Actuator for camera

Abstract

An actuator for a camera according to one embodiment of the present invention comprises: a bracket on which a magnet is provided; the base is used for accommodating the bracket; a coil facing the magnet; and a rear yoke including a rear portion of the magnet and disposed at the bracket, in which the rear yoke includes: a main body plate including a rear portion of the magnet; and a cover protruding from the main body plate in a coil direction to cover a side surface of the magnet, and forming a gap with the side surface of the magnet.

Description

Technical Field

[0001] The present invention relates to an actuator for a camera, and more particularly, to an actuator for a camera having improved driving performance through structural improvement of a back yoke. Background Art

[0002] Advances in hardware technology for image processing and growing consumer demand for making and capturing photos and videos have driven the implementation of functions such as auto focus (AF) and optical image stabilization (OIS) in standalone cameras and camera modules mounted on mobile terminals including cellular phones and smart phones.

[0003] An auto focus (AF) function (or auto focus function) refers to a function of focusing on a subject by linearly moving a bracket having a lens in an optical axis direction to produce a clear image at an image sensor (CMOS, CCD, etc.) located at the rear of the lens.

[0004] An optical image stabilization (OIS) function refers to a function of improving image clarity by adaptively moving a bracket having a lens in a direction to compensate for a shake when the lens shakes due to vibration.

[0005] One of the representative methods for realizing the autofocus or OIS function is to mount a magnet (coil) on a moving body (bracket), and mount a coil (magnet) on a fixed body (housing, base or other type of bracket), and then generate an electromagnetic force between the coil and the magnet to move the moving body in the direction of the optical axis or in a direction perpendicular to the optical axis.

[0006] Since the driving method utilizes magnetic force or electromagnetic force between the coil and the magnet, a greater driving force can be achieved as the sizes of the coils or / and magnets facing each other increase or their facing areas expand.

[0007] However, a camera actuator having an OIS function, etc. is mounted on a mobile terminal (such as a smartphone) having basic elements such as being slim and light, and therefore is subject to physical limitations such as thickness and volume. Therefore, the size of a magnet, etc. cannot be expanded without limit to increase a driving force, etc.

[0008] Furthermore, given that the weight and volume of the mounted lens increases as demand for higher specification camera modules increases, increased actuation force is required, and an expanded space is also required in which the higher specification lens can be mounted while maintaining the overall volume, the spatial efficiency of the camera actuator is likely to become an increasingly important issue.

[0009] Meanwhile, in the case of an actuator in which AF and OIS are integrated according to an embodiment, an AF frame (such as an AF bracket) that implements AF and an OIS frame (such as an OIS bracket) on which the AF frame is mounted or mounted on the AF frame are generally provided together. In this case, magnetic interference may occur between the AF magnet mounted on the AF frame and the OIS magnet mounted on the OIS frame.

[0010] If magnetic interference occurs between adjacent magnets as described above or if the magnets are mutually influenced by their magnetic forces, the linear relationship between position detection and resulting position control is broken, and thus the driving performance of the precise feedback control itself may deteriorate.

[0011] Furthermore, when magnetic interference occurs, posture errors such as rotation and tilt are caused in each bracket, particularly in the OIS bracket that moves slightly, so the driving accuracy of the OIS may also be reduced in this regard. Summary of the invention

[0012] Technical issues

[0013] These and other objects and advantages of the present disclosure can be understood from the following detailed description and will become more apparent from the exemplary embodiments of the present disclosure. Moreover, it is easily understood that the objects and advantages of the present disclosure can be achieved by the means shown in the appended claims and their combinations.

[0014] Other technical purposes and advantages of the present invention can be understood with reference to the following description, which will be clarified by the accompanying examples. In addition, the technical purposes and advantages of the present invention can be achieved by the embodiments described in the appended claims and their combinations.

[0015] Technical Solution

[0016] In one aspect of the present disclosure, an actuator for a camera is provided, the actuator for a camera comprising: a bracket on which a magnet is mounted; a base configured to accommodate the bracket; a coil configured to face the magnet; and a back yoke disposed at the rear of the magnet and mounted on the bracket.

