KR20100124135A - Lens actuator for image pickup apparatus - Google Patents

Abstract

PURPOSE: A lens actuator for an image photographing device is provided to safely execute a focusing process by arranging a yoke controlling the magnetic force of a magnet and minimizing the generation of a leakage flux. CONSTITUTION: A lens part stores a lens unit for taking a picture of a subject. A driving part transfers the lens part in an optical axis direction by the driving force from the interaction between a magnet and a coil. A magnet(310) is arranged in the outer periphery of the lens part. A first yoke is arranged to surround the upper side and the upper end inner circumference side of the magnet in order to control a magnetic force which is generated from the magnet. A second yoke(330) is arranged to be contacted with the bottom side of the magnet. A coil(340) is reeled in the outer circumference of the lens part.

Description

Lens Actuator for Image Imaging Apparatus {Lens Actuator for Image Pickup Apparatus}

 TECHNICAL FIELD The present invention relates to an imaging device, and more particularly, to a lens actuator mounted on a small imaging device such as a mobile communication device.

In the past, cameras have been used, which are mechanical devices capable of photographing subjects through lenses. Typically, a camera includes a plurality of lenses for focusing and / or zooming, and is configured to adjust focus by adjusting a relative distance between the plurality of lenses.

In particular, recently, as a digital image pickup device, a mobile communication device such as a mobile phone and a small optical device such as a digital camera have been widely used. However, the camera module mounted in the digital image capturing apparatus is provided with various lens actuators as a driving device for zooming or auto-focusing, and is suitable for the inside thereof. The focus and / or magnification is adjusted by moving the lens formed along the optical axis direction.

Conventionally, in a camera module mounted on such a small optical device, a so-called rotary motor type mechanical device for changing a rotational motion of a motor into a linear motion through a gear or the like has been widely used to automatically adjust a focus on a photographed subject. . However, such a mechanical device is difficult to finely adjust the focus due to the friction force between the gear and the motor, and it is difficult to miniaturize due to the space problem occupied by each mechanical device. And had limits.

Accordingly, in particular, in the camera module mounted on a mobile communication device such as a mobile phone and a PDA, many methods have been proposed to satisfy the miniaturization, light weight, and multifunctionality required by the mobile communication device. However, in order to clearly see a subject in an optical system of a camera module mounted on a gradually miniaturized mobile communication device, the subject is clearly imaged on the image sensor by adjusting the distance between the plurality of lenses and the image sensor or changing the curvature of the lens. It should be equipped with a focusing function. That is, in order to implement the focusing function, the position of the image of the subject imaged by the image sensor is changed according to the position of the subject. In other words, the focus is performed as the position of the image is changed according to the distance between the subject and the lens.

Accordingly, in order to implement a clear image in the image sensor, one or more lenses have a structure in which they move relative to each other. In order to realize the focusing function in the lens configured as described above, as a separate driving unit, for example, a manual, a step motor, a piezoelectric element, a voice coil motor (VCM), etc. are requested.

Here, the voice coil motor (VCM) or the voice coil actuator (VCA) method refers to a method of precisely focusing using the induction magnetic force of the permanent magnet and the coil, and FIG. 1 illustrates a conventional mobile communication device. It is sectional drawing which shows schematically the lens actuator 1 of the applied VCM system.

As shown in FIG. 1, the lens actuator 1 applied to a conventional mobile communication device is a screw unit 10 formed of a plurality of focus adjusting lenses through a screw fastening method to a hollow portion of a carrier 12 having a substantially cylindrical shape. It is accommodated, the O-ring magnet 20, the yoke 22 having a substantially U-shaped cross section so as to control the magnetic force of the magnet along the outer periphery of the carrier 12, and the cylindrical coil 24 is Are arranged. In such a VCM-type lens actuator, the magnet 20 generating the magnetic force and the coil 24 to which the current is applied are disposed to face each other, and the coil 24 interacts in the magnetic force generated by the magnet 20. The lens unit 10 and the carrier 12 receiving the same are driven in the optical axis direction by using the Lorentz force generated in the vertical direction of the current and the magnetic field, that is, the optical axis direction, by the induced magnetic force. At this time, in order to add an appropriate elastic force, the upper spring 32 and the lower spring 34 are disposed at the upper and lower ends of the carrier 12, respectively.

In addition, the carrier 12 and the driving unit such as the magnet 20 for driving the same are all accommodated in the housing 40, and the cover plate 14 is formed inside the upper end of the housing 40. In addition, in the auto focusing device of the camera module used in a mobile communication device, a high resolution image sensor (not shown) such as a CCD and a CMOS is provided at the bottom of the carrier 12.

