Actuator for camera

Abstract

An actuator for a camera according to one embodiment of the present invention is characterized by comprising: a carrier which moves linearly; a housing which supports the linear movement of the carrier; a magnet which is installed on the carrier; a coil which is installed on the housing so as to face the magnet; and a plurality of balls which are arranged between the carrier and the housing, wherein the plurality of balls include one main ball which has the largest diameter.

Description

Actuator for camera

[0001] The present invention relates to an actuator for a camera, and more particularly, to an optical actuator having improved driving precision by improving a structure for supporting linear movement of a carrier.

[0002] As hardware technology for image processing advances and user needs for video shooting increase, functions such as autofocus (AF) and optical image stabilization (OIS) are being implemented in standalone camera devices as well as camera modules mounted on mobile terminals such as cell phones and smartphones.

[0003] The autofocus function is a function that adjusts the focal distance from the subject by linearly moving the carrier equipped with the lens, etc. in the direction of the optical axis, thereby creating a clear image on the image sensor (CMOS, CCD, etc.) installed at the rear of the lens.

[0004] Image stabilization is a function that improves the clarity of an image by adaptively moving the carrier on which the lens (or image sensor) is mounted in a direction that compensates for the shaking that occurs in the lens or image sensor due to hand shake.

[0005] One of the representative methods for implementing autofocus or OIS function is to install a magnet (coil) on a moving body (carrier) and a coil (magnet) on a fixed body (housing, base, or other type of carrier), and then generate a driving 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] Recently, actuators or camera modules that use a reflector placed at the front end of the lens to reflect (refract) light from a subject have been disclosed in order to organically integrate the physical characteristics of a zoom lens with the geometrical characteristics of a portable terminal.

[0007] Actuators that utilize a reflector implement OIS by rotating or moving the reflector along one or two axes, and implement AF or zoom functions by linearly moving a carrier on which a lens is mounted.

[0008] In the case of actuators for cameras, multiple balls are generally placed between a moving body (such as a carrier) and a fixed body (such as a housing) to suppress noise, reduce load, and improve driving precision.

[0009] In the case of a conventional actuator, a structure in which multiple balls are arranged on each of two rails that are positionally symmetrical with respect to a driving magnet (51) is generally applied to ensure stable support of a carrier (50), as illustrated in FIG. 1.

[0010] Although there may be some differences depending on the size, behavioral characteristics, specifications, etc. of the actuator, in the case of a conventional actuator, for the stability of physical support, etc., four balls having the same diameter (d2) but a larger diameter (d2>d1) than other balls (b12, b22) are arranged at the outermost side, and physical support and movement guiding of the carrier (50) are performed by these four balls (b11, b13, b21, b23) (hereinafter referred to as 'support balls').

[0011] However, since the diameters of the balls cannot be perfectly matched, in reality, these four support balls cannot contact the carrier (50) at the same time, so when the carrier (50) moves, the support balls that actually contact the carrier (50) are changed frequently.

[0012] The behavioral characteristics of the carrier, such as the random movement and stopping, may also be the reason for causing the phenomenon in which the support ball actually contacting the carrier (50) changes frequently when the carrier (50) moves.

[0013] In this way, if the carrier (50) and the actual support ball are changed frequently, the posture of the carrier (50) may be poor, tilt may occur, etc., and accordingly, the driving precision of the carrier may be deteriorated, and the optical performance of the actuator may also be deteriorated, such as the image being deteriorated.

[0014] The present invention was created to solve the problems described above against the background described above, and its purpose is to provide an actuator for a camera that can further improve the carrier's attitude stability and driving precision by improving the structure for physical support and guiding of the carrier.

[0015] Other objects and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, the objects and advantages of the present invention can be realized through the configurations and combinations of configurations set forth in the claims.

[0016] According to one embodiment of the present invention for achieving the above object, an actuator for a camera includes: a linearly moving carrier; a housing that supports linear movement of the carrier; a magnet installed on the carrier; a coil installed on the housing so as to face the magnet; and a plurality of balls arranged between the carrier and the housing, wherein the plurality of balls may be configured to include one main ball having the largest diameter.

[0017] According to an embodiment, an actuator for a camera according to one embodiment of the present invention may further include a first rail formed on at least one of the carrier and the housing; and a second rail formed on at least one of the carrier and the housing, but formed at a different position from the first rail.

[0018] In this case, two or more of the plurality of balls of the present invention may be arranged on each of the first and second rails.

