JP2017207630A - Light deflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient S/N ratio in an output of a rotational angle sensor even when a frequency of reciprocal rotation of a movable support in a light deflector is low.SOLUTION: A light deflector 1 includes: an outside piezoelectric actuator 14 that reciprocally rotates a movable frame 13 around a first axial line Lx; and a piezoelectric film member 3 that is stuck to the movable frame 13 and protruding from the movable frame 13 in a direction of a second axial line Ly orthogonal to the first axial line Lx, and outputs a voltage in response to deformation of a protruding part 18a, 18b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical deflector that reciprocally rotates a mirror part to reflect and emit incident light by the mirror part.

  An optical deflector having a general structure includes a mirror portion and a piezoelectric actuator, and the piezoelectric actuator reciprocates and rotates the mirror portion around a predetermined axis. And the incident light from a light source is reflected in a mirror part, and is radiate | emitted in the direction corresponding to the rotation angle of a mirror part.

  When such an optical deflector is installed in various devices, it is necessary to accurately control the emission direction at each time point. For this reason, the optical deflector is equipped with a sensor for detecting the rotation angle of the mirror portion around the axis.

  The rotation angle sensor of the optical deflector of Patent Document 1 is manufactured as a piezoelectric sensor together with other piezoelectric elements such as a piezoelectric actuator, and is disposed on a support portion that supports the mirror portion via the piezoelectric actuator. The piezoelectric sensor detects vibration transmitted from the piezoelectric actuator to the support portion as the mirror portion reciprocates.

  The optical deflector of Patent Document 2 has a cantilever of a piezoelectric actuator and a cantilever of a piezoelectric sensor as a rotation angle sensor separately. One end of the cantilever of the piezoelectric sensor is coupled to the movable support and the other end is a free end. The piezoelectric sensor is manufactured together with another piezoelectric element such as a piezoelectric actuator, and the piezoelectric sensor outputs a voltage corresponding to the deformation of the cantilever when the mirror portion reciprocally rotates.

  The rotation angle sensor of the optical deflector of Patent Document 3 is manufactured together with another piezoelectric element such as a piezoelectric actuator as a piezoelectric sensor. The piezoelectric sensor is coupled to the mirror portion from the outside in the direction orthogonal to the axis. The piezoelectric sensor reciprocates integrally with the mirror portion around the axis, and outputs a voltage corresponding to the deformation of the piezoelectric layer.

JP 2013-007780 A JP 2014-164101 A International Publication No. 2013/136759

  The piezoelectric sensor of the optical deflector of Patent Document 1 is formed not on a portion that is displaced with the reciprocating rotation of the mirror portion, but on a fixed support portion, and from the mirror portion or the displacement portion of the piezoelectric actuator to the support portion. Detect vibrations transmitted. Therefore, there is a problem that the detection accuracy of the rotation angle of the mirror part is inferior.

  In the optical deflector of Patent Document 2, the piezoelectric sensor is built together with other piezoelectric elements such as a piezoelectric actuator when the optical deflector is manufactured. Since the piezoelectric layer of the piezoelectric actuator needs to have a sufficient thickness in order to ensure the acting force of the piezoelectric actuator, the piezoelectric layer of the piezoelectric sensor also becomes thick. Since the piezoelectric sensor converts the deformation of the piezoelectric film due to acceleration into electricity and outputs it, if the piezoelectric layer is thick, the amount of deformation decreases and the output decreases. Also, when the frequency of reciprocating rotation of the mirror portion is low (eg, 60 Hz), the acceleration decreases, so the output of the piezoelectric sensor decreases. Therefore, the piezoelectric sensor has a problem that when the frequency of the reciprocating rotation of the mirror portion is low, the output is greatly reduced, and it is difficult to ensure a sufficient S / N ratio of the piezoelectric sensor.

  Since the piezoelectric sensor of the optical deflector of Patent Document 3 reciprocally rotates together with the mirror portion around the axis, the detection accuracy of the rotation angle of the mirror portion increases. However, similar to the piezoelectric sensor of the optical deflector of Patent Document 2, since the acceleration is detected by deformation of the piezoelectric layer, the output when the frequency of the reciprocating rotation of the mirror portion is low is greatly reduced. There is a problem that it is difficult to ensure a sufficient S / N ratio.

  An object of the present invention is to provide an optical deflector that overcomes the above problems.

The optical deflector of the present invention is
A mirror that reflects light;
A movable support for supporting the mirror part;
A fixed support that supports the movable support around a first axis;
A first actuator for reciprocatingly rotating the movable support around the first axis;
And a piezoelectric film member that projects from the movable support in a direction perpendicular to the first axis, is attached to the movable support, and outputs a voltage corresponding to deformation of the projecting portion.

  According to the optical deflector of the present invention, the piezoelectric film member projects from the movable support in the direction orthogonal to the first axis, is adhered to the movable support, and outputs a voltage corresponding to the deformation of the projecting portion. As a result, the overhanging portion of the piezoelectric film member reciprocally rotates integrally with the movable support, so that the rotation angle of the mirror portion can be detected with high accuracy based on the deformation of the overhanging portion.

