KR20070100057A - Lens driving apparatus - Google Patents

Abstract

A lens driving apparatus is provided to move a lens holder elastically supported by membrane spring and support a middle part of the lens holder by the membrane spring, thereby moving a lens at high speed and preventing abnormal movement of lens. A lens driving apparatus for moving a lens to an optical axis direction as much as predetermined quantity comprises the followings: a frame(10); a lens holder(20) which is installed inside the frame while supporting the lens; a membrane spring(30) for elastically supporting the lens holder by an optical axis direction by taking a middle part of the lens holder; and an actuator(40), which is constructed with a magnet and a coil member, for moving the lens holder to optical axis direction by applying current to the coil member.

Description

Lens drive device {LENS DRIVING APPARATUS}

1 is a cross-sectional view showing a lens driving apparatus according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing an exploded lens driving device shown in FIG. 1; FIG.

3 is an exploded perspective view showing the main part of the lens driving device shown in FIGS. 1 and 2;

4 is a cross-sectional view for explaining a state of use of the lens driving apparatus according to the present embodiment.

<Code Description of Main Parts of Drawing>

10: frame 12: base frame

14: upper frame 20: lens holder

22: holder body 24: auxiliary holder

30: membrane spring 40: actuator

42: coil body 44: magnet

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving apparatus used in a portable compact camera embedded in a digital camera or a mobile phone, and more particularly, a lens driving for driving a zoom lens or an auto focus lens to move a lens in an optical axis direction. Relates to a device.

Background Art A lens driving apparatus for adjusting the focus of a lens by changing the linear motion of a lens by rotating a motor using a ball, a screw, or a gear is known. Such a lens driving apparatus has been disclosed in, for example, Japanese Patent Laid-Open No. 7-140523. However, such a lens driving apparatus has a large driving loss because the direction of the motor driving force and the moving direction of the lens are not the same, and thus, the speed and response of lens movement are inferior.

In the related art, a lens driving apparatus including a magnet and a coil for generating an electromagnetic force, a yoke for installing the magnet and the coil, and a leaf spring for elastically supporting the lens holder have been proposed. The lens driving device provides a yoke between the frame and the lens holder to form a space in which the magnet and the coil are disposed to face each other, and fixes the magnet to the inner circumferential surface of the yoke while extending the coil body to the lower side of the lens holder. It is fixed to the part and configured to move the lens holder in the optical axis direction by applying current to the coil body. The conventional lens driving apparatus as described above is configured to support the upper or lower end of the lens holder while avoiding the installation position of the yoke while the ring-shaped leaf spring is connected to the lens holder and the yoke at the inner and outer circumferences, respectively.

However, the lens driving apparatus as described above has a problem that it is difficult to implement a compact structure in that the configuration for the installation of the magnet, the coil body and the leaf spring is complicated, and additional components such as yokes are required. In addition, the leaf spring has a very complicated structure for limiting the movement range of the lens holder, and also supports the top or bottom of the lens holder, so that when rotating the camera or when photographing the camera, rotating and shifting It could cause abnormal flow of the lens holder such as shifting and / or tilting.

In particular, in the conventional lens driving apparatus, when the lens holder is laid down for camera shooting, a large moment due to its own weight is generated around the top or bottom of the lens holder supported by the leaf spring, which distorts the photographed image. It is a big cause.

On the other hand, a lens driving device has been developed that supports both the upper and lower ends of the lens holder with two leaf springs to reduce the shake and / or impact of the lens holder and the lens installed therein. -128392 and the like. However, such a conventional lens drive device also has problems such as complicated configuration for the installation of the coil body, the magnet, the leaf spring, and additional components of a complicated structure such as yoke are still required. And a compact configuration of the digital camera or the camera cellular phone including the lens driving device.

Accordingly, the present invention is to solve the problems of the prior art, while having a simple and compact structure, for example, it is possible to strictly limit the abnormal flow of the lens holder, such as shifting, rotating, tilting, etc. It is to provide a lens driving device of the structure.

According to an embodiment of the present invention, there is provided a lens driving device for a desired amount of movement of the lens in the optical axis direction, the lens driving device, a lens holder positioned inside the frame while supporting the lens, A membrane spring for holding the intermediate portion of the lens holder and elastically supporting the lens holder in the optical axis direction, a magnet and a coil body, and an actuator for moving the lens holder in the optical axis direction by applying current to the coil body. Include.

Preferably, the actuator is located above or below the lens holder to avoid the middle portion of the lens holder in which the membrane spring is located, wherein the membrane spring has an inner circumferential portion fixed to the frame and an inner circumferential portion of the lens It is coupled to the middle part of the holder.

Here, the frame is composed of a base frame and the upper frame, the outer periphery of the coil body and the membrane spring can be fixed together interposed up and down between the base frame and the upper frame, the lens holder is a holder body And an auxiliary holder detachably coupled to a lower outer circumferential portion of the holder main body, and the inner circumference of the magnet and the membrane spring may be interposed up and down together between the holder main body and the auxiliary holder.