[0019] Preferably, the main ball of the present invention may be arranged at the outermost side among the plurality of balls arranged on the first rail or at the outermost side among the plurality of balls arranged on the second rail.

[0020] In addition, the plurality of balls of the present invention may be arranged in groups of three or more on each of the first and second rails.

[0021] In this case, the main ball of the present invention may be one of the support balls that is arranged at the outermost side of each rail among the balls arranged on the first and second rails, and two or more of the remaining three support balls excluding the main ball may have a diameter smaller than the main ball and a diameter larger than the other balls.

[0022] In addition, among the balls arranged on the first and second rails, it is preferable that the support balls, which are the outermost balls on each rail, are arranged so as to be spaced apart from each other on the same rail.

[0023] According to an embodiment, the plurality of balls of the present invention may include two main balls.

[0024] In this case, the two main balls may be the first main ball positioned at the outermost side among the balls positioned on the first rail and the second main ball positioned at the outermost side among the balls positioned on the second rail.

[0025] According to one embodiment of the present invention, the main ball with the largest diameter can be induced to constantly contact the carrier. Therefore, when the carrier moves, the change in the balls contacting the carrier can be minimized, thereby more effectively reducing tilt and poor posture of the carrier.

[0026] According to one embodiment of the present invention, since the change in the posture of the carrier can be minimized when the carrier moves, the precision of the drive control that controls the movement of the carrier by using the detection of the position of the carrier can be increased, and the reliability of the AF function, etc. can be increased.

[0027] In one embodiment of the present invention, balls having different diameters are placed on the same rail, so that problems due to tolerance accumulation that may occur when multiple balls having the same diameter are placed together on the rail can be resolved.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to more effectively understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to the matters described in these drawings.

[0029] Figure 1 is a drawing explaining the structure of a ball placed in a conventional actuator.

[0030] Figure 2 is a drawing showing the configuration of an actuator according to a preferred embodiment of the present invention;

[0031] Figures 3 and 4 are drawings explaining the ball, first rail and second rail shown in Figure 2.

[0032] Figure 5 is a drawing explaining the configuration of a ball according to a preferred embodiment of the present invention;

[0033] Fig. 6 is a drawing explaining the configuration of a ball according to another embodiment of the present invention.

[0034] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention, they should be interpreted in a way that conforms to the technical spirit of the present invention.

[0035] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0036]

[0037] FIG. 2 is a drawing showing the configuration of an actuator for a camera (hereinafter referred to as an “actuator”) according to a preferred embodiment of the present invention, and FIGS. 3 and 4 are drawings explaining the ball (B), the first rail (R1), and the second rail (R2) shown in FIG. 2.

[0038] Below, the general configuration of the actuator (100) of the present invention will be described in detail, and the specific details of the present invention, such as the structural relationship between the ball and the rail, will be described later.

[0039] As illustrated in FIG. 2, the actuator (100) of the present invention may be configured to include a carrier (110), a housing (120), a circuit board (140), a magnet (M), and a coil (C), and may include a case (160) that functions as a shield can according to an embodiment.

[0040] The actuator (100) according to the present invention corresponds to a device that implements an AF or zoom function by linearly moving a carrier (110) forward or backward using the electromagnetic force (magnetic force) between a coil (C) and a magnet (M) as a driving force.

[0041] Although the drawing only shows an embodiment of moving the carrier (110) in a specific direction, for example, in the direction of the optical axis (Z-axis), the actuator (100) of the present invention can be implemented not only in an actuator to which the AF function and the OIS function are applied in an integrated manner, but also in an actuator to which a reflector is applied.

[0042] The carrier (110) of the present invention corresponds to a moving body that moves by a driving force from a magnet (M) and a coil (C), and from a corresponding viewpoint, the housing (120) that supports the linear movement of the carrier (110) corresponds to a relative fixed body.

[0043] According to an embodiment, one or more lenses or lens assemblies (hereinafter referred to as “lenses”) may be mounted on the carrier (110). When the lens is mounted on the carrier (110) in this manner, the lens moves linearly by the movement of the carrier (110), and the relative distance between the lens and the image sensor is adjusted by the movement of the lens, thereby implementing the AF or zoom function.

[0044] The driving unit that linearly moves the carrier (120) in the direction of the optical axis is configured to move the carrier (110) in a specific direction using an external control signal or a detected signal system, and can be implemented by various means such as a shape memory alloy (SMA), a piezoelectric element, or a micro electro mechanical system (MEMS).

