KR100759095B1 - An independent two-axis micro-electro-mechanical systems mirror using a piezoelectric force - Google Patents

Abstract

A two-axis driven MEMS(Micro-Electro-Mechanical System) mirror using piezoelectric force is provided to secure independent driving along the directions of first and second axes perpendicular to each other and to implement a two-axis drive MEMS mirror having an improved fill-factor by using piezoelectric power. A two-axis driven MEMS mirror(300) using piezoelectric force is composed of a substrate; a silicon layer(310) formed on the substrate; a piezoelectric driving unit layer(320) formed on the silicon layer to tilt the MEMS mirror in the directions of first and second axes crossing each other and composed of first and second symmetrical parts(322,323) separated from each other and piezoelectric materials; a pair of mirror pedestals(330) arranged on the silicon layer and positioned in the first and second symmetrical parts, respectively; and a mirror plate(340) disposed on a pair of mirror pedestals. The first and second symmetrical parts comprise a first piezoelectric driving unit(326) of a first inverse-staple form having a rotary shaft(324) crossing adjacently to the center of the mirror plate and a second piezoelectric driving unit(328) of a second inverse-staple form installed in the first inverse-staple form of the first piezoelectric driving unit to surround the mirror plate.

Description

2-axis-driven ultra-fine electromechanical system mirror using piezoelectric power {AN INDEPENDENT TWO-AXIS MICRO-ELECTRO-MECHANICAL SYSTEMS MIRROR USING A PIEZOELECTRIC FORCE}

1 is a view showing an example of various driving methods that can be used in the MEMS mirror, Figures 1a to 1d is a driving method using a constant power, a driving method using an electromagnetic force, a driving method and a thermal deformation, respectively Fig. 1A shows a driving method using electric power, and in particular, in Fig. 1A showing a driving method using electrostatic power, a left side shows a parallel plate driving method and a right side shows a comb-type driving method.

2 shows the driving principle of a piezoelectric actuator;

3 illustrates an independent two-axis drive MEMS mirror using piezoelectric force in accordance with one embodiment of the present invention.

4 illustrates simulation results of an independent two-axis drive MEMS mirror using piezoelectric power designed according to one embodiment of the invention.

<Explanation of symbols for main parts of the drawings>

210: fixing part

220: upper electrode

230: piezoelectric material

240: lower electrode

250: substrate

300: MEMS mirror using piezoelectric power (according to an embodiment of the present invention)

310: silicon layer

312: portion where the mirror stand is provided

314: fixed part

320: piezoelectric drive part layer

322: first symmetry part

323: second symmetry

324: axis of rotation

326: first piezoelectric drive unit

328: second piezoelectric drive unit

329: Fixed point for Y-axis rotation

330 mirror stand

340 mirror plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially-driven microelectromechanical apparatus (MEMS) mirror using piezoelectric force, and more particularly to a first axis direction and a second axis direction orthogonal to each other using piezoelectric force. And independent two-axis drive MEMS mirrors with improved fill-factor.

Micro-electro-mechanical systems (MEMS), a combination of small mechanical devices such as sensor valves, gears, reflectors, and semiconductor chip actuators, has recently come to the fore. MEMS, also known as 'smart meters', are devices that have a microcircuit of tiny silicon chips that are used in the manufacture of mechanical devices such as reflectors or sensors, inflating the airbag to match the speed detected by the car airbag and the weight of the guardian. Global positioning system sensor for continuous tracking and handling of cargo transport, interactive sensor to detect changes in air flow according to the surface air resistance of the aircraft wing, and to produce optical signals at speeds of 20 nanoseconds It is used in many applications such as light switching devices, sensor-operated cold and warm devices, and sensors in buildings that change the flexibility of materials reacting to atmospheric pressure. As such, MEMS has been widely applied in various fields because it greatly improves the performance of the product to which the application is applied, and at the same time, the size and size are reduced.

Such MEMS is also applied to implement mirrors. The mirror implemented by MEMS (hereinafter referred to as 'MEMS mirror') is a mirror using electrostatic force, a mirror using electromagnetic force, a mirror using piezoelectric force, and thermal deformation, depending on the driving method of driving the mirror. It can be divided into a used mirror and the like. The mirror using the electrostatic force can be further divided into a parallel plate driving method and a comb-drive method. 1 is a diagram illustrating examples of various driving schemes that can be used in a MEMS mirror. 1A to 1D are diagrams illustrating a driving method using a constant power, a driving method using an electromagnetic force, a driving method using a thermal deformation, and a driving method using a piezoelectric force, respectively. The left side shows the parallel plate drive system, and the right side shows the comb-type electrostatic drive system.