  The piezoelectric film member is thinner than a piezoelectric sensor manufactured together with other piezoelectric elements such as a piezoelectric actuator by a MEMS optical deflector. As a result, a sufficient amount of deformation can be ensured even at low acceleration, and an output with a sufficient S / N ratio can be ensured even when the reciprocating frequency of the movable support is low.

  In the optical deflector of the present invention, the piezoelectric film member has a laminated structure in which a plurality of piezoelectric films are laminated with an elastic conductive film interposed therebetween, and outputs a voltage between both surfaces of the laminated structure. preferable.

  According to this configuration, since the piezoelectric film member has a multilayer structure of piezoelectric films, the output voltage can be greatly increased as compared with the case where the piezoelectric film has a single layer structure.

  In the optical deflector according to the aspect of the invention, the piezoelectric film member is attached to the movable support so that the protruding portion is formed at two positions away from the first axis in the opposite directions of the orthogonal direction. It is preferable.

  According to this configuration, each overhanging part is deformed in the opposite direction in the front and back direction of the optical deflector, so that outputs of mutually opposite phases can be obtained from the overhanging parts. Moreover, since each overhang | projection part receives a large inertia force and air viscosity resistance, so that it is far from the 1st axis, the absolute value of the output of a piezoelectric film member is related to the distance of each piezoelectric film member and the 1st axis. The first axis may be deviated from the reference point, but the value of a factor other than the rotation angle of the mirror part around the first axis (e.g., amount of deviation) using the output from the overhanging part on each side Can also be detected.

  In the optical deflector according to the aspect of the invention, it is preferable that the first actuator reciprocally rotates the mirror unit around the first axis at a non-resonant frequency of the mirror unit.

  According to this configuration, the piezoelectric film member outputs a sufficient S / N ratio despite the non-resonant frequency reciprocating rotation of the mirror portion around the first axis, that is, the non-resonant low-frequency reciprocating rotation. Can be obtained from

  In the optical deflector of the present invention, the mirror portion supported by the movable support is reciprocally rotated at a resonance frequency of the mirror portion higher than the non-resonance frequency around a second axis perpendicular to the first axis. It is preferable that a second actuator to be provided is provided.

  According to this configuration, in the biaxial optical deflector that rotates the mirror portion around the first and second axes, the rotation angle of the mirror portion around the first axis can be detected.

The front view of the optical deflector which isolate | separated the piezoelectric film member from the main body. The front view of the optical deflector as a finished product in which the piezoelectric film member was stuck. The shape of the piezoelectric film member attached to the movable frame is shown in the x-axis direction, FIG. 3A is a diagram showing the shape of the movable frame when it is stationary, and FIG. 3B is the shape of the movable frame when it is reciprocally rotated. Figure. Sectional drawing when a piezoelectric film member is cut in the thickness direction. The timing chart which shows the relationship between the drive voltage of an outer side piezoelectric actuator, and the output of a piezoelectric film member. Process drawing of the manufacturing method of an optical deflector. FIG. 7 is a process diagram subsequent to the process of FIG. 6.

  1 and 2, the optical deflector 1 is manufactured as MEMS (Micro Electro Mechanical Systems) and includes a main body 2 and a piezoelectric film member 3. The piezoelectric film member 3 itself is manufactured by a general manufacturing method of the piezoelectric film member 3 separately from the component manufacturing in MEMS. The piezoelectric film member 3 is added to the main body 2 during the manufacturing process of the optical deflector 1 as a MEMS (the piezoelectric sheet material 46 in STEP 2 in FIG. 6).

  Hereinafter, for convenience of description of the configuration, the top, bottom, left, and right in the front view of the main body 2 in FIGS. 1 and 2 are referred to as the top, bottom, left and right of the optical deflector 1.

  The main body 2 generally includes a mirror portion 11, inner piezoelectric actuators 12a and 12b, a movable frame 13, outer piezoelectric actuators 14a and 14b, and a fixed frame 15.

  The mirror unit 11 has a circular shape when viewed from the front, and is disposed at the center of the main body 2 (intersection of diagonal lines of the rectangular fixed frame 15). For convenience of explanation, the center o, the x axis, and the y axis are defined on the surface (mirror surface) of the mirror unit 11. The center o is set at the center of the circular mirror unit 11. Further, the z-axis (FIG. 3) is defined in the direction of the normal line at the center o of the mirror unit 11.

  In FIG. 2, the first axis Lx and the second axis Ly mean the rotation axis of the mirror unit 11. The first axis Lx and the second axis Ly are orthogonal to each other at the center o and extend in the left-right direction and the up-down direction of the main body 2 that are orthogonal to each other. The first axis Lx and the second axis Ly correspond to the first axis and the second axis of the present invention, and the mirror unit 11 reciprocates around the first axis Lx and the second axis Ly at a non-resonant frequency and a resonant frequency, respectively. Rotate. The second axis Ly and the y axis coincide. The first axis Lx and the x axis coincide only when the z axis is parallel to the thickness direction of the main body 2. As the mirror unit 11 reciprocates around the second axis Ly, the x-axis changes the tilt angle with respect to the first axis Lx.

