JP2006320089A - Actuator, manufacturing method of actuators, focus changing apparatus, optical scanner, and image displaying apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator, a manufacturing method for actuators, a focus changing apparatus, an optical scanner, and an image displaying apparatus wherein stress in a direction in which the stress is unwanted can be lessened to prevent damage. <P>SOLUTION: A piezoelectric actuator 109 is so constructed that by applying voltage to a distortion causing element 111 supported on an elastic member 113, the actuating portion of the distortion causing element 111 is actuated. Thus, the elastic member 113 can be deformed. The piezoelectric actuator 109 is so constructed that multiple driving units 111c, 111d to which voltage in the same phase is applied in the distortion causing element 111 are provided in parallel with the elastic member 113. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an actuator, an actuator manufacturing method, a focus variable device, an optical scanning device, and an image display device, and more particularly, by applying a voltage to a strain generating element supported by an elastic member. The present invention relates to an actuator in which an elastic member can be deformed by driving a drive unit, an actuator manufacturing method, a focus variable device, an optical scanning device, and an image display device.

  Conventionally, an actuator for actively driving a micromachine has been proposed and put into practical use. For example, an image display device for displaying an image includes a focus variable device for adjusting the focus, an optical scanning device for scanning light, and the like. Is known that includes an actuator for displacing a mirror.

  Such an actuator includes an elastic member and a strain generating element on the elastic member, and the elastic member and the strain generating element are driven by applying a voltage to the strain generating element. . Further, in such a strain generating element, for example, an upper electrode to which a voltage is applied, a lower electrode supported by an elastic member and applied with a voltage different from the voltage, and sandwiched between the upper electrode and the lower electrode Some have a piezoelectric element. By applying a voltage between the upper electrode and the lower electrode, the strain generating element is driven.

In addition, among such actuators, for example, as shown in Patent Document 1, the anode voltage is applied to a pair of torsion bars in which one end in the longitudinal direction is fixed to the fixing portion and a mirror is provided on the other end. And those for applying a cathode voltage respectively. As a result, the pair of torsion bars are driven to displace the mirror.
JP-A-7-270700

  However, in the actuator as described above, when the torsion bar is driven, in the vicinity of the fixed portion (frame body, mirror, etc.) to which the torsion bar is fixed, depending on the drive, the short side other than the stress in the longitudinal direction. Since unnecessary stress is generated in the direction, not only the unnecessary stress can drive the mirror etc. efficiently, but also the stress concentration becomes excessive and the fixed part and the torsion bar are damaged. There was a risk. This is because the deformation force of the piezoelectric element or the like is applied not only in the longitudinal direction but also in the lateral direction, and as a result, concentrates on a weak point in the structure.

  The present invention has been made in view of the above-described problems, and an actuator that can reduce unnecessary stress and prevent damage, an actuator manufacturing method, a focus variable device, an optical scanning device, and an image display device. The purpose is to provide.

  In order to achieve the above object, the present invention provides the following.

  That is, according to the first aspect of the present invention, in the actuator in which the elastic member can be deformed by driving the driving unit of the strain generating element by applying a voltage to the strain generating element supported by the elastic member. The actuator is characterized in that a plurality of drive units to which in-phase voltages are applied in the strain generating element are arranged in parallel with the elastic member.

  According to a second aspect of the present invention, there is provided the actuator according to the first aspect, wherein the plurality of driving units are formed by branching the strain generating element into a plurality of parts.

  According to a third aspect of the present invention, in the actuator according to the first or second aspect, the plurality of driving units are arranged in parallel in a direction parallel to the driving surface including the driving direction. did.

  Further, in the present invention according to claim 4, the strain generating element includes an upper electrode to which the in-phase voltage is applied, and a lower electrode that is supported by the elastic member and to which a voltage different from the in-phase voltage is applied. A piezoelectric element sandwiched between the upper electrode and the lower electrode, and a groove is formed in each of the upper electrode and the piezoelectric element, or the upper electrode, the piezoelectric element, and the lower electrode. The actuator according to claim 1, wherein the actuator is branched as a plurality of upper electrodes and a plurality of piezoelectric elements, or a plurality of upper electrodes, a plurality of piezoelectric elements, and a plurality of lower electrodes. did.

  According to a fifth aspect of the present invention, in the actuator according to the fourth aspect, the elastic members are arranged in parallel in a state of being branched into a plurality of portions.

  According to a sixth aspect of the present invention, the plurality of driving units in the strain-generating element are driven by applying a voltage between the upper electrode and the lower electrode. The actuator described in 5 was used.

  According to the seventh aspect of the present invention, there is provided an actuator that deforms the elastic member by driving a driving unit of the strain generating element by applying a voltage to the strain generating element supported by the elastic member. In the manufacturing method, the actuator manufacturing method is characterized in that a plurality of drive units to which in-phase voltages are applied in the strain generating element are arranged in parallel to the elastic member.

  Further, in the present invention according to claim 8, the elastic member is branched into a plurality by etching, and a plurality of lower electrodes are formed by sequentially laminating a lower electrode layer, a piezoelectric element layer, and an upper electrode layer on the elastic member. The method for manufacturing an actuator according to claim 7, wherein a plurality of piezoelectric elements and a plurality of upper electrodes are formed in order.

  In the present invention according to claim 9, the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are sequentially stacked on the elastic member, thereby forming the lower electrode, the piezoelectric element, and the upper electrode in order. The actuator manufacturing method according to claim 7, wherein a plurality of upper electrodes and a plurality of piezoelectric elements are formed by forming grooves in the upper electrode and the piezoelectric elements.

