JP7175816B2 - optical device - Google Patents

Description

The present invention relates to an optical device, and more particularly to an optical device having an optical path changing section that changes the optical path of incident light.

2. Description of the Related Art Conventionally, there has been known a mirror scanner that scans a predetermined area with reflected light by tilting a mirror that reflects incident light around two orthogonal axes.

For example, Patent Literature 1 discloses a mirror scanner having a pair of piezoelectric actuators arranged point-symmetrically with respect to the center of the light reflecting portion on both sides of the light reflecting portion. Each of the piezoelectric actuators is composed of two cantilevers and a piezoelectric thin film formed on the upper surface thereof. In other words, the pair of piezoelectric actuators has four cantilevers and piezoelectric thin films formed on the upper surfaces of the cantilevers, and tilts the light reflecting portion around the X-axis at high speed. Also, the light reflecting portion is tilted at a low speed around the Y-axis orthogonal to the X-axis.

For such operation, a plurality of voltage components are superimposed and applied to the piezoelectric thin films respectively formed on the four cantilevers. Specifically, a high-frequency voltage component for tilting around the X-axis and a low-frequency voltage component for tilting around the Y-axis are superimposed and applied to the respective piezoelectric thin films.

Japanese Patent No. 4400608

However, in general, there is a limit to the withstand voltage of a piezoelectric thin film. Therefore, as disclosed in Patent Document 1, when a plurality of voltage components are superimposed and applied to the piezoelectric thin film, the frequency component that moves each axis becomes The voltage amplitude it has is halved. As a result, there is a possibility that the amount of tilting of the light reflecting portion cannot be increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide an optical device in which the driving force of an actuator for tilting an optical path changing portion is increased.

To achieve the above object, an optical device according to the present invention includes an optical path changing portion, a pair of first connecting portions extending from both sides of the optical path changing portion along a first axis passing through the optical path changing portion, a first movable frame provided to surround the optical path changing portion inside and connected to each of the pair of first connecting portions; and the first movable frame along a second axis intersecting the first axis. a pair of second connecting portions extending from both sides of the frame; a second movable frame provided so as to surround the first movable frame inside and connected to each of the pair of second connecting portions; a first actuator provided across the first movable frame and the second movable frame; and a first actuator provided so as to surround the second movable frame and connected to the second movable frame. and a fixed frame, wherein the first actuator is a piezoelectric actuator that tilts the optical path changing portion about the first axis.

According to the optical device of the present invention, the driving force of the first actuator can be increased. Also, the optical path changing portion can be tilted around the first axis with a low voltage.

1 is a plan view of an optical device according to Embodiment 1 of the present invention; FIG. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1; FIG. 10 is a perspective view showing a state in which the mirror portion is tilted around the Y-axis; FIG. 3B is a schematic view of the optical device shown in FIG. 3A as viewed in the Y direction; FIG. 10 is a perspective view showing a state in which the mirror section is tilted around the X axis; FIG. 4B is a schematic view of the optical device shown in FIG. 4A as seen from the X direction; It is the top view which looked at a part of optical apparatus from Z direction lower side, (a) is a top view which concerns on this embodiment, (b) is a top view for a comparison. It is a top view which shows arrangement|positioning of the 2nd detection part which concerns on a modification. FIG. 5 is a plan view of an optical device according to Embodiment 2 of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following description of preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its applicability or its uses.

(Embodiment 1)
[Configuration of Optical Device]
1 is a plan view of an optical device according to this embodiment, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. It should be noted that the dimensions, thicknesses, detailed shapes, etc. of each member drawn in each drawing shown below are different from the actual ones. For convenience of explanation, the illustration of the passivation film 440 is omitted in FIG.

The optical device 100 shown in FIG. 1 has the following members obtained by subjecting an SOI substrate 200 (hereinafter sometimes simply referred to as substrate 200) to predetermined processing. Specifically, the optical device 100 includes a mirror portion 30 as an optical path changing portion, a pair of first connecting portions 41 and 41, a first movable frame 50, a pair of second connecting portions 42 and 42, It includes a second movable frame 60 , a pair of third connecting portions 43 , 43 , a pair of fourth connecting portions 44 , 44 , a fixed frame 10 , and a base frame 300 . The optical device 100 also includes a pair of first actuators 70 and 70 and a pair of second actuators 80 and 80 . The optical device 100 is a MEMS element obtained by processing a substrate 200 using micromachining technology to which semiconductor microfabrication technology is applied.

The optical device 100 tilts the mirror section 30 around the Y-axis passing through the center O of the mirror section 30 and the pair of first connecting sections 41 and 41 by driving the pair of first actuators 70 and 70 . Further, by driving the pair of second actuators 80, 80, the mirror section 30 is tilted around the X-axis passing through the center O of the mirror section 30 and the pair of second connecting sections 42, 42. As shown in FIG. By tilting the mirror section 30 around the X-axis and around the Y-axis, the optical device 100 reflects incident light incident on the mirror section 30 and scans a predetermined area with the reflected light. It is a so-called two-axis mirror scanner.

In the following description, the X axis may be called the second axis, and the Y axis may be called the first axis. Also, an axis that intersects with the X-axis and the Y-axis, specifically, an axis along the thickness direction of the substrate 200 may be called a Z-axis or a third axis. Also, the directions parallel to and including the X, Y, and Z axes are sometimes called the X direction, Y direction, and Z direction, respectively. In the X direction, the side on which the second detector 92 is provided is sometimes called the right side, and the opposite side is sometimes called the left side. In the Y direction, the side on which the fourth connecting portion 44 is arranged may be called the upper side, and the side on which the third connecting portion 43 is arranged may be called the lower side. Also, in the Z direction, the side on which the base frame 300 is arranged may be called the lower side, and the opposite side may be called the upper side. Moreover, in the fixing frame 10, the surface on which the pad electrodes 94 are formed is sometimes called the main surface. In other members as well, the surface on the same side as the main surface of the fixed frame 10 in the Z direction may be similarly called the main surface.

In the substrate 200, a first silicon layer 210 made of single crystal silicon, a first insulating layer 220 made of _SiO2 , and a second silicon layer 230 made of single crystal silicon are laminated in this order in the Z direction. configured as follows. A second insulating layer 240 made of SiO ₂ is formed on the main surface of the first silicon layer 210 . The thickness of the first silicon layer 210 is 30 μm, the thickness of the first insulating layer 220 is 1 μm, the thickness of the second silicon layer 230 is 250 μm, and the thickness of the second insulating layer 240 is 1 μm. , but not particularly limited to this. It can be changed as appropriate according to the specifications of the optical device 100 or the like.

In the optical device 100, the mirror portion 30 excluding the metal film 31 described later, the first to fourth connecting portions 41 to 44, the first and second movable frames 50 and 60, and the fixed frame 10 are formed from substrates. It has the same laminated structure as 200. By processing the substrate 200 so as to penetrate the substrate 200 according to the shapes of these members in the optical device 100, the members are connected to each other and arranged at predetermined intervals. Note that the substrate 200 is generally through-processed by a deep dry etching method (DRIE). Also, the structure of the first and second actuators 70, 80 will be described later.

In a plan view, the fixed frame 10 includes a mirror portion 30, first to fourth connecting portions 41 to 44, first and second movable frames 50 and 60, and first and second actuators 70 and 80. It is a rectangular member arranged so as to surround the inside. Each member except for the fixed frame 10 and the base frame 300 is a movable member that is deformed or displaced when the first and second actuators 70 and 80 are driven, whereas the fixed member is fixed in position. It supports the movable member stably and serves as a positional reference when the movable member is displaced. In addition, the fixed frame 10 has an extension portion 11 extending upward in the Y direction from the inner peripheral surface located on the lower side in the Y direction. is connected to a first cantilever 81 which will be described later.

In addition, a base frame 300 is arranged below the fixed frame 10 in the Z direction except for the extension portion 11 , and the fixed frame 10 is fixed to the main surface of the base frame 300 . Various methods can be used as appropriate for fixing the fixed frame 10 and the base frame 300 together. For example, both may be fixed to each other with an adhesive (not shown). Alternatively, the fixed frame 10 and the base frame 300 may be fixed together by an anodic bonding method or a diffusion bonding method. In addition, the member constituting the base frame 300 has a laminated structure of a silicon layer made of a single crystal and an insulating layer. Each member of the optical device 100 may be formed by processing the body. Also, the material of the base frame 300 may be silicon or SiO ₂ . Other materials such as ceramics, metal materials, and resin materials may be used. Considering the temperature change in the environment in which the optical device 100 is arranged, the material of the base frame 300 preferably has a coefficient of thermal expansion close to that of the substrate 200 . The thickness of the base frame 300 is about the same as or greater than that of the second silicon layer 230, but is not particularly limited to this. The thickness may be such that the movable member in the optical device 100 can be freely displaced downward in the Z direction.