In particular, as high resolution image sensors are commercially available, according to the trend of miniaturization and high precision of lenses, miniaturization and weight reduction of lens actuators are strongly demanded. However, the yoke 22 for controlling the leakage magnetic flux generated from the magnet 20 among the driving units disposed around the outer side of the lens actuator adopting the conventional VCM method, has an inner circumferential surface and an outer circumferential surface as well as the upper surface of the magnet 20. It has a U-shaped cross section so that it can be enclosed. In this case, due to the separation distance between the outer circumferential surface and the inner circumferential surface of the yoke 22, there is a limit in reducing the size of the driving part in the radial direction.

In addition, the carrier 12 generally has a cylindrical shape and accommodates the lens unit 10 in its hollow portion, and the magnet 20, the yoke 22, and the coil 30 disposed on the outer periphery of the carrier 12 are In general, it has a cylindrical shape. In this case, a space that is not utilized as a corner area of the housing 40 having a hexahedral shape as a whole is formed, which is a barrier to miniaturization of the lens actuator 10.

As a result, in the case of an optical device adopted in a small image pickup device such as a conventional mobile communication device, there is a limit in reducing the size of the lens actuator in the radial direction, and when the size of the driving unit is reduced, there is a problem in that a desired driving force cannot be obtained. As a result, there was a limit that does not properly meet the miniaturization trend of the camera module including the lens assembly, and there is a limit in efficiency in terms of power consumption.

The present invention has been proposed to solve the above problems, an object of the present invention is to provide a lens actuator that can be miniaturized through the shape and arrangement of the drive unit of the actuator mounted on the small optical device.

Another object of the present invention is to provide a lens actuator capable of exerting a desired driving force in order to enable stable focusing despite the reduction in the overall size of the driving unit.

Other advantages and objects of the present invention will become more apparent from the following detailed description of the invention and the accompanying drawings.

According to the present invention having the above object, a lens unit for receiving a lens unit for photographing a subject and movable in the optical axis direction; A driving unit for moving the lens unit in the optical axis direction by a driving force by the interaction of the magnet and the coil disposed on the outer periphery of the lens unit, the magnet disposed on the outer periphery of the lens unit and the magnetic force generated from the magnet In order to surround the upper and upper inner peripheral surface of the magnet and the first yoke and at least a second yoke disposed to be in contact with the bottom surface of the magnet, and wound around the outer peripheral surface of the lens portion and moves in conjunction with the lens portion Provided is a lens actuator for image pickup including a driving unit including a coil disposed to face the inner circumferential surface of the second yoke.

According to one embodiment, the magnet is composed of a plurality of magnets arranged radially around the lens portion, it is possible to further miniaturize the lens actuator.

In this case, the second yoke may have a cross section in contact with the bottom surface of the magnet and the inner circumferential surface opposite to the coil is bent downward, and preferably, the lens unit is mounted on the cylindrical carrier and the hollow part of the carrier. It includes a lens unit, and as the lens unit moves along the optical axis, a locking end is formed at the lower peripheral edge of the carrier so that the lens unit can contact the bottom surface of the second yoke enables stable focusing.

On the other hand, according to another embodiment of the present invention, the second yoke is formed so as to contact only the inner bottom surface of the magnet, it is also possible to reduce the size of the lens actuator.

According to the present invention, the coil may be configured to be stably seated on the upper surface of the locking end protruding outward from the outer periphery of the carrier.

In particular, the lens unit constituting the center of the lens actuator of the present invention includes a cylindrical carrier and a lens unit mounted to the hollow of the carrier, the lens actuator is provided with an elastic means for contacting the upper and lower ends of the carrier, respectively By further including, stable focusing is possible through the elastic force by these elastic means.

In this case, the elastic means may include a first elastic body disposed on an upper end of the carrier and the lens actuator, and a second elastic body disposed on a lower end of the carrier and the lens actuator.

In addition, the cover may further include an upper cover disposed on the upper end of the first elastic body, a lower cover disposed on the lower end of the second yoke, and a base supporting the lens unit at the lower end of the second elastic body. 2 yoke is disposed between the inner bottom surface of the magnet and the inner upper end of the lower cover, so that the engaging end formed on the outer peripheral lower end of the carrier can contact the inner peripheral surface of the lower cover as the lens unit moves along the optical axis An upper end of the lower cover may protrude inward.

Preferably, the method may further include a shield case coupled along the outer circumferential surfaces of the upper cover and the lower cover.

In the present invention, the size of the lens actuator can be greatly reduced through the ideal arrangement of the shape of the magnet and / or the yoke in the so-called VCM type lens actuator mounted on a small optical device such as a mobile communication device.

Accordingly, since the overall size of the lens actuator and the camera module including the same required in the small optical device can be reduced, it is expected to actively cope with the miniaturization trend of the optical device.

In particular, in the present invention, by appropriately disposing a yoke for controlling the magnetic force of the magnet, by minimizing the occurrence of leakage magnetic flux among the magnetic flux generated from the magnet, it is possible to realize stable focusing without reducing the driving force.