[0045] However, considering the efficiency of device miniaturization, power consumption, noise suppression, space utilization, linear movement characteristics, precision control, etc., it is preferable that the driving unit be implemented with a configuration that utilizes the electromagnetic force (magnetic force) generated between the magnet and the coil as illustrated in the drawing.

[0046] In this regard, a coil may be installed on a moving body and a magnet may be installed on a fixed body, but in order to increase the efficiency of electrical connection, structural design, etc., it is preferable that the magnet (M) be installed on a carrier (110) which is a moving body and the coil (C) be installed on a housing (120) which is a relatively fixed body, as illustrated in the drawing.

[0047] Depending on the embodiment, a Hall sensor for detecting the position of a magnet (M1) or a sensing magnet, and a driving drive (D) for controlling the magnitude and direction of the current supplied to the coil (C) using a signal output by the Hall sensor may be included. Since the Hall sensor is typically implemented in the form of a single electronic component (chip) integrated with the driving drive (D), it is not shown separately in the drawing.

[0048] The coil (C) and the driving drive (D) can be mounted on a circuit board (140), and it is preferable that the circuit board (140) be configured so that a portion thereof is exposed to the outside for interfacing with external modules, power supplies, external devices, etc.

[0049] A ball (B) is placed between the carrier (110) and the housing (120). Specifically, the ball (B) may include a first ball (B1) placed on a first rail (R1) formed on the carrier (110) and the housing (120), and a second ball (B2) placed on a second rail (R2) formed on the carrier (110) and the housing (120), but formed at a different position from the first rail (R1).

[0050] In order to effectively guide the linear movement of the carrier (110), it is preferable that the first ball (B1) be configured so that a portion of it is accommodated in the first rail (R1). The second ball (B2) is also configured in the same manner.

[0051] Although the drawing illustrates an embodiment in which the first rail (R1) is provided on both the carrier (110) and the housing (120), depending on the embodiment, only one of them may be provided with the first rail. In this case, a configuration without the first rail may be provided with a groove or pocket portion that accommodates the first ball (B1) and prevents the first ball (B1) from being dislodged from the outside. The second rail (R2) is also provided in the same manner.

[0052] In this way, when balls (B1, B2) are interposed between the carrier (110) and the housing (120), the moving body (carrier) can move more flexibly and linearly due to minimized friction caused by the ball's rolling, moving, rotation, point-contact with a facing object, etc., and it can have the advantage of improved driving precision as well as reduced noise and minimization of driving force.

[0053] With respect to the rails (R1, R2) on which the balls (B1, B2) are arranged, one of the first rail (R1) and the second rail (R2) may be configured such that its cross-section (horizontal cross-section based on the optical axis direction) has a “V” shape, and the other may be configured such that its cross-section has a “U” shape.

[0054] In this way, when the cross sections of the first rail (R1) and the second rail (R2) are configured to have different geometrical characteristics, the contact areas with the balls (B1, B2) and the rotational characteristics can be configured differently, thereby improving the driving characteristics such as the linear movement and driving efficiency of the carrier (110) moving in the direction of the optical axis.

[0055] When a second rail (R2) having a "V" cross-section is provided on both the carrier (110) and the housing (120), the second rails (R2) are arranged so that their open portions face each other, and the second ball (B2) is arranged between them. Therefore, the second ball (B2) comes into contact with both the second rail (R2) of the carrier (110) and the second rail (R2) of the housing (120) while a portion of the second ball (B2) is accommodated in the second rail (R2).

[0056] The carrier (110) moves precisely linearly through the physical support of the second ball (B2) and the guiding of the second rail (R2) by this physical structure.

[0057] Here, the cross-section being formed in a 'V shape' means that not only is it in the shape of the alphabet V, but it is also formed in a shape in which the second ball (B2) is in contact with the inner surface of the second rail (R2) at two points.

[0058] When the cross-section of the first rail (R1) provided in the housing (120) is U-shaped, it may be preferable for the linear movement of the carrier (110) to be configured so that the cross-section of the first rail (R1) provided in the carrier (110) facing the rail (R1) is V-shaped.

[0059] The fact that the cross-section is in a 'U shape' means that there can be a certain amount of free space on the inner side of the ball and rail, including shapes such as the letter U as well as trapezoids.

[0060] As an example of this, the drawing shows an embodiment in which the first and second rails (R1, R2) provided on the carrier (110) both have a V-shaped cross-section, and one of the first rail (R1) and the second rail (R2) provided on the housing (120) has a V-shaped cross-section and the other has a U-shaped cross-section.

