 0.2 mm is added as indicated by the thick solid line, it can be confirmed that the two cases in which the magnet part (1400) is formed in a Halbach arrangement have a superior shielding effect compared to the case in which a stainless steel shielding material (SUS 430) is added.

[0077] Next, the shape and material of the yoke (1800) are analyzed to determine the effect of magnetic flux amplification and shielding, and the process of forming the yoke (1800) according to an embodiment of the present invention is explained.

[0078] FIG. 6 is a drawing showing a yoke according to one embodiment of the present invention, where (a) is a perspective view, (b) is a plan view, and (c) is a front view.

[0079] Referring to FIG. 6, the yoke (1800) according to the present invention may be formed of a ferromagnetic material, with the upper surface and the lower surface in contact with at least one surface of the magnet part (1400) having different polarities. At this time, in order to compare the amplification and shielding effects according to the structure and material of the yoke (1800), the magnetic force is compared by applying a conventional rod magnet to the magnet part (1400) as a reference.

[0080] The yoke (1800) may be characterized by including a flat plate that contacts the lower surface of the magnet part (1400) and a reinforcing part that contacts the side of the magnet part (1400), and the upper end of the reinforcing part may be aligned with the upper surface of the rod magnet part (1400).

[0081] The reinforcing portion of the yoke (1800) can be formed by wrapping both end surfaces in the length direction (X-axis direction) of the magnet portion (1400) and bending in the height direction (Z-axis direction), and the height of the reinforcing portion can be formed to be equal to the height of the magnet portion (1400).

[0082] Accordingly, the yoke (1800) can be formed in the shape of a cuboid that opens three sides, including the top, front, and back of the magnet part (1400), and contacts the remaining three sides. At this time, the magnetic flux density in the direction toward the open side can be amplified, and the magnetic flux density in the direction toward the contact side can be reduced.

[0083] As described above, the conventional yoke (1800) is formed of a stainless steel shielding material (SUS 430) that contacts the lower surface of a rod magnet (1419) having different polarities on its upper and lower surfaces. The conventional yoke (1800) is formed only as a flat plate that contacts the lower surface of the rod magnet (1419) and does not include a reinforcing part that contacts the side of the rod magnet (1419).

[0084] A conventional magnet assembly (100) is formed by combining a rod magnet (1419) with a width, length, and height of 9.6 mm, 2.2 mm, and 0.8 mm, respectively, and a yoke (1800) with a width, length, and height of 9.6 mm, 2.2 mm, and 0.2 mm, respectively, into a rectangular prism shape with a width, length, and height of 9.6 mm, 2.2 mm, and 1.0 mm, respectively.

[0085] A magnet assembly (100) according to an embodiment of the present invention may be formed into a rectangular prism shape having width, length, and height of 9.6 mm, 2.2 mm, and 1.0 mm, respectively, by combining a magnet part (1400) having width, length, and height of 6.6 mm, 2.2 mm, and 0.8 mm, respectively, a flat plate having width, length, and height of 9.6 mm, 2.2 mm, and 0.2 mm, respectively, and reinforcing parts having width, length, and height of 1.45 mm, 2.2 mm, and 0.8 mm, respectively, at both ends of the flat plate. Meanwhile, the width, length, and height of the magnet assembly (100) according to an embodiment of the present invention are not limited to the examples described above, and it is sufficient that the width of the magnet assembly (100) is greater than the length and the length is greater than the height.

[0086] That is, compared to a conventional magnet assembly (100), the horizontal length of the magnet part (1400) is reduced by 3 mm, and a reinforcing part of 1.45 mm is added to each end of the reduced magnet part (1400). Therefore, the size of the magnet assembly (100) according to the embodiment of the present invention can be maintained at the same size as the conventional magnet assembly (100).

[0087] The yoke (1800) according to the present invention may be formed of a magnetic material capable of exhibiting a shielding effect, but preferably may be formed of a ferromagnetic material capable of enhancing the shielding effect.

[0088] That is, the stainless steel shielding material used as the yoke of the conventional magnet assembly (formed from a material having a higher saturation magnetic flux density than SUS 430) can amplify the magnetic flux density and increase the strength of the shielding.

[0089] Ferromagnetic materials can be used as shielding materials by concentrating magnetic flux within the material to prevent the influence of the magnetic field from reaching other areas.

[0090] The magnetic shielding rate follows the formula below.