The present inventors have increasingly miniaturized, for example, a lens actuator using a so-called Voice-coil Motor (VCM) system and an autofocus lens assembly including the same, mounted on a mobile communication device. In order to be adopted in the present invention, while reducing the overall size of the lens actuator constituting the camera module, while seeking to find a way to exhibit the desired driving force, the present invention was completed. EMBODIMENT OF THE INVENTION Hereinafter, with reference to attached drawing, specific embodiment and drive mechanism of this invention are described.

FIG. 2 is an exploded perspective view illustrating a coupling relationship between components constituting a lens actuator of a camera module mounted on a compact optical device such as a mobile communication device according to the first embodiment of the present invention, and FIG. 1 is a perspective view illustrating a state in which a lens actuator according to one embodiment is assembled. On the other hand, Figure 4 is a schematic perspective view showing the arrangement and coupling state of the first yoke and the magnet in a state in which the case member and the upper elastic means forming the outside of the lens actuator according to the first embodiment of the present invention, Figure 5 3 is a cross-sectional view taken along the line V-V of the lens actuator of the present invention, which is a cross-sectional view schematically showing a state before the lens actuator according to the present invention is driven.

As shown, the lens actuator 100 according to the present invention is a lens module 200, which is a lens module corresponding to a movable part moving in the optical axis direction during the imaging process for the subject, and a driving force for the movement of the lens unit 200. To the driving member 300 disposed along the outer periphery of the lens unit 200 and the case member 400 coupled in a form surrounding the outer periphery of the lens unit 200 and / or the driving unit 250 so as to occur Are distinguished. The lens actuator 100 according to the present invention constitutes a camera module in an image pickup device or a compact optical device such as a mobile communication device.

The lens unit 210 formed at the center of the lens actuator 100 according to the present invention includes a lens unit composed of one or more, typically a plurality of lenses having an appropriate curvature and size as necessary for imaging an image of a subject ( 210 and a substantially cylindrical carrier 220 having a hollow portion for accommodating the lens unit 210. The lens unit 210 may be assembled inside the carrier 220, for example, in the form of a lens holder assembly, or in a form assembled such that the optical axis for each lens coincides.

That is, the substantially cylindrical carrier 220 having the hollow portion is fastened to the outside of the lens unit 210 forming the lens receiving portion of the hollow cylindrical body in which at least one lens through which incident light is transmitted is aligned and disposed in the optical axis direction. To this end, by the screw coupling between the first screw thread 212 formed along the outer circumference of the lens unit 210 and the second screw thread 222 formed along the inner circumferential surface of the hollow carrier 220, the lens unit 210 is The lens unit 200 as a lens module may be configured to be firmly fastened into the carrier 220. In other words, the lens unit 210 constituting the lens unit 200 has at least one lens mounted at the center thereof, and the carrier 220 can firmly support the lens unit 210 mounted at the center thereof. It is configured to be. Accordingly, as will be described later, as the carrier 220 moves in the optical axis direction, the lens unit 210 assembled therein may move to change focusing distance by changing a focal length with respect to a subject.

As such, the carrier 220 forming the outer side of the lens unit 200 while having an approximately cylindrical shape with a hollow upper end to mount the lens is an insulating resin, for example, an insulating resin such as polycarbonate containing glass. Using a plastic material of, can be produced integrally by press molding process. Accordingly, the carrier 220 is accommodated in the upper cover 410, the lower cover 420 and the base 430 to be able to move up and down in the case member 400 which will be described later.

On the other hand, along the outer peripheral surface of the lower end of the substantially cylindrical carrier 220 which accommodates the lens unit 210 therein, the coil 340 electrically connected to the external power source, as described later, toward the outside to be seated An extended flange 224 is formed, and the locking end 226 extends outwardly to the outside of the flange 224. At this time, the locking end 226 may be configured in a continuous form along the outer circumferential surface of the flange 224, but as shown in the drawing, many of the outer circumferential surfaces of the flange 224 extend outwardly at equal intervals at a predetermined area. It can be formed as.

Meanwhile, in order to control an auto-focusing (AF) process for the subject along the outer periphery of the carrier 220 constituting the outer portion of the lens unit 200, the driving unit 300 and Many components for controlling operation are appropriately arranged and combined, which will be described. The lens actuator 100 according to the present invention is a driving unit 300 of a so-called voice coil motor (VCM) system. In particular, while the position of the magnet 310 is fixed, the coil 340 moves the lens unit 200. It forms a so-called 'coil actuated' drive unit whose position is changed according to.

The driving unit 300 may move the carrier 220 constituting the lens unit 200 and the lens unit 210 accommodated in the carrier 220 in the optical axis direction to adjust the focus of the image of the subject. It is disposed along the outer periphery of 220. The driving unit 300 includes a magnet 310 that generates a large magnetic field, yokes 320 and 330 disposed at the top and bottom of the magnet 310 to control the flow of the magnetic field generated from the magnet 310, that is, the magnetic flux. The coil 340 receives a predetermined power from an external power source.