  The inner piezoelectric actuators 12a and 12b are disposed on the left side and the right side with respect to the mirror unit 11, respectively. The upper and lower ends are coupled to each other, and as a whole, a vertically long elliptical ring surrounding the mirror portion 11 is formed. The movable frame 13 is formed as an elliptical frame having an elliptical outline whose inner and outer circumferences are vertically long, and surrounds an elliptical ring composed of the inner piezoelectric actuators 12a and 12b on the inner circumferential side.

  The torsion bars 21a and 21b protrude linearly up and down along the y-axis from the mirror part 11, are coupled to the coupling part of the inner piezoelectric actuators 12a and 12b at the intermediate part, and are coupled to the inner periphery of the movable frame 13 at the projecting end. To do. Since the second axis Ly coincides with the center line of the torsion bars 21a and 21b, the second axis Ly is displaced with a change in the rotation angle of the mirror portion 11 around the first axis Lx.

  The outer piezoelectric actuators 14 a and 14 b are disposed on the inner peripheral side of the rectangular fixed frame 15 and on the left side and the right side with respect to the movable frame 13, respectively. The outer piezoelectric actuator 14 includes a plurality of cantilevers 23 arranged in a meander arrangement.

  Specifically, the cantilevers 23 are arranged in a line in the left-right direction with the longitudinal direction aligned in the up-down direction. The plurality of cantilevers 23 are coupled to the left adjacent or right adjacent cantilevers 23 at the upper and lower ends so as to form a series connection as a whole. In addition, the length of the left and right cantilevers 23 in the arrangement is half the length of the other cantilevers 23, and the left and right cantilevers 23 are respectively connected to the movable frame 13 and the end on the first axis Lx. It is coupled to the fixed frame 15.

  A plurality of electrode pads 16a and 16b are arranged on the surfaces of the left and right side portions of the horizontally long rectangular fixed frame 15, respectively. The electrode pad 16a is connected to the electrodes of the left half electrical element (eg, the inner piezoelectric actuator 12a and the outer piezoelectric actuator 14a) of the optical deflector 1 via a conductive layer or wiring. The electrode pad 16b is connected to the electrodes of the electric elements (eg, the inner piezoelectric actuator 12b and the outer piezoelectric actuator 14b) in the right half part of the optical deflector 1 via a conductive layer or wiring.

  The piezoelectric film member 3 is formed in a vertically long rectangle. The long side of the piezoelectric film member 3 is slightly smaller than the short side of the rectangular inner peripheral contour of the fixed frame 15 and longer than the long axis of the elliptical outer peripheral contour of the movable frame 13. The short side of the piezoelectric film member 3 is substantially equal to the short axis of the outer peripheral contour of the ellipse of the movable frame 13. The piezoelectric film member 3 has an elliptical window 25 in the center. The window 25 is dimensioned to accommodate the inner piezoelectric actuators 12a and 12b on the inner side in a front view.

  The piezoelectric film member 3 is adhered to the movable frame 13 so that the center of the window 25 coincides with the center o. Thereby, overhanging portions 18a and 18b (FIG. 2) are formed on the piezoelectric film member 3 so as to project upward and downward from both ends in the major axis direction of the outer periphery of the elliptical contour.

  In the front view of the optical deflector 1 in FIG. 2, the piezoelectric film member 3 is a front view of the optical deflector 1, and the mirror portion 11, inner piezoelectric actuators 12 a and 12 b of the main body 2 on the inner peripheral side of the piezoelectric film member 3, and The torsion bars 21a and 21b are adhered to the surface of the movable frame 13 on the back surface side while being exposed from the window 25. The left and right outer piezoelectric actuators 14 a and 14 b are outside the long side of the piezoelectric film member 3 in the left-right direction of the optical deflector 1, and are exposed without being covered with the piezoelectric film member 3.

  Hereinafter, when the inner piezoelectric actuators 12a and 12b are not particularly distinguished, they are collectively referred to as “inner piezoelectric actuators 12”. When the outer piezoelectric actuators 14a and 14b are not particularly distinguished, they are collectively referred to as “outer piezoelectric actuators 14”. When the electrode pads 16a and 16b are not particularly distinguished, they are collectively referred to as “electrode pads 16”. When the overhang portions 18a and 18b are not particularly distinguished, they are collectively referred to as “the overhang portion 18”. When the torsion bars 21a and 21b are not particularly distinguished, they are collectively referred to as “torsion bar 21”.

  The general operation of the optical deflector 1 will be described. The optical deflector 1 is equipped as a two-dimensional scanner in an imager, a vehicle headlight, or the like. The optical deflector 1 is housed in a package, and the electrode pad 16 of the optical deflector 1 and the terminal of the package are connected by a bonding wire. An applied voltage is supplied from the electrode pad 16 to the inner piezoelectric actuator 12 and the outer piezoelectric actuator 14.

