JP2014102355A - Optical deflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical deflector which offers a greater swing angle of a reflective surface without changing dimensions of the optical deflector.SOLUTION: An optical deflector 1 includes a reflective surface 2a for reflecting light and actuators 5 for swinging the reflective surface 2a about a first axis X. Each actuator 5 includes a piezoelectric body 5b to which drive voltage is applied and a rectangular plate-like support body 5a which supports the piezoelectric body 5b and flexurally deforms together with the piezoelectric body 5b. The support body 5a is made of single crystal silicon such that the longitudinal direction thereof is in parallel with a crystal orientation <100> of the support body 5a.

Description

  The present invention relates to an optical deflector configured such that a reflecting surface can be swung by a support body made of single crystal silicon that is bent and deformed together with a piezoelectric body.

  2. Description of the Related Art Conventionally, an optical deflector having a reflecting surface that reflects light and an actuator that swings the reflecting surface around a predetermined axis is known (Patent Document 1). In this optical deflector, the actuator includes a piezoelectric cantilever having a piezoelectric body to which a driving voltage is applied and a rectangular plate-like support body that supports the piezoelectric body and bends and deforms together with the piezoelectric body.

JP 2008-20701 A

  In the optical deflector described in Patent Document 1, it may be desired to increase the swing angle of the reflecting surface. In such a case, in order to increase the displacement amount of the support, it is conceivable to make the support thin. However, it is difficult to thin only the support of the actuator among the supports constituting the optical deflector.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an optical deflector that can increase the swing angle of the reflecting surface without changing the dimensions of the optical deflector.

  The present invention provides an optical deflector having a reflecting surface for reflecting light and an actuator for swinging the reflecting surface about a predetermined axis, wherein the actuator includes a piezoelectric body to which a driving voltage is applied, and the piezoelectric body. And a rectangular plate-like support that bends and deforms together with the piezoelectric body. The support is made of single crystal silicon, and its longitudinal direction is parallel to the <100> orientation of the crystal orientation of the support. It is formed so that it becomes.

  Here, since the crystal orientation in the present invention is the crystal orientation in single crystal silicon, the predetermined orientation includes an orientation equivalent to the orientation. For example, the <100> orientation when the predetermined orientation is the <100> orientation includes, for example, <010>, <001>, <-100>, and the like.

  When manufacturing an optical deflector of MEMS (Micro Electro Mechanical Systems), a wafer formed of single crystal silicon is used. At this time, the main surface of the wafer is generally the (100) surface in view of the etching process. For this reason, the crystal orientation along the main surface of the wafer is mainly the <110> orientation or the <100> orientation.

  The displacement amount of the cantilever (the magnitude of bending deformation) is inversely proportional to the Young's modulus E. That is, in order to increase the swing angle of the reflecting surface, it is desirable that the Young's modulus E is small in order to increase the displacement of the cantilever.

  Here, the Young's modulus E of the single crystal silicon is about 160 [GPa] when the crystal orientation of the single crystal silicon is the <110> orientation, and is about 130 [GPa] when the crystal orientation of the single crystal silicon is the <100> orientation. ]. Therefore, by forming the support so that the longitudinal direction of the support is parallel to the <100> orientation of the crystal orientation of the single crystal silicon, it is parallel to the <110> orientation of the crystal orientation of the single crystal silicon. Thus, the magnitude of the bending deformation of the support is larger than that in which the support is formed.

  Thereby, the rocking | fluctuation angle of a reflective surface can be enlarged. At this time, it is not necessary to change the dimensions of the torsion bar. Accordingly, the swing angle of the reflecting surface can be increased without changing the dimensions of the optical deflector.

  In the present invention, the torsion bar is formed of single crystal silicon and is twisted around a longitudinal axis by the actuator to swing the reflecting surface. The torsion bar has the axial direction of the torsion bar. It is preferably formed so as to be parallel to the <100> orientation of the crystal orientation.

  Here, the shear elastic modulus G of single crystal silicon is about 62 [GPa] when the crystal orientation of the single crystal silicon is <110>, and about 79 [GP] when the crystal orientation of the single crystal silicon is <100>. GPa]. The spring constant k of the torsion bar increases as the shear modulus G increases.