First, the magnet 310 may use a permanent magnet used in a conventional voice coil motor system, for example, a neodymium-based permanent magnet. For example, as shown in FIG. It is also possible to arrange the polarity of the pole or vice versa. That is, according to a preferred aspect of the present invention, the magnets 310 may be arranged in different polarities in the vertical direction, and when the bipolar pole is configured using a method of dividing a single pole into an upper and a lower pole, or magnetized into a bipolar pole. It can be configured as a single magnet.

The magnet 310 is disposed with a predetermined interval along the outer periphery of the upper end of the carrier 220, as shown in the inner peripheral surface may be composed of a plurality of arc-shaped magnets having a constant curvature. Preferably, in order to generate a uniform driving force in the optical axis direction with respect to the lens unit 200, which is a movable part, the magnet 310 has a plurality of magnets having a radial shape in a horizontal direction with respect to the center of the optical axis direction are arranged at equal intervals. In particular, when the case member 400 coupled to the outside of the driving unit has a hexahedral shape as a whole, as shown in FIG. 4, the magnet 310 is formed by four magnets located at the corners of the case member 400. Can be configured. When the magnet 310 is disposed as described above, the magnet 310 is not disposed at the center of each inner circumferential surface of the case member 400. Accordingly, a separate space for disposing the magnet 310 is not required between the outer periphery of the lens unit 200 and the inner periphery of the intermediate region of each side among the inner periphery of the case member 400, so that the case member 400 is horizontal. By reducing the size of the direction it is possible to utilize the space that can be miniaturized the lens actuator.

On the other hand, to control the flow (magnetic flux) of the magnetic force generated in the magnet 310, for example, yoke (320, 330) that can be made of a conductive material such as iron, cold rolled steel or nickel having excellent magnetic transmittance ) Is arranged around the magnet 310. In particular, according to the present embodiment, the first yoke 320 having a shape surrounding the upper end of the magnet 310 and the upper end of the inner circumferential surface and the bottom surface of the magnet 310 are disposed to extend opposite to the outer circumferential surface of the coil 340. It consists of a second yoke 330 having an inner peripheral surface.

According to the present invention, the first yoke 320 and the second yoke 330 have an o-ring shape having a hollow portion as a whole, but in the present embodiment, both the first yoke 320 and the second yoke 330 The upper end 322, 332 is characterized in that the form extending toward the outside. In particular, unlike the conventional VCM method, since the yoke is not disposed on the outer circumferential surface of the magnet 310, the size of the yoke 320 and 330 in the horizontal direction can be reduced, so that the lens actuator 100 can be provided with respect to the optical axis direction. Can reduce the size of the horizontal direction.

In this case, the first yoke 320 is disposed along the outer periphery of the upper end of the carrier 220. The upper end 322 extending in the outward direction is seated in contact with the upper surface of the magnet 310, but the lower end thereof is Compared with the hollow part of the magnet 310, it is a substantially cylindrical shape which has a small hollow part. That is, as shown in FIG. 5, the lower end of the first yoke 330 has a shape such that a cross section is bent, so that the lower end of the first yoke 330 may be in a vertical direction between the upper end of the inner circumferential surface of the magnet 310 and the upper outer circumferential surface of the carrier 220. Is extended.

Accordingly, since the first yoke 320 surrounds the upper inner circumferential surface of the magnet 310 as well as the upper end of the magnet 310, magnetic flux leakage may be reduced at the upper inner circumferential surface of the magnet 310. In addition, since the magnet 310 is not disposed between the lower end of the first yoke 320 and the upper end of the coil 340, that is, the lower end of the first yoke 320 is disposed opposite to the upper end of the coil 340. Therefore, the magnetic flux generated by the magnet 310 can be controlled efficiently, and the same driving force can be exhibited even though the size of the radial direction is reduced at least compared with the conventional yoke. At this time, in order to prevent the magnet 310 from coming into contact with another member due to dimensional error between the parts constituting the driving part 300 or a misalignment during assembly, the lower outer peripheral surface of the first yoke 320 and the magnet 330 The shape of the first yoke 320 may be adjusted to form a predetermined gap d between the inner circumferential surfaces.

In addition, the second yoke 330 of the present embodiment disposed along the outer periphery of the approximately middle height of the carrier 220 is also placed between the bottom of the magnet 310 and the upper end of the inner circumferential side of the lower cover 420 described later. For 332, the lower end has a bent section extending downward along the upper inner circumferential surface of the lower cover 420 while having a hollow portion substantially the same as the magnet 310. As such, while the second yoke 330 contacts the bottom surface of the magnet 310, the lower inner circumferential surface of the second yoke 330 is disposed to face the outer circumferential surface of the coil 340 wound around the carrier 220. Accordingly, the magnetic flux can be efficiently controlled while suppressing leakage magnetic flux from the magnet 310.

By the first yoke 320 and the second yoke 330 having such an arrangement, the flow of magnetic flux in the magnet 310 is controlled to flow only in the radial direction of the lens actuator 100, and the magnet 310 By concentrating the magnetic field generated by the coil 340, it is possible to finally improve the driving force of the lens actuator.