[0017] In this case, the back yoke of the present disclosure may include: a main body plate, which is arranged at the rear of the magnet; and a cover, which is configured to protrude from the main body plate toward the coil to cover the side surface of the magnet while forming a gap with the side surface of the magnet.

[0018] Here, the bracket of the present invention may include: a first bracket, which is configured to move in the optical axis direction and is equipped with an AF magnet; and a second bracket, which is configured to move in a plane direction perpendicular to the optical axis and is equipped with an OIS magnet, and in this case, the rear yoke can be set at the rear of the OIS magnet.

[0019] In addition, the OIS magnet of the present disclosure may be provided in plural at orthogonal positions, and the back yoke is preferably provided at the rear of the OIS magnet arranged at a position close to the AF magnet among the plural OIS magnets.

[0020] The actuator for a camera of the present disclosure may further include a traction yoke, which is configured to generate an attractive force with the OIS magnet, and in this case, the cover may be configured to cover the side surface of the OIS magnet except for the side surface of the OIS magnet facing the traction yoke, so that the portion of the OIS magnet facing the traction yoke is exposed.

[0021] According to an embodiment, one or more holes or openings are preferably formed on a portion of the cover arranged in a direction toward the traction yoke.

[0022] Beneficial effects

[0023] According to a preferred embodiment of the present disclosure, the leaked magnetic field can be reduced by structural improvement of the back yoke that concentrates the magnetic field of the induction magnet, and a further enhanced driving force can be provided in the relationship between the magnet and the coil facing the magnet.

[0024] Since the driving force can be increased based on the same specification of magnets in this way, the entire structure and shape of the actuator can be implemented in a more space-intensive form, which not only minimizes the total space but can also be further optimized to miniaturize the mobile terminal.

[0025] According to an embodiment of the present disclosure, magnetic interference between the AF magnet and the OIS magnet installed at a position relatively close to the AF magnet among magnets for driving in each direction of the OIS can be reduced, thereby more effectively achieving independence of the OIS driving which is driven particularly finely.

[0026] According to an embodiment of the present disclosure, the driving force can be increased in the relationship between the magnet and the coil, and the efficiency of the attraction force between the magnet and the traction yoke can also be improved at the same time for the contact efficiency with the ball device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not interpreted as being limited to the accompanying drawings.

[0028] Figure 1 is a diagram showing an overall configuration of an actuator for a camera according to a preferred embodiment of the present disclosure,

[0029] Figure 2 and Figure 3 is an exploded view showing a detailed configuration of an actuator for a camera according to a preferred embodiment of the present disclosure,

[0030] Figure 4 is a diagram illustrating a detailed configuration of a second bracket (OIS bracket) according to an embodiment of the present disclosure.

[0031] Figure 5 and Figure 6 It is a diagram for explaining the structural relationship between the back yoke and the magnet.

[0032] Figure 7 is a diagram showing an embodiment of a back yoke, and

[0033] Figure 8 is a diagram showing the structural relationship between the magnet and the traction yoke. DETAILED DESCRIPTION

[0034] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but are interpreted based on the meaning and concept corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms for the best interpretation.

[0035] Therefore, the descriptions presented herein are merely preferred examples for illustrative purposes, and are not intended to limit the scope of the present disclosure, and it should be appreciated that other equivalents and modifications may be made thereto without departing from the scope of the present disclosure.

[0036] Figures 1 to 3 1 is a diagram showing an overall configuration and a detailed configuration of an actuator 1000 for a camera (hereinafter referred to as an “actuator”) according to the present disclosure.

[0037] exist Figure 1 The actuator 1000 of the present disclosure shown in and other drawings is an embodiment in which AF and OIS are implemented together, but of course, depending on the embodiment, the actuator 1000 of the present disclosure may be implemented as an actuator for OIS or only for AF.

[0038] In addition, the actuator 1000 of the present disclosure may be implemented as a single device, and may also be implemented in the form of a camera module including the lens 50 and an image sensor (not shown).