A passivation film 440 made of SiO ₂ is formed over the entire main surface of the fixing frame 10 (see FIG. 2). This passivation film 440 is similarly formed on the main surfaces of the first and second movable frames 50 and 60, the second to fourth connecting portions 42 to 44, and the first and second actuators 70 and 80, respectively. . The passivation film 440 mechanically protects each member of the optical device 100, and also protects the first and second actuators 70 and 80 and first and second detectors 91 and 92, which will be described later, from moisture and the like in the external atmosphere. is doing. In addition, a plurality of pad electrodes 94 are formed on the main surface of the passivation film 440 at the lower portion of the fixed frame 10 in the Y direction at predetermined intervals. A pair of first actuators 70 , 70 , a pair of second actuators 80 , 80 , and first and second detectors 91 , 92 to be described later are connected to each of these pad electrodes 94 via wiring 93 . Note that the passivation film 440 is not formed on the main surface of the mirror section 30 in order to reflect the incident light in a predetermined direction. Also, the passivation film 440 is not formed on the main surface of the first connecting portion 41 .

Further, between the fixed frame 10, the fourth connecting portion 44, the second movable frame 60, and the second actuator 80, there is a second electrode formed penetrating the substrate 200 in the Z direction so as to partition them. 1 through opening 21 is formed. Similarly, a second through opening 22 is formed between a first cantilever 81, a second cantilever 83, a fourth connecting portion 44, an extension portion 11, and a second movable frame 60, which will be described later, so as to partition them. ing. A third through opening 23 is formed between the first cantilever 81, the third connecting portion 43, the extension portion 11, and the second movable frame 60 so as to partition them. A fourth through opening 24 is formed between the first movable frame 50 and the second movable frame 60 so as to partition them. A fifth through opening 25 is formed between the mirror portion 30 and the first movable frame 50 so as to partition them.

The first through opening 21 has an inverted U shape surrounding the pair of second actuators 80 and 80 in plan view. The first through opening 21 is formed so as to have a substantially constant width, except for portions facing convex portions 44a and 62, which will be described later. Here, in the specification of the present application, the term "substantially constant" allows a difference of about several tenths from the design value, and does not mean that the width is strictly constant. Both ends 21a of the first through opening 21 extend closer to the outer peripheral surface of the fixed frame 10 than the joint between the fixed frame 10 and the second cantilever 83, in this case, downward in the Y direction. are formed (see FIG. 5(a)). The second through openings 22 have an inverted C shape surrounding the first cantilever 81 and the extension portion 11 in plan view, and are formed one by one at positions symmetrical to each other with respect to the Y axis. One end 22a of the second through-opening is formed extending downward in the Y direction closer to the outer peripheral surface of the fixed frame 10 than the connecting end portion between the second cantilever 83 and the fixed frame 10. ing. The other end 22b of the second through-opening 22 is positioned closer to the outer peripheral surface of the fixed frame 10 than the connecting end portion between the first cantilever 81 and the second movable frame 60, in this case, the third through-opening described later. 23 and extends downward in the Y direction (see FIG. 5(a)). The third through-opening 23 has a U-shape in plan view surrounding the pair of first cantilevers 81 and 81 and the second movable frame 60, and both ends 23a of the third through-opening 23 extend from the first cantilever 81. It is formed on the side closer to the outer peripheral surface of the fixed frame 10 than the connection end portion with the portion 11, in this case, the side closer to the second through opening 22 and extending upward in the Y direction (Fig. 5 (a)). In the fixing frame 10, the length of one side in the X direction is about several mm, and the length of one side in the Y direction is about several mm.

The mirror section 30 is a member having a metal film 31 formed on the main surface of a substantially elliptical or substantially circular member having the same laminated structure as the substrate 200 . The metal film 31 functions as a mirror that reflects the light incident on the mirror section 30 and changes the optical path of the light. The configuration of the metal film 31 can be appropriately changed according to the wavelength, intensity, etc. of incident light. For example, if the incident light is visible light, an Al/Ti laminated film is used, and if the incident light is infrared light, an Au/Ti laminated film is used. Note that the planar shape of the mirror section 30 may be other shapes such as a rectangle or a polygon.

The pair of first connecting portions 41 , 41 is a pair of rod-like members extending along the Y-axis from the Y-direction upper side and the Y-direction lower side of the mirror portion 30 and connected to the first movable frame 50 respectively. A pair of first connecting portions 41, 41 connect the mirror portion 30 to the first movable frame 50 so as to be tiltable about the Y-axis. Further, when driving the first actuator 70, a force is applied to the pair of first connecting portions 41, 41 so as to cause torsional deformation around the Y axis.

The first movable frame 50 is an annular member provided so as to surround the mirror portion 30 and the pair of first connecting portions 41, 41 inside. is doing. However, it is not particularly limited to this, and other shapes can be adopted. In addition, second connecting portions 42 are provided extending from the right side in the X direction and the left side in the X direction of the first movable frame 50 along the X axis. The pair of second connecting portions 42, 42 connect the first movable frame 50 to the second movable frame 60 so as to be tiltable about the Y-axis.

The second movable frame 60 is an annular member provided so as to surround the first movable frame 50 and the pair of second connecting portions 42 , 42 inside. The second movable frame 60 is provided at a predetermined distance from the mirror section 30 in a plan view, and its inner circumference resembles the outer shape of the first movable frame 50 . The outer circumference of the second movable frame 60 is rectangular, and includes a pair of third connecting portions 43, 43 extending in the X direction from the lower end in the Y direction, and extending in the X direction from the upper end in the Y direction. It is connected to a pair of fourth connecting portions 44 and 44 . It should be noted that the outer and inner circumferences of the second movable frame 60 are not particularly limited to this, and may take other shapes. In addition, the second movable frame 60 has a different inner peripheral shape than an outer peripheral shape, and the width changes in a plan view. A portion of the second movable frame 60 that is connected to the second connecting portion 42 is a narrow portion 61 that is narrower than the other portions. The width of the narrow portion 61 is set to be narrower than twice the width of the widest portion of the first movable frame 50 .

The first actuator 70 straddles the first movable frame 50, the second connecting portion 42, and the second movable frame 60, and is formed at a line-symmetrical position with respect to the Y-axis with the mirror portion 30 interposed therebetween. It is A first actuator 70 includes a piezoelectric element 71 . The piezoelectric element 71 is formed across the main surfaces of the first movable frame 50, the second connecting portion 42, and the second movable frame 60, respectively, and includes the lower electrode 410, the piezoelectric layer 420, and the upper electrode. 430 is a laminated body laminated in this order in the Z direction. The piezoelectric element 71 is also formed in the narrow portion 61 of the second movable frame 60 . A laminated film of Pt/Ti is used as the lower electrode 410 and the upper electrode 430, respectively. However, it is not particularly limited to this, and for example, an Au/Ti laminated film may be used as the upper electrode 430 . In this case, the upper electrode 430 may be formed simultaneously with the metal film 31 of the mirror section 30 . This simplifies the manufacturing process of the optical device 100 . Further, lead zirconate titanate (PZT) is used as the piezoelectric layer 420 . However, it is not particularly limited to this, and piezoelectric bodies made of other materials may be used. For example, barium titanate (BaTiO ₃ ) or lithium niobate (LiNbO ₃ ) may be used.

In addition, in this embodiment, the lower electrode 410 and the piezoelectric layer 420 are formed over the entire main surface of each member of the optical device 100 excluding the base frame 300, the mirror section 30, and the first connecting section 41. there is On the other hand, the upper electrode 430 is processed to have the shape shown in FIG. By processing the upper electrode 430 into a predetermined shape, the driving mode of the first actuator 70, in other words, the first movable frame 50, the second connecting portion 42, and the second movable frame 60, on which the piezoelectric element 71 is formed, can be changed. It is possible to define a form in which and are deformed. Note that the lower electrode 410 and the piezoelectric layer 420 may be processed into shapes similar to the upper electrode 430 . The first actuator 70 is set so that the area of the portion provided on the second movable frame 60 is larger than the area of the portion provided on the first movable frame 50 . In other words, the upper electrode 430 of the piezoelectric element 71 is set so that the area of the portion provided on the second movable frame 60 is larger than the area of the portion provided on the first movable frame 50. .