On the other hand, the coil 340 is electrically connected to an external power source so that a predetermined current is applied to interact with the magnetic field generated by the magnet 310 to generate the Lorentz force, that is, the driving force. It is seated on the upper surface of the flange 224 protruding outward in the lower region of the 220, and staked in a form wound along the outer periphery of the carrier 220, the position along the lens unit 200 in the optical axis direction Is configured to be changed. The outer circumferential surface of the coil 340 is formed to have a predetermined gap with the inner circumferential surface of the magnet 310. As described above, the upper end of the coil 340 surrounds the upper and inner circumferential surfaces of the magnet 310. ) And the outer circumferential surface of the coil 340 are disposed opposite to the inner circumferential surface of the second yoke 330 in contact with the bottom surface of the magnet 310.

The magnetic field generated by the magnet 310 is transmitted to the coil 340 formed as described above. The electromagnetic force generated by the interaction between the magnetic field and the electric field, that is, the Lorentz force is generated. That is, when a current is applied to the coil 340 through an electrode (not shown) connected to the coil 340 from an external electronic circuit, a magnetic field is formed in the coil 340, and a magnet (a magnet) around the coil 340. Since the magnetic field is formed in the direction from 310 to the yokes 320 and 340, the carrier 220 is coupled to the coil 340 by the Lorentz force and the lens unit 210 assembled therein. The lens unit 200 is driven in the optical axis direction perpendicular to the magnetic field direction. That is, the lens unit 200 performs an upward or downward linear movement in the optical axis direction by the induction magnetic force along the magnet 310 and the coil 340 having the arrangement as described above. That is, when a current is applied to the coil 340 coupled to the carrier 220 according to the present invention, the magnetic flux is controlled by the coil 340 and the yoke 320, 330 by the magnet 310. The induced magnetic force of the coil 340 acts as a Lorentz force in the formed magnetic field to cause linear motion of the lens unit 200 in the optical axis direction, which will be described later.

The coil 340 is generally formed by winding in a substantially cylindrical shape using a copper alloy wire, and both ends of the coil 340 are drawn downward from the bottom of the base 430 and made of a conductor such as a copper alloy. The electrodes may be connected to the electrodes (not shown) by soldering or the like.

In addition, the outer shape of the elastic means (350, 360) and the lens actuator 100 for maintaining the position according to the driving in the optical axis direction of the lens actuator 100 having the above-mentioned 'coil-operated' drive unit 300 A case member 400 for providing is formed.

First, the carrier 220 as a resilient means for fastening between the carrier 220 and the driving coil 340 repeating the up and down reciprocating motion along the optical axis and the magnet 310 / yoke 320 and 330 whose position is fixed. The upper and lower ends of the 220 are provided with elastic bodies 350 and 360, respectively. The elastic members 350 and 360 supply current to both ends of the coil 340, and provide a restoring force to the movement of the lens unit 200 in the optical axis direction, thereby determining the relative position of the carrier 220. It is configured to be. The elastic members 350 and 360 are preferably in the form of a thin plate made of metal such as steel or copper alloy.

To this end, the elastic members 350 and 360 may have upper surfaces of the movable part and the fixing part so as to elastically connect the carrier 220 / coil 340 as the movable part and the magnet 310 / yoke 320 and 330 as the fixed part to each other. And it is preferable to be installed in the vicinity of the bottom surface coupling. Specifically, the elastic body of the present invention may be composed of the first elastic body 350 is installed to the top of the carrier 220 and the first yoke 320, and the second elastic body 360 is installed to the bottom of the carrier 220. have. The first elastic body 350 and the second elastic body 360 according to the present invention may be in the form of a plate-spring, for example.

As such, for example, the elastic members 350 and 360 having a leaf spring shape not only support the driving unit 300, but also press the upper and lower ends of the carrier 220 by elastic force so that the carrier 220 is predetermined along the optical axis. Function to be maintained at the position of. To this end, the first elastic member 350 is disposed between the bottom surface of the upper cover 410 and the upper surface of the carrier 220, which will be described later, the first elastic body 360 and the bottom surface of the carrier 220 and the lower cover 420 Placed between the top of base 430.

In addition, the upper cover 410 via the first elastic guide 352 to the top of the first elastic member 350 to form the appearance of the lens actuator 100 that can be mounted in a small optical device such as a mobile communication device. ) Is provided at the open top of the carrier 220, and a lower cover 420 is formed to engage the bottom surface of the upper cover 410. In addition, the base 430 for supporting the bottom surface of the lens unit 200 and the driving unit 400 is coupled to the lower end of the lower cover 420, the shield along the outer peripheral surface of the upper cover 410, lower cover 420 The case 440 is disposed. Such case members 410, 420, 430, and 440 may be made of an insulating resin, for example.