[0091] Magnetic shielding rate ∝ Permeability x Thickness

[0092] As such, the higher the permeability of the shielding material, the higher the shielding rate, and the thicker the shielding material, the higher the shielding rate.

[0093] The objective of the present invention is to increase the amplification of magnetic flux density and the shielding effect compared to a conventional magnet assembly, so a yoke (1800) can be formed using a material having a higher permeability than a conventional shielding material.

[0094] Figure 7 is a diagram showing the magnetic field strength of the magnet part.

[0095] Referring to FIG. 7, it can be seen that the magnetic field strength around the rod magnet (1419) is formed in the shape of contour lines centered on the two ends of the rod magnet (1419), the N pole or the S pole.

[0096] Point “A” in Fig. 7 is a location where a magnetic field of 100 kA / M is formed, and point “B” is a location where a magnetic field of 50 kA / M is formed.

[0097] Figure 8 is a diagram showing the magnetic flux density by shielding material of the yoke.

[0098] Referring to Fig. 8, the horizontal axis represents the strength of the formed magnetic field in units of A / m, and the vertical axis represents the strength of the magnetic field formed by the magnetic field and the magnetization of the shielding material in units of Tesla. This is a BH graph.

[0099] When a yoke is formed for each shielding material at a location where a magnetic field of 50 kA / M is formed, for example, at the location marked “B” in FIG. 7, the magnetic flux density amplified by the rod magnet (1419) and the yoke (1800) can be compared.

[0100] Referring to the first graph (solid line) from the top, a CoFe alloy containing 49% by weight of Co (cobalt) exhibits a magnetic flux density of 2.3T at a location where a magnetic field of 50kA / M is formed.

[0101] In this case, as the amount of Co increases, the permeability increases, leading to a higher magnetic flux density. This is advantageous for securing amplification and shielding effects, but it may increase costs. According to experiments, a CoFe alloy containing 27% by weight of Co exhibits a magnetic flux density of 2.2T at a location where a magnetic field of 50kA / M is formed.

[0102] Referring to the second graph from the top (dotted line), pure iron exhibits a magnetic flux density of 2.1T at the location where a magnetic field of 50kA / M is formed.

[0103] At this time, the lower the carbon (C) content, the higher the permeability of the pure iron, which increases the magnetic flux density. This is advantageous for securing amplification and shielding effects, but it makes manufacturing difficult and may increase manufacturing costs. Since a magnetic flux density of 2.1T is exhibited when carbon (C) is included in an amount of 0.02% or less by weight, it is desirable to include the above amount of 0.02% or less by weight.

[0104] Referring to the third graph from the top (dotted line), steel containing 3% by weight of Si exhibits a magnetic flux density of 2.0 T at a location where a magnetic field of 50 kA / M is formed.

[0105] At this time, the lower the Si (silicon) content, the higher the permeability and thus the higher the magnetic flux density, which is advantageous for securing amplification and shielding effects, but may increase costs. Since a magnetic flux density of 2.0T is exhibited when Si (silicon) is included in an amount of 3% or less by weight, it is desirable to include the above amount of 3% or less by weight.

[0106] Referring to the fourth graph from the top (dotted line), it shows a case where the shielding material is formed with a conventional stainless steel shielding material (SUS 430), and shows a magnetic flux density of 1.6T at a location where a magnetic field of 50kA / M is formed.

[0107] As such, it can be confirmed that the magnetic flux density of the material adopted as an embodiment of the present invention is significantly higher than that of the stainless steel shielding material (SUS 430) used as a conventional shielding material, and therefore the yoke according to the present invention can have a high shielding effect and amplification degree.

[0108] FIG. 9 is a diagram showing the distribution of magnetic flux density with a yoke applied according to one embodiment of the present invention, where (a) shows an amplification effect and (b) shows a shielding effect.

[0109] Referring to Figure 9 (a), the horizontal axis represents the length in the horizontal direction (X-axis direction) where the magnet is installed in mm, and the vertical axis represents the magnetic flux density measured in mT at a position 5 mm above (positive Z-axis direction) from the magnet (M).

[0110] In this case, the dotted line represents a conventional magnet assembly, and the solid line represents a magnet assembly according to an embodiment of the present invention.

[0111] When comparing the graphs of the dotted and solid lines, it can be seen that the magnetic assembly according to the embodiment of the present invention has a magnetic flux density that is about 8.4% stronger than that of a conventional magnetic assembly.