Conversely, the frame is composed of a base frame and the upper frame, the outer peripheral portion of the magnet and the membrane spring can be fixed together interposed up and down between the base frame and the upper frame, the lens holder is a holder body And an auxiliary holder detachably coupled to a lower outer peripheral portion of the holder body, and between the holder body and the auxiliary holder, the inner circumferential portion of the coil body and the membrane spring may be interposed and fixed together up and down. .

Example

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a lens driving apparatus according to an embodiment of the present invention, Figure 2 is an exploded perspective view showing the lens driving apparatus shown in Figure 1, Figure 3 is a lens holder, a magnet, and a membrane spring It is an exploded perspective view.

As shown in FIGS. 1 to 3, the lens driving apparatus 1 according to the present exemplary embodiment includes a frame 10, a lens holder 20, a membrane spring 30, and an actuator 40. The lens holder 20 is positioned inside the frame 10 with the lens 2 schematically shown inside fixed thereto, and the membrane spring 30 is formed in a ring shape in the frame 10. It is provided to elastically support the lens holder 20 in the optical axis direction. In addition, the actuator 40 serves to move the lens holder 20 elastically supported by the membrane spring 30 according to the application of a current.

In this embodiment, the frame 10 includes a base frame 12 and an upper frame 14 seated thereon. The base frame 12 includes a ring-shaped membrane spring 30 and a hollow cylindrical support 122 extending upwardly for fixing the hollow cylindrical coil body 42 (as shown in FIG. 2). In addition, the upper frame 14 has a circular opening 142 (as shown in FIG. 2) at the top, and the membrane spring 30 and the coil body between the bottom of the upper portion and the support 122 described above. A gap is provided in which the 42 can be fixed together.

Accordingly, the frame 10 may be fixed between the upper bottom surface of the upper frame 14 and the support 122 of the base frame 12 by interposing the coil body 42 and the membrane spring 32 up and down. . In addition, for convenience of assembly, a ring-shaped spacer 5 may be further interposed between the upper frame 14 and the base frame 12.

In the drawings and the description above, although the outer circumference of the coil body 42 and the membrane spring 30 is fixed together between the upper frame 14 and the base frame 12, the hollow cylindrical magnet is placed on the outside. In consideration of the case of positioning the coil body inside the hollow of the magnet, the magnet may be fixed between the upper frame 14 and the base frame 12 together with the outer circumference of the membrane spring 30.

On the other hand, the lens holder 20 is a portion provided for fixing and holding the lens 2, the middle portion thereof is elastically supported by the membrane spring 30 described above. At this time, the membrane spring 30 is held by the middle portion of the lens holder 20 to support, for example, a lens holder such as shifting, tilting or rotating (rotating). The abnormal flow of 20) can be greatly suppressed. This is because the moment caused from the support of the upper or lower end of the lens holder in the conventional lens driving apparatus can be greatly suppressed by supporting the middle portion of the lens holder 20. At this time, the support position of the lens holder 20 by the membrane spring 30 is preferably a position where the moment O, in this case, the abnormal behavior of the lens holder 20, such as shifting, tilting or rotating Can be almost completely excluded.

According to the exemplary embodiment of the present invention, the lens holder 20 is screwed with the holder body 22 and the holder body 22 at the lower outer peripheral portion of the holder body 22 substantially fixing the lens 2. Auxiliary holder 24 is included. A gap of a predetermined interval is provided between the holder body 22 and the auxiliary holder 24 coupled to each other, and the gap is fixed with the inner circumferences of the magnet 44 and the membrane spring 30 interposed therebetween. In the present embodiment, the magnet 44 and the membrane spring 30 are interposed and fixed in the gap, but the positions of the magnet 44 and the coil body 42 constituting the actuator 40 are changed. In this case, the coil body 42 and the membrane spring 30 may be fixed together in the gap.

Accordingly, the membrane spring 30 elastically supports the middle portion of the lens holder 20, and the actuator 40 formed of the coil body 42 and the magnet 44 is used to adjust the installation position of the membrane spring 30. The damage will be located above the membrane spring 30. According to the preferred embodiment of the present invention, although the actuator 40 is located above the membrane spring 30, it may be contemplated to install the actuator 40 below the membrane spring 30.

The lens driving device 1 described above can omit complicated parts such as yokes, which are inevitably added in the prior art, and despite the omission of these additional parts, the lens driving device 1 according to the present embodiment is a nose. The lens holder 20 can be moved in the optical axis direction by the generation of an electromagnetic force between the nose unit 42 and the magnet 44 due to the current applied to the unit 42.

As mentioned above, the membrane spring 30 has a ring shape and an outer circumferential portion is fixed inside the frame 10 and an inner circumferential portion is fixed outside the lens holder 20. A curved portion 32 (refer to FIG. 4) for elastic behavior of the membrane spring 30 is formed between the outer peripheral portion and the inner peripheral portion. Even with this simple curved portion 32, the membrane spring 30 allows the lens holder 20 to be moved by a desired amount in the optical axis direction. At this time, the membrane spring 30 may have a variety of shapes and spring constants, but preferably has a shape and spring constant that can be suppressed elastic deformation by an external unintended force.