The upper cover 410 provides an upper shape of the lens actuator 100, and has a hollow through which the carrier 220 can penetrate and a bottom of the lens actuator 100 having a substantially rectangular parallelepiped shape. In particular, the four corner regions of the upper cover 410 constitute a downward vertical portion 412, in particular, the magnet 310 and the first yoke 320 is configured so as not to be separated, the lower end of the four corners constitute a fastening portion have. In addition, the outer circumferential surface of the down-vertical vertical portion 412 of the upper cover 410 forms a first guide portion 414 protruding to the outside so that the shield case 440 can be fitted therethrough, and fixed to protrude outward from the top. A stage 416 is formed and configured to fix the upper end of the shield case 440.

On the other hand, the lower cover 420 coupled with the upper cover 410 also has an overall hexahedral shape having a hollow portion, the second yoke 330 is seated on the upper end, the lower end of the second yoke 330 along the inner peripheral surface By contacting the outer circumferential surface, the second yoke 330 can be disposed stably. Fastening holes are formed at four corners of the lower cover 420 so that the fastening portions at the lower ends of the four corners of the upper cover 410 may be penetrated. In particular, the four corner regions of the lower cover 410 are also extended downward (422), and is configured to accommodate the lens unit 200, the second yoke 330, the coil 340, the downward vertical portion 422 The outer circumferential surface of the second guide portion 424 protruding to the outside to form a shield case 440 through it. In addition, the lower cover 420 is formed so that the size and shape of the lower cover 420 can correspond to the shape of the second elastic body 360 disposed on the lower end, so that the lower cover 420 is the center of the second elastic body 420 and It is pressurized to fix the outer periphery firmly.

Meanwhile, by firmly supporting the lower end of the carrier 220 and the lower end of the lower cover 420, the base 430 having a hexahedron shape surrounds the lower end of the carrier 220 as a whole for the lower end of the lens actuator 100. . The base 430 has a hollow 432 large enough to accommodate the carrier 220, and a fastening hole into which the fastening portion of the upper cover 410 is inserted is formed at the top of four corners. On the other hand, the receiving groove 434 is formed at the upper end of the four side, the shield case 440 can be fitted through it, the upper end of the second fixed end 436 is formed in the shield case 440 You can fix the bottom of). Although not shown in the drawings, a filter (for example, an IR filter) for controlling the amount of light by blocking a part of incident light entering through the lens to the hollow area of the base 470 is disposed, and toward the bottom of the base 440. An image sensor is formed.

On the other hand, as the case member 400 of the present invention, the shield case 440 having a hollow portion formed on the upper side of the upper cover 410 of the substantially rectangular parallelepiped forming the upper outer side of the lens actuator 100 can be further coupled. have. The shield case 440, for example, blocks a magnetic field generated by a magnet formed in another module in a mobile communication device in which the auto focus lens actuator 100 of the present invention is actually mounted, thereby preventing problems such as poor focus due to the magnetic field. It is for hexahedron shape as a whole to solve. To this end, the outer side of the shield case 440 forms a shielding portion 442 extending downward, the shielding portion 442 is the first guide portion 414 formed on the upper cover 410, the lower cover 420 It is coupled to the receiving groove 434 of the base 430 in the state fitted to the inner end of the second guide portion 424 formed in the. Meanwhile, the first fixing hole 444 and the second fixing hole 446 are formed at the upper and lower ends of the shield case 430, and the first fixing end 416 and the base (outside the upper end of the upper cover 410) are formed. 430 The shield case 440 is stably fixed by the method of fitting the second fixing end 436 on the outer side of the upper end into the first fixing hole 444 and the second fixing hole 446, respectively.

Next, the operation between the voice coil motor as the driving unit forming the lens actuator 100 according to the present embodiment will be described with reference to FIG. 5 and FIG. 6 which is a sectional view showing the driving state of the lens actuator according to the present embodiment. . For example, when a predetermined current is applied to the coil 340 while the coil 340 connected to an external power source is wound around the carrier 220 through an electrode (not shown) formed at the bottom of the base 430. , The magnetic field (magnetic field) in the horizontal direction is formed by the magnets 310 and the yokes 320 and 330 disposed along the periphery thereof, and according to Fleming's left hand law, the Lorentz force, that is, the driving force is generated. do. Accordingly, the carrier 220 accommodating the lens unit 210 may move in the optical axis direction according to the current applied thereto.

That is, when the magnetic circuit of the driver 300 is made perpendicular to the winding direction of the coil 340, the magnetic density generated from the magnet 310 and the current vector applied to the coil 340. The vector becomes a right angle to maximize driving force. At this time, the magnetic field and the induced magnetic field formed by the applied current repel each other or are forced by the attraction force, and the barrel portion provided with the coil moves in the direction of the optical axis. According to the inventors, although the size was reduced compared to the conventional VCM lens actuator, the desired driving force (4.1 g) was obtained by the proper arrangement of the yokes 320 and 330 for efficiently controlling the flux flow. This is similar to the driving force obtained in a drive having a conventional yoke that has a U-shaped cross section and encloses the magnet in the same condition. As a result, in the present invention, it is possible to reduce the size of the entire lens actuator and to arrange the driving unit without any problem in the driving force.