[0112] In particular, by controlling the magnetic field concentrated at both ends of the magnet assembly (100) according to the purpose, it can be confirmed that the magnetic flux density near the unnecessary ends is low, and a section of 6 mm or more is secured in the middle part where amplified magnetic flux density is required. In the actuator to which the magnet assembly (100) according to the present invention is applied, the driving distance of the magnet assembly (100) is 5 to 6 mm, so stable driving of the actuator is possible.

[0113] Referring to Figure 9 (b), the horizontal axis represents the length in the horizontal direction (X-axis direction) where the magnet is installed in mm, and the vertical axis represents the magnetic flux density measured in mT at a position 5 mm away from the magnet (M) downward (negative Z-axis direction).

[0114] In this case, the dotted line represents a conventional magnet assembly, and the solid line represents a magnet assembly according to an embodiment of the present invention.

[0115] When comparing the graphs of the dotted and solid lines, it can be seen that the magnet assembly according to the embodiment of the present invention has an improved shielding effect, with the magnetic flux density reduced by about 15% compared to a conventional magnet assembly.

[0116] The dimensions of the conventional magnet part (1400) are 9.6 mm in width, 2.2 mm in height, and 0.8 mm in depth, respectively, and the dimensions of the magnet part (1400) according to the embodiment of the present invention are 6.6 mm in width, 2.2 mm in depth, and 0.8 mm in depth, respectively, so the size of the magnet part (1400) is reduced by about 30%.

[0117] However, by reinforcing the magnetic flux of the magnet part (1400) and simultaneously reinforcing the shape and material of the yoke (1800) to maintain its size, a magnet assembly (100) can be obtained that achieves amplification and shielding effects that are significantly improved compared to a conventional magnet assembly (100).

[0118] As described above, a magnet assembly can be formed by applying a yoke with improved shape and material to amplify and shield magnetic flux.

[0119] Furthermore, by forming a magnet assembly that incorporates a magnet section with a Halbach array of magnets into a yoke with improved shape and material, greater magnetic flux amplification and shielding can be obtained. A magnet assembly incorporating both of these features will be explained with reference to the drawings.

[0120] FIG. 10 is a drawing showing a magnet assembly according to one embodiment of the present invention, where (a) is a perspective view, (b) is a plan view, and (c) is a front view.

[0121] Referring to FIG. 10, a magnet assembly (100) according to the present invention comprises a magnet part (1400) in which a plurality of magnets (1411 to 1413) are formed in the shape of a cuboid, and a yoke (1800) that contacts the lower surface, left side, and right side of the magnet part (1400), and the yoke (1800) may be formed of a ferromagnetic material.

[0122] The magnet section (1400) may be formed by arranging a plurality of magnets (1411 to 1413) in a Halbach array to enhance amplification and shielding.

[0123] The magnet according to the present invention can be applied to all types of magnets, including general magnets, but it is preferable to use a neodymium magnet, which is a powerful permanent magnet.

[0124] A neodymium magnet is a magnet made by alloying neodymium, boron, and iron in a ratio of 2:1:14 using a sintering method. Meanwhile, the composition ratio of the neodymium magnet is not limited to the examples described above, and it goes without saying that the present disclosure can also be applied to neodymium magnets having different composition ratios.

[0125] The magnet portion (1400) according to the present invention may include a plurality of magnets (1411 to 1413) having a Halbach array as shown in FIG. 10.

[0126] The magnet portion (1400) is characterized by having a second magnet (1412) with polarity divided in the vertical direction (e.g., the z-axis direction of (c) of FIG. 10) and a first magnet (1411) and a third magnet (1413) with polarity divided in the diagonal direction (e.g., the horizontal direction on a plane consisting of the x-axis and z-axis of (c) of FIG. 10) arranged on both sides of the second magnet (1412) (e.g., the sides in the x-axis direction of (c) of FIG. 10).

[0127] Referring to Fig. 10 (c), the lower surface of the magnet part (1400) may have the N pole of the first to third magnets (1411 to 1413) formed thereon, and the upper surface of the magnet part (1400) may have the S pole of the first to third magnets (1411 to 1413) formed thereon.

[0128] The magnet part (1400) may have various shapes, but preferably, it may be formed in the shape of a cuboid plate to form a strong magnetic flux with a constant intensity in the space where the actuator moves in a straight line.