The first detection unit 91 is provided above the first actuator 70 in the Y direction with a predetermined gap therebetween. are formed respectively. The first detection section 91 is a laminate having the same configuration as the piezoelectric element 71, and the upper electrode 430 of the first detection section 91 is arranged with a predetermined gap from the upper electrode 430 of the piezoelectric element 71. . As will be described later, when the first actuator 70 is driven, the piezoelectric element 71 is compressed or expanded, and the first and second movable frames 50 and 60 and the second connecting portion 42 provided with the piezoelectric element 71 are deformed. . According to this deformation, the pair of first detectors 91, 91 also distorts, and charges are induced in the respective upper electrodes 430, and current signals or voltage signals are output. Since the signals output from each of 91 have opposite polarities, the drive amount of the first actuator 70 is detected by inputting the signals to a differential amplifier (not shown) and amplifying them. Further, the amount of tilting of the mirror section 30 around the Y-axis is detected based on this driving amount.

Wirings 93 are connected to the upper electrodes 430 of the pair of first detecting portions 91, 91, respectively. They are connected to pad electrodes 94 formed on the fixed frame 10 through the second cantilevers 83 . In the second cantilever 83 , the wiring 93 connected to the upper electrode 430 of one first detection section 91 is arranged on the left side of the second piezoelectric element 84 in the X direction, while the other first detection section 91 The wiring 93 connected to the upper electrode 430 is arranged on the right side of the second piezoelectric element 84 in the X direction.

A pair of second actuators 80 , 80 are provided at positions facing each other in the X direction with the second movable frame 60 interposed therebetween, and are composed of a first cantilever 81 , a first piezoelectric element 82 , a second cantilever 83 and a second actuator 80 . 2 piezoelectric elements 84, respectively. In this case, the pair of second actuators 80 and 80 are arranged at positions that are symmetrical about the Y-axis with the second movable frame 60 interposed therebetween.

The first cantilever 81 is arranged at a position closer to the second movable frame 60 than the second cantilever 83 is. , are provided so as to extend in the Y direction with a space therebetween. The first cantilever 81 is connected to the third connecting portion 43 at its lower end in the Y direction and to the extended portion 11 of the fixed frame 10 at its upper end in the Y direction. Also, the first cantilever 81 is composed only of the first silicon layer 210 except for the connecting end portion with the third connecting portion 43 and the connecting end portion with the extension portion 11 . After forming a mask pattern (not shown) according to the shape of each member in the optical device 100 , the original shape of each member is formed on the substrate 200 by processing so as to penetrate the substrate 200 . Thereafter, another mask pattern (not shown) is formed on the back surface of the substrate 200, that is, the surface opposite to the main surface so as to open a predetermined region of the first cantilever 81 and a predetermined region of the second cantilever 83. By removing the second silicon layer 230 and the first insulating layer 220 using the mask pattern as an etching mask, the first cantilever 81 can be composed of the first silicon layer 210 alone. In addition, the second cantilever 83 is also composed only of the first silicon layer 210 except for the connecting end portion with the fourth connecting portion 44 and the connecting end portion with the fixed frame 10 . The first insulating layer 220 may remain on the lower surface of the first silicon layer 210 in the first cantilever 81 and the second cantilever 83 . In that case, the first insulating layer 220 may remain with the original thickness, or may remain with a reduced thickness.

Further, when the width in the X direction of the first cantilever 81 is W, the length in the Y direction is L, and the thickness in the Z direction is T, the first cantilever 81 is formed so as to satisfy the relationship shown in Equation (1). Dimensions are set.

W>10 ⁻⁵ ×L ³ /T ³ (1)

A first piezoelectric element 82 is formed on the main surface of the first cantilever 81 . The layered structure of the first piezoelectric element 82 is the same as the layered structure of the piezoelectric element 71 in the first actuator 70 . The upper electrode 430 of the first piezoelectric element 82 has a concave portion 431 at the upper end in the Y direction and in the central portion along the X direction in plan view. One of the pair of second detectors 92 , 92 is provided inside the recess 431 . On the other hand, the second detection section 92 is a laminated body having the same configuration as the first piezoelectric element 82, and the upper electrode 430 of the second detection section 92 is spaced apart from the upper electrode 430 of the first piezoelectric element 82. are placed. In the first piezoelectric element 82 located on the left side in the Y direction with the second movable frame 60 interposed therebetween, the upper electrode 430 is formed with the recess 431 described above. Not provided.

The second cantilever 83 is provided between the second movable frame 60 and the fixed frame 10 so as to extend in the Y direction with a gap therebetween. The second cantilever 83 is connected to the fixing frame 10 at the lower end in the Y direction and to the fourth connecting portion 44 at the upper end in the Y direction. Moreover, as described above, the second cantilever 83 is composed only of the first silicon layer 210, except for a part. In addition, the second cantilever 83 is wider than the first cantilever 81, and the dimensions of the second cantilever 83 in the X, Y, and Z directions naturally satisfy the relationship shown in Equation (1). do.

A second piezoelectric element 84 is formed on the main surface of the second cantilever 83 . The layered structure of the second piezoelectric element 84 is the same as the layered structure of the piezoelectric element in the first actuator 70 . The upper electrode 430 of the second piezoelectric element 84 has a concave portion 432 at the lower end in the Y direction and in the central portion along the X direction in plan view. The other of the pair of second detectors 92 , 92 is provided inside the recess 432 . The other second detection section 92 is a laminate having the same configuration as the second piezoelectric element 84, and the upper electrode 430 of the second detection section 92 is separated from the upper electrode 430 of the second piezoelectric element 84. are placed. As will be described later, when the second actuator 80 is driven, the first piezoelectric element 82 and the second piezoelectric element 84 are compressed or expanded in opposite directions, and the first cantilever 81 and the second cantilever 83 are moved in opposite directions. curved. In response to this bending deformation, an electric charge is induced in each of the upper electrodes 430 of the pair of second detection sections 92 and 92, and a current signal or a voltage signal is output from each of the pair of second detection sections 92 and 92. Since the polarities of the output signals are opposite to each other, the drive amount of the second actuator 80 is detected by inputting the signals to a differential amplifier (not shown) and amplifying them. Further, based on this drive amount, the tilting amount of the second movable frame 60 and thus the mirror section 30 around the X-axis is detected. In the second piezoelectric element 84 located on the left side in the Y direction with the second movable frame 60 interposed therebetween, the upper electrode 430 is formed with the recess 432 described above. Not provided.

In addition, projections 44a and 62 projecting upward in the Y direction are provided on the Y-direction upper side portions of the fourth connecting portion 44 and the second movable frame 60 connected thereto. In addition, a protrusion projecting downward in the Y direction is provided on the side of the fixed frame 10 that faces the upper side in the Y direction of the second movable frame 60 . That is, the width in the Y direction of the fourth connecting portion 44 and the side portion of the second movable frame 60 to which the fourth connecting portion 44 is connected varies. In addition, the width in the Y direction of the Y-direction upper side of the fixed frame 10 facing the side of the second movable frame 60 varies. On the other hand, the first through opening 21 provided between them is formed to have a substantially constant width. These will be explained later.

Further, the plurality of wirings 93 are connected to the piezoelectric element 71, the first and second piezoelectric elements 82 and 84, and the upper electrodes 430 of the first and second detection units 91 and 92 through through holes (not shown) formed in the passivation film 440. are connected to each. Moreover, the plurality of wirings 93 are pulled out and extended to the principal surfaces of the passivation films 440 formed on the principal surfaces of the second movable frame 60, the first and second cantilevers 81 and 83, and the fourth connecting portion 44, respectively. and are connected to a plurality of pad electrodes 94 provided on the main surface of passivation film 440 covering fixed frame 10 . For example, the wiring 93 connected to the first piezoelectric element 82 and the second detection portion 92 provided on the first cantilever 81 is connected to the corresponding pad electrode 94 through the extension portion 11 located on the right side in the X direction. be. The wiring 93 and the pad electrode 94 are each composed of a laminated film of Au/Ti. Although not shown, the first and second piezoelectric elements 82 and 84 and the lower electrodes 410 of the first and second detection units 91 and 92 are also connected to the plurality of pad electrodes 94 provided on the fixed frame 10, respectively. ing. The electrical connection between the lower electrode 410 and the pad electrode 94 can take various configurations. In a preferred configuration, the metal film forming the lower electrode 410 is left so as to be pulled out from the first actuator 70 or the second actuator 80 to the vicinity of the pad electrode 94 provided on the fixed frame 10, and has a role of wiring. It is to do so. In this case, a through hole (not shown) is provided in the passivation film 440 directly below the pad electrode 94 to electrically connect the lower electrode 410 and the pad electrode 94 . In FIG. 1, the reason why the pad electrode 94 present at the bottom center in the Y direction is not connected to any wiring 93 is because of the above-described configuration, which is electrically connected to the lower electrode 410 . there is

[About the operation of the optical device]
Next, the operation of the optical device 100 shown in FIGS. 1 and 2 will be described. FIG. 3A is a perspective view of the mirror portion tilted about the Y axis, and FIG. 3B is a schematic view of the optical device shown in FIG. 3A viewed from the Y direction. 4A is a perspective view of a state in which the mirror portion is tilted around the X axis, and FIG. 4B is a schematic view of the optical device shown in FIG. 3A viewed from the X direction. In order to make the operation of the optical device 100 easier to understand, FIG. 3A shows a state in which the amount of tilting of the mirror section 30 is larger than it actually is. 3A to 4B, illustration of components other than each layer of the substrate 200 and the upper electrode 430 of the first actuator 70 is omitted for convenience of explanation.