  According to a tenth aspect of the present invention, a lower electrode layer is laminated on the elastic member to form a lower electrode, masking is performed on the lower electrode at a predetermined interval, and a piezoelectric element layer is laminated. A plurality of upper electrodes are formed by forming a plurality of piezoelectric elements by laminating an upper electrode layer on the plurality of piezoelectric element layers. It was set as the manufacturing method.

  Further, in the present invention according to claim 11, the plurality of upper electrodes are formed by masking each edge on the plurality of piezoelectric elements and laminating an upper electrode layer on the plurality of piezoelectric elements. An actuator manufacturing method according to claim 8 or 10 is provided.

  According to a twelfth aspect of the present invention, there is provided a variable focus apparatus including the actuator according to any one of the first to sixth aspects.

  According to a thirteenth aspect of the present invention, there is provided an optical scanning device including the actuator according to any one of the first to sixth aspects.

  According to a fourteenth aspect of the present invention, there is provided an image display device including any one or both of the variable focus device according to the twelfth aspect and the optical scanning device according to the thirteenth aspect.

  According to the invention of any one of claims 1, 2, 6, 7, and 12 to 14, a plurality of drive units to which in-phase voltages are applied are arranged in parallel on the elastic member. Compared with the case where a strain generating element is provided, unnecessary stress generated by driving the drive unit of the strain generating element can be reduced, and unnecessary strain can be suppressed.

  According to the third aspect of the present invention, the plurality of driving units are arranged in parallel in a direction (horizontal direction) parallel to a driving surface (for example, vertical surface) including the driving direction (for example, vertical direction). As a result, unnecessary stress generated by driving the drive unit of the strain generating element can be reduced more efficiently, and unnecessary strain can be suppressed.

  Further, according to the invention described in claim 4, grooves are formed in each of the upper electrode and the piezoelectric element (for example, the lower electrode may be included), and a plurality of upper electrodes and a plurality of piezoelectric elements ( For example, a plurality of lower electrodes may be included), so that unnecessary stress caused by driving the drive unit of the strain generating element can be more efficiently reduced, and unnecessary strain can be suppressed. Can do.

  According to the invention described in claim 5, since the elastic members are arranged in parallel in a state where the elastic members are branched into a plurality, it is possible to more efficiently reduce unnecessary stress caused by driving of the driving portion of the strain generating element. And unnecessary distortion can be suppressed.

  According to the eighth aspect of the present invention, the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are sequentially laminated on the elastic member branched into a plurality of parts by etching, so that the plurality of lower electrodes and the plurality of piezoelectric elements are stacked. Since the element and the plurality of upper electrodes are sequentially formed, the elastic member can be finely branched by etching, and further, the lower electrode, the piezoelectric element, and the upper electrode can also be finely branched. Further, since the physical cutting is not performed, the elastic member can be finely branched without applying extra force.

  According to the ninth aspect of the invention, the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are sequentially laminated on the elastic member, so that the lower electrode, the piezoelectric element, and the upper electrode are sequentially formed on the elastic member. Since the plurality of upper electrodes and the plurality of piezoelectric elements are formed by forming and forming grooves in at least the upper electrode and the piezoelectric elements, the upper electrode and the piezoelectric elements are branched into a plurality without performing masking or the like. be able to. Further, since no masking or the like is performed, the actuator can be manufactured with relatively few steps. Further, since the masking is not performed, the upper electrode can be formed widely, and a large generation force can be obtained.

  According to the tenth aspect of the present invention, a plurality of piezoelectric elements are formed by masking at a predetermined interval on the lower electrode formed on the elastic member, and laminating the piezoelectric element layers. A plurality of upper electrodes are formed by laminating the upper electrode layer on the piezoelectric element layer, so that the piezoelectric element can be finely branched by masking, and accordingly, the upper electrode can also be finely branched. . Moreover, since physical cutting is not performed, it is possible to branch finely without applying extra force.

  According to the eleventh aspect of the present invention, the plurality of upper electrodes are formed by masking each edge on the plurality of piezoelectric elements and laminating the upper electrode layer. Can be reliably prevented.

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

[Configuration of image display device]
Hereinafter, an image display apparatus according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of a retinal scanning display 1 which is an example of an image display device according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the retinal scanning display 1 is provided with a light source unit 2 for processing a video signal supplied from the outside. The light source unit 2 is provided with a video signal supply circuit 3 that receives an external video signal and generates each signal as an element for synthesizing the video based on the video signal. A signal 4, a horizontal synchronization signal 5, a vertical synchronization signal 6, and a depth signal 7 are output. The light source unit 2 also includes lasers that are intensity-modulated based on the red (R), green (G), and blue (B) video signals transmitted from the video signal supply circuit 3 as video signals 4. An R laser driver 10, a G laser driver 9, and a B laser driver 8 for driving the R laser 13, the G laser 12, and the B laser 11 are provided so as to emit light. Furthermore, the first collimating optical system 14 provided so as to collimate the laser light emitted from each laser into parallel light, the dichroic mirror 15 for combining the collimated laser lights, and the combined laser light Is coupled to the optical fiber 17. As the R laser 13, G laser 12, and B laser 11, a semiconductor laser such as a laser diode or a solid-state laser may be used. The light source unit 2 in this embodiment corresponds to an example of a modulation unit that modulates the intensity of at least one light source and a light beam emitted from the light source according to an image signal.