[0129] In one embodiment, the horizontal length of the second magnet (1412) (e.g., the x-axis direction of FIG. 10(a)) may be 5 to 15 times longer than the horizontal length of the first magnet (1411) and the third magnet (1413). The horizontal lengths of the first magnet (1411) and the third magnet (1413) may be equal to each other. And the vertical length of the second magnet (1412) (e.g., the y-axis direction of FIG. 10(a)) may be equal to the vertical length of the first magnet (1411) and the third magnet (1413). And the height direction of the second magnet (1412) (e.g., the z-axis direction of FIG. 10(a)) may be the same as the height direction of the first magnet (1411) and the third magnet (1413).

[0130] The above yoke (1800) may be characterized by including a flat plate that contacts the lower surface of the magnet part (1400) and a reinforcing part that contacts the side of the magnet part (1400), and the upper end of the reinforcing part may coincide with the upper surface of the magnet part (1400).

[0131] The reinforcing portion of the yoke (1800) can be formed by wrapping both end surfaces along the longitudinal direction (X-axis direction) of the magnet portion (1400) and bending upward (Z-axis direction), and the height of the reinforcing portion can be formed to be equal to the height of the magnet portion (1400).

[0132] Accordingly, the yoke (1800) may be a hollow cuboid shape that opens three sides, including the top, front, and back of the magnet part (1400), and contacts the remaining three sides. At this time, the magnetic flux density in the direction toward the open side can be amplified, and the magnetic flux density in the direction toward the contact side can be reduced to shield it.

[0133] Next, an embodiment of a camera actuator with a magnet part according to an embodiment of the present invention will be described with reference to the drawings.

[0134] FIG. 11 is a perspective view of a camera actuator according to one embodiment of the present invention, FIG. 12 is a cross-sectional view cut along BB' in FIG. 11, and FIG. 13 is a perspective view showing a driving-related component of the actuator according to FIG. 11.

[0135] In FIGS. 11 to 13, the first direction is the X-axis direction in the drawings, and the second direction is the Y-axis direction in the drawings. The second direction is perpendicular to the first direction. Also, the third direction is the Z-axis direction in the drawings. It is a direction perpendicular to both the first direction and the second direction. Here, the third direction (Z-axis direction) corresponds to the direction of the optical axis, and the first direction (X-axis direction) and the second direction (Y-axis direction) are directions perpendicular to the optical axis. Additionally, in the following description of the camera actuator (1000), the optical axis direction corresponds to the optical path and is the third direction (Z-axis direction).

[0136] Referring to FIGS. 11 to 13, the actuator for a camera according to the present invention comprises a housing (1100), a first lens assembly (1200) and a second lens assembly (1300) that move along the optical axis direction within the housing (1100), a first magnet assembly (100a) and a second magnet assembly (100b) respectively disposed on the first lens assembly (1200) and the second lens assembly (1300); and a coil portion (1700) that drives the magnet assembly (100), wherein the magnet assembly (100) may include a magnet portion (1400) formed by arranging a plurality of magnets in a Halbach arrangement and a yoke (1800) that contacts the lower surface and side surface of the magnet portion (1400).

[0137] A first magnet assembly (100a) disposed on the first lens assembly (1200) may be formed by combining a first magnet part (1410) and a first yoke (1810), and a second magnet assembly (100b) disposed on the second lens assembly (1300) may be formed by combining a second magnet part (1420) and a second yoke (1820).

[0138] A camera actuator (1000) according to an embodiment may include a housing (1100), a first lens assembly (1200), a second lens assembly (1300), a magnet part (1400), a substrate (1500), a housing cover (1600), a coil part (1700), a yoke (1800), and a stopper part (S).

[0139] The housing (1100) may form the outer wall of the camera actuator (1000). A housing cover (1600) may be placed on one side of the housing (1100). Inside the housing (1100), a first lens assembly (1200), a second lens assembly (1300), a magnet part (1400), a coil part (1700), a yoke (1800), and a stopper part (S) may be included.

[0140] A magnet portion (1400), a coil portion (1700), and a yoke (1800) may be disposed on a side parallel to the optical axis direction of the housing (1100). A surface perpendicular to the optical axis direction of the housing (1100) may include an opening. A substrate (1500) may be disposed on the outside of the housing (1100).