  Light (for example, laser light) from a light source (for example, laser light source) not shown enters the center o of the mirror unit 11 of the optical deflector 1.

  The outer piezoelectric actuator 14 is operated by a driving voltage from the electrode pad 16 to reciprocate the movable frame 13 around the first axis Lx. The operation of the outer piezoelectric actuator 14 will be described in detail. Each outer piezoelectric actuator 14 is composed of a plurality of cander levers 23 arranged in a meander arrangement, and the total amount of relative rotation at both ends of each cantilever 23 around an axis parallel to the first axis Lx is a movable frame around the first axis Lx. 13 is related to the amount of rotation. Therefore, when the cantilever 23 is numbered in order from the coupling end side with the fixed frame 15 in the outer piezoelectric actuator 14 to the coupling end with the movable frame 13, the odd-numbered cantilever 23 and the even-numbered cantilever 23 are: The applied voltage is set to the opposite phase, and the direction of the bending deformation is set to be reversed.

  In each outer piezoelectric actuator 14, an applied voltage is supplied to the upper electrode of the odd-numbered cantilever 23 at the electrode pad 16 in order to apply a reverse phase voltage to the odd-numbered cantilever 23 and the even-numbered cantilever 23. The electrode pad and the electrode pad that supplies the applied voltage to the upper electrode of the even-numbered cantilever 23 are separated.

  The reciprocating rotation of the movable frame 13 around the first axis Lx by the outer piezoelectric actuator 14 causes the mirror unit 11 and the movable frame 13 to reciprocate integrally around the first axis Lx. The frequency of the driving voltage of the outer piezoelectric actuator 14 is set to the non-resonant frequency (eg, 60 Hz) of the mirror unit 11 and is much smaller than the resonant frequency (eg, 30 kHz) of the mirror unit 11.

  The inner piezoelectric actuator 12 is operated by a driving voltage from the electrode pad 16 to reciprocately rotate the torsion bar 21 around the second axis Ly. The operation of the inner piezoelectric actuator 12 will be described in detail. The inner piezoelectric actuators 12a and 12b are supplied with driving voltages having opposite phases, displace the torsion bar 21 in the opposite direction in the thickness direction of the optical deflector 1 from both the left and right sides, and rotate around the second axis Ly. The frequency of the reciprocating rotation of the mirror portion 11 around the second axis Ly by the inner piezoelectric actuator 12 is matched to the resonance frequency (eg, 30 kHz) of the mirror portion 11 and the torsion bar 21 around the second axis Ly.

  Thus, the mirror unit 11 reciprocates around the first axis Lx at a non-resonant frequency while reciprocating around the second axis Ly at the resonance frequency. As a result, the z axis swings up, down, left and right.

  Incident light from the light source to the optical deflector 1 enters the center o of the mirror unit 11. Then, the light is emitted as reflected light in a direction corresponding to the direction of the z-axis with a reflection angle = an incident angle with the z-axis interposed therebetween.

  Next, the piezoelectric film member 3 will be described with reference to FIGS. FIG. 3 shows the shape of the piezoelectric film member 3 adhered to the movable frame as viewed in the direction of the x-axis, FIG. 3A is a diagram showing the shape of the movable frame when it is stationary, and FIG. FIG. Since the mirror unit 11 is on the inner peripheral side of the movable frame 13, it is not visible behind the movable frame 13 in FIG. 3.

  Here, the rotation angle θ of the mirror unit 11 around the first axis Lx is defined. In FIG. 3B, Hs indicates a reference surface as a surface that passes through the center o of the mirror portion 11 and is parallel to the thickness direction of the main body 2. The rotation angle θ is defined as the intersection angle of the z axis with respect to the reference plane Hs.

  In FIG. 3B, Fr indicates the rotation direction of the movable frame 13. The overhang portions 18a and 18b receive inertial force and air viscous resistance in the opposite direction to Fr. Further, in the upper overhanging portion 18a and the lower overhanging portion 18b, the Fr of the overhanging portion 18a and the Fr of the overhanging portion 18b are opposite to each other in the thickness direction of the main body 2, so that the overhanging portions 18a and 18b are in the main body 2. Deforms in the opposite direction to the thickness direction.

  FIG. 4 is a cross-sectional view of the piezoelectric film member 3 cut in the thickness direction. In FIG. 4, only the range of the overhang portion 18 that is actually deformed with the reciprocating rotation of the movable frame 13 around the first axis Lx is illustrated in the piezoelectric film member 3. The whole has a laminated structure shown in FIG. However, the portion of the piezoelectric film member 3 that is adhered to the surface of the movable frame 13 is not deformed as shown in FIG.