  Therefore, by forming the torsion bar so that the axial direction of the torsion axis is parallel to the <100> orientation of the crystal orientation of the single crystal silicon, it becomes parallel to the <110> orientation of the crystal orientation of the single crystal silicon. Thus, the spring constant around the torsion axis is larger than that in which the torsion bar is formed, and as a result, the resonance frequency of the torsion bar can be increased. At this time, it is not necessary to change the dimensions of the torsion bar. Therefore, the scanning speed of the reflecting surface can be increased without changing the dimensions of the optical deflector.

  As described above, even when the displacement amount of the cantilever is increased, the scanning speed of the reflecting surface can be increased.

  In the present invention, the actuator includes a plurality of the piezoelectric bodies and the support bodies, and each of the plurality of support bodies is arranged side by side so that both ends thereof are adjacent to each other. It is preferable that the end portions are connected so as to be folded back with respect to the adjacent supports, and each support is formed so as to be bent and deformed in a direction perpendicular to the arrangement direction of the supports. As a result, when a voltage is applied to the piezoelectric bodies supported by a plurality of supports, on the path where all the supports are connected, the end of the support opposite to the reflective surface side is used as a fulcrum. Angular displacement occurs at the end of the reflecting surface. Thus, the angular displacement of each support is accumulated, so that the swing angle of the reflecting surface can be increased.

The figure which shows the structure of the optical deflector of 1st Embodiment of this invention. It is a figure which shows the layout of an optical deflector when producing an optical deflector from a wafer whose main surface is a (100) plane, (a) is when the orientation flat shows <110> orientation, (b) is The figure when an orientation flat shows a <100> azimuth | direction. FIG. 3 is a diagram when the III-III line in FIG. 1 is viewed in the direction of the arrow, and FIG. 3A is a diagram schematically illustrating a wafer stack before etching when manufacturing an optical deflector; FIG. 5B is a diagram simply showing the state after etching (a). The figure which shows the structure of the optical deflector of 2nd Embodiment of this invention.

[First Embodiment]
An optical deflector according to a first embodiment of the present invention will be described with reference to FIG. The optical deflector 1 of the present embodiment includes a mirror part 2 having a circular reflecting surface 2a, two torsion bars 3, a frame body 4, and four actuators 5.

  The mirror part 2 is formed in a circular shape having substantially the same size as the reflecting surface 2a. The center of the mirror unit 2 is arranged at the center of the optical deflector 1. The mirror unit 2 receives incident light from a laser light source (not shown) on the reflection surface 2a, and emits the reflected light in a direction according to the rotation angle around the axis of the torsion bar 3. The axis line (longitudinal axis line) of the torsion bar 3 is also the rotation axis line of the mirror unit 2 (hereinafter, this axis line is referred to as “first axis X”). The two torsion bars 3 are connected to the periphery of the mirror part 2 from the left and right sides of the mirror part 2 so that the respective axes are on the same diameter of the mirror part 2.

  Each of the four actuators 5 includes a support body 5a formed of a single crystal silicon in a substantially rectangular plate shape, and a piezoelectric body 5b supported on substantially the entire surface of one side of the support body 5a.

  Two four actuators 5 are arranged on both sides of the mirror unit 2 (left and right sides in FIG. 1). At this time, on the right side of the mirror part 2, the two actuators 5 are respectively arranged above and below the base end part of the right torsion bar 3 in FIG. 1, and the front end part is connected to the base end part of the torsion bar 3. doing. On the left side of the mirror part 2, the two actuators 5 are respectively arranged above and below the base end part of the left torsion bar 3 in FIG. 1, and the front end part is connected to the base end part of the torsion bar 3. .

  The frame 4 is formed as a rectangular frame (the upper side 4u and the lower side 4d are parallel and the left side 4l and the right side 4r are parallel), and surrounds the mirror part 2, the torsion bar 3, and the actuator 5 from the outside. To do. The base end portion of the actuator 5 is connected to the upper side 4u portion or the lower side 4d portion of the frame body 4.

  The torsion bar 3 is arranged in parallel to the upper side 4 u and the lower side 4 d of the frame body 4. Further, the support 5 a (and hence the actuator 5) of the actuator 5 is arranged in parallel to the left side 4 l and the right side 4 r of the frame body 4.