[0061] According to an embodiment, the housing (120) of the present invention may be provided with a magnet (M) provided in the carrier (110) and a yoke plate (150) made of a magnetic material that generates an attractive force.

[0062] When a force of attraction or suction is generated between the magnet (M) and the yoke plate (150), the carrier (110) is brought into close contact with the housing (120) in the direction of the ball (B1, B2) mediated between the carrier (110) and the housing (120) (X-axis direction based on the drawing), so that physical contact can be maintained between the ball (B1, B2) and the carrier (110), as well as between the ball (B1, B2) and the housing (120).

[0063]

[0064] Figures 5 and 6 are drawings explaining the configuration of a ball (B) according to preferred embodiments of the present invention.

[0065] The actuator (100) according to the present invention includes a plurality of balls (B) arranged between a housing (120) and a carrier (110), and the plurality of balls (B) can be provided at positions symmetrical with respect to a magnet (M) installed on the carrier (110) so as to face a coil (C) as shown in the drawing.

[0066] In the embodiment illustrated in the drawing, the ball on the left side of the magnet (M) is referred to as the first ball (B1), and the ball on the right side is referred to as the second ball (B2).

[0067] The first rail (R1) on which the first ball (B1) is placed and the second rail (R2) on which the second ball (B2) is placed have a shape in which their grooves extend in the same direction as the path along which the carrier (110) moves (Z-axis direction based on the drawing).

[0068] A plurality of balls (B) arranged between the carrier (110) and the housing (120) are configured to include a ball (BM) having the largest diameter (hereinafter referred to as a 'main ball'). In the embodiment illustrated in the drawing, the ball located at the outermost end in the downward direction among the first balls (B1) arranged in the vertical direction (based on the Z-axis) is the main ball (BM).

[0069] In this way, when the main ball (BM) with the largest diameter is included in the plurality of balls (B), the carrier (110) can be induced to always contact this main ball (BM), thereby reducing the phenomenon in which the ball (B) that contacts the carrier (110) is frequently changed when the carrier (110) moves forward and backward in the direction of the optical axis.

[0070] The above main ball (BM) may be any one of a plurality of balls (B), but it is preferable to place it on the outermost side of the first ball (B1) or the second ball (B2) as illustrated in the drawing rather than in the center of the first ball (B1) or the second ball (B2) to reduce tilting of the carrier (110) and minimize the phenomenon of changing the contact point.

[0071] The balls (B) that actually support the carrier (110) by being placed against the carrier (110) can support the carrier (110) more stably as the gap between them becomes larger.

[0072] To this end, it is preferable that the first ball (B1) and the second ball (B2) are arranged in groups of three or more on their respective rails (R1, R2), and that among the balls (B) arranged on the first and second rails (R1, R2), one of the balls arranged at the outermost side on each rail (R1, R2) (hereinafter referred to as a “support ball”) is configured to become the main ball (BM).

[0073] In addition, it is preferable that at least two of the remaining support balls (BS1, BS2) excluding the main ball (BM) be configured to have a diameter smaller than the main ball (BM) and a diameter larger than the other balls (BB1, BB2).

[0074] According to the embodiment of the present invention, the carrier (110) is supported and guided at four points (4 points) forming an extended area based on the embodiment illustrated in the drawing, so that the physical support of the carrier (110) is more stable, and since the carrier (110) is guided to always contact the main ball (BM), the possibility of change in contact point can also be reduced.

[0075] In order to further increase the stability of the physical support of the carrier (110) and further reduce the possibility of change in contact point, it is preferable that the support balls (BS1, BS2) except for the main ball (BM) among the support balls (BS1, BS2) have the same diameter.

[0076] For example, based on the embodiment illustrated in Fig. 5, the diameter of the main ball (BM) may be the largest (D1 > D2, D4, D6), and the diameters of the three support balls (BS1, BS2) excluding the main ball (BM) may be the same (D2 = D4 = D6), but may be larger than the diameters of the other balls (BB1, BB2) (D2 > D3, D5).

[0077] In case the diameters of the support balls (BS1, BS2) are different from each other according to the embodiment, or the diameters of the support balls other than the main ball (BM) among the support balls are different from each other, the point that contacts the carrier (110) can be always maintained the same.