[0039] The actuator 1000 of the present disclosure may include a base 400 and a housing 600. The base 400 corresponds to Figure 1 The basic frame of the actuator 1000 is shown and provides an internal space, and the housing 600 is coupled to the base 400 from above and serves as a shielding cover.

[0040] The bracket 100 of the present disclosure may be an AF bracket (first bracket) that moves in the direction of the optical axis or an OIS bracket (second bracket) that moves in a direction perpendicular to the optical axis. The following description is based on an embodiment in which the bracket 100 is an OIS bracket (second bracket) that moves in a direction perpendicular to the optical axis. However, it should be understood that the bracket 100 may also be a bracket that implements AF within the scope of the technical concept of the present disclosure.

[0041] The axes shown in the accompanying drawings, terms relating to the axes, and terms such as top, bottom, front, back, vertical, horizontal, etc. described relative to the axes are intended to present relative standards for describing the embodiments of the present disclosure, and it goes without saying that these terms are not intended to absolutely specify any direction or position. Of course, these terms may change relatively depending on the position of the target object, the position of the observer, the viewing direction, etc.

[0042] Hereinafter, when describing the present disclosure, the directional axis corresponding to the path of light introduced into the lens or lens assembly 50 (hereinafter, referred to as "lens"), that is, the directional axis corresponding to the vertical longitudinal direction of the lens 50 is defined as the optical axis (Z axis), and two axes on a plane perpendicular to the optical axis (Z axis) are defined as the X axis and the Y axis.

[0043] like Figure 2 As shown, the actuator 1000 of the present disclosure may include an OIS bracket 100 , a middle guide 200 , an AF bracket 300 , and the like.

[0044] The OIS bracket 100 may have OIS magnets M1 and M2 mounted on one side surface or two side surfaces orthogonal to each other, and driving coils C1 and C2 facing the OIS magnets M1 and M2 mounted on the OIS bracket 100 , respectively, are arranged on the base 400 .

[0045] Hereinafter, the OIS magnet installed on one side (X-axis direction) of the OIS bracket 100 is referred to as the first magnet M1, and the OIS magnet installed in a direction orthogonal to the first magnet M1 is referred to as the second magnet M2. In addition, correspondingly, the driving coil facing the first magnet M1 is referred to as the first coil C1, and the driving coil facing the second magnet M2 is referred to as the second coil C2.

[0046] The intermediate guide 200 may be arranged below the OIS bracket 100 based on the optical axis direction to cause linear movement of the OIS bracket 100, and the first ball B1 is arranged between the OIS bracket 100 and the intermediate guide 200. In addition, the intermediate guide 200 on which the OIS bracket 100 is mounted is accommodated in the AF bracket 300, and the second ball B2 is arranged between the intermediate guide 200 and the AF bracket 300.

[0047] If power of appropriate magnitude and direction is applied to the driving coils C1 and C2 by controlling the operating drivers D1 and D2, an electromagnetic force (magnetic force) is generated between the driving coils C1 and C2 and the magnets M1 and M2 facing the driving coils C1 and C2, and the OIS bracket 100 on which the lens 50 is mounted moves in a combined direction of the X-axis direction and the Y-axis direction perpendicular to the optical axis by the generated electromagnetic force, thereby correcting the jitter caused by hand tremor.

[0048] The intermediate guide 200 is a component that further improves the accuracy of linear motion in the X-axis direction and the Y-axis direction. If the driving coils C1 and C2 generate electromagnetic force in the X-axis direction, the OIS bracket 100 mounted with the lens 50 moves in the X-axis direction using the intermediate guide 200 as a relatively fixed body.

[0049] Furthermore, if the driving coils C1 and C2 generate electromagnetic force in the Y-axis direction, the OIS bracket 100 moves in the Y-axis direction together with the intermediate guide 200 due to the directivity (X-axis direction) of the track guiding the first ball B1 and the physical coupling structure.