  The optical deflector 1 is manufactured using a semiconductor planar process and a MEMS process using a photolithography technique, a dry etching technique, and the like as follows. First, as shown in FIG. 3A, a lower electrode layer L1, a piezoelectric layer L2, an upper electrode layer L3, and the like are laminated on a single crystal silicon wafer 10 as shown in FIG. Is done. Then, unnecessary portions are appropriately removed by an etching process or the like, so that the mirror part 2, the torsion bar 3, the frame body 4, and the actuator 5 are formed (FIG. III section is shown). At this time, the lower electrode layer L1, the piezoelectric layer L2, and the upper electrode layer L3 are left only in the portion of the actuator 5, and other portions are removed.

  Further, wiring (conducting to the portion (upper electrode) t + remaining after etching the upper electrode layer L3 so that a driving voltage can be applied to the piezoelectric body 5b (location remaining after the piezoelectric layer L2 is etched)). (Not shown) and a wiring (not shown) that is electrically connected to a portion (lower electrode) t− remaining after the etching of the lower electrode layer L1 is provided.

  When a driving voltage is applied between the wiring that conducts to the upper electrode t + and the wiring that conducts to the lower electrode t−, the piezoelectric body 5b has a longitudinal direction of the support 5a due to the piezoelectric effect caused by the application. Reduce to. Accordingly, the support 5a supporting the piezoelectric body 5b faces the inner surface of the support 5a supporting the piezoelectric body 5b (the base end of the support 5a is directed upward in FIG. 3). And the piezoelectric body 5b is bent and deformed. Hereinafter, such bending deformation of the piezoelectric body 5 b and the support body 5 a is also simply referred to as bending deformation of the actuator 5.

  Further, the mirror surface 2 is formed with a reflective surface 2a on the wafer 10 by processing a metal thin film (one metal thin film in this embodiment) using a semiconductor planar process.

  The torsion bar 3 and the support 5a of the actuator 5 are formed by etching the wafer 10 and the like, and thus are formed of the same material as the wafer 10, that is, single crystal silicon.

  The wafer 10 is made of single crystal silicon. The main surface of the wafer 10 is the (100) plane. For this reason, the crystal orientation along the main surface of the wafer 10 is mainly the <110> orientation or the <100> orientation. An orientation flat 11 is provided on the wafer 10 so as to indicate the <110> orientation (see FIG. 2A). That is, the direction at an angle of 45 degrees with respect to the orientation flat 11 is the <100> orientation.

  Then, as shown in FIG. 2A, the optical deflector 1 to be formed is laid out on the wafer so that the upper side 4u of the frame 4 is inclined by 45 degrees with respect to the orientation flat 11. As a result, the upper side 4u of the frame 4 is parallel to the <100> orientation. The direction parallel to the upper side 4u and the direction perpendicular thereto are all <100> orientations. For this reason, the longitudinal direction of the torsion bar 3 parallel to the upper side 4u and the longitudinal direction of the support 5a of the actuator 5 orthogonal to the upper side 4u are the <100> orientation.

  As shown in FIG. 2B, an orientation flat 11 may be provided on the wafer 10 whose main surface is the (100) plane so as to indicate the <100> orientation. In this case, the optical deflector 1 to be formed on the wafer 10 may be laid out on the wafer 10 so that the upper side 4u of the frame 4 is parallel to the orientation flat 11.

  Next, the operation of the optical deflector 1 will be described. The optical deflector 1 is configured such that the torsion bar 3 is twisted around the first axis X by driving the actuator 5.

  Specifically, of the four actuators 5, two actuators (hereinafter referred to as “upper actuators”) 5 on the upper side in FIG. 1 are connected to the torsion bar 3 with respect to the base end portion connected to the frame body 4. The distal end portion that is bent is deformed and the remaining two actuators (two actuators on the lower side of FIG. 1, hereinafter referred to as “lower actuator”) 5 are connected to the frame body 4. A driving voltage is applied to the piezoelectric body 5b so that the tip connected to the torsion bar 3 is bent and deformed relative to the portion. At this time, a driving voltage is applied to the piezoelectric body 5b of the upper actuator 5 so that the bending deformation of each of the upper actuators 5 has the same magnitude. Further, a drive voltage is applied to the piezoelectric body 5b of the lower actuator 5 so that the bending deformation of each of the lower actuators 5 has the same magnitude.