[0141] A camera actuator (1000) according to an embodiment may include a first lens assembly (1200) and a second lens assembly (1300).

[0142] The first lens assembly (1200) and the second lens assembly (1300) may be moving lenses that move through a coil, a magnet, and a guide pin.

[0143] The second lens assembly (1300) can perform the function of a variantr that re-forms the image formed by focusing light into another location. Meanwhile, the distance to the subject or the image distance may change significantly in the second lens assembly (1300), resulting in a large change in magnification, and the second lens assembly (1300), as a variantr, can play an important role in the change in focal length or magnification of the optical system.

[0144] Meanwhile, the image formed by the second lens assembly (1300), which is a variable, may differ slightly depending on the position. Accordingly, the first lens assembly (1200) can perform a position compensation function for the image formed by the variable. For example, the first lens assembly (1200) can perform a compensator function that accurately forms the image formed by the second lens assembly (1300), which is a variable, at the actual image sensor position. For example, the first lens assembly (1200) and the second lens assembly (1300) can be driven by electromagnetic force resulting from the interaction between a coil and a magnet.

[0145] The first lens assembly (1200) and the second lens assembly (1300) can be placed inside the housing (1100).

[0146] The first lens assembly (1200) and the second lens assembly (1300) can move along the optical axis direction inside the housing (1100) by means of the magnet part (1400), the yoke (1800), and the coil part (1700).

[0147] The first lens assembly (1200) and the second lens assembly (1300) may be spaced apart from each other along the optical axis direction. The first lens assembly (1200) and the second lens assembly (1300) may partially overlap with the stopper portion (S) in the optical axis direction. The first lens assembly (1200) and the second lens assembly (1300) may partially overlap with the housing cover (1600) in the optical axis direction.

[0148] The first lens assembly (1200) can be driven by a first magnet assembly (100a) in which a first magnet part (1410) and a first yoke (1810) are combined. The first lens assembly (1200) can be coupled to the first yoke (1810). The first lens assembly (1200) is coupled to the first yoke (1810), and the first magnet part (1410) is coupled to the first yoke (1810), so that the first magnet part (1410) can be fixed to the first lens assembly (1200). The first lens assembly (1200) can be superimposed with the coil part (1700) in a first direction perpendicular to the optical axis direction. The first lens assembly (1200) can be overlapped in the optical axis direction with the first stopper (S1), the third stopper (S3), and the fifth stopper (S5).

[0149] The second lens assembly (1300) can be driven by a second magnet assembly (100b) in which the second magnet part (1420) and the second yoke (1820) are combined. The second lens assembly (1300) can be coupled with the second yoke (1820). The second lens assembly (1300) is coupled with the second yoke (1820), and the second magnet part (1420) is coupled to the second yoke (1820), so that the second magnet part (1420) can be fixed to the second lens assembly (1300). The second lens assembly (1300) can be overlapped with the coil part (1700) in a first direction perpendicular to the optical axis direction. The second lens assembly (1300) can be overlapped with the second stopper (S2) and the fourth stopper (S4) in the optical axis direction.

[0150] The camera actuator (1000) according to the embodiment may include a substrate (1500).

[0151] A substrate (1500) may be placed in a housing (1100). A substrate (1500) may be placed on the outside of the housing (1100). A driver IC (not shown) and a coil section (1700) may be placed on the substrate (1500). A driver IC and a coil section (1700) may be placed on the inside of the substrate (1500). The substrate (1500) may fix the driver IC and the coil section (1700). The substrate (1500) may transmit information of an optical signal from the driver IC to the coil section (1700).

[0152] The substrate (1500) may include a first sub-substrate (1510), a second sub-substrate (1520), and a third sub-substrate (1530).

[0153] A first sub-substrate (1510) may be placed on the side of the housing (1100). The first sub-substrate (1510) may be placed in the optical axis direction and a second direction. A second sub-substrate (1520) may be placed on the upper surface of the housing. The second sub-substrate (1520) may be placed in the optical axis direction and a first direction. A third sub-substrate (1530) may be placed on the side of the housing (1100). The third sub-substrate (1530) may be placed in the optical axis direction and a second direction. The first sub-substrate (1510) and the third sub-substrate (1530) may be placed parallel to each other. The first sub-substrate (1510) and the third sub-substrate (1530) may be placed perpendicular to the second sub-substrate (1520). A coil portion (1700) may be placed on the first sub-substrate (1510) and the third sub-substrate (1530).