  The piezoelectric film member 3 has a laminated structure in which an elastic conductive polymer film Mp and a piezoelectric polymer film Me are alternately bonded in the thickness direction. The output of the piezoelectric film member 3 is generated as a voltage between both surfaces of the laminated structure. Both surfaces in the thickness direction of the piezoelectric film member 3 are made of an elastic conductive polymer film Mp, and the piezoelectric polymer film Me is sandwiched between the elastic conductive polymer films Mp on both surfaces in the thickness direction. The elastic conductive polymer film Mp also serves as an electrode layer of the piezoelectric polymer film Me adjacent in the thickness direction.

  In FIG. 4, Ca indicates a center line in the thickness direction of the piezoelectric film member 3. The center line Ca is included in the elastic conductive polymer film Mp disposed at the center in the thickness direction of the piezoelectric film member 3. The role of the elastic conductive polymer film Mp is to deform with a predetermined resistance against the deformation force on the piezoelectric film member 3, to return to the original shape when the deformation force is released, and to be conductive. That is. Cb indicates the position where the overhang portion 18 has the maximum amount of displacement in the thickness direction. In the piezoelectric polymer film Me on the upper side with respect to the center line Ca, as indicated by the arrow, the piezoelectric polymer film Me on the lower side with respect to the center line Ca is extended in the surface direction in a direction away from the maximum displacement amount position Cb. Then, as the arrow indicates, the surface is extended in the direction approaching the maximum displacement amount position Cb.

  The piezoelectric film member 3 of FIG. 4 has a laminated structure of five layers, and is a multilayer piezoelectric film member 3 having two piezoelectric polymer films Me, so that only one piezoelectric polymer film Me is present. Compared with a single-layer piezoelectric film member, the output for the same acceleration can be greatly increased. Even if the piezoelectric film member 3 is not a multilayer but a single layer, it is possible to obtain a larger output than the piezoelectric sensors disclosed in Patent Documents 1 and 2.

  The piezoelectric film member 3 in FIG. 4 has a laminated structure of five layers, and is a multilayer piezoelectric film member 3 having two piezoelectric polymer films Me. Instead of the multilayer piezoelectric film member 3, a single-layer piezoelectric film member 3 having only one piezoelectric polymer film Me may be employed. However, the piezoelectric film member 3 of the two-layer piezoelectric polymer film Me has an output about 100 times that of the single-layer piezoelectric film member 3 although the amount of deformation is reduced for the same acceleration.

  In the optical deflector 1 of the embodiment, outputs are separately taken out from the overhang portions 18a and 18b. Therefore, the piezoelectric film member 3 in the optical deflector 1 needs to electrically separate the overhang portion 18a and the overhang portion 18b. . For this reason, the piezoelectric film member 3 is formed with a slit (not shown) as an electrical separation portion between the overhanging portion 18a and the overhanging portion 18b in the direction of the second axis Ly.

  FIG. 5 is a timing chart showing the relationship between the driving voltage of the outer piezoelectric actuator 14 and the output of the piezoelectric film member 3. The drive voltage of the outer piezoelectric actuator 14 in FIG. 5 shows the drive voltage of the odd-numbered cantilever 23 described above as a representative of the cantilever 23.

  The drive voltage of the outer piezoelectric actuator 14 is a sawtooth wave. In FIG. 5, only one sawtooth wave is shown for simplification of illustration, but the driving voltage of the outer piezoelectric actuator 14 when the optical deflector 1 is actually operated is the same as the sawtooth wave of FIG. Repeated in a cycle.

  The overhang portions 18a and 18b of the piezoelectric film member 3 receive the inertial force and air viscosity resistance described in FIG. 3 in the direction opposite to Fr as the movable frame 13 reciprocates around the first axis Lx. Since the rotation direction Fr with respect to the overhanging portions 18a and 18b is opposite to the thickness direction of the optical deflector 1, the direction of deformation is opposite to the thickness direction of the optical deflector 1, and the output is in reverse phase. .

  In FIG. 5, t1 indicates the rise time of the output of the piezoelectric film member 3, t2 indicates the time when the output of the piezoelectric film member 3 becomes the maximum value, and t3 indicates the time when the output of the piezoelectric film member 3 becomes the minimum value. Yes.

  The output of the piezoelectric film member 3 is the time t1 when the driving voltage of the outer piezoelectric actuator 14 starts to gradually increase and the cantilever 23 starts to deform, and the driving voltage of the outer piezoelectric actuator 14 suddenly decreases and the cantilever 23 is reversed. A significant change appears at time t2 when the deformation starts. If the times t1 and t2 are determined, the rotation angle change pattern of the movable frame 13 between the times t1 and t3 is constant, and therefore the rotation angle of the movable frame 13 between the times t1 and t3 can be calculated. . The cycle of the reciprocating rotation of the mirror unit 11 can be detected from the time difference between each time t1 or t3 and the time t1 or t3 related to the next cycle.

  6 and 7 show the manufacturing method of the optical deflector 1 in the order of steps.