[0050] Since the first ball B1 and the second ball B2 are disposed between the intermediate guide 200 and the OIS bracket 100 and between the intermediate guide 200 and the AF bracket 300 , respectively, the movement in each direction is supported and achieved by these balls B1 and B2 .

[0051] If the ball is inserted as described above, the mover can move linearly more flexibly due to the minimum friction caused by the rolling, movement, rotation and point contact of the ball with the facing object, and also has the advantages of reducing noise and minimizing driving force and improving driving accuracy.

[0052] In order to achieve effective guidance of linear motion, preferably, the first ball B1 is configured to be partially accommodated in at least one of a track formed on the lower portion of the OIS bracket 100, etc. and / or a track formed on the upper portion of the intermediate guide 200, etc.

[0053] In the corresponding views, the second ball B2 may be configured to be partially accommodated in at least one of a track formed on a lower portion of the intermediate guide 200 and / or a track formed on the AF bracket 300 .

[0054] According to an embodiment, the actuator may further include Hall sensors H1 and H2 that detect changes in magnitude and direction of a magnetic field of a magnet present in a detection area using the Hall effect and output electrical signals to the operation drivers D1 and D2 accordingly.

[0055] The operation driver may be implemented as an independent electronic component, element, etc., but may also be implemented as a single electronic component (chip) integrated with the Hall sensor through SOC (System on Chip), etc. Therefore, in the drawings, the Hall sensors H1 and H2 and the operation drivers D1 and D2 for each direction are shown in the same configuration.

[0056] In addition, the operation driver may be provided in the same number as the individual Hall sensors and implemented as a single chip with each individual Hall sensor. However, according to an embodiment, the number of channels for electrical connection with the Hall sensors, etc. may be adjusted so that the operation driver may not be provided in the same number as the individual Hall sensors and may be implemented as a single chip with some individual Hall sensors.

[0057] The AF bracket 300 of the present disclosure accommodates the OIS bracket 100 and the intermediate guide 200 which are vertically arranged based on the optical axis direction, and corresponds to a moving body which linearly moves in the optical axis direction based on the base 400 .

[0058] Even in this case, if the third Hall sensor H3 detects the position of the AF magnet M3 serving as a driving magnet for AF and outputs a signal corresponding thereto to the third operating driver D3 as described above, the third operating driver D3 controls the power of appropriate magnitude and direction to be applied to the AF coil C3 serving as a driving coil for AF, thereby causing the AF bracket 300 to move linearly in the optical axis direction.

[0059] The third ball B3 is arranged between a rail formed on the outer surface of the AF bracket 300 and a rail formed on the inner surface of the base 400 to guide the linear movement (optical axis direction) of the AF bracket 300 .

[0060] According to an embodiment, the actuator of the present disclosure may include a stopper 700 that limits the movement of the OIS bracket 100, etc. in the Z-axis direction and guides the movement in the X-axis direction and / or the Y-axis direction, so that when driving the OIS, deviation phenomena such as separation or lifting of the OIS bracket 100 and / or the intermediate guide 200 in the Z-axis direction can be suppressed.

[0061] The above-mentioned first coil C1, second coil C2, AF coil C3, etc. can be arranged to be mounted on a single circuit board or multiple circuit boards (not shown) arranged on the outer surface of the base 400, and according to an embodiment, the actuator 1000 of the present disclosure may include a yoke plate (not shown) arranged on the outside of the base 400 to generate an attractive force on the AF magnet M3.

[0062] Since the AF bracket 300 adjusted by the third ball B3 is pulled toward the base 400 (based on the X-axis direction of the drawing) by the attraction between the yoke plate and the AF magnet M3, the contact between the third ball B3 and the AF bracket 300 and between the third ball B3 and the base 400 can be continuously maintained.

[0063] Figure 4 is a diagram illustrating a detailed configuration of a second bracket (OIS bracket) 100 according to an embodiment of the present disclosure.

[0064] The second bracket 100 according to an embodiment of the present disclosure includes a body 110 having a mounting space 105 formed in a central portion where the lens 50 is mounted, and a mounter 120 .