  The retinal scanning display 1 also includes a second collimating optical system 18 that collimates the laser light propagated from the light source unit 2 into parallel light again, and wavefront curvature modulation for wavefront curvature modulation of the collimated laser light. The system 100, the horizontal scanning system 19 that scans the modulated laser light in the horizontal direction using the micro scanner 19a, and the laser that is scanned by the horizontal scanning system 19 and incident through the first relay optical system 20 A vertical scanning system 21 that scans light in the vertical direction by using a galvano mirror 21a, and a second relay optical system so that laser light scanned by the vertical scanning system 21 is incident on the pupil 24 of the observer. 22 is provided. The first relay optical system 20 is conjugated with the microscanner 19a of the horizontal scanning system 19 and the galvano mirror 21a of the vertical scanning system 21, and the second relay optical system 22 is connected with the galvano mirror 21a. Each of them is provided so as to be conjugate with the pupil 24 of the person.

  As a specific example, the horizontal scanning system 19 performs horizontal scanning (this is the first scanning) in which the laser beam is raster scanned horizontally along a plurality of horizontal scanning lines for each frame of the image to be displayed. This is an example. On the other hand, the vertical scanning system 21 performs vertical scanning in which the laser beam is scanned vertically from the first scanning line toward the last scanning line for each frame of the image to be displayed (this is an example of the second scanning). .). The horizontal scanning system 19 is designed to scan the laser beam at a higher speed, that is, at a higher frequency than the vertical scanning system 21.

  Further, the wavefront curvature modulation system 100 is connected to the video signal supply circuit 3 and performs wavefront curvature modulation of the incident laser beam (light beam) based on the depth signal 7 output from the video signal supply circuit 3. The horizontal scanning system 19 and the vertical scanning system 21 are connected to the video signal supply circuit 3 and scan the laser beam in synchronization with the horizontal synchronization signal 5 and the vertical synchronization signal 6 output from the video signal supply circuit 3, respectively. Is configured to do. The wavefront curvature modulation system 100 adjusts the focal position for each pixel, for example, based on the depth signal 7 output from the video signal supply circuit 3, but is not limited to this. For example, the depth signal 7 Based on the above, the focus may be adjusted for each of a plurality of pixels. Furthermore, the focus may be adjusted for each line or a plurality of lines.

  The wavefront curvature modulation system 100 includes a beam splitter 101, a convex lens 102, and a movable mirror 103, as will be described in detail later with reference to FIG.

  Note that the horizontal scanning system 19 and the vertical scanning system 21 in this embodiment form a frame by scanning an incident light beam in a first direction and a second direction substantially perpendicular to the first direction. It is an example of an optical scanning device. In addition, the first relay optical system 20 and the second relay optical system 22 in the present embodiment correspond to an example of an optical unit for making a light beam enter an observer's pupil. Further, the wavefront curvature modulation system 100 in the present embodiment corresponds to an example of a variable focus device that changes the focus of an incident light beam.

  Next, the process from when the image display apparatus according to the embodiment of the present invention receives an image signal from the outside to when the image is projected onto the retina of the observer will be described with reference to FIG.

  As shown in FIG. 1, in the retinal scanning display 1 of the present embodiment, when the video signal supply circuit 3 provided in the light source unit 2 is supplied with an external video signal, the video signal supply circuit 3 is A video signal 4 composed of R video signal, G video signal and B video signal for outputting laser beams of red, green and blue, horizontal synchronizing signal 5, vertical synchronizing signal 6 and depth signal 7; Is output. The R laser driver 10, the G laser driver 9, and the B laser driver 8 respectively drive the R laser 13, the G laser 12, and the B laser 11 based on the input R video signal, G video signal, and B video signal. Output a signal. Based on this drive signal, the R laser 13, the G laser 12, and the B laser 11 each generate intensity-modulated laser light and output each to the first collimating optical system 14. The laser light generated from the point light source is collimated into parallel light by the first collimating optical system 14, and further, is incident on the dichroic mirror 15 to be combined into one light beam, and then combined optical system 16. To be incident on the optical fiber 17.

  When the laser light propagated through the optical fiber 17 is emitted from the optical fiber 17, it is collimated again by the second collimating optical system 18 and enters the wavefront curvature modulation system 100.

  Here, the modulation of the wavefront curvature will be described. First, all objects can be considered as a collection of innumerable point light sources, and luminous flux is emitted from each point light source. Light emitted from a light source is propagated as a so-called spherical wave that travels at the same speed and in the same phase in all directions centered on the light source, so-called spherical waves, but depending on the distance between the light source and the observer, The radius of curvature is different. When the light source is close, it enters the observer's eye as a light beam with a small radius of curvature, and when the light source is far, the light beam has a large radius of curvature. The observer can recognize this difference in radius of curvature and feel it as a sense of perspective. According to the present invention, the curvature of the light beam, that is, the wavefront curvature can be artificially modulated. There are two main ways in which humans can sense the distance of objects, by means of congestion detection and by wavefront curvature detection. However, most of the image display apparatuses that realize stereoscopic vision that are currently being developed in the world use only convergence adjustment. On the other hand, by applying the present invention to the image display device, in addition to the convergence adjustment, the wavefront curvature adjustment can be performed, so that it is possible to provide the observer with a stereoscopic view and a sense of depth similar to a mechanism in which a human sees an object. .