  When the magnitude of the bending deformation of the upper actuator 5 is different from the magnitude of the bending deformation of the lower actuator 5, the torsion bar 3 is twisted around the first axis X, and the mirror portion 2 (and hence the reflecting surface 2a) is Swing around one axis X. When the magnitude of the bending deformation of the upper actuator 5 and the magnitude of the bending deformation of the lower actuator 5 are the same, the swing angle of the mirror portion 2 is the mirror when the upper actuator 5 and the lower actuator 5 are not bent and deformed. It becomes the same as the swing angle of the part 2. Thus, the swing angle of the reflecting surface 2a around the first axis X can be adjusted according to the magnitude of the bending deformation of the upper actuator 5 and the magnitude of the bending deformation of the lower actuator 5.

  In the optical deflector 1 of the present embodiment, the voltage signal applied to the piezoelectric body 5b of the upper actuator 5 and the voltage signal applied to the piezoelectric body 5b of the lower actuator 5 have periodicity, and Voltage signals having opposite phases to each other (that is, voltage signals that are 180 degrees out of phase with each other) are applied. At this time, the frequency of the voltage signal is set to the mechanical resonance frequency of the optical deflector 1. Thereby, the reflecting surface 2a can be swung around the first axis X with a large deflection angle.

  As described above, the torsion bar 3 swings around the first axis X by twisting around the first axis (the longitudinal axis of the torsion bar 3) X. As described above, the longitudinal direction of the torsion bar 3 is the <100> orientation. Here, the shear elastic modulus G of single crystal silicon is about 62 [GPa] when the crystal orientation of the single crystal silicon is <110>, and about 79 [GP] when the crystal orientation of the single crystal silicon is <100>. GPa]. The spring constant k of the torsion bar 3 increases as the shear elastic modulus G of the torsion bar 3 increases. For example, when the torsion bar 3 has a long plate shape as in this embodiment, the spring constant k of the torsion bar 3 is expressed by the following equation (1).

  Here, G indicates the shear elastic modulus of the torsion bar 3, w indicates the length in the width direction of the torsion bar 3, t indicates the thickness of the torsion bar 3, and L indicates the length in the longitudinal direction of the torsion bar 3. It shows.

  Therefore, the torsion bar 3 is formed so that the longitudinal axis X of the torsion bar 3 is parallel to the <100> orientation of the crystal orientation of the single crystal silicon, so that <110> of the crystal orientation of the single crystal silicon. The spring constant k around the longitudinal axis X of the torsion bar 3 is larger than that in which the torsion bar 3 is formed so as to be parallel to the azimuth, and as a result, the resonance frequency of the torsion bar 3 can be increased. At this time, it is not necessary to change the dimensions of the torsion bar 3. Therefore, the scanning speed of the reflecting surface 2a can be increased without changing the dimensions of the optical deflector (suppressing the enlargement of the optical deflector 1).

  Further, when the torsion bar 3 is twisted, the distal end portion of the actuator 5 is bent and deformed starting from the base end portion. Thus, the actuator 5 is a cantilever supported by the frame body 4. The amount of displacement of the tip of the cantilever is inversely proportional to the Young's modulus E of the cantilever. For example, the amount of displacement y of the distal end relative to the proximal end of the cantilever (support 5a) is expressed by the following equation (2). Since the support 5a supports the piezoelectric body 5b on almost the entire surface thereof, when the support 5a is bent and deformed, an equal force acts on almost the entire surface of the support 5a.

  Here, L represents the length of the support 5a in the longitudinal direction, q represents the load per unit length of the support 5a (force for bending deformation due to the piezoelectric effect of the piezoelectric body), and E represents the support 5a. The Young's modulus is shown, and I is the cross-sectional second moment of the support 5a.

  The Young's modulus E of single crystal silicon is about 160 [GPa] when the crystal orientation of the single crystal silicon is <110>, and is about 130 [GPa] when the crystal orientation of the single crystal silicon is <100>. . As described above, the longitudinal direction of the support 5a is the <100> orientation. Therefore, the support 5a is formed so as to be parallel to the <100> orientation of the crystal orientation of the single crystal silicon, so that the support 5a is parallel to the <110> orientation of the crystal orientation of the single crystal silicon. Compared to what is formed, the magnitude of the bending deformation of the distal end portion with respect to the proximal end portion of the support 5a is increased. Thereby, the rocking | fluctuation angle of the reflective surface 2a can be enlarged.