[0065] The mounter 120 is a space where the first magnet M1 and the second magnet M2 are mounted, and is formed on the side surface of the body 110. Here, as shown in the figure, preferably, the first magnet M1 and the second magnet M2 are formed in directions orthogonal to each other based on the direction of the plane (XY plane) perpendicular to the Z axis.

[0066] Ideally, the mounter 120 is configured to have an open shape in the lower direction (based on the Z-axis direction). If the lower portion of the mounter 120 is opened in this way, ease of installation and spatial fixation can be more effectively achieved, and the attraction efficiency of the traction yoke 800 mounted on the first bracket 300 can also be improved.

[0067] In order to increase the position fixing force of the magnets M1 and M2 and increase the efficiency of the assembly process such as alignment, preferably, the mounter 120 is configured such that a side surface thereof is inserted into the inside of the OIS bracket 100 as shown in the figure so as to serve as a guide wall.

[0068] The back yoke 500 of the present disclosure is disposed behind the first magnet M1 and the second magnet M2 , ie, in the opposite direction of the first magnet M1 facing the first coil C1 , and is mounted on the mounter 120 together with the first magnet M1 .

[0069] The back yoke 500 is a component made of a magnetic material for preventing magnetic leakage and concentrating magnetic force, and according to an embodiment, the back yoke 500 may be configured to be partially or completely embedded in the mounter 120 by insert injection molding or the like.

[0070] Specifically, the back yoke 500 is disposed at the rear of the first magnet M1 (based on Figure 4 , and includes a body plate 510 and a cover 520 serving as a body of the back yoke 500.

[0071] The cover 520 of the back yoke 500 is configured to protrude from the body plate 510 toward the first coil C1 to cover the side surface of the first magnet M1 by bending, bonding, pressing, etc. The back yoke 500 disposed behind the second magnet M2 also has the same configuration and will not be described in detail.

[0072] Figure 5 and Figure 6 1 is a diagram for explaining the structural relationship between the back yoke 500 and the magnet. Hereinafter, a specific configuration of the back yoke 500 of the present disclosure is described in detail with reference to the accompanying drawings.

[0073] The cover 520 of the back yoke 500 is configured to cover the side surface of the first magnet M1. As shown in the figure, preferably, the cover 520 is configured to be spaced a predetermined distance from the side surface of the first magnet M1 so that gaps G1 and G2 are formed with the side surface of the first magnet M1.

[0074] The magnetic field of a magnet has a curved shape and is formed in three-dimensional space. When a magnet exists in an appropriate position adjacent to it, the magnetic field lines have a behavioral characteristic of extending or expanding to the position where the magnet is located.

[0075] Therefore, if the cover 520 of the back yoke 500 is installed to cover the side surface of the first magnet M1 but to be spaced apart from the side surface of the first magnet M1 as shown in the figure, the magnetic field formed in the first magnet M1 extends toward the cover 520, which is an adjacent magnet. Since this magnetic field expansion phenomenon is induced based on the entire three-dimensional space, the electromagnetic force (magnetic force) can be enhanced relative to the facing first coil C1.

[0076] Therefore, even if a smaller magnet is used compared to a magnet of the same specification, the smaller magnet can have the same or greater magnetic force (electromagnetic force), thereby improving the driving efficiency with respect to the coil.

[0077] Since the magnet is a component provided in the moving body (AF, OIS), in the embodiment of the present disclosure, a relatively small-sized magnet can be used, which can reduce the weight of the moving body, thereby further improving the driving efficiency.

[0078] Furthermore, since relatively small sized magnets are used, the leakage magnetic field can also be reduced, which can also reduce magnetic interference between adjacent magnets.

[0079] Therefore, if the actuator 1000 is an actuator combining AF and OIS, it is more desirable that the back yoke 500 having the above-described structure is disposed at the rear of the OIS magnet close to the AF magnet among the OIS magnets.

[0080] Based on the embodiment shown in the drawings, since the first magnet M1 is closer to the AF magnet M3 than the second magnet M2 , the back yoke 500 of the above structure may be disposed at the rear of the first magnet M1 .