  The laser light emitted from the wavefront curvature modulation system 100 is incident on the deflection surface 19b of the microscanner 19a of the horizontal scanning system 19. The micro scanner 19a calculates a rotation speed based on a BD (Beam Detector) signal output by an optical sensor (not shown), and outputs a horizontal synchronization signal output from the video signal supply circuit 3 based on the BD signal. The speed of constant speed rotation is adjusted so as to synchronize with 5. The laser beam incident on the deflection surface 19b of the micro scanner 19a is scanned in the horizontal direction and enters the deflection surface 21b of the galvanometer mirror 21a of the vertical scanning system 21 via the first relay optical system 20. In the first relay optical system 20, the deflection surface 19b of the micro scanner 19a and the deflection surface 21b of the galvano mirror 21a are adjusted so as to have a conjugate relationship, and the surface tilt of the micro scanner 19a is corrected. Similar to the micro scanner 19a, the galvano mirror 21a is reciprocally oscillated so that the deflection surface 21b reflects incident light in the vertical direction in synchronization with the vertical synchronizing signal 6, and the galvano mirror 21a causes the laser light to be emitted. Scans vertically. Laser light that is two-dimensionally scanned in the horizontal and vertical directions by the horizontal scanning system 19 and the vertical scanning system 21 is provided so that the deflection surface 21b of the galvano mirror 21a and the pupil 24 of the observer have a conjugate relationship. The second relay optical system 22 is incident on the observer's pupil 24 and projected onto the retina. The observer can thus recognize the image by the laser light that is two-dimensionally scanned and projected onto the retina. The microscanner 19a of the horizontal scanning system 19 and the galvanometer mirror 21a of the vertical scanning system 21 have been described with different names. However, the reflecting surfaces (deflection surfaces 19b and 21b) swing so as to scan light. Needless to say, any drive system such as piezoelectric drive, electromagnetic drive, or electrostatic drive may be used as long as it can be moved.

[Configuration of wavefront curvature modulation system]
The configuration of the wavefront curvature modulation system 100 described above will be described with reference to FIG.

  As shown in FIG. 2, the wavefront curvature modulation system 100 splits the incident laser light into transmitted light and reflected light reflected in a direction perpendicular to the traveling direction of the transmitted light, as described above. 101, a convex lens 102 for converging the laser light reflected by the beam splitter 101, and a laser light converged on the convex lens 102 in a direction parallel to the incident direction (that is, the movable mirror surface 103) And a movable mirror 103 that can be displaced (driven) in a vertical direction.

  The beam splitter 101 has a cube shape in which two right-angle prisms each having a dielectric multilayer film are attached to a slope, and the light quantity of incident light from the direction indicated by the arrow A on the slope 101a. By reflecting 50% as it is in the direction perpendicular to the propagation direction same as the incident direction, it is reflected again to the beam splitter 101. Thereafter, about 50% is reflected and about 50% is transmitted as in the case of incidence, and incident light is guided to the convex lens 102 and the movable mirror 103, and about 50% is transmitted. Incident light guided to the convex lens 102 and the movable mirror 103 is emitted by the movable mirror 103 in the direction of the micro scanner 19a (the direction indicated by the arrow B).

  Although the movable mirror 103 will be described later in detail with reference to FIG. 3, the focal position of the laser beam is adjusted by moving the reflecting mirror unit 108 (see FIG. 3A).

[Configuration of movable mirror]
The configuration of the movable mirror 103 described above will be described with reference to FIGS. FIG. 3 is a perspective view showing the movable mirror 103 and the like. FIG. 4 is an explanatory view showing the piezoelectric actuator 109. FIG. 5 is an explanatory view of the piezoelectric actuator 109 and the like viewed from the longitudinal direction.

  As shown in FIG. 3A, the movable mirror 103 includes, for example, a reflection mirror unit 108 having a reflection surface 108a obtained by applying a mirror coating of a metal film to the surface of a plate material such as silicon or glass, and a piezoelectric piezoelectric element, for example. Etc., and a piezoelectric actuator 109 in which such layers are stacked.

  The piezoelectric actuator 109 is driven by applying a driving voltage from a driving circuit 106 (see FIG. 4), which will be described later, so that the positional relationship between the reflecting mirror 108 fixed to the piezoelectric actuator 109 and the convex lens 102 is changed. It has become. The movable mirror 103 is movable in a direction perpendicular to the reflecting surface 108a of the reflecting mirror unit 108 (Z-axis direction in FIG. 3A), and the optical axis of the laser beam passing through the beam splitter 101 and the convex lens 102 is linear. Configured to match above.

  In addition, the piezoelectric actuator 109 that moves the reflection mirror unit 108 includes an elastic member 113 to which the reflection mirror unit 108 is fixed, a pair of strain generating elements 111 and 112 that are supported by the elastic member 113 and move the elastic member, These elastic members 113 and a frame 114 for fixing the pair of strain generating elements 111 and 112 are provided.

  The frame body 114 is formed in a rectangular shape. The frame body 114 is formed integrally with an elastic member 113 described later. The frame body 114 and the elastic member 113 are mainly made of silicon (Si) or the like. In the present embodiment, the frame body 114 has a length of about 1600 μm in the longitudinal direction (X-axis direction in FIG. 3A) and a width of about 800 μm in the lateral direction (Y-axis direction in FIG. 3A). It is a size.

  A rectangular opening 114a is formed at the center of the frame body 114 so that the elastic member 113 and the like can be driven in a direction perpendicular to the reflecting surface 108a of the reflecting mirror unit 108. In this embodiment, the opening 114a is about 1000 μm in the longitudinal direction (X-axis direction in FIG. 3A) and about 600 μm in the lateral direction (Y-axis direction in FIG. 3A). Size. An elastic member 113 is integrally fixed to the edge of the opening 114a of the frame 114 in the longitudinal direction (X-axis direction in FIG. 3A).

