KR20120125449A - Mems actuator and camera module comprising the same - Google Patents

Abstract

PURPOSE: A MEMS actuator and a camera module with the same are provided to sufficiently distribute stress in a horizontal direction and a vertical direction by a flexure and to obtain excellent impact resistance. CONSTITUTION: A MEMS actuator comprises a lens fixing unit(100). A moving lens is fixed to the lens fixing unit comprising a circular ring(130), a body unit(110), and a flexure(120). A plurality of mount pads(131) of the circular ring is connected by a circular arc unit(132). An opening(111) receiving the circular ring is formed in a central portion of the body unit. The flexure connects the body unit in a central portion of the circular arc unit.

Description

MEMS actuator and camera module including the same {MEMS ACTUATOR AND CAMERA MODULE COMPRISING THE SAME}

The present invention relates to a MEMS actuator, and more particularly, to a MEMS actuator and a camera module including the same, in which the length of the flexure is extended and the thickness is optimized, so that the stress is easily dispersed and the impact resistance against external impact is improved.

Generally The compact camera module is compact and is applied to portable mobile communication devices such as camera phones, PDAs and smart phones and various IT devices.

Such a camera module is manufactured with an image sensor such as a CCD or a CMOS as a main component, and is manufactured to be able to adjust focus to adjust an image size.

At this time, the camera module includes a plurality of lenses, and the optical focal length is adjusted by moving each lens to change its relative distance.

Recently, researches to implement auto focus using micro electromechanical systems (MEMS) actuators instead of conventional voice coil motors (VCMs) are active.

In the MEMS actuator, a moving lens is fixed to a silicon wafer instead of a conventional voice coil. Therefore, when the voltage is applied, the portion where the moving lens is fixed by the electrostatic force moves up and down, thereby finely adjusting the moving lens to perform an auto focusing function.

However, these MEMS actuators are vulnerable to impact because they are formed in a thin silicon wafer with a fine pattern. Especially, the moving lens is fixed to the MEMS actuator in a thin thickness so that they are easily deformed so that they are easily broken even in small external impacts. There is a problem that can not function properly.

An object of the present invention is to provide a MEMS actuator excellent in impact resistance and a camera module including the same.

MEMS actuator of the present invention is a MEMS actuator for a camera module including a lens fixing to which the moving lens is fixed in order to achieve the above object, the lens fixing is an annular ring in which a plurality of mount pads are connected by an arc portion. A body portion having an opening for accommodating the annular ring is formed at the center, and a complex connecting the body portion at the center of the arc portion.

In addition, a recess is formed in the opening to accommodate the mount pad, and the flexure extends and branches from the center of the arc to be connected to both boundary points of the recess.

The thickness of the annular ring is 50 ~ 55㎛, the thickness of the complex may be composed of 50 ~ 60㎛.

In addition, the extension lines extending in the center direction of the annular ring in the adjacent mounting pads may be formed to be perpendicular to each other.

Due to the configuration described above, the flexure can sufficiently disperse the stresses in the horizontal and vertical directions and has excellent impact resistance against external impact.

In addition, since the strain is small in the vertical direction, it is possible to prevent the posture stabilization time from increasing due to the inertial force of the lens.

1 is a cross-sectional view of a camera module according to an embodiment of the present invention,
2 is a plan view of a MEMS actuator according to an embodiment of the present invention.
3 is a plan view of a lens fixing part according to an embodiment of the present invention;
4 is an enlarged view of a portion A of FIG. 3;
5a is a simulation showing the horizontal internal stress of the comparative example,
Figure 5b is a simulation showing the internal stress in the horizontal direction on the lens fixing in accordance with an embodiment of the present invention,
6A is a simulation showing the internal stress in the vertical direction of the comparative example,
Figure 6b is a simulation showing the internal stress in the vertical direction to the lens fixing according to an embodiment of the present invention,

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms.

The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In addition, it is to be understood that the accompanying drawings in this application are shown enlarged or reduced for convenience of description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the drawings. Like reference numerals designate like elements throughout, and duplicate descriptions thereof will be omitted.

1 is a cross-sectional view of a camera module according to an embodiment of the present invention, Figure 2 is a plan view of a MEMS actuator according to an embodiment of the present invention, Figure 3 is a plan view of a lens fixing according to an embodiment of the present invention, Figure 4 is an enlarged view of portion A of FIG. 3.

The camera module according to the embodiment of the present invention includes a MEMS actuator 10 which moves the moving lens 410 up and down, and a barrel 20 which fixes the MEMS actuator 10 and includes a plurality of lenses 420, 430, and 440 therein. And a holder 30 positioned below the barrel 20 to fix the barrel 20 and a cover 40 to shield the inside.

The barrel 20, the holder 30, and the cover 40 generally have the same configuration as the camera module in which the MEMS actuator is built, and thus the detailed description thereof will be omitted.

The MEMS (Micro electromechanical Systems) actuator 10 uses a silicon wafer instead of the conventional voice coil to move the moving lens 410 up and down to finely adjust the moving lens 410 to perform an auto focusing function. Perform.

Referring to FIG. 2, the MEMS actuator 10 is formed by forming a pattern on a silicon wafer, and is positioned in the center of the rectangular frame 300 and the frame 300 to fix the moving lens. The fixing unit 100 and the lens fixing unit 100 and the motion controller 200 connected to the frame 300 is divided.

As the drawings are illustrated to help understand, the configuration may be variously modified to suit the implementation.

The MEMS actuator 10 is driven by an electrostatic force so that when the voltage is applied, the lens fixing part 100 moves up and down by the attraction force and the repulsive force with the frame 300.