[0081] Figure 7 1 is a diagram showing an embodiment of a back yoke 500 . Figure 8 is a diagram showing the structural relationship between the magnets M1 and M2 and the traction yoke 800 .

[0082] like Figure 7 As shown, the cover 520 of the back yoke 500 can be implemented in the form of covering the entire side surface of the first magnet M1, and according to an embodiment, preferably, the cover 520a located at the lower part (based on the Z axis) is configured to have one or more holes or openings 521 formed as shown in the drawings.

[0083] A component serving as a relatively fixed body relative to the OIS bracket (second bracket) 100 (AF bracket (first bracket) 300 in the drawings of the present disclosure) may include a traction yoke 800 that generates an attractive force with the OIS magnets M1 and M2 and causes centering when the OIS operation is terminated.

[0084] The OIS bracket (second bracket) 100 is pulled toward the AF bracket 300 by the attraction between the OIS magnets M1 and M2 and the pulling yoke 800, thereby improving the contact efficiency among the OIS bracket 100, the first ball B1, the intermediate guide 200, the second ball B2 and the AF bracket (first bracket) 300.

[0085] If the lower portion of the rear yoke 500 is configured to be open as described above, that is, when the cover 520 of the rear yoke 500 is configured to cover the side surfaces of the OIS magnets M1 and M2 except the side surfaces facing the traction yoke 800, so that the portions of the OIS magnets M1 and M2 facing the traction yoke 800 are exposed, the reduction in the attractive force between the OIS magnets M1 and M2 and the traction yoke 800 can be minimized.

[0086] If the hole or opening 521 is formed in the lower cover 520a of the back yoke 500 covering the side surface of the first magnet M1, as in the embodiment Figure 7 As shown in the figure below, the driving force generated relative to the first coil C1 can be increased, and the reduction in the attractive force utilizing the traction yoke 800 can also be suppressed.

[0087] The present disclosure has been described in detail. However, it should be understood that although the preferred embodiments of the present disclosure are indicated, the detailed description and specific examples are given by way of illustration only, because various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0088] In the above description of the present specification, terms such as “first” and “second” are merely conceptual terms used to identify components relative to each other, and thus they should not be construed as terms used to express a specific order, priority, and the like.

[0089] In order to emphasize or highlight the technical content of the present disclosure, the drawings used to illustrate the present disclosure and its embodiments may be shown in a slightly exaggerated form, but it should be understood that those skilled in the art may consider making various modifications to the above description and the illustrations of the drawings without departing from the scope of the present invention.

Claims

1. An actuator for a camera, the actuator for a camera comprising: a bracket on which a magnet is mounted; a base configured to receive the bracket; a coil, the coil being configured to face the magnet; as well as a rear yoke disposed at the rear of the magnet and mounted on the bracket, Wherein, the back yoke comprises: a main body plate disposed at the rear of the magnet; and A cover is configured to protrude from the body plate toward the coil to cover a side surface of the magnet while forming a gap with the side surface of the magnet.

2. The actuator for a camera according to claim 1, in, The bracket comprises: a first bracket configured to move in the optical axis direction and having an AF magnet mounted thereon; and a second bracket configured to move in a plane direction perpendicular to the optical axis and mounted with an OIS magnet, Wherein, the rear yoke is arranged at the rear of the OIS magnet.

3. The actuator for a camera according to claim 2, in, The OIS magnets are arranged in plural at orthogonal positions, and The back yoke is disposed at a rear portion of an OIS magnet disposed at a position close to the AF magnet among the plurality of OIS magnets.

4. The actuator for a camera according to claim 2, further comprising: a traction yoke configured to generate an attractive force with the OIS magnet, The cover covers a side surface of the OIS magnet except for a side surface of the OIS magnet facing the pulling yoke, so that a portion of the OIS magnet facing the pulling yoke is exposed.

5. The actuator for a camera according to claim 2, further comprising: a traction yoke configured to generate an attractive force with the OIS magnet, Wherein, one or more holes or openings are formed on a portion of the cover arranged in a direction toward the traction yoke.

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