The mirror portion 30 may be warped due to heat treatment during processing, stress received from the metal film 31, or the like. If such a warp occurs, the optical path length of the reflected light reflected by the mirror section 30 changes, which may affect the image quality of the image projected on the predetermined area. In order to correct this, first, the upper electrodes 430 of the pair of piezoelectric elements 71 and 71 and the upper electrodes 430 of the pair of first piezoelectric elements 82 and 82 are arranged so that the mirror section 30 is positioned on a predetermined initial plane. , and the upper electrodes 430 of the pair of second piezoelectric elements 84, 84, respectively. How the voltage is applied to each of the upper electrodes 430 depends on the state of the initial warp of the mirror section 30 . It should be noted that whether or not the warpage of the mirror section 30 has been corrected can be confirmed using various methods as appropriate. For example, light is incident on the metal film 31 of the mirror section 30 at a predetermined angle, and the reflected light is detected by a light receiving section (not shown). state is detected, and a predetermined voltage is applied to each upper electrode 430 to correct the warp of the mirror section 30 as described above. Further, the output signals of the first and second detection units 91 and 92 and the state of the warp of the mirror unit 30 are obtained experimentally in advance, and a predetermined voltage is applied to each upper electrode 430. By adjusting the applied voltage value based on the output signals of the first and second detectors 91 and 92, the warping of the mirror section 30 can be corrected. Alternatively, conversely, even when the mirror section 30 is not warped, the upper electrodes 430 of the pair of piezoelectric elements 71, 71 are preliminarily arranged so that the reflected light reflected by the mirror section 30 is intentionally focused. A predetermined DC voltage is applied to the upper electrodes 430 of the pair of first piezoelectric elements 82 and 82 and to the upper electrodes 430 of the pair of second piezoelectric elements 84 and 84, respectively, so that the reflected light on the light receiving section The applied voltage value may be adjusted according to the position, spread, or the like. Note that depending on the form in which the light reflected by the mirror section 30 is scanned over a predetermined area, the mirror section 30 may be actively warped in advance.

As shown in FIGS. 3A and 3B, by driving the pair of first actuators 70, 70, the mirror section 30 can be tilted around the Y-axis. When voltages having opposite phases are applied to the upper electrodes 430 of the pair of piezoelectric elements 71, 71, for example, the piezoelectric element 71 arranged on the left side in the X direction and the first movable frame positioned directly below the piezoelectric element 71 The body 50, the second connecting portion 42, and the second movable frame 60 are lifted upward in the Z direction and curved to form an upward convex shape. In addition, the piezoelectric element 71 arranged on the right side in the X direction and the first movable frame 50, the second connecting portion 42, and the second movable frame 60 positioned directly below the piezoelectric element 71 are pushed downward in the Z direction. , curved downwards. By bending and deforming the first movable frame 50 in this manner, the first movable frame 50 located on the left side of the Y-axis in the X direction, except for the first actuator 70, bends downward in the Z direction. The first movable frame 50, which is pushed down and located on the right side of the Y axis in the X direction, is curved and lifted upward in the Z direction. As a result, the mirror portion 30 connected to the first movable frame 50 via the first connecting portion 41 tilts around the Y-axis.

Further, in this case, by applying to the upper electrode 430 an AC voltage having a frequency close to the resonance frequency of the vibration system composed of the mirror portion 30, the pair of first connecting portions 41, 41, and the first movable frame 50, , the mirror section 30 is resonantly driven around the Y axis. Depending on the mass distribution of the vibration system, the rigidity of each member, and the like, the resonance frequency is usually several kHz to several tens of kHz. By resonance driving the mirror section 30, the mirror section 30 can be tilted at high speed, and the amount of tilting of the mirror section 30 can be increased with a low applied voltage. In order to resonantly drive the mirror section 30 with a low voltage, it is preferable to dispose the piezoelectric element 71, particularly the upper electrode 430, at a position where the bending deformation of the first actuator 70 is the largest.

Further, as shown in FIGS. 4A and 4B, by driving the pair of second actuators 80, 80, the mirror section 30 can be tilted around the X axis. In each of the first piezoelectric element 82 and the second piezoelectric element 84, when voltages having phases opposite to each other are applied to the upper electrode 430, the second piezoelectric element 84 contracts in the Y direction, for example, resulting in a unimorph structure. The related second cantilever 83 curves downward in the Z direction. At this time, since the Y-direction lower end of the second cantilever 83 is connected to the fixed frame 10, this portion is not displaced. The second cantilever 83 bends and deforms such that the portion connected to the portion 44 is lifted upward in the Z direction. Also, the first piezoelectric element 82 extends in the Y direction, and accordingly, the first cantilever 81, which has a relationship of unimorph structure, is curved so as to protrude upward in the Z direction. At this time, since the upper end in the Y direction of the first cantilever 81 is connected to the extension 11 of the fixed frame 10, this portion is not displaced, and the reaction causes the tip of the second cantilever 83, that is, The first cantilever 81 bends and deforms as the portion connected to the third connecting portion 43 is pushed downward in the Z direction.

Further, the deformation of the first cantilever 81 pushes the third connecting portion 43 downward in the Z direction, and the deformation of the second cantilever 83 lifts the fourth connecting portion 44 upward in the Z direction. Therefore, the second movable frame 60 whose Y-direction end portions are respectively connected to the third connecting portion 43 and the fourth connecting portion 44 tilts about the X-axis. The first movable frame 50 connected to the second movable frame 60 via the second connecting portion 42 and the mirror portion 30 connected to the first movable frame 50 via the first connecting portion 41 are similarly connected. , about the X axis. In this way, by deforming the first cantilever 81 and the second cantilever 83 in opposite directions along the Z direction, the driving force corresponding to the deformation amount of the first cantilever 81 and the deformation amount of the second cantilever 83 are changed. A high driving force is generated in the second actuator 80 by adding together the corresponding driving force. Therefore, the second drive frame having a relatively large mass, the first movable frame 50 connected thereto, and the mirror section 30 can be quickly tilted.

Note that the frequency of the AC voltage applied to the second actuator 80, that is, the driving frequency of the second actuator 80 is lower than the driving frequency of the first actuator 70, and is about several tens of Hz. Resonance driven.

By tilting the mirror section 30 around the X axis and around the Y axis in this way, the reflected light reflected by the mirror section 30 can scan a predetermined area. For example, by tilting the mirror section 30 around the Y-axis at the resonance frequency, the reflected light is linearly scanned in a predetermined direction. An image can be generated and displayed on a predetermined area by repeating the operation of shifting the scanning line of the reflected light in a direction intersecting the . Thus, the optical device 100 of the present embodiment can be used as a scanning light source for screen display in a projector, head-up display (hereinafter referred to as HUD), head-mounted display (hereinafter referred to as HMD), or the like.

[Effects, etc.]
As described above, the optical device 100 according to the present embodiment includes the mirror section 30 as an optical path changing section, and a pair of mirror sections extending from both sides of the mirror section 30 along the Y-axis (first axis) passing through the mirror section 30 . The first connecting portions 41, 41, the first movable frame 50 provided so as to surround the mirror portion 30 inside and connected to each of the pair of first connecting portions 41, 41, and the X axis intersecting the Y axis. A pair of second connecting portions 42, 42 extending from both sides of the first movable frame 50 along an axis (second axis), and a pair of second connecting portions 42, 42 provided so as to surround the first movable frame 50 inside. A second movable frame 60 connected to each of the parts 42, 42, and a fixed frame 10 provided so as to surround the second movable frame 60 inside and connected to the second movable frame 60. at least have.