The motion controller 200 is connected to the lens fixing part 100 and the hinge 210 to facilitate the vertical movement of the lens fixing part 100.

By such a configuration, the MEMS actuator 10 has a relatively small current to drive, and thus has an advantage over the conventional VCM (Voice Coil Motor) actuator in power consumption.

Referring to FIG. 3, the lens fixing part 100 connects the annular ring 130 and the body portion 110 in which the annular ring 130 is accommodated, and the annular ring 130 and the body portion 110. It is composed of a flexure 120.

The annular ring 130 is formed of a plurality of mount pads 131 to which a moving lens can be fixed, and is formed of a plurality of arc portions 132 connecting the plurality of mount pads 131 to the annular ring 130. The convex portion (410a of FIG. 1) of the moving lens is fitted into the inner hole H of FIG.

The mount pad 131 may be formed in plurality in symmetrical structure with each other. For example, two mount pads 131 facing each other or four mount pads 131 may be formed. If four mount pads 131 are formed, extension lines extending from each mount pad 131 to the center of the annular ring 130 may be formed to have 90 ° to each other.

The body part 110 has an opening 111 formed to accommodate the annular ring 130, and a recess 112 for accommodating the mount pad 131 is further formed in the opening 111. Is formed.

The complex 120 extends and branches from the center of the arc portion 132 and is connected to the boundary point 112a of the recess 112, respectively. (Here, the boundary point of the concave portion refers to a point where the opening formed in the body portion and the concave portion meet.)

In detail, the flexure 120 includes a first connection portion 123 extending from the arc portion P and an extension portion 122 and the extension portion 122 branching from the first connection portion 123. Both sides of the) is composed of a second connection portion 121 is connected to the boundary point 112a of the recess 112.

In this case, the thickness of the annular ring 130 is 50 ~ 55㎛, the thickness of the extension 122 is formed of 50 ~ 60㎛ can be configured to improve the structural strength and impact resistance.

A long hole H1 having an arc is formed between the extension part 122 and the body part 110. By such a configuration, when the convex portion 410a of the moving lens is inserted into the inner hole H of the annular ring 130, the extension portion 122 is pushed sufficiently backward to fix the moving lens. .

Looking at the process of dispersing the horizontal stress applied to the flexure 120 when the moving lens is inserted, the most stress is generated in the first connector 123, but the extension part connected to the first connector 123 Since 122 extends as far as possible in the longitudinal direction, stress is easily dispersed.

The stopper 113 may protrude from the recess 112 so that the moving lens may be excessively inserted into one side to prevent the first connector 123 from breaking.

Looking at the process of dispersing the vertical stress applied to the flexure 120, the lens fixing part 100 is continuously moved up and down to focus the camera by the moving lens.

After that, when the lens is fixed and the lens is fixed, the moving lens has an inertial force in the vertical direction.

However, since the flexure 120 is designed to have a small amount of deformation in the vertical direction, the moving lens has a reduced vibration time due to inertial force, thereby shortening the posture stabilization time.

Therefore, the inertial force acts as an internal stress in the direction perpendicular to the flexure. However, since the extension part 123 of the complex is formed to extend as long as possible to both boundary points 112a of the recess 112, the vertical stress is effectively distributed.

In addition, the extension is formed to have a thickness of 50 ~ 60㎛ is not broken by the impact.

That is, by increasing the thickness and length of the extension portion of the flexure, while the vibration time during autofocus decreases, the structural strength increases by the thickness and the stress is easily dispersed, so that it is not broken by vertical stress or external impact.

Hereinafter, a state in which stresses according to the present invention are dispersed will be described with reference to FIGS. 5 and 6. At this time, the lens fixing part 100 according to the embodiment of the present invention has a thickness of the annular ring 130 is 50㎛, the thickness of the extension 122 is 55㎛, the distance between the annular ring and the extension is 45㎛, the extension The distance between the body portion and the body portion was 45 μm, and in the comparative experimental example, the thicknesses of the two complexes between the two mount pads were 30 μm and tilted, respectively.

Looking at the internal stress in the horizontal direction first, the comparative experimental example has a maximum stress value of 521 MPa as shown in Figure 5a, the lens fixing part 100 of the present invention as shown in Figure 5b the maximum stress value applied to the first connection portion This 225 MPa shows that the maximum stress value was reduced by 56% compared with the comparative experimental example.

In addition, the comparative stress in the vertical direction is a maximum stress value of 460 MPa as shown in Figure 6a, while the lens fixing part 100 of the present invention is 298MPa as shown in Figure 6b, the maximum stress value is 35% compared to the comparative example It can be seen that the decrease.

The embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having various ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

100: lens fixing 110: body portion
111: opening 112: recess
120: lens fixing 121: first connection portion
122: extension portion 123: second connection portion
130: annular ring 131: mount pad
132: arc 410: moving lens

Claims (6)

In the MEMS actuator comprising a lens fixing to which the moving lens is fixed,
The lens fixing part includes an annular ring having a plurality of mount pads connected by an arc portion, a body portion having an opening for accommodating the annular ring, and a complex connecting the body portion at the center of the arc portion. Actuator. The MEMS actuator of claim 1, wherein a recess is formed in the opening to receive the mount pad, and the flexure extends and branches from the center of the arc and is connected to both boundary points of the recess. The MEMS actuator according to claim 2, wherein the annular ring has a thickness of 50 to 55 µm and the thickness of the flexure ring is 50 to 60 µm. The MEMS actuator of claim 1, wherein the extension lines extending from the neighboring mount pads toward the center of the annular ring are perpendicular to each other. The MEMS actuator of claim 2, wherein at least one stopper is formed in the recess. Camera module comprising the MEMS actuator of any one of claims 1 to 5.

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