Each driving scheme shown in FIG. 1 has its own advantages and disadvantages compared to other driving schemes. The driving method using the piezoelectric power to be dealt with in the present invention, compared with other driving methods, (1) can make a large displacement with a low driving voltage, (2) almost no power consumption, (3) displacement with respect to voltage Since it is linear, it has the advantage that the control of driving is easy. However, there have been few examples of applying the driving method using piezoelectric power to implement MEMS mirrors, and these cases are not suitable for the MEMS mirror array because the fill-factor is very low. In particular, there has been no example of implementing a biaxially-driven MEMS mirror that rotates in a direction perpendicular to each other by a driving method using piezoelectric force. Therefore, there is a need to implement a MEMS mirror using piezoelectric power, which is suitable for implementing a MEMS mirror array while having a high fill factor, and capable of independent two-axis driving.

The present invention originates from the above problem and need recognition, and can independently drive in the first and second axial directions orthogonal to each other, and significantly improves the filling-factor, which is independent two-axis drive MEMS mirror. The purpose is to implement using.

According to a feature of the present invention for achieving the above object, an independent two-axis drive ultra-fine electromechanical system (MEMS) mirror using a piezoelectric power,

(1) a substrate;

(2) a silicon layer provided on the substrate;

(3) a first axial direction provided on the silicon layer, the first symmetry part and the second symmetry part of which the shapes are symmetrical and separated, the piezoelectric material including the piezoelectric material perpendicular to each other; And a piezoelectric driver layer for driving to rotate in the second axial direction.

(4) a pair of mirror pedestals provided on the silicon layer and located in the first symmetric part and the second symmetric part, respectively; And

(5) including a mirror plate (mirror plate) provided on the pair of mirror pedestal,

' 형상의 제1 압전 구동부와, 상기 제1 압전 구동부의 상기 제1 '

' 형상 내부에 상기 미러 받침대를 둘러싸는 제2 '

' 형상의 제2 압전 구동부를 더 포함하며,(6) the first symmetric part and the second symmetric part each include a first axis including a rotation axis traversing adjacent to a central portion of the mirror plate;

A first piezoelectric drive part having a shape and the first first piezoelectric drive part

'A second' surrounding the mirror pedestal inside the shape

'Further comprises a second piezoelectric drive part,

' 형상의 양 끝점에서 상기 기판에 고정되어, 상기 MEMS 미러의 상기 제1 축 방향의 회전에 대한 고정점 역할을 하는 고정부를 더 포함하고, 상기 제2 압전 구동부는 상기 제2 '

' 형상의 중심변과 상기 회전축이 접속하여, 상기 MEMS 미러의 상기 제2 축 방향의 회전에 대한 고정점 역할을 하는 접속점을 더 포함하는 것을 그 특징으로 한다.(7) wherein the silicon layer and the piezoelectric driver layer are formed on the first ′ of the first piezoelectric driver.

And a fixing part fixed to the substrate at both ends of the shape and serving as a fixing point for the first axial rotation of the MEMS mirror, wherein the second piezoelectric driving part includes the second '

It characterized in that it further comprises a connection point that the center side of the 'shape and the rotation axis is connected, which serves as a fixed point for the rotation in the second axial direction of the MEMS mirror.

Independent two-axis drive MEMS mirror using a piezoelectric force according to another feature of the present invention,

The piezoelectric driving unit layer may include an upper electrode, a piezoelectric material, and a lower electrode in order from above.

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

2 is a view showing a driving principle of a piezoelectric actuator. As shown in FIG. 2, the piezoelectric driver fixed to the fixing unit 210 includes an upper electrode 220, a piezoelectric material 230, a lower electrode 240, and a substrate 250. The driving principle of the piezoelectric driver is that when a voltage is applied to the upper electrode 220 and the lower electrode 240, the piezoelectric material 230 positioned between the upper electrode 220 and the lower electrode 240 contracts, and as a result, As shown in FIG. 2, a rotational displacement is generated toward the upper side with the fixing part 210 as the fixing point. If the mirror plate is provided on the upper electrode 220 of the piezoelectric driver, the mirror plate is lifted together by the generated displacement. The present invention applies the driving principle of such a piezoelectric driver to a MEMS mirror.

3 is a view showing an independent two-axis drive MEMS mirror using a piezoelectric force according to an embodiment of the present invention. As shown in FIG. 3, the MEMS mirror 300 according to the present invention is provided on a silicon layer 310 provided on a substrate (not shown), a silicon layer 310, and includes a piezoelectric material to be independent of each other. Piezoelectric driver layer 320, a pair of mirror pedestals 330 and mirror pedestals provided at symmetrical positions on the silicon layer 310 to enable driving in the X-axis and Y-axis directions And a mirror plate 340 provided on the 330.