  As described above, even when the resonance frequency of the torsion bar 3 is increased, the swing angle of the reflecting surface 2a can be increased (when the displacement amount of the cantilever (support 5a) is increased). Can also increase the scanning speed of the reflecting surface 2a).

[Second Embodiment]
An optical deflector according to a second embodiment of the present invention will be described with reference to FIG. The optical deflector 201 of the present embodiment includes the inner deflector 1 around the second axis Y in addition to the optical deflector (hereinafter referred to as “inner deflector” in the present embodiment) 1 of the first embodiment. A pair of outer actuators 205 to be swung and an outer frame 204 are provided.

  The outer frame 204 is formed as a rectangular frame (the upper side 204u and the lower side 204d are parallel, and the left side 204l and the right side 204r are parallel), and surrounds the inner deflection unit 1 and the outer actuator 205 from the outside.

  The pair of outer actuators 205 are disposed to face each other with the inner deflection unit 1 interposed therebetween. The pair of outer actuators 205 are connected to the outer sides of the left side 4l of the inner deflection unit 1 and the base ends thereof are connected to the inner sides of the left side 204l and the right side 204r of the outer frame 204.

  Each of the pair of outer actuators 205 includes a plurality of piezoelectric cantilevers 206. In the present embodiment, the number of piezoelectric cantilevers 206 is four, but other numbers may be used. In the outer actuator 205, each of the plurality of piezoelectric cantilevers 206 is arranged side by side with an interval so that both end portions of each piezoelectric cantilever 206 are adjacent to each other so that the length directions thereof are the same. Each piezoelectric cantilever 206 is connected so as to be folded back with respect to the adjacent piezoelectric cantilever. Thus, the outer actuator 205 has a plurality of piezoelectric cantilevers 206 formed in a bellows shape (a meander shape).

  Similar to the optical deflector 1 of the first embodiment, the optical deflector 201 of the present embodiment is manufactured using a semiconductor planar process and a MEMS process using a photolithography technique, a dry etching technique, and the like. That is, after the lower electrode layer L1, the piezoelectric layer L2, the upper electrode layer L3, and the like are laminated on the single crystal silicon wafer 10, unnecessary portions are appropriately removed by an etching process or the like. A deflection unit 1 (mirror unit 2, torsion bar 3, frame body 4, and actuator 5), outer actuator 205, and outer frame 204 are formed. At this time, the lower electrode layer L1, the piezoelectric layer L2, and the upper electrode layer L3 are left only in the portions of the actuator 5 of the inner deflection unit 1 and the piezoelectric cantilever 206 of the outer actuator 205, and other portions are removed.

  Then, the upper electrode layer L3 is etched and left on the upper electrode t + so that a driving voltage can be applied to the actuator 5 and the piezoelectric body 5b of the piezoelectric cantilever 206 (the portion left after the piezoelectric layer L2 is etched). Conductive wiring (not shown) and wiring (not shown) conductive to the lower electrode t− remaining after etching the lower electrode layer L1 are provided. Thus, when a driving voltage is applied between the wiring that is conductive to the upper electrode t + and the wiring that is conductive to the lower electrode t−, the piezoelectric body 5b is supported by the piezoelectric body 5a due to the applied piezoelectric effect. It shrinks with respect to the longitudinal direction. Along with this, the support body 5a supporting the piezoelectric body 5b is bent and deformed together with the piezoelectric body 5b so that the surface on the side supporting the piezoelectric body 5b becomes the inside.

  Here, in the following description, among the four piezoelectric cantilevers 206, the odd-numbered two piezoelectric cantilevers and the even-numbered two piezoelectric cantilevers are counted from the distal end side to the proximal end side of the outer actuator 205. , “O” is added to the end of the odd-numbered two piezoelectric cantilevers and represented as 206o, and “e” is added to the end of the even-numbered two piezoelectric cantilevers. Represent as

  The optical deflector 201 is wired so that a drive voltage can be applied to each of the piezoelectric body 5b of the actuator 5, the piezoelectric body 5b of the odd-numbered piezoelectric cantilever 206o, and the piezoelectric body 5b of the even-numbered piezoelectric cantilever 206e. Has been.