[0154] The camera actuator (1000) according to the embodiment may include a housing cover (1600).

[0155] The housing cover (1600) may be fixedly positioned on one side of the housing (1100). The housing cover (1600) may overlap with the housing (1100) in the direction of the optical axis. A first stopper part (Sa) may be positioned on the housing cover (1600).

[0156] The housing cover (1600) may partially overlap with the first lens assembly (1200) and the second lens assembly (1300) in the direction of the optical axis.

[0157] The camera actuator (1000) according to the embodiment may include a stopper part (S).

[0158] The stopper part (S) may be disposed inside the housing (1100). The stopper part (S) may be disposed inside the housing (1100) to prevent the first lens assembly (1200) and the second lens assembly (1300) from colliding inside the housing (1100). The stopper part (S) may absorb impact by contacting the first lens assembly (1200) and the second lens assembly (1300). The stopper part (S) may include a Poron. The shape of the stopper part (S) is not limited. For example, the stopper part (S) may include a rectangular shape.

[0159] The stopper portion (S) may include a first stopper portion (Sa) and a second stopper portion (Sb). The first stopper portion (Sa) may be disposed on the housing cover (1600). The first stopper portion (Sa) may be disposed on one side of the housing cover (1600) facing the interior of the housing (1100). The first stopper portion (Sa) may be disposed on the housing cover (1600) so as to overlap with the first lens assembly (1200) or the second lens assembly (1300). The second stopper portion (Sb) may be disposed on one side of the interior of the housing (1100). The second stopper portion (Sb) may be disposed on one side of the interior of the housing (1100) so as to overlap with the first lens assembly (1200) or the second lens assembly (1300) in the direction of the optical axis. The first stopper part and the second stopper part may be spaced apart from each other in opposite directions in the optical axis direction with respect to the first lens assembly (1200) and the second lens assembly (1300).

[0160] The first stopper part (Sa) may include a first stopper (S1) and a second stopper (S2). The first stopper (S1) and the second stopper (S2) may be spaced apart from each other in a first direction.

[0161] The first stopper (S1) can overlap with the first lens assembly (1200) in the direction of the optical axis.

[0162] The second stopper (S2) can overlap with the second lens assembly (1300) in the direction of the optical axis.

[0163] The first stopper (S1) can come into contact with the bottom of the first lens assembly (1200).

[0164] The second stopper (S2) can come into contact with the bottom of the second lens assembly (1300).

[0165] The second stopper portion (Sb) may include a third stopper (S3), a fourth stopper (S4), and a fifth stopper (S5). The third stopper (S3), the fourth stopper (S4), and the fifth stopper (S5) may be spaced apart from each other in a first direction. The third stopper (S3) and the fifth stopper (S5) may overlap with the first lens assembly (1200) in the optical axis direction. The fourth stopper (S4) may overlap with the second lens assembly (1300) in the optical axis direction. The third stopper (S3), the fourth stopper (S4), and the fifth stopper (S5) may be placed at different heights inside the housing (1100) in the optical axis direction. The fifth stopper (S5) may be placed between the third stopper (S3) and the fourth stopper (S4) in the first direction. The third stopper (S3) can contact the top of the first lens assembly (1200). The fourth stopper (S4) can contact the top of the second lens assembly (1300).

[0166] The first to fourth stoppers (S1, S2, S3, S4) may not overlap with the second magnet part (1420) in the first direction. When the second lens assembly (1300) moves to the top of the housing (1100) and comes into contact with the fourth stopper (S4), the second magnet part (1420) may not overlap with the third stopper (S3) and the fourth stopper (S4) in the first direction. Additionally, when the second lens assembly (1300) moves to the bottom of the housing (1100) and comes into contact with the second stopper (S2), the second magnet part (1420) may not overlap with the first stopper (S1) and the second stopper (S2) in the first direction.

[0167] The fifth stopper (S5) may overlap with the magnet part (1420) in the first direction. When the first lens assembly (1200) and the second lens assembly (1300) move to the top of the housing (1100) and come into contact with the third stopper (S3) and the fourth stopper (S4), the first magnet part (1410) and the second magnet part (1420) may overlap with the fifth stopper (S5) in the first direction.

[0168] The camera actuator (1000) according to the embodiment may include a magnet part (1400).