The silicon layer 310 is a layer on which the piezoelectric driver layer 320 and the mirror pedestal 330 are provided, and as shown in FIG. 3, four fixing portions near each vertex of the rectangular shape of the MEMS mirror ( 314 is fixed to the substrate together with the piezoelectric driver layer 320. The fixing part 314 serves as a fixing point when the first piezoelectric driving part 326 of the piezoelectric driving part layer 320 is displaced by piezoelectric power. On the other hand, the silicon layer 310 includes a separate portion 312 in which a pair of mirror pedestal 230 may be provided, so that the mirror pedestal 330 is not directly provided on the substrate, but rather the substrate and the substrate. Since it is provided on the silicon layer 310 which is fixed only at four fixing portions 314, the floating state of the substrate is maintained. This is why the mirror plate 340 can freely tilt with respect to the substrate.

' 형상을 형성함으로써 MEMS 미러가 제1 축 방향으로 회전할 수 있도록 구동하기 위한 제1 압전 구동부(326)(전술한 바와 같이, 제1 축 방향의 회전에 대한 고정점은 고정부(314)가 됨)와, 제1 압전 구동부(326)의 제1 '

' 형상 내부에 미러 받침대(330)를 둘러싸는 제2 '

' 형상을 형성하며 제2 '

' 형상의 중심변과 회전축(324)이 접속하는 접속점(329)을 포함함으로써 MEMS 미러가 제2 축 방향으로 회전할 수 있도록 구동하기 위한 제2 압전 구동부(328)(제2 축 방향의 회전에 대한 고정점은 접속점(329)이 됨)를 더 포함한다.The piezoelectric driver layer 320 includes a first symmetric part 322 and a second symmetric part 323, the shapes of which are symmetrical and separated from each other, and include a first symmetric part 322 and a second symmetric part 323. Each includes a rotation shaft 324 traversing the center of the mirror plate 340 adjacent to each other, the rotation shaft 324 and the fixing portion 314 includes a first '

The first piezoelectric driver 326 for driving the MEMS mirror to rotate in the first axial direction by forming a shape (as described above, the fixed point for rotation in the first axial direction is determined by the fixing part 314). And the first 'of the first piezoelectric driver 326.

'' A second '' surrounding the mirror pedestal 330 inside the shape

'Shaping second'

A second piezoelectric drive unit 328 (rotating in the second axial direction) for driving the MEMS mirror so that the MEMS mirror can rotate in the second axial direction by including a connection point 329 to which the central side of the shape and the rotation shaft 324 are connected. The fixed point is further a connection point 329).

The mirror pedestal 330 is provided at the portion indicated by the reference numeral 312 on the silicon layer 310, in particular, the first symmetric portion 322 and the second symmetric portion 323 are provided at positions symmetrical with each other, the mirror plate ( 340 serves as a pillar to support.

The mirror plate 340 is provided on the mirror pedestal 330, and one of four parts of the top, bottom, left, and right sides of the mirror plate 340 is pushed up by the driving force generated by the piezoelectric driving part layer 320. When the upper and lower portions of the mirror plate 340 are pushed up, the rotation is about the Y-axis, and when the left and right portions of the mirror plate 340 are pushed up, the rotation is about the X-axis.

Referring to Figure 3 will be described in more detail the principle of driving the MEMS mirror 300 according to the present invention.

' 형상의 좌측 변에 전압을 인가하면, 제1 압전 구동 부(326)는 고정부(314)를 고정점으로 하여 상부 쪽으로 회전 변위를 발생시킨다(도 3의 적색 화살표 중 ‘X-축 회전’ 표시 부분 참조). 이에 따라, 미러의 좌측 부분을 밀어 올리는 구동력이 발생하게 되어, 미러는 X-축 방향 중 시계 방향으로 회전하게 된다. 마찬가지로, 제1 대칭부(322) 및 제2 대칭부(323) 각각의 제1 '

' 형상의 우측 변에 전압을 인가하면, 미러의 우측 부분을 밀어 올리는 구동력이 발생하게 되어 미러는 X-축 방향 중 반시계 방향으로 회전하게 된다.First, the driving principle in the X-axis direction is as follows. First ′ of each of the first and second symmetry portions 322 and 323.

When a voltage is applied to the left side of the 'shape, the first piezoelectric driver 326 generates a rotational displacement toward the upper side with the fixing part 314 as a fixed point (' X-axis rotation 'in the red arrow of FIG. 3). See marking). As a result, a driving force for pushing up the left portion of the mirror is generated so that the mirror rotates clockwise in the X-axis direction. Similarly, the first 'of each of the first and second symmetry portions 322 and 323 ′.