In addition, the optical device 100 includes a pair of first movable frame members 50 and 60 provided at positions facing each other along the X axis with the mirror unit 30 interposed therebetween. 1 actuators 70, 70 are provided, and a pair of first actuators 70, 70 are piezoelectric actuators that tilt the mirror section 30 around the Y-axis.

By configuring the optical device 100 in this way, the driving force of the first actuator 70 can be increased, and the mirror section 30 can be tilted around the Y-axis with a low voltage. In particular, by providing the first actuator 70 so as to straddle the first movable frame 50 and the second movable frame 60, compared to the case where the first actuator 70 is provided only in the first movable frame 50, the , the area of the piezoelectric element 71 can be increased, and the driving force of the first actuator 70 can be increased. In addition, compared to the case where the first actuator 70 is provided only on the second movable frame 60, the amount of deformation of the first movable frame 50 connected to the mirror section 30 can be increased, and the driving force of the first actuator 70 can be increased. Increased. Also, the amount of tilting of the mirror section 30 can be increased with a low voltage.

The pair of first actuators 70, 70 are preferably arranged at positions that are symmetrical with respect to the Y-axis. By doing so, when the two first actuators 70 and 70 are driven in mutually opposite directions, the amount of tilting of the mirror section 30 can be made symmetrical with respect to the Y-axis.

The second movable frame 60 preferably has a narrow portion 61 narrower than twice the width of the widest portion of the first movable frame 50 .

By providing the narrow portion 61 in the second movable frame 60, the amount of deformation of the second movable frame 60 when the first actuator 70 is driven can be increased. As a result, the driving force of the first actuator 70 can be increased, and the amount of tilting of the mirror section 30 can be increased.

The area of the first actuator 70 provided on the second movable frame 60 is preferably larger than the area of the first actuator 70 provided on the first movable frame 50 .

When the first movable frame 50 is enlarged, the resonance frequency of the vibration system including the mirror section 30 and the first movable frame 50 is lowered, and there is a possibility that the mirror section 30 cannot be resonantly driven at a desired frequency. Therefore, the size of the first movable frame 50 is limited. However, in such a case, if the first actuator 70 is provided only on the first movable frame 50, the area of the piezoelectric element 71 becomes small, and there is a possibility that the driving force of the first actuator 70 cannot be sufficiently obtained. rice field.

On the other hand, according to the present embodiment, by making the area of the first actuator 70 provided on the second movable frame 60 larger than the area of the first actuator 70 provided on the first movable frame 50, The driving force of the first actuator 70 can be increased while suppressing the first movable frame 50 from increasing in size. Also, the amount of tilting of the mirror section 30 can be increased.

By applying opposite-phase voltages to one and the other of the pair of first actuators 70, 70, the pair of first actuators 70, 70 tilt the mirror section 30 around the Y-axis. The mirror section 30 is resonantly driven at the resonance frequency of the vibration system including the mirror section 30 and the first movable frame 50, and is tilted around the Y-axis.

According to this embodiment, the mirror section 30 can be tilted at high speed, and the amount of tilting of the mirror section 30 can be increased with a low applied voltage.

The mirror section 30 has a metal film 31 as a mirror for reflecting incident light, and can reliably scan a predetermined area with the reflected light reflected by the metal film 31 .

The optical device 100 also includes a pair of third connecting portions 43, 43 extending from both sides of the second movable frame 60, and a pair of third connecting portions 43, 43 extending from both sides of the second movable frame 60. A pair of fourth connecting portions 44, 44 are provided at a predetermined interval along the Y direction, and the pair of third connecting portions 43, 43 and the pair of fourth connecting portions 44, 44 are further provided. and each have a predetermined elastic modulus. A pair of third connecting portions 43 , 43 and a pair of fourth connecting portions 44 , 44 extend in the X direction and connect the second movable frame 60 and the fixed frame 10 .

By configuring the optical device 100 in this manner, the second movable frame 60 can be reliably connected to the fixed frame 10 . Also, the second movable frame 60 can be displaced or tilted with respect to the fixed frame 10 .

Further, the optical device 100 further includes a pair of second actuators 80, 80 arranged at opposite positions along the X-axis with the second movable frame 60 interposed therebetween. A piezoelectric actuator 80 tilts the second movable frame 60 around the X axis.

By providing the pair of second actuators 80, 80, the second movable frame 60 can be tilted around the X axis. Also, the first movable frame 50 connected to the second movable frame 60 via the second connecting portion 42 and the mirror portion 30 connected to the first movable frame 50 via the first connecting portion 41 Similarly, it can be tilted around the X axis.

It is preferable that the pair of second actuators 80, 80 be arranged at positions that are symmetrical with respect to the Y-axis. By doing so, when the pair of second actuators 80 and 80 are driven in the same direction, the amount of tilting of the second movable frame 60 and thus the amount of tilting of the mirror section 30 can be made symmetrical about the X axis. can be done.

The second actuator 80 includes a first cantilever 81 having one end connected to the fixed frame 10 and the other end connected to the third connecting portion 43 , and a first piezoelectric element 82 formed on the main surface of the first cantilever 81 . , a second cantilever 83 having one end connected to the fixed frame 10 and the other end connected to the fourth connecting portion 44, and a second piezoelectric element 84 formed on the main surface of the second cantilever 83. there is

Voltages having opposite phases are applied to the first piezoelectric element 82 and the second piezoelectric element 84, respectively, and the connection end portion of the first cantilever 81 with the third connection portion 43 and the connection end portion of the second cantilever 83 with the fourth connection portion 44 The second movable frame 60 is tilted about the X-axis by moving the connecting ends in opposite directions along the Z-direction.

By configuring the second actuator 80 in this way, the driving force corresponding to the amount of deformation of the first cantilever 81 and the driving force corresponding to the amount of deformation of the second cantilever 83 are added together. A driving force is generated. As a result, the second drive frame, which has a relatively large mass, and the first movable frame 50 and the mirror section 30 connected thereto can be quickly tilted about the X axis.

The fixed frame 10 has an extension portion 11 which passes between the first cantilever 81 and the second cantilever 83 and whose tip extends near the fourth connecting portion 44. One end of the first cantilever 81 is It is connected to the tip of the extension part 11 .

By doing so, the length of the first cantilever 81 in the Y direction can be brought close to the length of the second cantilever 83 in the Y direction. Therefore, when the second actuator 80 is driven, the amount of displacement of the connecting end portion of the first cantilever 81 with the third connecting portion 43 displaced downward in the Z direction and the amount of displacement between the four connecting portions of the second cantilever 83 are The displacement amount by which the connecting end portion is displaced upward in the Z direction can be made substantially equal. As a result, the second movable frame 60 and thus the mirror section 30 can be tilted around the X-axis, and the amount of tilting of the mirror section 30 can be made symmetrical with respect to the X-axis. In addition, if one end of the first cantilever 81 is fixed, the desired movement can be given to the mirror section 30 in principle. There may be a structure (not shown), and one end of the first cantilever 81 may be joined to that portion. Even if the base frame 300 is not penetrated but has a bottom plate portion (not shown) and has an island-like projecting structure (not shown), and one end of the first cantilever 81 is connected to that portion. good.

In at least one of the first cantilever 81 and the second cantilever 83, where W is the width in the X direction, L is the length in the Y direction, and T is the thickness in the Z direction, W>10 ⁻⁵ ×L ³ / It is preferable to satisfy the relationship of ^T3 .

By configuring the first cantilever 81 and the second cantilever 83 in this way, it is possible to secure the amount of deformation in the Z direction and to provide the rigidity to mechanically withstand impacts from the outside. For example, when the length L of the first cantilever 81 is several millimeters, that is, several thousand μm, the width W is approximately several hundred μm, which is a fraction of the length L to approximately one tenth. Also, the thickness T is approximately equal to the thickness of the first silicon layer 210, so it is about 30 μm. Thus, since the first cantilever 81 is thin in the Z direction and long in the Y direction, it is likely to be bent and easily deformed by an external impact. In addition, there is a risk of damage due to impact when handling the optical device 100 .

On the other hand, according to the present embodiment, by defining the width W of the first cantilever 81 in the X direction as described above, the rigidity of the first cantilever 81 as a whole is increased, and the first cantilever 81 is prevented from being bent by an external impact or the like. 81 can be prevented from being damaged or deformed. In addition, unintentional tilting of the mirror portion 30 around the X axis can be suppressed. It goes without saying that the same effect can be obtained by defining the same relationship for each dimension of the second cantilever 83 .

The optical device 100 is provided at different positions on the second movable frame 60 across the Y-axis, and includes a pair of first detectors 91, 91 for detecting the drive amount of the first actuator 70, and the second actuator 80. and a pair of second detectors 92, 92 for detecting the amount of driving.