  Further, each of the plurality of piezoelectric cantilevers 206 is disposed so as to be orthogonal to the upper side 204u and the lower side 204d of the outer frame 204. Further, in the inner deflection unit 1, the left side 4l and the right side 4r of the frame body 4 are arranged in parallel with the upper side 204u and the lower side 204d of the outer frame 204. Therefore, each of the plurality of piezoelectric cantilevers 206 is orthogonal to the support 5 a of the inner deflection unit 1 and is parallel to the torsion bar 3 of the inner deflection unit 1. Also in this embodiment, as in the first embodiment, the wafer 10 is formed of single crystal silicon. The main surface of the wafer 10 is a (100) plane, and an orientation flat 11 is provided so as to indicate the <110> orientation. That is, the direction at an angle of 45 degrees with respect to the orientation flat 11 is the <100> orientation.

  Then, the optical deflector 201 to be formed on the wafer 10 is laid out so that the upper side 204 u of the outer frame 204 is inclined by 45 degrees with respect to the orientation flat 11. As a result, the upper side 204u of the outer frame 204 becomes parallel to the <100> direction. The direction parallel to the upper side 204u and the direction orthogonal thereto are all <100> orientations. Therefore, the longitudinal direction of the torsion bar 3 orthogonal to the upper side 204u, the “longitudinal direction of the support 5a of the actuator 5 of the inner deflection unit 1” parallel to the upper side 204u, and the “support of the outer actuator 205” orthogonal to the upper side 204u. The “longitudinal direction of the body 5a” is the <100> orientation.

  When the wafer 10 is used in which the main surface is the (100) plane and the orientation flat 11 has the <100> orientation, the upper side 204u of the outer frame 204 is parallel to the orientation flat 11. Thus, the optical deflector 201 to be formed on the wafer 10 may be laid out.

  Next, the operation of the optical deflector 201 will be described.

  In this optical deflector 201, the torsion bar 3 is twisted around the first axis X by driving the actuator 5 of the inner deflection unit 1. Thereby, the reflecting surface 2a swings around the first axis X. The details of this operation are the same as those in the first embodiment, and a description thereof will be omitted.

  Further, the inner deflection unit 1 swings around the second axis Y by driving the outer actuator 205. Thereby, the reflecting surface 2a swings around the second axis Y.

  Specifically, the piezoelectric body 5b of the odd-numbered piezoelectric cantilever 206o has a periodic unipolar voltage signal (for example, a signal obtained by adding a direct current component to a sine wave or a sawtooth wave. Hereinafter, referred to as a "first voltage signal". ) Is applied to the piezoelectric body 5b of the even-numbered piezoelectric cantilever 206e, and the first voltage signal is a voltage signal that is opposite in phase to the first voltage signal (that is, a voltage signal that is 180 degrees out of phase with each other. Is applied). Accordingly, when the value of the first voltage signal is equal to the value of the second voltage signal, the magnitude of the bending deformation of each piezoelectric cantilever 206 becomes equal (hereinafter, this state is referred to as “state 2A”). When the value of the first voltage signal is larger than the value of the second voltage signal, the bending deformation of the odd-numbered piezoelectric cantilever 206o becomes larger than the bending deformation of the even-numbered piezoelectric cantilever 206e (hereinafter, this state is referred to as “ State 2B)). When the value of the first voltage signal is smaller than the value of the second voltage signal, the bending deformation of the odd-numbered piezoelectric cantilever 206o is smaller than the bending deformation of the even-numbered piezoelectric cantilever 206e (hereinafter, this state is referred to as “ State 2C)).

  Since the first voltage signal and the second voltage signal having opposite phases are applied to the piezoelectric body 5b of the odd-numbered piezoelectric cantilever 206o and the piezoelectric body 5b of the even-numbered piezoelectric cantilever 206e, “state 2B → state “2A → State 2C (→ State 2B...)” Is repeated. By such movement of each piezoelectric cantilever 206, the reflecting surface 2a rotates around the second axis Y.

  Further, since each piezoelectric cantilever 206 is connected in a meander shape, the outer actuator 205 generates an angular displacement having a magnitude obtained by accumulating the magnitude of bending deformation of each piezoelectric cantilever 206. Therefore, for example, a large angular displacement can be obtained as compared with the actuator 5 of the inner deflection unit 1, and therefore, the frequency of the first voltage signal and the second voltage signal is not the mechanical resonance frequency of the optical deflector 201. Even so, the deflection angle of the reflecting surface 2a is sufficiently large.