[0078] FIG. 5 illustrates an example in which intermediate balls (BB1, BB2) are arranged between the support balls (BS1, BS2) so that the spacing between the support balls (BS1, BS2) arranged on each rail is expanded, i.e., the area where the carrier (110) is physically supported is expanded. In this regard, various configurations for spacing out the support balls (BS1, BS2), such as protrusions, blocks, and walls, may be provided between the support balls (BS1, BS2).

[0079] The embodiment illustrated in FIG. 6, which implements the technical idea of ​​the present invention described above, is an embodiment in which balls (B) having three types of sizes (diameters) are arranged on rails (R1, R2), the diameter of the main ball (BM) is the largest, and the remaining three support balls (BS1, BS2) excluding the main ball (BM) are configured to have diameters larger than the intermediate balls (BB1, BB2), but smaller than the main ball (BM).

[0080] In this way, when balls having multiple sizes based on diameter are arranged together on the same rail, friction or impact between the balls can be reduced, and problems such as intermittent movement of the carrier due to tolerance accumulation can be resolved.

[0081] The embodiments illustrated in (a) to (c) of FIG. 6 correspond to embodiments in which a single main ball (BM) is placed at the uppermost or lowermost end of the first or second rail (R1, R2). As previously described, the balls placed at the outermost end (uppermost end, lowermost end) of the first rail (R1) and the second rail (R2) correspond to support balls (BS1, BS2), one of which becomes the main ball (BM).

[0082] The embodiment illustrated in (d) of FIG. 6 is an embodiment in which, unlike the embodiment described above, two main balls (BM) are included in a plurality of balls (B) arranged between the carrier (110) and the housing (120), and corresponds to an embodiment in which one main ball (BM) having the largest diameter is arranged on each rail (R1, R2).

[0083] The main ball (BM) of this embodiment includes a first main ball (BM1) that is positioned at the outermost side among the balls (B1) positioned on the first rail (R1) and a second main ball (BM2) that is positioned at the outermost side among the balls (B2) positioned on the second rail (R2) and has the same diameter as the first main ball (BM1).

[0084] In the case of the embodiment of the present invention as described above, although the point contact of a specific single ball may not always be maintained, the possibility that the two main balls (BM1, BM2) will come into contact with the carrier (110) can be relatively increased, thereby simplifying the form in which the contact point changes and reducing the degree of tilting due to the contact point change.

[0085]

[0086] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0087] In the description of the present invention described above, modifiers such as first and second are merely instrumental conceptual terms used to relatively distinguish components from each other, and should be interpreted as not being terms used to indicate a specific order, priority, etc.

[0088] The drawings attached for the purpose of explaining the present invention and illustrating embodiments thereof may be illustrated in a somewhat exaggerated form to emphasize or highlight the technical contents of the present invention. However, it should be interpreted that it is obvious that various modified application examples may be possible at the level of a person skilled in the art in consideration of the contents described above and matters illustrated in the drawings.

Claims

1. Linearly moving carrier; A housing supporting linear movement of the carrier; A magnet installed on the above carrier; A coil installed in the housing so as to face the magnet; and comprising a plurality of balls arranged between the carrier and the housing; An actuator for a camera, characterized in that the plurality of balls includes one main ball having the largest diameter.

2. In paragraph 1, A first rail formed on at least one of the carrier and the housing; and A second rail formed on at least one of the carrier and the housing, but formed at a different position from the first rail, The above multiple balls are, An actuator for a camera, characterized in that two or more are arranged on each of the first and second rails.

3. In the second paragraph, the main ball, An actuator for a camera, characterized in that the ball is positioned at the outermost side among a plurality of balls positioned on the first rail or at the outermost side among a plurality of balls positioned on the second rail.

4. In the second paragraph, the plurality of balls are At least three are placed on each of the first and second rails, The above main ball is, Among the balls arranged on the first and second rails, one of the support balls is the ball arranged at the outermost side on each rail. An actuator for a camera, characterized in that at least two of the three support balls excluding the main ball have a diameter smaller than the main ball and a diameter larger than the other balls.

5. In paragraph 2, An actuator for a camera, characterized in that the support balls, which are the outermost balls on each rail among the balls arranged on the first and second rails, are arranged so as to be spaced apart from each other on the same rail.

6. In the second paragraph, the plurality of balls are Contains two of the above main balls, An actuator for a camera, characterized in that the two main balls are a first main ball positioned at the outermost side among the balls positioned on the first rail and a second main ball positioned at the outermost side among the balls positioned on the second rail.

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