  The elastic member 113 is a rectangular thin plate and is disposed on the opening 114a. As described above, the elastic member 113 is integrally fixed to the edge of the opening 114a of the frame body 114 in the longitudinal direction (X-axis direction in FIG. 3A). The elastic member 113 is mainly formed using an elastic material such as silicon (Si).

  A reflection mirror unit 108 is provided at the center of the elastic member 113. In addition, strain-generating elements 111 and 112 are attached to the upper surface of the elastic member 113 on both sides of the reflection mirror unit 108. As will be described in detail later, by applying a voltage to the strain-generating elements 111 and 112, the elastic member is driven in the vertical direction (Z-axis direction in FIG. 3A), and the reflecting mirror unit 108 is moved with respect to the reflecting surface 108a. Therefore, it is driven in the vertical direction (vertical direction). That is, such a piezoelectric actuator 109 can deform the elastic member 113 by applying a voltage to the strain-generating element 111 supported by the elastic member 113 to drive a drive unit 111b described later of the strain-generating element 111. Thus, the reflecting mirror unit 108 can be moved up and down.

  The strain generating elements 111 and 112 are respectively attached on the elastic members 113 on both sides of the reflection mirror 108. In addition, the strain generating elements 111 and 112 are pasted across the elastic member 113 and the frame body 114, respectively. These strain generating elements 111 and 112 are mainly composed of a lower electrode 131, a piezoelectric element 132, and an upper electrode 133 (both see FIG. 4), which will be described later, and a voltage is applied between the upper electrode 133 and the lower electrode 131. Thus, the elastic member 113 and the reflection mirror portion 108 are driven in a direction perpendicular to the reflection surface 108a (vertical direction, Z-axis direction in FIG. 3A). Further, as will be described in detail later, by applying a voltage between the upper electrode 133 and the lower electrode 131, a plurality of driving units 111c and 111d described later can be driven. Since the pair of strain generating elements 111 and 112 have the same formation and the same function, the description of the strain generating element 112 is omitted to facilitate the understanding of the invention, and the strain generating element is omitted. 111 will be described below as a representative.

  The strain generating element 111 has a rectangular shape and is provided such that the longitudinal direction thereof faces the reflection mirror unit 108. The strain generating element 111 is affixed on the frame 114 and includes a fixed part 111a that does not contribute to driving even when a voltage is applied, and a driving part 111b that is affixed on the elastic member 113 and is driven when a voltage is applied. Composed. In the present embodiment, the strain generating element 111 has a size of about 500 μm in the longitudinal direction and about 200 μm in the lateral direction. In the present embodiment, the strain generating element 111 is disposed on the frame body 114 by about 150 μm in the longitudinal direction, and the remaining about 350 μm is disposed on the elastic member 113.

  A groove 111e extending in the longitudinal direction is formed in the driving portion 111b of the strain generating element 111, and is divided into a plurality of driving portions 111c and 111d. Note that a groove is not formed in the fixing portion 111 a of the strain generating element 111. In the present embodiment, the groove 111e has a size of about 350 μm in the longitudinal direction and about 20 μm in the short direction. In other words, each of the plurality of driving units 111c and 111d is branched to a size of about 350 μm in the longitudinal direction and about 90 μm in the short direction. In the conventional example, the drive unit 191b in the strain generating element 111 is not branched into a plurality of pieces, and has a size of about 350 μm in the longitudinal direction and about 180 μm in the short direction. For this reason, in the present embodiment, the aspect ratio is changed so that the longitudinal direction of the drive units 111c and 111d becomes longer. As described above, the driving unit 111b in the strain generating element 111 is branched into a plurality of driving units 111c and 111d. In other words, in such a piezoelectric actuator 109, a plurality of drive units 111c and 111d to which in-phase voltages are applied in the strain generating element 111 are arranged in parallel with the elastic member 113. In particular, the driving unit 111b in the strain generating element 111 has grooves 111e formed in the upper electrode 133, the piezoelectric element 132, and the lower electrode 131, and branches as a plurality of upper electrodes, a plurality of piezoelectric elements, and a plurality of lower electrodes. Has been. That is, the plurality of drive units 111c and 111d are formed by branching the strain generating element 111 (drive unit 111b) into a plurality. Further, the plurality of drive units 111c and 111d have a drive surface Q including a vertical direction (drive direction, Z-axis direction in FIG. 3A) (surface including X-axis and Z-axis in FIG. 3A). Are parallel to each other (the short direction, the Y-axis direction in FIG. 3A). It should be noted that such a groove 111e or the like may be formed by etching or the like or may be formed by physical cutting. In the present embodiment, it may be referred to as a “concave portion” because it is formed by etching or the like. Further, the groove 111e may or may not penetrate the bottom surface.