In STEP 1 of FIG. 6, the plate body 40 has a structure in which a lower Si layer 41, a SiO ₂ layer 42, and an upper structure layer 43 are laminated in order from the lower surface (back surface) to the upper surface (front surface). . In FIG. 6, the manufacturing process until the plate body 40 of STEP 1 is manufactured is not illustrated, but the plate body 40 is manufactured from an SOI substrate as a wafer. The lower Si layer of the SOI substrate and the SiO ₂ layer laminated thereon constitute the lower Si layer 41 and the SiO ₂ layer 42 of the plate body 40.

The upper structure layer of the upper structure layer 43 is used as a generic name for any laminated structure formed on the surface side of the SiO ₂ layer 42. The lowermost layer of each upper structure layer 43 is composed of an upper Si layer in the SOI substrate. The upper structure layer 43 also includes a piezoelectric structure on the upper Si layer in the formation range of the inner piezoelectric actuator 12 and the outer piezoelectric actuator 14. The piezoelectric structure includes a lower electrode layer, a PZT (lead zirconate titanate) film, and an upper electrode layer in order from the bottom.

  Strictly speaking, in the thickness direction of the plate body 40, the upper surface positions of the formation range of the mirror portion 11 and the formation ranges of the inner piezoelectric actuator 12 and the outer piezoelectric actuator 14 are different, but are slightly small. In the figure, the same upper surface position is shown. A plurality of optical deflectors 1 are manufactured simultaneously from one wafer and separated by sourcing.

  In STEP 1, La represents the center line of the optical deflector 1, and Lb represents the boundary line of the adjacent optical deflector 1 in the plate body 40.

  In STEP 2, the piezoelectric sheet material 46 is applied to the surface side of the plate body 40, and the contact plate 47 is applied to the surface side of the piezoelectric sheet material 46. Both the piezoelectric sheet material 46 and the contact plate 47 are made of a transparent material that transmits UV (ultraviolet light). In addition, an adhesive is attached to the front and back surfaces (upper and lower surfaces in FIG. 6) of the piezoelectric sheet material 46, respectively. For this reason, the piezoelectric sheet material 46 is adhered to the front surface of the plate body 40 on the back surface side, and is adhered to the back surface of the backing plate 47 on the front surface side.

  The piezoelectric sheet material 46 is previously cut so that it can be separated with a slight force along a line corresponding to the outer peripheral contour of the piezoelectric film member 3 and the peripheral contour of the window 25. When the piezoelectric film member 3 is separated from the remaining portion at the outer peripheral contour break, the piezoelectric film member 3 covers the movable frame 13 as shown in FIG. The piezoelectric sheet material 46 is placed on the plate body 40 so as to be positioned on the actuator 12.

  An adhesive is applied over the entire surface on the front and back sides of the piezoelectric sheet material 46. The adhesive strength of the adhesive per unit area is set so that the back side is larger than the front side. Further, the adhesive on the back side loses the adhesive force when irradiated with UV, whereas the adhesive on the front side is selected so as not to lose the adhesive force even when irradiated with UV. The difference in properties with respect to adhesive force and UV irradiation will be described in STEPs 6 and 7 in FIG.

  In STEP3, the front and back of the plate 40 that has been processed in STEP2 are reversed.

In STEP 4, the back side of the plate 40 is etched to form a back side space 49 on the back side. In the etching, the lower Si layer 41 and the SiO ₂ layer 42 in the back space 49 are removed on the back surface side of the plate body 40. As a result, the motion elements such as the cantilever 23 of the outer piezoelectric actuator 14 of the main body 2 are held in the coupled state by the piezoelectric sheet material 46 and the contact plate 47 on the front surface side, but are separated on the back surface side.

  In STEP 4 of FIG. 6, the mirror unit 11, the movable frame 13, and the torsion bar 21 are collectively illustrated as one block 51 for the sake of simplicity of illustration.

  In STEP 5 of FIG. 7, sourcing is performed from the position Lb of STEP 4 to the position of the back surface of the piezoelectric sheet material 46 from the back surface side of the plate body 40. STEP 5 Lc indicates a break caused by sourcing. As a result, the plurality of optical deflectors 1 manufactured on the common plate 40 are held in the coupled state by the piezoelectric sheet material 46 and the contact plate 47 on the front side, but are separated on the back side.

  In STEP6, the plate 40 is turned upside down and returned to the original vertical relationship before STEP3. Thereby, the surface side of the plate 40 is on the top. In STEP 6, UV (ultraviolet light) is further irradiated to the contact plate 47 through a mask pattern (not shown). UV passes through the translucent part of the mask pattern.

  As a result, in the adhesive layer on the front surface side and the back surface side of the piezoelectric sheet material 46, the region corresponding to the mask of the mask pattern is not irradiated with UV, and the region corresponding to the light transmitting portion of the mask pattern is irradiated with UV. Irradiated. The areas of the adhesive on the front surface side and the back surface side of the piezoelectric sheet material 46 corresponding to the mask of the mask pattern are the arrangement regions of the piezoelectric film member 3 in FIG. 1, and the piezoelectric sheet material 46 corresponding to the light transmitting portion of the mask pattern. The area | region of the adhesive agent of the surface side and back surface side is an area | region other than the arrangement | positioning area | region of the piezoelectric film member 3 of FIG. The portion of the window 25 (FIG. 1) of the piezoelectric film member 3 is included in the adhesive region on the front surface side and the back surface side of the piezoelectric sheet material 46 corresponding to the light-transmitting portion of the mask pattern.