Subsequently, driving of the lens actuator 100 for a mobile communication device according to an embodiment of the present invention will be described. As described above, the lens actuator 100 of the present invention is based on the interaction between the magnet 310, the yoke 320, 330 and the coil 340 of the carrier 220 and the lens unit 210 therein. Focusing is performed by changing the position. That is, the image of the subject passing through the center of the lens unit 210 is transferred to an image sensor (not shown) through a filter (not shown) and converted into an electrical signal, the image data converted into an electrical signal is a camera module Focusing is transmitted to the control unit provided in the main body, and according to the direction of the applied current, the carrier 220, the coil 340 wound around the carrier 220, and the lens unit accommodated in the carrier 220 in this process ( 210 may move back and forth along the optical axis.

As described above, the lens unit 200 moves in the optical axis direction, thereby allowing focus adjustment to the subject, that is, auto focusing. That is, in order to focus the optical image on the subject with the image sensor, the lens unit 210, in which the lens unit 210 is assembled, must move in the optical axis direction to adjust the focal length. Specifically, auto focusing generates the autofocusing data by data-contrast the captured image, and adjusts the focus by positioning the lens at the largest position. If the subject is in focus, the shape of the subject is clear and the contrast is high. Since the distinction is clear, the autofocusing data is utilized.

That is, when the user of the mobile communication device adopting the lens actuator 100 according to an embodiment of the present invention presses the shooting button, the image sensor is operated, so that the image of the subject located in front of the lens actuator 100 is hollow. Passed through the unit 200 and the filter is converted into an electrical signal from the image sensor and transmitted to a controller (not shown) in the camera module. If the image signal of the subject transmitted from the control unit to the image sensor is blurry, the lens actuator determines that there is a focusing error, and a current for moving the lens unit 200 in the optical axis direction is electrically connected to both ends of the power supply means. It is applied to the coil 340 is connected.

Accordingly, as shown in FIG. 6, when a predetermined current is applied to the coil 340, a magnetic field is generated in the coil 340, and the Lorentz force is caused by the repulsive force or attraction force with the magnetic flux transmitted from the magnet 310. This happens. By the driving force, the carrier 220, the lens unit 210 accommodated in the carrier 220, and the coil 340 coupled to the carrier 220 move in the optical axis direction. The controller in the camera module controls the direction of the current. By converting, the carrier 220 may be moved up and down on the optical axis to realize focusing for sharpening an image of a subject captured by the image sensor. If the current is supplied to the coil 340 in the opposite direction, the lens unit 200 including the carrier 220 may be moved downward.

In particular, according to the present embodiment, since the locking end 226 extending outward is formed to the flange 224 formed along the outer circumferential surface of the carrier 220 to seat the coil 340, the carrier 220 is an optical axis When moving upwardly along the direction, the locking end 226 contacts the bottom of the second yoke 330 which is disposed opposite the outer circumferential surface of the coil 340, whereby the carrier 220 is no longer there. To restrict movement. Accordingly, the driving distance of the carrier 220 is also limited, so that the elastic bodies 350 and 360 respectively formed at the upper and lower ends thereof by the movement in the excessive optical axis direction of the carrier 220 can be prevented from being damaged beyond its restoring force. As a result, stable focusing can be realized.

Meanwhile, in the above-described first embodiment, the first yoke 320 and the second yoke 330 disposed around the magnet 310 have substantially the same shape, but the yoke of the present embodiment may be different. 7A and 7B are cross-sectional views schematically showing the positional relationship of each component before and after driving the lens actuator according to the second embodiment of the present invention, respectively. Detailed description of the same configuration as that of the first embodiment is omitted, but the second yoke 330 of the present embodiment does not have a bent cross section, but is long along the optical axis direction in contact with the bottom of the inner circumferential surface of the magnet 310. It is extended. In order to stably fix the second yoke 330, the lower portion 426 protrudes toward the center of the upper inner circumference of the lower cover 420 formed to be in contact with the bottom of the magnet 310. Thus, the second yoke 330 is configured to be seated. Accordingly, a substantially cylindrical second yoke 330 extending long in the optical axis direction opposite to the outer circumferential surface of the coil 340 is stably interposed between the inner bottom surface of the magnet 310 and the lower cover 420. In particular, as the carrier 220 moves upwards, the upper inner circumferential lower end 426 of the lower cover 420 protruding toward the center as compared with the first embodiment has a locking end 226 of the carrier 220. By contacting, stable focusing may be implemented by limiting driving of the carrier 220.