[0169] The magnet portion (1400) may be placed on the first lens assembly (1200) and the second lens assembly (1300). The magnet portion (1400) may be placed on the first lens assembly (1200) and the second lens assembly (1300) to move the first lens assembly (1200) and the second lens assembly (1300).

[0170] The magnet part (1400) can move the first lens assembly (1200) and the second lens assembly (1300) by receiving magnetic force from the coil part (1700).

[0171] The magnet portion (1400) can be positioned in a first direction on the side of the first lens assembly (1200) and the second lens assembly (1300).

[0172] The magnet portion (1400) can be placed between the first lens assembly (1200) and the second lens assembly (1300) and the coil portion (1700).

[0173] The magnet portion (1400) can be overlapped with the coil portion (1700) in the first direction.

[0174] The magnet portion (1400) can be fixed to the first lens assembly (1200) and the second lens assembly (1300) by the yoke (1800).

[0175] A yoke (1800) is disposed between the magnet part (1400), the first lens assembly (1200), and the second lens assembly (1300), so that the yoke (1800) can fix the magnet part (1400) onto the first lens assembly (1200) and the second lens assembly (1300).

[0176] The magnet portion (1400) may include a first magnet portion (1410) disposed on a first lens assembly (1200) and a second magnet portion (1420) disposed on a second lens assembly (1300).

[0177] The first magnet part (1410) may be placed on the first lens assembly (1200). The first magnet part (1410) may move the first lens assembly (1200). The first magnet part (1410) may be placed on a side perpendicular to the first direction of the first lens assembly (1200). The first magnet part (1410) may be placed between the first lens assembly (1200) and the coil part (1700). The first magnet part (1410) may be fixed on the first lens assembly (1200) by the first yoke (1810). A first yoke (1810) is positioned between the first magnet part (1410) and the first lens assembly (1200) so that the first yoke (1810) can fix the first magnet part (1410) on the first lens assembly (1200). The first magnet part (1410) may not overlap with the first to third stoppers (S1, S2, S3) in the first direction.

[0178] The second magnet part (1420) may be placed on the second lens assembly (1300). The second magnet part (1420) may move the second lens assembly (1300). The second magnet part (1420) may be placed on a side perpendicular to the first direction of the second lens assembly (1300). The second magnet part (1420) may be placed between the second lens assembly (1300) and the coil part (1700). The second magnet part (1420) may be fixed on the second lens assembly (1300) by the second yoke (1820). A second yoke (1820) is positioned between the second magnet part (1420) and the second lens assembly (1300) so that the second yoke (1820) can fix the second magnet part (1420) onto the second lens assembly (1300). The second magnet part (1400) may not overlap with the first to fourth stoppers (S1, S2, S3, S4) in the first direction.

[0179] In one embodiment, the first magnet section (1410) and / or the second magnet section (1420) may be the magnet section (1400) of FIG. 10. The first magnet section (1410) and / or the second magnet section (1420) may include a plurality of magnets arranged in a Halbach array. For example, the first magnet section (1410) and / or the second magnet section (1420) may include a first magnet (1411), a second magnet (1412), and a third magnet (1413). The plurality of magnets included in the first magnet section (1410) and / or the second magnet section (1420) may be arranged sequentially side by side along the optical axis direction. For example, the first magnet (1411), the second magnet (1412), and the third magnet (1413) may be arranged sequentially side by side along the optical axis direction. Additionally, the upper surface of the first magnet part (1410) may be arranged in one direction of the x-axis direction, and the upper surface of the second magnet part (1410) may be arranged facing the other direction of the x-axis direction.

[0180] Referring to FIGS. 11 to 13, the camera actuator (1000) according to the embodiment may further include a yoke (1800) disposed between the first lens assembly (1200) and the second lens assembly (1300) and the magnet part (1400).

[0181] The yoke (1800) is positioned between the first and second lens assemblies (1200, 1300) and the magnet portion (1400) to fix the magnet portion (1400) onto the first and second lens assemblies (1200, 1300). The yoke (1800) may be positioned in a first direction on the side of the first and second lens assemblies (1200, 1300).

[0182] The yoke (1800) may include a first yoke (1810) disposed between the first lens assembly (1200) and the first magnet part (1410), and a second yoke (1820) disposed between the second lens assembly (1300) and the second magnet part (1420).

[0183] The first yoke (1810) may be positioned between the first lens assembly (1200) and the first magnet part (1410). The first yoke (1810) may be positioned on the side of the first lens assembly (1200) to secure the first magnet part (1410) onto the first lens assembly (1200).