  As described above, since the plurality of driving units 111c and 111d to which in-phase voltages are applied are arranged in parallel with the elastic member 113, for example, compared to the conventional example in which the strain generating element 191 is provided as one driving unit 191b. Unnecessary stress generated by driving the drive units 111c and 111d of the strain generating element 111 can be reduced, and unnecessary strain can be suppressed. The plurality of driving units 111c and 111d are parallel to a driving surface Q (for example, a vertical surface) including a driving direction (for example, a vertical direction, a Z-axis direction in FIG. 3A) (horizontal direction). Direction, the short direction, and the Y-axis direction in FIG. 3A), unnecessary stress caused by driving of the driving portions 111c and 111d of the strain generating element 111 can be more efficiently reduced. Unnecessary distortion can be suppressed. Note that, for example, a plurality of drive units 111c and 111d that are fixed at one end in the longitudinal direction and are driven in the vertical direction (drive direction) with respect to the longitudinal direction are arranged in parallel in the short direction parallel to the vertical direction. In other words, it can be paraphrased. Further, a groove 111e is formed in each of the upper electrode 133 and the piezoelectric element 132 (for example, the lower electrode 131 may be included), and a plurality of upper electrodes and a plurality of piezoelectric elements (for example, a plurality of lower electrodes) are formed. Therefore, unnecessary stress generated by driving the driving portions 111c and 111d of the strain generating element 111 can be reduced more efficiently, and unnecessary strain can be suppressed. .

  The elastic member 113 described above is also formed with grooves 113a and 113b extending in the longitudinal direction. The groove 113a is continuously provided so as to penetrate the groove 111e in the driving unit 111b. That is, in the piezoelectric actuator 109, the elastic members 113 are arranged in parallel in a state where the elastic members 113 are branched into a plurality. As described above, since the elastic members 113 are arranged in parallel in a state where the elastic members 113 are branched, unnecessary stress generated by driving the driving portions 111c and 111d of the strain generating element 111 can be more efficiently reduced. Necessary distortion can be suppressed. In addition, the structure is such that unnecessary stress generated in one strain generating element 111 hardly affects the other strain generating element 112. The groove 113a in the elastic member 113 is formed longer in the longitudinal direction than the groove 111e formed in the drive unit 111b. As a specific example in the present embodiment, the groove 113a in the elastic member 113 has a size of about 375 μm in the longitudinal direction and about 30 μm in the lateral direction. For this reason, unnecessary stress generated by driving the drive units 111c and 111d of the strain generating element 111 can be more efficiently reduced, and unnecessary strain can be suppressed.

  Further, as shown in FIG. 4, the strain generating element 111 includes a lower electrode 131 formed on the elastic member 113, a piezoelectric element 132 formed on the lower electrode 131 and configured by a piezoelectric element, and the like. The upper electrode 133 is formed on the piezoelectric element 132. That is, the strain generating element 111 is supported by the upper electrode 133 to which a voltage having the same phase is applied, the lower electrode 131 to which a voltage different from the voltage having the same phase is applied, and the upper electrode 133 and the lower electrode 131. And a piezoelectric element 132 sandwiched between the two. In this embodiment, the thickness of the lower electrode 131 and the upper electrode 133 is about 0.2 μm, and the thickness of the piezoelectric element 132 is about 1 μm.

  In such a configuration, when a voltage is applied between the upper electrode 133 and the lower electrode 131, the piezoelectric element 132 contracts (extends) in a direction perpendicular to the upper electrode 133 and the lower electrode 131. At this time, the piezoelectric element 132 is displaced so as to extend (shrink) isotropically in a plane parallel to the upper electrode 133 and the lower electrode 131. On the other hand, since the elastic member 113 does not expand or contract by voltage application, it is bent downward (upward) by in-plane expansion (contraction) parallel to the upper electrode 133 and the lower electrode 131 of the piezoelectric element formed on the upper surface. Cause deformation. As a result, the reflection mirror portion 108 provided on the elastic member 113 is displaced in the direction perpendicular to the reflection surface 108a.

  Longitudinal relative to the elastic member 113 due to in-plane expansion of the strain generating element 111, in particular, the piezoelectric element 132, such as in-film stress at the time of film formation and piezoelectric strain at the time of voltage application accompanying such displacement (drive) Not only the stress for the direction but also the stress for the short direction is generated. In the conventional example, as shown in FIGS. 3C and 5B, the drive unit 191b is integrated, and the stress F0 with respect to the short side direction is not only useless but also extra stress. Concentration may be caused, and the strain generating elements 111 and 112, the elastic member 113, the frame body 114, or the joint between the two may be damaged or broken. Therefore, in the present embodiment, as shown in FIGS. 3A and 5A, the drive unit 111b in the strain generating element 111 is branched into a plurality of (for example, two) drive units 111c and 111d. As a result, the driving surface Q (the X axis shown in FIG. 3) including the driving direction (Z axis direction shown in FIG. 3) of the mirror unit 108 is maintained while maintaining the amount of displacement even if the volume is the same as that of the conventional example. , The stresses F1 and F2 with respect to the short direction perpendicular to the Z-axis) (the Y-axis direction shown in FIG. 3 and the short direction perpendicular to the long direction) can be released and reduced, and unnecessary strain can be reduced. Can be suppressed. In particular, it is possible to suppress stress concentration and unnecessary strain that are likely to occur in the frame body 114 to which the fixing portions 111a and 112a of the strain generating elements 111 and 112 are attached, between the elastic member 113 and the frame body 114, and the like. Thus, it is possible to provide an actuator that can be controlled more accurately and has high durability.