  As a result, the adhesive on the back surface side of the piezoelectric sheet material 46 is released from the adhesive force to the surface of the other plate body 40 while maintaining the adhesive force to the piezoelectric film member 3. On the other hand, the surface side adhesive of the piezoelectric sheet material 46 maintains the original adhesive force. Accordingly, both the adhesive on the front side and the back side of the piezoelectric sheet material 46 maintain the original adhesive force, but the initial adhesive force per unit area is the same as that of the adhesive on the back side of the piezoelectric sheet material 46. Is sufficiently stronger than the adhesive on the surface side of the piezoelectric sheet material 46, the piezoelectric sheet material 46 remains on the surface of the plate body 40 without being pulled up together with the backing plate 47 when the backing plate 47 is pulled up.

  In STEP 7, the contact plate 47 is pulled up from the plate body 40. In the piezoelectric sheet material 46, a cut is formed at a portion corresponding to the contour of the piezoelectric film member 3, so that a portion of the piezoelectric sheet material 46 corresponding to the piezoelectric film member 3 remains on the upper surface of the block 51, and the others This part is separated from the plate 40. In FIG. 7, reference numeral 54 denotes a portion corresponding to the window 25 in the piezoelectric sheet material 46. The portion 54 is also attached to the backing plate 47 and separated from the plate body 40.

  Further, with the lifting of the contact plate 47 from the plate body 40, the plate body 40 is separated by Lc as a cut by sourcing. As a result, the optical deflector 1 shown in FIG. 2 is completed.

  As described above, the upper structure layer 43 includes the lower electrode layer, the PZT film, and the upper electrode layer in order from the bottom in the formation range of the inner piezoelectric actuator 12 and the outer piezoelectric actuator 14. The lower electrode layer is used as a ground wiring in the optical deflector 1 and extends from the fixed frame 15 to the inner piezoelectric actuator 12 via the outer piezoelectric actuator 14 and the movable frame 13 as a continuous conductive layer. The continuous conductive layer serves as a lower electrode layer in the inner piezoelectric actuator 12 and the outer piezoelectric actuator 14. The continuous conductive layer is set to, for example, a ground potential.

  The elastic conductive polymer film Mp on the front surface side and the back surface side of the piezoelectric film member 3 constitutes a pair of output terminals of the piezoelectric film member 3, and the elastic conductive polymer film Mp on the back surface side is used as a ground electrode, and a movable frame Connected to 13 continuous conductive layers. As a result, the ground electrode of the pair of output terminals of the piezoelectric film member 3 is connected to the predetermined electrode pad 16 of the fixed frame 15 via the continuous conductive layer without providing a dedicated wiring. Wiring of the deflector 1 can be simplified.

  Specific materials and characteristics of the piezoelectric film member 3 will be described. The piezoelectric polymer film Me is, for example, polyvinylidene fluoride (PVDF) or polylactic acid. The elastic conductive polymer film Mp includes silicon and polyurethane. The thickness of the piezoelectric polymer film Me is 40 μm.

A figure of merit (FOM) used for evaluating the performance of the vibration power generation element is represented by (e _{31, f} ) ² / ε ₀ ε _r . The figure of merit increases as the piezoelectric constant increases and the relative permittivity decreases. Index _{e 31, f} when the piezoelectric effect due to bending displacement of the cantilever of the PZT film is about _{^{-20C / m 2, e 31,}} f polyvinylidene fluoride (PVDF), but greater than -2.5C / m ² Also, the relative dielectric constant is as large as about 1200. On the other hand, the relative dielectric constant of PVDF is as small as about 8.4. Accordingly, the value of the figure of merit is 0.33 for PZT and 0.74 for PVDF, which is twice as large for PVDF. Therefore, when the PZT / silicon detector and the piezoelectric polymer detector are deformed by the same amount, even if the piezoelectric film member 3 is a single-layer piezoelectric film member having only one piezoelectric polymer film Me, the intensity of the detection signal The piezoelectric polymer is twice as large.

  Furthermore, when the structure of the piezoelectric film member 3 is silicon, the rigidity is strong at the same thickness (30 to 40 μm) as the actuator, and the inertial force itself is small at a low speed drive of about 60 Hz, so that it does not deform much. In the case of a single-layer piezoelectric film member, since it has flexibility, it is sufficiently deformed even at low speed driving. Therefore, the amount of deformation is also advantageous.