By providing the first detection section 91 and the second detection section 92, the driving amount of the first actuator 70 and the second actuator 80 can be detected, and the tilting amount of the mirror section 30 around the X axis and the Y axis can be detected. can do. For example, by feeding back the output signals of the first detection unit 91 and the second detection unit 92 to a control unit (not shown) and adjusting the voltage values applied to the first actuator 70 and the second actuator 80, the mirror unit 30 can be controlled to a desired value.

One of the second detectors 92 is provided at the center of the first cantilever 81 along the X direction with a predetermined distance from the first piezoelectric element 82, and the other of the second detectors 92 is the second cantilever. It is preferable that the second piezoelectric element 84 and the second piezoelectric element 84 are provided at a central portion along the X direction at a predetermined distance from the second piezoelectric element 84 .

By doing so, it is possible to suppress the influence when the first cantilever 81 and the second cantilever 83 are twisted and deformed. As described above, the first cantilever 81 is formed thin in the Z direction and long in the Y direction. Further, when the third connecting portion 43 is deformed, a force is applied to the connecting end portion with the third connecting portion 43 so as to rotate in the XZ plane, and the first cantilever 81 may undergo torsional deformation. A similar event can occur with the second cantilever 83 . In such a case, if the second detector 92 is positioned at the end of the first cantilever 81 or the second cantilever 83 in the X direction, the amount of drive of the second actuator 80 is reduced due to the torsional deformation. Accurate detection may not be possible.

On the other hand, according to the present embodiment, by arranging the second detector 92 at the position described above, the influence of torsional deformation can be suppressed, and the drive amount of the second actuator 80 can be detected accurately.

One of the second detectors 92 is provided near the connection end of the first cantilever 81 with the fixed frame 10 , and the other of the second detectors 92 is connected with the fixed frame 10 of the second cantilever 83 . More preferably, it is provided near the end.

By arranging the second detection part 92 at the connection end with the fixed frame 10, the influence of torsional deformation is reduced, and the drive amount of the second actuator 80 can be detected accurately.

The pair of second detectors 92 , 92 may be provided on only one of the pair of second actuators 80 , 80 and can detect the drive amount of the second actuator 80 . In this case, the planar shape of the first and second piezoelectric elements 82 and 84 included in one of the pair of second actuators 80 and 80 and the first and second piezoelectric elements included in the other of the pair of second actuators 80 and 80 It is preferable that the planar shape of the second piezoelectric elements 82 and 84 be the same. In the present embodiment, with regard to the second actuator 80 on the side where the second detection section 92 is not provided, this Seeking to fulfill a relationship. By doing so, the driving characteristics of the pair of second actuators 80, 80 can be made the same, the mirror section 30 can be tilted around the X axis, and the amount of tilting can be made symmetrical with respect to the X axis. can be done.

A plurality of pad electrodes 94 are provided on the main surface of the fixed frame 10, and a pair of first actuators 70, 70, a pair of second actuators 80, 80, a pair of first detectors 91, 91 and a pair of Each of the second detection units 92 , 92 is connected to one of the plurality of pad electrodes 94 via wiring 93 .

Each of the pair of first detectors 91 , 91 is connected to a different pad electrode 94 via a wiring 93 provided across the second movable frame 60 , the fourth connecting part 44 and the second cantilever 83 . , and the wiring 93 connected to one first detection section 91 is provided on the opposite side of the wiring 93 connected to the other first detection section 91 with the second piezoelectric element 84 interposed therebetween. .

By arranging the wiring 93 connected to each of the pair of first detection units 91, 91 in this manner, the crosstalk components entering the wiring 93 become equal, and if the difference is taken by the detection circuit, these components are canceled. Therefore, the driving amount of the first actuator 70 can be accurately detected.

As described above, the pair of first detection units 91 and 91 are distorted according to the amount of deformation of the first movable frame 50 and the second movable frame 60, and charges are induced in the respective upper electrodes 430. A current signal or a voltage signal is generated. Based on this signal, the drive amount of the first actuator 70 is detected. Since the pair of first detectors 91 and 91 deform in opposite directions in the Z direction, the signals output from them are in opposite phases to each other. On the other hand, since the wiring 93 is routed for a long time, capacitive coupling occurs with another conductor, for example, the upper electrode 430 of the second piezoelectric element 84, and a crosstalk component is superimposed on the signal transmitted to the wiring 93. I have something to do. This crosstalk component becomes a noise component of the signal, and the driving amount of the first actuator 70 may not be detected accurately.

On the other hand, according to the present embodiment, by arranging the wiring 93 connected to each of the pair of first detection units 91, 91 as described above, the amplitude of the crosstalk component superimposed on each wiring 93 is are almost the same, and their phases are in phase with each other. Therefore, by taking the difference between these signals, the crosstalk component, that is, the noise component of the signal is canceled, and the driving amount of the first actuator 70 can be accurately detected.

Further, the width in the Y direction of the fourth connecting portion 44 may be changed. Specifically, the fourth connecting portion 44 may be provided with a convex portion 44a that protrudes upward in the Y direction. By doing so, it is possible to suppress unintentional displacement of the second actuator 80 when the mirror section 30 is resonantly driven. As a result, the reflected light reflected by the mirror section 30 can be reliably scanned onto the predetermined area. This will be further explained.

As described above, when the first actuator 70 is driven, the mirror section 30 is resonantly driven at the resonance frequency of the vibration system including the mirror section 30 and the first movable frame 50 . On the other hand, the second movable frame 60 is connected to the first movable frame 50 via the second connecting portion 42, and the second actuator 80 is connected to the second movable frame via the third connecting portion 43 and the fourth connecting portion 44. It is connected to the frame 60 . Therefore, when the mirror section 30 is resonantly driven, its influence may be transmitted to the second actuator 80 . In general, the resonance frequency of the vibration system including the mirror section 30 and the first movable frame 50 (hereinafter sometimes referred to as the first resonance point) and the vibration system of the second actuator 80, particularly the first It is away from the resonance frequency at which the cantilever 81 and the second cantilever 83 are periodically curved and deformed (hereinafter sometimes referred to as the second resonance point). The amount of deformation is very small.

However, depending on the size of the optical device 100, the size and mass of each member included in the optical device 100, the distance between each member, etc., the first resonance point and the second resonance point become close to each other. , the second actuator 80 may be greatly deformed due to the resonance drive of . If this happens, the mirror section 30 will unintentionally tilt around the X-axis, and the light incident on the mirror section 30 will be reflected out of the desired direction.

On the other hand, according to the present embodiment, by changing the width of the fourth connecting portion 44 in the Y direction, the moment of inertia and bending rigidity of the fourth connecting portion 44 are changed, and the fourth connecting portion 44 connected to the fourth connecting portion 44 is changed. The resonance frequency of the two actuators 80 can be shifted. In this manner, the first resonance point and the second resonance point can be separated by a predetermined amount or more, and unintended tilting of the mirror section 30 is suppressed, so that the light reflected by the mirror section 30 is reliably reflected on a predetermined area. Reflected light can be scanned.

For the same reason, the width in the Y direction may be changed at the side portion of the second movable frame 60 to which the fourth connecting portion 44 is connected. Specifically, a convex portion 62 that protrudes upward in the Y direction is provided on the side portion. In this case as well, the first resonance point and the second resonance point can be separated by a predetermined amount or more, suppressing unintended tilting of the mirror section 30 and ensuring that the reflection is reflected by the mirror section 30 onto a predetermined area. Light can be scanned.

It is preferable that the distance between the fixed frame 10 and the second movable frame 60 is substantially constant. When the substrate 200 is pierced by DRIE, if the widths of the first to fifth through openings 21 to 25 are different, the etching speed may change. This tendency becomes remarkable in the first to third through openings 21 to 23 in which the ratio of the depth to the width of the groove to be penetrated is large. However, if the etching speed is different, the finally formed width may vary. If this happens, the dimensions and mass of each member will change, and there is a possibility that the amount of tilting of the mirror section 30 will change, or the frequency during resonance driving will change.

In this embodiment, as shown in FIG. 1, by providing unevenness on the sides of the fixed frame 10 according to the arrangement of the fourth connecting portion 44 connected to the second movable frame 60, the fixed frame The distance between 10 and the second movable frame 60 is kept substantially constant to suppress variations in the dimensions and mass of each member of the optical device 100 . As a result, the mirror section 30 can be tilted at a desired frequency and the amount of tilting can be set to a desired value.