  In this embodiment, as shown in FIG. 3A, grooves are formed in the elastic member 113 in addition to the strain-generating elements 111 and 112. However, the present invention is not limited to this. For example, FIG. ), Grooves are formed in the strain-generating elements 111 and 112, but grooves may not be formed in the elastic member 113. That is, in the strain generating elements 111 and 112, the upper electrode 133, the piezoelectric element 132, and the lower electrode 131 may be divided so that only the elastic member is not divided. Further, in the strain generating elements 111 and 112, the grooves 111e and 112e are formed in the driving units 111b and 112b, and the grooves are not formed in the fixing units 111a and 112a. You may form a groove | channel in this. Of course, each of the strain generating elements 111 and 112 has a plurality of driving units 111c, 111d, 112c, and 112d integrated with the fixing units 111a and 112a, but is not limited thereto. For example, the fixing units 111a and 112a The plurality of driving units 111c, 111d, 112c, and 112d may not be formed integrally. Further, for example, it is not necessary to completely divide the drive units 111b and 112b in the longitudinal direction, and all or a part of the drive units 111b and 112b may be branched.

  Further, in FIGS. 3 to 5, the driving portions 111b and 112b in the strain generating elements 111 and 112 are formed with grooves 111e and 112e, respectively, and branched into two driving portions 111c, 111d, 112c and 112d, respectively. For example, as shown in FIG. 6, two or more drive units may be branched.

  Here, the number of divisions of the strain-generating element and the elastic member in the piezoelectric actuator and the result of calculating the stress for the displacement thereof by simulation will be described with reference to FIG. The case where the drive unit is not branched as in the prior art will be described with reference to FIG. 7A, and the case where the drive unit is branched into two will be described with reference to FIG. A case of branching into pieces will be described with reference to FIG. The experimental results will be described with reference to FIG. In this simulation, the stress when the drive unit is displaced by 5.8 μm in the strain generating element and the elastic member having the same volume is calculated. The stress in this experimental result indicates the maximum value of the stress, and the reduction of the stress can be recognized by this maximum stress.

  Referring to FIG. 7D, when the drive unit is displaced by 5.8 μm without branching as shown in FIG. 7A, the stress becomes 1083 Pa (Pascal), as shown in FIG. 7B. When the drive unit is displaced by 5.8 μm in the case of dividing into two parts, the stress becomes 777.1 Pa (Pascal), and in the case of dividing into ten parts as shown in FIG. Was displaced by 5.8 μm, the stress was 720.5 Pa (pascal).

  Thus, by branching the drive unit of the strain-generating element into a plurality, the stress can be reduced while maintaining the amount of displacement even with the same volume. This is thought to be because the stress in the short direction can be suppressed when the drive unit is branched into a plurality of parts. In particular, it can be seen from this experimental result that stress is reduced and stress concentration is suppressed as the number of divisions is increased. In addition, in this experimental result, the stress can be most efficiently suppressed when branched into two.

[Actuator manufacturing method]
A method of manufacturing the piezoelectric actuator 109 having the above-described configuration will be described with reference to FIGS. In addition, the manufacturing method of the piezoelectric actuator 109 demonstrated below is a typical manufacturing method, and is not restricted to these. That is, a plurality of drive units 111c and 111d to which in-phase voltages are applied in the strain generating element 111 and the like may be manufactured so as to be arranged in parallel on the elastic member 113 including the reflection mirror unit 108.

  First, the first manufacturing method will be described with reference to FIG.

  First, as shown in FIG. 8A, the formed elastic member 113 is branched into a plurality of elastic members 113 by etching. Then, as shown in FIG. 8B, a plurality of lower electrodes 131 are formed on the branched elastic members 113 as shown in FIG. 8C by forming the lower electrode material. The Similarly, a plurality of piezoelectric elements 132 are formed on the plurality of lower electrodes 131 as shown in FIG. 8D by depositing the piezoelectric element material. Subsequently, on the plurality of piezoelectric elements 132, masking is performed on each edge of the plurality of piezoelectric elements 132. Similarly, by depositing the upper electrode material, a plurality of upper electrodes 133 are formed on the plurality of piezoelectric elements 132 as shown in FIG.

  That is, in such a manufacturing method of the piezoelectric actuator 109, the elastic member 113 is branched into a plurality by etching, and the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are sequentially laminated on the elastic member 113, A plurality of lower electrodes 131, a plurality of piezoelectric elements 132, and a plurality of upper electrodes 133 are formed in this order. In particular, by masking each edge on the plurality of piezoelectric elements 132 and stacking the upper electrode layer on the plurality of piezoelectric elements 132, the plurality of upper electrodes 133 are formed. By manufacturing in this way, the elastic member 113 can be finely branched by etching, and accordingly, the lower electrode 131, the piezoelectric element 132, and the upper electrode 133 can also be finely branched. Moreover, since physical cutting is not performed, it is possible to branch finely without applying extra force. Further, by masking each edge on the plurality of piezoelectric elements 132 and laminating the upper electrode layer, the plurality of upper electrodes 133 are formed, so that a short circuit between the lower electrode 131 and the upper electrode 133 is surely prevented. can do.

  The second manufacturing method will be described with reference to FIG.

  First, as shown in FIG. 9A, the lower electrode 131 is formed on the elastic member 113 by depositing the lower electrode material on the elastic member 113 as shown in FIG. 9B. Is done. Similarly, by forming a film of the piezoelectric element material, the piezoelectric element 132 is formed on the lower electrode 131 as shown in FIG. Subsequently, the upper electrode material is formed in the same manner, whereby the upper electrode 133 is formed on the piezoelectric element 132 as shown in FIG. By physically cutting the elastic member 113, the lower electrode 131, the piezoelectric element 132, and the upper electrode 133 stacked in this way by means such as dicing, a plurality of lower portions are obtained as shown in FIG. An electrode 131, a piezoelectric element 132, and an upper electrode 133 are formed.