When a voltage is applied to the right side of the shape, a driving force for pushing up the right side of the mirror is generated so that the mirror rotates counterclockwise in the X-axis direction.

' 형상의 양쪽 변에 전압을 인가하면, 제2 압전 구동부(328)는 접속점(329)을 고정점으로 하여 상부 쪽으로 회전 변위를 발생시킨다(도 3의 적색 화살표 중 ‘Y-축 회전’ 표시 부분 참조). 이에 따라, 미러의 아래쪽 부분을 밀어 올리는 구동력이 발생하게 되어, 미러는 Y-축에 대하여 회전하게 된다. 마찬가지로, 제2 대칭부(323)의 제2 '

' 형상의 양쪽 변에 전압을 인가하면, 제2 압전 구동부(328)에서는 접속점(329)을 고정점으로 하여 미러의 위쪽 부분을 밀어 올리는 구동력이 발생하게 되어, 미러는 Y-축에 대하여 조금 전과는 반대 방향으로 회전하게 된다.Next, the driving principle in the Y-axis direction will be described. Second ′ of first symmetry 322

When a voltage is applied to both sides of the 'shape, the second piezoelectric driver 328 generates a rotational displacement toward the upper side with the connection point 329 as a fixed point (the' Y-axis rotation 'display portion of the red arrow in FIG. 3). Reference). This generates a driving force that pushes up the lower part of the mirror, causing the mirror to rotate about the Y-axis. Similarly, the second 'of the second symmetry portion 323

When a voltage is applied to both sides of the 'shape, the second piezoelectric drive unit 328 generates a driving force for pushing up the upper part of the mirror by using the connection point 329 as a fixed point, and the mirror is slightly before the Y-axis. Will rotate in the opposite direction.

At this time, the rotation about the Y-axis, the second piezoelectric drive unit 328 located inside the first piezoelectric drive unit 326 is completely independent of the first piezoelectric drive unit 326 that generates a rotation about the X-axis rotation axis (324) (It should be borne in mind that the deformation occurs with the connection point 329, which is exactly part of the rotational axis as a fixed point, so that it is hardly affected by rotation about the X-axis. The MEMS mirror according to is configured to minimize the mechanical coupling of rotation about the X-axis and rotation about the Y-axis.

4 is a diagram illustrating a simulation result of an independent two-axis drive MEMS mirror using piezoelectric power designed according to an embodiment of the present invention. As shown in FIG. 4, when the bias voltage is 50 V, it is possible to rotate 3.9 degrees clockwise with respect to the X-axis and 3.0 degrees in one direction with respect to the Y-axis. This result is interpreted as a large displacement (7.8 degrees (3.9 degrees x 2) for the entire X-axis, 6.0 degrees (3.0 degrees x 2) for the entire Y-axis) with a relatively low drive voltage (50V). When using the piezoelectric power, there is almost no power consumption, and considering that the linear control of displacement with respect to voltage is easy, it is determined that the application range of the present invention may be very diverse.

The present invention described above may be variously modified or applied by those skilled in the art, and the scope of the technical idea according to the present invention should be defined by the following claims.

According to the present invention, it is possible to independently drive in the first and second axial directions orthogonal to each other, and to implement an independent two-axis drive MEMS mirror with a significantly improved fill factor using piezoelectric force.

Claims (2)

As an independent two-axis-drive Micro-Electro-Mechanical Systems (MEMS) mirror using piezoelectric force, Board; A silicon layer provided on the substrate; First and second axial and second symmetrical portions provided on the silicon layer, the first and second symmetrical portions being symmetrical and separated in shape, and including a piezoelectric material, in which the MEMS mirrors are perpendicular to each other; A piezoelectric driver layer for driving to rotate in the axial direction; A pair of mirror pedestals provided on the silicon layer and positioned in the first symmetric part and the second symmetric part, respectively; And It includes a mirror plate (mirror plate) provided on the pair of mirror pedestal, The first symmetric part and the second symmetric part each include a first axis including a rotation axis traversing the central portion of the mirror plate adjacently;

A first piezoelectric drive part having a shape and the first first piezoelectric drive part

'A second' surrounding the mirror pedestal inside the shape

'Further comprises a second piezoelectric drive part, The silicon layer and the piezoelectric driver layer may be formed in the first ′ of the first piezoelectric driver.

And a fixing part fixed to the substrate at both ends of the shape and serving as a fixing point for the first axial rotation of the MEMS mirror, wherein the second piezoelectric driving part includes the second '

The MEMS mirror further comprises a connection point at which the central side of the shape and the rotation axis are connected to serve as a fixed point for the rotation in the second axial direction of the MEMS mirror. The method of claim 1, The piezoelectric driver layer may include an upper electrode, a piezoelectric material, and a lower electrode sequentially from above.

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