The optical device 100 also includes a first through-opening 21 that at least separates the second actuator 80 and the fixed frame 10, a second through-opening 22 that at least separates the second cantilever 83 and the first cantilever 81, A third through opening 23 that at least partitions the first cantilever 81 and the second movable frame 60 is formed. One end 21 a of the first through opening 21 is formed closer to the outer peripheral surface of the fixed frame 10 than the connecting end portion between the second cantilever 83 and the fixed frame 10 . One end 22a of the second through-opening 22 is formed closer to the outer peripheral surface of the fixed frame 10 than the connecting end portion between the second cantilever 83 and the fixed frame 10, and the other end 22b is formed between the first cantilever 81 and the first cantilever 81. They are formed so as to extend closer to the outer peripheral surface of the fixed frame 10 than the connection ends with the two movable frames 60 . Both ends 23 a of the third through-opening 23 are formed so as to extend closer to the outer peripheral surface of the fixed frame 10 than the connecting ends of the first cantilever 81 and the extension portion 11 .

By doing so, processing defects of the first cantilever 81 and the second cantilever 83 can be reduced. Further description will be made with reference to FIG.

FIG. 5 shows a partial plan view of the optical device viewed from below in the Z direction, where (a) shows a plan view according to this embodiment and (b) shows a plan view for comparison. . 5, illustration of the base frame 300 is omitted.

As described above, after forming the first to fifth through openings 21 to 25 in the substrate 200, the first insulating layer 220 and the second silicon layer in the regions corresponding to the thin plate portions of the first and second cantilevers 81 and 83 are removed. By removing 230, the optical device 100 is formed. At this time, mask patterns (not shown) having different shapes are used for the former processing and the latter processing.

However, if misalignment of the mask pattern more than a predetermined amount occurs during the latter processing, for example, shape defects may occur at the ends 21a, 22a, 22b, and 23a of the first to third through openings 21 to 23. (See FIG. 5(b)). In particular, if such a shape defect occurs at both ends 22a, 22b of the second through opening or both ends 23a of the third through opening, the first cantilever 81 or the second cantilever 83 near the ends 22a, 22b, 23a may be damaged. Unexpected stress concentration may occur, and problems such as cracks may occur. In particular, when the thin plate portions of the first cantilever 81 and the second cantilever 83 are deformed, this tendency becomes remarkable.

On the other hand, as shown in FIG. 5(a), the first to third openings 21a, 22a, 22b, and 23a of the first to third through openings 21 to 23 are placed in the positions described above. By setting the shapes of the through openings 21 to 23, it is possible to suppress defects in the final processed shapes of the first and second cantilevers 81 and 83 even when the aforementioned misalignment occurs. As a result, problems such as cracks due to stress concentration in the first and second cantilevers 81 and 83 can be avoided.

<Modification>
FIG. 6 shows a plan view of the arrangement of the second detector 92 according to this modification. For convenience of explanation, in FIG. 6, the same reference numerals are given to the same parts as in the first embodiment, and detailed explanations thereof are omitted.

The second detectors 92 shown in this modified example are provided at two locations on the main surface of the first cantilever 81 with a predetermined interval in the X direction. different from Also, the wirings 93 respectively connected to the two second detection portions 92a and 92b are combined into one and connected to the corresponding pad electrodes 94. As shown in FIG. The two second detectors 92a and 92b are arranged symmetrically with respect to a line of symmetry (not shown) passing through the center of the first cantilever 81 in the X direction in the Y direction.

The second detection section 92 may be configured in this manner, and in this case also, the same effects as in the first embodiment can be obtained. In addition, by providing a plurality of second detectors 92a and 92b along the X direction, erroneous detection of the tilt amount due to torsional deformation of the first cantilever 81 can be reliably suppressed.

Although not shown, the second detector 92 provided on the second cantilever 83 is also divided and arranged in the same manner as shown in FIG. By doing so, the shape symmetry of the second detector 92 can be maintained, and the drive amount of the second actuator 80 can be detected correctly. Also, the amount of tilting of the mirror section 30 around the X-axis can be set to a desired value.

Also, three or more second detection units 92 may be provided on the main surfaces of the first and second cantilevers 81 and 83 along the X direction. In this case as well, the symmetry line (not shown) passing through the X-direction central portion of the first cantilever 81 in the Y-direction is symmetrical, and the second cantilever 83 is symmetrical in the Y-direction through the X-direction central portion. By arranging the second detectors 92 so as to be symmetrical with respect to a line (not shown), erroneous detection of the tilt amount due to torsional deformation of the first cantilever 81 and the second cantilever 83 can be reliably suppressed. can be done.

(Embodiment 2)
FIG. 7 shows a plan view of the optical device according to this embodiment. For convenience of explanation, in FIG. 7, the same reference numerals are assigned to the same parts as those in the first embodiment, and detailed explanation thereof will be omitted. Also, the wiring 93 and the pad electrode 94 are omitted from the drawing.

The optical device 110 according to this embodiment differs from the optical device 100 according to the first embodiment in that the second actuator 80 is omitted.

In this case, the optical device 110 functions as a uniaxial mirror scanner that scans the reflected light from the mirror section 30 in one direction by tilting the mirror section 30 around the Y axis.

In addition, each of the pair of third connecting portions 43, 43 extends linearly in the Y direction to connect the fixed frame 10 and the Y-direction lower side portion of the second movable frame 60, Each of the connecting portions 44 , 44 linearly extends in the Y direction and connects the fixed frame 10 and the Y-direction upper side portion of the second movable frame 60 . Also, as in the first embodiment, the third and fourth connecting portions 43 and 44 are elastic bodies each having a predetermined elastic modulus. Accordingly, when the first actuator 70 is driven, the second movable frame 60 is connected to the fixed frame 10 so as to be deformable and displaceable.

According to this embodiment, similarly to the first embodiment, the driving force of the first actuator 70 can be increased, and the mirror section 30 can be tilted with a low voltage.

In addition, in the configuration shown in this embodiment, while the width of the first through opening 21 is substantially constant, the second actuator 80, which is affected by the resonance driving of the mirror section 30, is omitted. 60, the fourth connecting portion 44, and the fixed frame 10 are not provided with a convex portion. By doing so, the pattern design and processing of each member of the optical device 110 are simplified.

Both the third connecting portion 43 and the fourth connecting portion 44 are bent and deformed when the first actuator 70 is driven, and return to their original shapes when the first actuator 70 is not driven. In other words, both the third connecting portion 43 and the fourth connecting portion 44 are elastic bodies having a predetermined elastic modulus. The third connecting portion 43 and the fourth connecting portion 44 shown in FIG. 1 are also elastic bodies having a predetermined elastic modulus.

The planar shapes of the third and fourth connecting portions 43 and 44 are not limited to the shape shown in FIG. 7, and may be other shapes. The planar shape of the third and fourth connecting portions 43 and 44 is such that the second movable frame 60 is connected to the fixed frame 10 so as to be deformable and displaceable when the first actuator 70 is driven. It is sufficient if they are set respectively.

(Other embodiments)
It is also possible to combine the constituent elements described in the above embodiments and modified examples to create new embodiments. Also, the first actuator 70 may be provided only at one location in the X direction across the Y axis, as long as it is formed across the first movable frame 50 and the second movable frame 60. good. Also in this case, the mirror section 30 can be tilted around the Y-axis. As shown in FIG. 1, by providing a pair of first actuators 70, 70 at positions opposed to each other along the X-axis with the mirror section 30 interposed therebetween, the amount of tilting of the mirror section 30 can be made symmetrical about the Y-axis. In addition, the amount of tilting of the mirror section 30 can be increased. In addition, it becomes easy to suppress the movement of the center O of the mirror section 30 into which light is incident in the Z direction. As a result, the optical path length of the reflected light can be made constant. Similarly, the second actuator 80 may also be provided only at one location in the X direction across the Y axis. Also in this case, the mirror section 30 can be tilted around the X axis. As shown in FIG. 1, by providing a pair of second actuators 80, 80 at positions opposed to each other along the X-axis with the second movable frame 60 interposed therebetween, the amount of tilting of the mirror section 30 can be controlled by the X-axis. It becomes easy to control so as to be symmetrical about the periphery, and the amount of tilting of the mirror section 30 can be increased. In addition, it becomes easy to suppress the movement of the center O of the mirror section 30 into which light is incident in the Z direction. As a result, the optical path length of the reflected light can be made constant.