  On the other hand, the piezoelectric film member 3. When the piezoelectric polymer film Me is a plurality of multilayer piezoelectric film members, polyvinylidene fluoride (PVDF) is used as the material of the piezoelectric polymer film Me, and silicon rubber (SG) is used as the material of the elastic conductive polymer film Mp. The thickness is 40 μm for the piezoelectric polymer film Me and 100 μm for the elastic conductive polymer film Mp. As a result, the thickness of the multilayer piezoelectric film member 3 increases as a whole, so that the amount of deformation of the multilayer piezoelectric film member 3 is reduced to, for example, about 1/10 of that of the multilayer piezoelectric film member 3. To do. However, in the optical deflector 1 in which the piezoelectric polymer film Me has a plurality of layers, the output increases to about 100 times that of the single layer structure, and thus the output increases to several times to 10 times that of the single layer structure.

  The present invention is not limited to the embodiments and includes various modifications within the scope of the technical idea of the present invention.

  The drive voltage of the outer piezoelectric actuator 14 in the embodiment is a sawtooth wave (FIG. 5). The waveform of the driving voltage of the first actuator of the present invention is not limited to the sawtooth wave, and may be a sine wave or a triangular wave.

  In the optical deflector 1 of the embodiment, the shape of the movable frame 13 is an elliptical annular frame as a movable support that supports the mirror portion. The movable support of the present invention may not be a frame, but may be other shapes such as a linear shape, a ring shape, or a rectangular shape.

  In the optical deflector 1 of the embodiment, the shape of the fixed frame 15 as a fixed support is rectangular. The fixed support of the present invention may not be a frame, and may be other shapes such as a circle and a square.

  In the optical deflector 1 of the embodiment, the piezoelectric film member 3 is rectangular, but the piezoelectric film member of the present invention can adopt other shapes such as a circle and a square.

  In the optical deflector 1 of the embodiment, the elastic conductive polymer film Mp as the elastic conductive film and the piezoelectric polymer film Me as the piezoelectric film are both polymers, but the elastic conductive film and the piezoelectric film of the present invention are not necessarily high. It does not have to be a molecule.

  In the embodiment, the piezoelectric film member 3 has the overhang portions 18a and 18b at two positions separated from the first axis Lx in the direction opposite to the extending direction of the second axis Ly as its orthogonal direction. In the optical deflector of the present invention, there may be only one overhang portion.

  In the optical deflector 1 of the embodiment, the outer piezoelectric actuator 14 as the first actuator and the inner piezoelectric actuator 12 as the second actuator are both piezoelectric actuators. However, the first actuator and the second actuator of the present invention are not limited to piezoelectric actuators, and electromagnetic actuators or the like can also be adopted.

  The piezoelectric film member 3 of the embodiment detects only the rotation angle (rotation angle θ in FIG. 3) of the mirror portion 11 around the first axis Lx. Since the overhang portions 18a and 18b are deformed in opposite directions in the front and back direction of the optical deflector 1, outputs of opposite phases can be obtained from the overhang portions 18a and 18b. Further, since the overhang portions 18a and 18b receive a larger inertia force and air viscosity resistance as they are farther from the first axis Lx, the absolute values of the outputs of the overhang portions 18a and 18b are the same as the overhang portions 18a and 18b and the first axis Lx. And is related to the distance. Although the first axis Lx may deviate from the reference point, the values of factors other than the rotation angle of the mirror unit 11 around the first axis Lx using the difference in output from the overhanging portions 18a and 18b. (Example: The amount of deviation of the first axis Lx with respect to the reference line) can also be detected.

DESCRIPTION OF SYMBOLS 1 ... Optical deflector, 3 ... Piezoelectric film member, 11 ... Mirror part, 12a, 12b ... Inner piezoelectric actuator (2nd actuator), 13 ... Movable frame (movable support body), 14a, 14a ... outer piezoelectric actuator (first actuator), 15 ... fixed frame (fixed support), 18a, 18b ... overhang, Lx ... first axis, Ly ... second Axis, Mp ... elastic conductive polymer film (elastic conductive film), Me ... piezoelectric polymer film (piezoelectric film).

Claims (5)

A mirror that reflects light;
A movable support for supporting the mirror part;
A fixed support that supports the movable support around a first axis;
A first actuator for reciprocatingly rotating the movable support around the first axis;
An optical deflector comprising: a piezoelectric film member that projects from the movable support in a direction orthogonal to the first axis, is attached to the movable support, and outputs a voltage corresponding to deformation of the projecting portion. . The optical deflector according to claim 1.
The optical deflector, wherein the piezoelectric film member has a laminated structure in which a plurality of piezoelectric films are laminated with an elastic conductive film interposed therebetween, and outputs a voltage between both surfaces of the laminated structure. The optical deflector according to claim 1 or 2,
The piezoelectric film member is affixed to the movable support so that the projecting portion is formed at two positions away from the first axis in opposite directions of the orthogonal direction. Deflector. The optical deflector according to any one of claims 1 to 3,
The optical actuator according to claim 1, wherein the first actuator reciprocally rotates the mirror portion around the first axis at a non-resonant frequency of the mirror portion. The optical deflector according to claim 4, wherein
A second actuator that reciprocally rotates the mirror portion supported by the movable support around a second axis perpendicular to the first axis at a resonance frequency of the mirror portion higher than the non-resonance frequency. Characteristic light deflector.