  Further, when the inner deflection unit 1 is swung around the second axis Y, it is not necessary to apply a voltage signal having periodicity as described above, and a DC voltage signal may be applied. In this case, the magnitude of bending deformation generated in the piezoelectric cantilever 206 changes linearly according to the magnitude of the DC voltage. Therefore, for example, unlike the case where the piezoelectric cantilever is resonantly driven by applying a voltage signal having periodicity, an arbitrary output can be obtained from the outer actuator 205 by controlling the magnitude of the DC voltage. Thus, in the optical deflector 201, when swinging around the second axis Y, the deflection angle can be controlled linearly according to the magnitude of the DC voltage applied as the drive voltage. An arbitrary deflection angle can be obtained at a speed of.

  Since the optical deflector 201 of the present embodiment includes the optical deflector 1 of the first embodiment as the inner deflector 1, the inner deflector 1 has the same effect as the optical deflector 1 of the first embodiment. It is done.

  In the optical deflector 201 of this embodiment, the longitudinal direction of the support 5a of each piezoelectric cantilever 206 of the outer actuator 205 is the <100> direction. Therefore, compared to the piezoelectric cantilever 206 in which the longitudinal direction of the support 5a is <110>, the magnitude of the bending deformation of the distal end portion with respect to the proximal end portion of the support 5a is increased. Thereby, the rocking | swiveling angle around the 2nd axis | shaft Y of the inner side deflection | deviation part 1 can be enlarged.

  In the optical deflectors of the first embodiment and the second embodiment, a piezoelectric body is used as an actuator for twisting the torsion bar 3, but the present invention is not limited to this, and the torsion bar 3 is twisted according to other modes. An actuator may be configured as described above.

  In the optical deflectors of the first embodiment and the second embodiment, the reflection surface 2a is swung around the first axis X by the torsion bar 3. However, the present invention is not limited to this. The reflecting surface may be swung around a predetermined axis. For example, in the optical deflector 201 shown in the second embodiment, the inner deflection unit 1 may be configured as a mirror unit having a reflection surface. In this case, the outer actuator 205 swings the reflection surface around the second axis Y (predetermined axis). Further, in the optical deflector 201 shown in the second embodiment, an actuator configured in a meander shape such as the outer actuator 205 may be provided instead of the actuator 5 and the torsion bar 3 of the inner deflection unit 1. Good. As a result, the reflecting surface 2 a can be swung around the first axis X by the actuator, and the inner deflection unit 1 can be swung around the second axis Y by the outer actuator 205.

  DESCRIPTION OF SYMBOLS 1 ... Optical deflector (1st Embodiment), 2a ... Reflecting surface, 3 ... Torsion bar, 5 ... Actuator, 5a ... Supporting body, 5b ... Piezoelectric body, X ... 1st axis (predetermined axis, longitudinal axis) ), 201... Optical deflector (second embodiment), Y... Second axis (predetermined axis), 205.

Claims (3)

In an optical deflector having a reflective surface that reflects light and an actuator that swings the reflective surface about a predetermined axis,
The actuator includes a piezoelectric body to which a driving voltage is applied, and a rectangular plate-shaped support body that supports the piezoelectric body and bends and deforms together with the piezoelectric body,
The optical deflector according to claim 1, wherein the support is made of single crystal silicon and has a longitudinal direction parallel to a <100> orientation of a crystal orientation of the support. The optical deflector according to claim 1.
A torsion bar that is made of single crystal silicon and is twisted around a longitudinal axis by the actuator to swing the reflecting surface,
The torsion bar is formed so that the axial direction is parallel to the <100> orientation of the crystal orientation of the torsion bar. The optical deflector according to claim 1 or 2,
The actuator includes a plurality of the piezoelectric body and the support body,
Each of the plurality of supports is arranged side by side so that both ends are adjacent to each other,
The ends of the plurality of supports are connected to each other so as to be folded back with respect to adjacent supports, and each support is formed to bend and deform in a direction perpendicular to the direction in which the supports are arranged. An optical deflector characterized by comprising:

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