Further, in Embodiments 1 and 2, the configuration in which the optical path changing portion is the mirror portion 30 has been described as an example, but the optical path changing portion may be a member having another optical function. For example, it may be a member that has a refractive index greater than 1 with respect to incident light and transmits the incident light. Also, a light source such as a light emitting diode (LED) or a surface emitting laser (VCSEL) may be arranged directly in the optical path changing portion. In this case, the formation of the metal film 31 as a mirror is omitted. Further, by using a plurality of optical devices 100 and 110 shown in FIG. can be For example, the light emitted from the RGB three-color light source may be scanned by the optical device 100 or 110 to generate an image. Alternatively, an image may be generated by arranging the optical devices 100 or 110 in an array, causing light to enter each of them, and scanning the reflected light over a predetermined area.

Alternatively, the second detector 92 may be arranged on the second actuator 80 located on the left side in the X direction. The pair of second actuators 80 , 80 may be arranged at points symmetrical with respect to the center O of the mirror section 30 .

Also, the first actuators 70 , 70 may be arranged point-symmetrically with respect to the center O of the mirror section 30 . In that case, the pair of first detectors 91 , 91 are also arranged point-symmetrically with respect to the center O of the mirror part 30 .

Further, in Embodiment 1, an example of using a piezoelectric actuator as the second actuator 80 that tilts the mirror section 30 around the X axis has been described. good too. For example, an electromagnetic actuator using an exciting coil may be used, or an electrostatic actuator may be used.

In addition, in FIG. 2, the fourth connecting portion 44 is provided with a convex portion, but the third connecting portion 43 may be provided with a convex portion, or both the third connecting portion 43 and the fourth connecting portion 44 may A protrusion may be provided. Also, a protrusion may be provided on the lower side of the second movable frame 60 in the Y direction. You may make it provide a convex part in both the side parts of a Y direction upper side and a lower side. These can be appropriately selected depending on the layout of each member in the optical device 100 . It is sufficient if the resonance point of the vibration system including the mirror section 30 and the first movable frame 50 and the resonance point of the vibration system including the second movable frame 60 and the second actuator 80 are separated by a predetermined distance or more. Moreover, in order to achieve the same purpose, the shapes of the second movable frame 60 and the third and fourth connecting portions 43 and 44 may be changed in another way. For example, the thickness of part of the second movable frame 60 and the third and fourth connecting parts 43 and 44 may be changed, or another heavy object may be adhered to these.

In Embodiments 1 and 2, an example in which the second cantilever 83 is wider than the first cantilever 81 is shown, but the present invention is not limited to this, and the width of the second cantilever 83 in the X direction is the The width may be equal to or narrower than the width of one cantilever 81 in the X direction. It can be changed as appropriate depending on the size of the optical device 100, the driving characteristics required for the second actuator 80, and the like. By making the X-direction width of the second cantilever 83 and the X-direction width of the first cantilever 81 different from each other, it becomes easier to change the second resonance point. Also in this case, it goes without saying that the dimensions of the second cantilever 83 in the X direction, the Y direction, and the Z direction naturally satisfy the relationship shown in Equation (1).

Further, by matching the natural resonance frequency of the mirror section 30 and the natural resonance frequency of the first movable frame 50, the mirror section 30 is resonantly driven. On the other hand, depending on the size of the optical device 100, the size of the first movable frame 50 may need to be reduced. may not work. In such a case, the frequency matching may be performed by changing the planar size of the first connecting portion 41 or changing the thickness of a part of it. Similarly, frequency matching may be performed by changing the thickness of part of the mirror section 30 or part of the first movable frame 50 .

INDUSTRIAL APPLICABILITY The optical device according to the present invention is useful as an optical scanner used in projectors, HUDs, HMDs, etc., because it can increase the driving force of the actuator that tilts the optical path changing portion.

10 Fixed frame 11 Extensions 21 to 25 First to fifth through openings 30 Mirror section (optical path changing section)
31 metal film (mirror)
41 to 44 First to fourth connecting portions 50 First movable frame 60 Second movable frame 70 First actuator 71 Piezoelectric element 80 Second actuator 81 First cantilever 82 First piezoelectric element 83 Second cantilever 84 Second piezoelectric element Element 91 First detection section 92 Second detection section 93 Wiring 94 Pad electrodes 100 and 110 Optical device 200 SOI substrate (substrate)
210 First silicon layer 220 First insulating layer 230 Second silicon layer 300 Base frame 410 Lower electrode 420 Piezoelectric layer 430 Upper electrode 440 Passivation film

Claims (16)

an optical path changing unit;
a pair of first connecting portions extending from both sides of the optical path changing portion along a first axis passing through the optical path changing portion;
a first movable frame provided to surround the optical path changing portion inside and connected to each of the pair of first connecting portions;
a pair of second connecting portions extending from both sides of the first movable frame along a second axis that intersects with the first axis;
a second movable frame provided so as to surround the first movable frame inside and connected to each of the pair of second connecting portions;
a first actuator provided across the first movable frame and the second movable frame;
a fixed frame provided to surround the second movable frame inside and connected to the second movable frame;
The optical device, wherein the first actuator is a piezoelectric actuator that tilts the optical path changing portion about the first axis. a pair of third connecting portions extending from both sides of the second movable frame;
a pair of fourth connecting portions extending from both sides of the second movable frame and provided at a predetermined interval in a direction parallel to the pair of third connecting portions and the first axis; prepared,
2. The optical device according to claim 1, wherein said pair of third connecting portions and said pair of fourth connecting portions each have a predetermined elastic modulus. 3. The pair of third connecting parts and the pair of fourth connecting parts according to claim 2, each extending in a direction parallel to the second axis and connecting the second movable frame and the fixed frame. optical device. 4. The optical device according to claim 2, further comprising a second actuator that tilts the second movable frame around the second axis. The second actuator is
a first cantilever having one end connected to the fixed frame and the other end connected to the third connecting portion;
a first piezoelectric element formed on the main surface of the first cantilever;
a second cantilever having one end connected to the fixed frame and the other end connected to the fourth connecting portion;
and a second piezoelectric element formed on the main surface of the second cantilever. In at least one of the first cantilever and the second cantilever, W is the width in the direction parallel to the second axis, L is the length in the direction parallel to the first axis, and the first axis and the second axis When the thickness in the direction parallel to the third axis that intersects with each is T,
W>10 ⁻⁵ ×L ³ /T ³
6. The optical device according to claim 5, which satisfies the relationship: a pair of first detection units provided at different positions of the second movable frame with the first axis interposed therebetween for detecting the drive amount of the first actuator;
7. The optical device according to claim 5, further comprising a pair of second detectors that detect the drive amount of said second actuator. one of the second detectors is provided at a central portion of the first cantilever along a direction parallel to the second axis with a predetermined gap from the first piezoelectric element;
8. The other of the second detectors is provided at a central portion of the second cantilever along the direction parallel to the second axis with a predetermined gap from the second piezoelectric element. Optical device as described. 9. The optical device according to claim 7, wherein the pair of second detectors is provided on only one of the pair of second actuators. Each of the pair of first detection units is connected to the main surface of the fixed frame via wiring provided across the second movable frame, the fourth connecting portion, and the second cantilever. are connected to provided pad electrodes different from each other,
8. The wiring connected to one of the pair of first detection units is provided on the opposite side of the wiring connected to the other of the pair of first detection units across the second piezoelectric element. 10. The optical device according to any one of items 1 to 9. A first through opening that at least partitions the second actuator and the fixed frame, a second through opening that partitions at least the second cantilever and the first cantilever, the first cantilever and the second movable frame. a third through opening that at least partitions the body,
One end of the second through opening extending in a direction parallel to the first axis is closer to the outer peripheral surface of the fixed frame than the connection end between the second cantilever and the fixed frame. , extending to a side closer to the outer peripheral surface of the fixed frame than the connection end between the first cantilever and the second movable frame, and
both ends of the third through-opening extending in a direction parallel to the first axis extend closer to the outer peripheral surface of the fixed frame than the connection end between the first cantilever and the fixed frame; The optical device according to any one of claims 5 to 10. At least one of the third connecting portion, the fourth connecting portion, and the side portion of the second movable frame opposed to the fixed frame has a variable width in a direction parallel to the first axis. An optical device according to any one of claims 2 to 11. The optical device according to any one of claims 1 to 12, wherein the second movable frame has a narrow portion narrower than twice the width of the widest portion of the first movable frame. . The area of the first actuator provided on the second movable frame is wider than the area of the first actuator provided on the first movable frame, according to any one of claims 1 to 13. optical device. 15. The optical path changing section according to any one of claims 1 to 14, wherein the optical path changing section is resonantly driven at a resonance frequency of an oscillation system including the optical path changing section and the first movable frame, and is tilted about the first axis. 2. The optical device according to item 1. 16. The optical device according to any one of claims 1 to 15, wherein said optical path changing section has a mirror that reflects incident light.

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