[0184] The second yoke (1820) may be positioned between the second lens assembly (1300) and the second magnet part (1420). The second yoke (1820) may be positioned on the side of the second lens assembly (1300) to secure the second magnet part (1420) onto the second lens assembly (1300).

[0185] FIG. 14 is a drawing showing the thrust of an actuator according to one embodiment of the present invention, where the horizontal axis represents the stroke driven by the actuator in mm units, and the vertical axis represents the thrust driven by the magnet in μN units.

[0186] At this time, the thin solid line at the bottom represents the thrust of an actuator with a conventional magnet assembly, the dotted line represents the thrust of an actuator with a yoke with added reinforcement and CoFe alloy, the two-dot dashed line represents the thrust of an actuator including a yoke with added reinforcement and a Halbach magnet, and the thick solid line represents the thrust of an actuator including a yoke with added reinforcement and CoFe alloy and a Halbach magnet.

[0187] An actuator (thick solid line) including a yoke and Halbach magnet with added reinforcement and CoFe alloy applied improves thrust by up to approximately 13.6% compared to a conventional actuator. In such an embodiment of the present invention, the improved amplification is combined, and by mutually compensating for each deviation, an actuator with the best characteristics having flat characteristics can be formed.

[0188] In the case where a reinforcing member is added and a yoke made of CoFe alloy is applied (dotted line), it can be seen that the thrust is improved by up to about 7.0% in the middle of the stroke. Although relatively low thrust is obtained in the initial and final stages, by controlling the driving current according to the position in consideration of these characteristics, an actuator with a magnet assembly having improved magnetic flux characteristics can be formed.

[0189] In the case including a yoke with added reinforcement and a Halbach magnet (dotted line), it can be seen that the thrust is improved by up to approximately 11.4% at the beginning and end of the stroke. Although low thrust is obtained in the middle, by controlling the driving current according to the position in consideration of these characteristics, an actuator with a magnet assembly having improved magnetic flux characteristics can be formed.

[0190] The camera actuator according to the present invention maintains the same size as conventional ones and applies a magnet assembly that amplifies the magnetic flux in areas requiring strong magnetic flux and shields the magnetic flux in areas where it is not required to a lower level, thereby making it possible to drive a lens module with a stronger driving force by applying the same current to a coil of the same size. In addition, due to the improved shielding rate, magnetic interference with other components, which increases as the magnetic force increases, can be prevented.

[0191] Although the present invention has been described above, those skilled in the art will recognize that the invention may be implemented in other forms while maintaining the technical concept and essential features of the invention.

[0192] The scope of the present invention shall be defined by the claims, but all modifications or variations derived from configurations directly derived from the descriptions in the claims, as well as configurations equivalent thereto, shall be interpreted as being included within the scope of the present invention.

Claims

1. Housing; A first lens assembly and a second lens assembly that move along the optical axis direction within the housing; A first magnet assembly and a second magnet assembly respectively disposed on the first lens assembly and the second lens assembly; and It includes a coil portion that drives the above magnet assembly, A camera actuator characterized in that the first magnet assembly and the second magnet assembly comprise a magnet portion formed by arranging a plurality of magnets in a Halbach arrangement, and a yoke that contacts at least a portion of the lower surface and side surface of the magnet portion, wherein the yoke is formed of a ferromagnetic material.

2. In Paragraph 1, A camera actuator characterized in that the yoke comprises a flat plate in contact with the lower surface of the magnet part and a reinforcing part in contact with the side of the magnet part, and the upper end of the reinforcing part coincides with the upper surface of the magnet part.

3. In Paragraph 1, The above yoke is a camera actuator formed of CoFe alloy.

4. In Paragraph 3, A camera actuator in which the Co content of the above CoFe alloy is 27% or more by weight.

5. In Paragraph 1, The above yoke is a camera actuator formed of pure iron.

6. In Paragraph 5, A camera actuator in which the carbon content of the above-mentioned pure iron is 0.02% or less by weight.

7. In Paragraph 1, The above yoke is a camera actuator formed of iron containing Si.

8. In Paragraph 7, A camera actuator in which the Si content of the iron is 3% or less by weight.

9. In Paragraph 1, A camera actuator characterized in that at least one of the above magnets has polarity divided diagonally.

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