In addition, referring to FIG. 8, which is a cross-sectional view of the lens actuator according to the third embodiment of the present invention, the second yoke 330 is a cylindrical shape extending in a horizontal direction, and the bottom and bottom cover 420 of the magnet 310 are positioned. May appear between the top of the inner circumference. In this case, the upper inner circumferential surface 426 of the lower cover 420 is extended in comparison with the first embodiment, so that when the carrier 220 is moved upward, the lower end of the upper inner circumferential surface 426 of the lower cover 420 is formed by the carrier ( By contacting the end 226 of the 220 to limit the driving of the carrier 220 it is possible to stable focusing.

In the above, a preferred embodiment of the present invention has been described, but it is only presented to help those skilled in the art for the sake of understanding only, and the present invention is not limited thereto. Rather, it will be apparent to those skilled in the art that various modifications and variations can be made easily from the above-described embodiments and the accompanying drawings. However, it will be more apparent from the following claims that such modifications and variations fall within the scope of the present invention without departing from the spirit of the present invention.

1 is a cross-sectional view schematically showing an auto focus lens assembly constituting a camera module that has been mounted in a conventional mobile communication device.

FIG. 2 is an exploded perspective view showing a coupling relationship between components constituting a lens actuator of a camera module mounted on a compact optical device such as a mobile communication device according to the first embodiment of the present invention.

3 is a perspective view showing a state in which the lens actuator according to the first embodiment of the present invention is assembled.

4 is a schematic perspective view illustrating an arrangement and a coupling state of a first yoke and a magnet in a state in which a case member and an upper elastic means that form an outer side of a lens actuator according to a first embodiment of the present invention are removed.

5 is a cross-sectional view taken along the line V-V of the lens actuator of the present invention shown in Figure 3, a schematic cross-sectional view showing a state before the lens actuator according to the present invention is driven.

FIG. 6 is a cross-sectional view schematically illustrating a state in which the lens actuator according to the exemplary embodiment of the present invention shown in FIG. 5 is driven for focusing.

7A and 7B are cross-sectional views schematically showing states before and after driving a lens actuator according to a second embodiment of the present invention, respectively.

8 is a cross-sectional view schematically showing a state before the lens actuator according to the third embodiment of the present invention is driven.

<Explanation of symbols for the main parts of the drawings>

100: lens actuator 200: lens unit (lens module)

210: lens unit 220: carrier

300: driving unit 310: magnet

320: first yoke 330: second yoke

340: coil 410: top cover

420: lower cover 430: base

Claims (11)

A lens unit which accommodates a lens unit for photographing a subject and is movable in an optical axis direction; A driving unit for moving the lens unit in the optical axis direction by a driving force by the interaction of the magnet and the coil disposed on the outer periphery of the lens unit, the magnet disposed on the outer periphery of the lens unit and the magnetic force generated from the magnet In order to surround the upper and upper inner peripheral surface of the magnet and the first yoke and at least a second yoke disposed to be in contact with the bottom surface of the magnet, and wound around the outer peripheral surface of the lens portion and moves in conjunction with the lens portion A drive unit including a coil disposed opposite the inner circumferential surface of the second yoke. Lens actuator for image pickup comprising a. The method of claim 1, The magnet is a lens actuator, characterized in that consisting of a plurality of magnets arranged radially around the lens unit. The method according to claim 1 or 2, And the second yoke is in contact with a bottom surface of the magnet and has a cross section in which an inner circumferential surface opposite to the coil is bent downward. The method of claim 3, wherein The lens unit includes a cylindrical carrier and a lens unit mounted to the hollow part of the carrier, and the outer periphery of the carrier to allow the lens unit to contact the bottom surface of the second yoke as the lens unit moves along the optical axis. A lens actuator, characterized in that the locking end is formed at the bottom. The method according to claim 1 or 2, And the second yoke is formed to contact only the inner bottom surface of the magnet. The method of claim 4, wherein The coil is a lens actuator, characterized in that seated on the upper surface of the locking end protruding outward from the outer periphery of the carrier. The method according to claim 1 or 2, The lens unit includes a cylindrical carrier and a lens unit mounted to the hollow portion of the carrier, the lens actuator further comprises an elastic means for contacting the upper and lower ends of the carrier, respectively. The method of claim 7, wherein The elastic means includes a first elastic body disposed on an upper end of the carrier and the lens actuator, and a second elastic body disposed on a lower end of the carrier and the lens actuator. The method of claim 8, And a top cover disposed at an upper end of the first elastic body, a lower cover disposed at a lower end of the second yoke, and a base supporting the lens unit at a lower end of the second elastic body. The method of claim 9, The second yoke is disposed between an inner bottom surface of the magnet and an inner upper end of the lower cover, and as the lens unit moves along an optical axis, a locking end formed at an outer peripheral lower end of the carrier may contact the inner circumferential surface of the lower cover. A lens actuator, characterized in that the upper end of the lower cover protrudes inwardly. The method of claim 9, The lens actuator further comprises a shield case coupled along the outer circumferential surface of the upper cover and the lower cover.

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