FIG. 4 is a cross-sectional view of the lens driving apparatus 1 described above laid down laterally, which is a cross-sectional view illustrating a state of use of the lens driving apparatus 1 most frequently performed.

As shown in FIG. 4, the membrane spring 30 elastically supports the lens holder 20 near the center of gravity of the lens holder 20. That is, the membrane spring 30 supports the lens holder 20 at a point where the moment to its own weight becomes approximately zero, which serves to eliminate displacement caused by the weight of the lens holder 20 during camera shooting. .

In addition, the above structure, the height difference between the flat portion (31, 33) and the flat portion (31, 33) formed inside and outside of the curved portion 32 for elastic deformation of the membrane spring (30) Makes it possible to determine a smaller. In addition, the shape of the membrane spring 30, which is simple and efficient to move in the optical axis direction as described above, is realized by the organic relationship between the frame 10, the lens holder 20, the membrane spring 30, and the actuator 40 described above. It can be.

In the figure, the lens 2 is shown in schematic form, but the lens 2 is composed of a plurality of lenses including a convex lens or a concave lens, and the lenses are the lens holder 20 described above. It is fixed by the whole.

As used herein, the term "lens holder" means at least a holder body 22, which is commonly referred to as a "barrel" as a part where the lens is seated and held, and the above-described auxiliary holder 24 is a component such as a membrane spring. When the barrel (or holder body) is configured to be a structure capable of maintaining the structure, it may be omitted.

In addition, the lens driving apparatus according to the present invention acquires an image at the moment when the focus is matched in the process of applying power to the actuator 40 and the displacement of the lens holder 20 accordingly in a state where the focus of the lens is not matched. It can be particularly useful for this, whereby, in the conventional lens driving device, and moreover, in the conventional camera assembly process, a complicated configuration of setting the zero by screwing the barrel by using the barrel and the carrier screwed thereto and / or Or it allows you to skip the assembly process. However, it is also within the scope of the present invention to employ the existing barrel and carrier as it is for compatibility with existing parts.

 While the invention has been described above with reference to specific embodiments, various modifications, changes, or modifications may be made in the art within the spirit and scope of the appended claims, and thus, the foregoing description and drawings It should be construed as illustrating the present invention rather than limiting the technical spirit of the present invention.

According to an embodiment of the present invention, by moving the lens holder elastically supported by the membrane spring with an electromagnetic force, the lens can be moved in a quick response, in particular, by the membrane spring supporting the middle portion of the lens holder It can prevent abnormal lens behavior such as tilting, rotating or shifting caused by the lens driving apparatus of the conventional spring supporting structure.

In addition, while the spring mounting structure of the existing lens drive device has a complicated configuration, including complicated additional parts such as yokes, the lens drive device provided according to the present embodiment is simple in configuration and greatly reduces the number of parts. Accordingly, it can greatly contribute to compactness and miniaturization of a device such as a digital camera or a camera mobile phone in which it is embedded.

Furthermore, unlike the conventional lens driving apparatus in which the leaf springs are installed at the upper and lower ends of the lens holder to prevent the vibration or abnormal behavior of the lens, the lens driving apparatus according to the present embodiment has the vibration of the lens with only one membrane spring. Alternatively, there is an advantage that it is very effective in preventing the abnormal behavior of the lens more effectively.

Claims (7)

In the lens driving device for moving the lens a desired amount in the optical axis direction, A frame; A lens holder positioned inside the frame while supporting the lens; A membrane spring which grasps an intermediate portion of the lens holder and elastically supports the lens holder in an optical axis direction; An actuator formed of a magnet and a coil body and configured to move the lens holder in the optical axis direction by applying current to the coil body; Lens drive device comprising a. The lens driving apparatus of claim 1, wherein the actuator is positioned above or below the lens holder while avoiding an intermediate portion of the lens holder where the membrane spring is located. The lens driving apparatus of claim 1, wherein the membrane spring is coupled to an intermediate portion of the lens holder while its outer circumference is fixed to the frame. 4. The lens driving apparatus of claim 3, wherein the frame comprises a base frame and an upper frame, and an outer circumferential portion of the coil body and the membrane spring is interposed up and down between the base frame and the upper frame. . The lens holder of claim 4, wherein the lens holder comprises an auxiliary holder detachably coupled to a holder body and a lower outer peripheral portion of the holder body, and an inner circumference of the magnet and the membrane spring between the holder body and the auxiliary holder. Lens drive device characterized in that the interposed up and down together. 4. The lens driving apparatus of claim 3, wherein the frame comprises a base frame and an upper frame, and an outer circumferential portion of the magnet and the membrane spring are interposed up and down and fixed between the base frame and the upper frame. The inner peripheral portion of the coil body and the membrane spring according to claim 4, wherein the lens holder comprises an auxiliary holder detachably coupled to a holder body and a lower outer peripheral portion of the holder body, and between the holder body and the auxiliary holder. Lens driving device, characterized in that the interposed up and down fixed together.

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