  That is, in such a manufacturing method of the piezoelectric actuator 109, the lower electrode 131, the piezoelectric element 132, and the upper electrode 133 are formed by sequentially laminating the lower electrode layer, the piezoelectric element layer, and the upper electrode layer on the elastic member 113. A plurality of upper electrodes 133 and a plurality of piezoelectric elements 132 are formed by sequentially forming and forming grooves in at least the upper electrode 133 and the piezoelectric elements 132. By manufacturing in this way, the upper electrode 133 and the piezoelectric element 132 can be branched into a plurality without masking. Further, since no masking or the like is performed, the actuator can be manufactured with relatively few steps. Further, since the upper and lower electrodes cannot be short-circuited because masking is not performed, the upper electrode 133 can be formed widely, and an area for generating a driving force can be gained.

  Finally, the third manufacturing method will be described with reference to FIG.

  First, as shown in FIG. 10A, the lower electrode 131 is formed on the elastic member 113 by depositing a lower electrode material on the elastic member 113 as shown in FIG. Is done. Then, masking is performed on the lower electrode 131 at a predetermined interval. Subsequently, a plurality of piezoelectric elements 132 are formed on the lower electrode 131 by depositing a piezoelectric element material as shown in FIG. Subsequently, on the plurality of piezoelectric elements 132, masking is performed on each edge of the plurality of piezoelectric elements 132. Similarly, by depositing the upper electrode material, a plurality of upper electrodes 133 are formed on the plurality of piezoelectric elements 132 as shown in FIG.

  That is, in such a manufacturing method of the piezoelectric actuator 109, the lower electrode 131 is formed by laminating the lower electrode layer on the elastic member 113, masking is performed on the lower electrode 131 at a predetermined interval, and piezoelectric A plurality of piezoelectric elements 132 are formed by stacking the element layers, and a plurality of upper electrodes 133 are formed by stacking the upper electrode layers on the plurality of piezoelectric elements 132. In particular, by masking each edge on the plurality of piezoelectric elements 132 and stacking the upper electrode layer on the plurality of piezoelectric elements 132, the plurality of upper electrodes 133 are formed. By manufacturing in this way, the piezoelectric element 132 can be finely branched by masking, and accordingly, the upper electrode 133 can also be finely branched. Moreover, since physical cutting is not performed, it is possible to branch finely without applying extra force. Further, by masking each edge on the plurality of piezoelectric elements 132 and laminating the upper electrode layer, the plurality of upper electrodes 133 are formed, so that a short circuit between the lower electrode 131 and the upper electrode 133 is surely prevented. can do.

  In the above-described embodiment, as shown in FIGS. 8 and 9, the elastic member 113, the lower electrode 131, the piezoelectric element 132, and the upper electrode 133 are all branched into a plurality, or as shown in FIG. In addition, the elastic member 113 and the lower electrode 131 are not branched into a plurality of parts, and the piezoelectric element 132 and the upper electrode 133 are all branched into a plurality of parts. However, the present invention is not limited thereto. For example, as shown in FIG. In addition, the elastic member 113, the lower electrode 131, and the piezoelectric element 132 are not branched into a plurality of parts, and the upper electrode 133 is branched into a plurality of parts, as shown in FIG. The lower electrode 131, the piezoelectric element 132, and the upper electrode 133 may all be branched into a plurality.

  In the above-described embodiment, the lower electrode material, the piezoelectric element material, and the upper electrode material are sequentially deposited, and the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are sequentially stacked to form the lower electrode, the piezoelectric element, and the upper electrode. The physical vapor deposition method (PVD: Physical Vapor Deposition) is used. In the physical vapor deposition method, for example, an inert gas is introduced into a vacuum while a DC voltage or an AC voltage is applied between the substrate and the target, and the ionized inert gas is collided with the target to be blown off. There is also an AD method in which a film is formed by sputtering to spray a substance on a substrate or by spraying nano-sized fine particles. However, the present invention is not limited thereto, and at least one of the lower electrode layer, the piezoelectric element layer, and the upper electrode layer may be formed by a chemical vapor deposition (CVD) method.

  In the above-described embodiment, the present invention is applied to the piezoelectric actuator 109 in the wavefront curvature modulation system 100 as an example of the focus changing device. However, the present invention is not limited to this, and for example, the micro scanner 19a and the galvano described in FIG. The present invention may be applied to at least one (or both) of the piezoelectric actuator in the optical scanning device such as the mirror 21a. Further, the present invention may be applied to an image display device provided with at least one (or both) of the variable focus device and the optical scanning device.

  Thus, a preferred embodiment in which the present invention is applied to a piezoelectric actuator in an optical scanning device will be described below with reference to FIGS. In this embodiment, in the retinal scanning display 1 shown in FIG. 1, an optical scanner 204 shown in FIG. 12 is provided instead of the micro scanner 19a in the horizontal scanning system 19. Further, items different from the above-described embodiment will be described below, and description of similar items will be omitted. The optical scanner 204 is used for horizontal scanning with laser light, but is not limited thereto, and may be used for vertical scanning, for example.

  As shown in FIG. 12, an optical scanner 204 as an example of an optical scanning device is configured by mounting a main body 210 on a base 212.

  The main body 210 is formed mainly using an elastic material such as silicon (Si). As shown in the upper part of FIG. 12, the main body part 210 generally has a thin plate rectangular shape having a through hole 214 through which light can pass. The main body 210 is provided with a fixed frame 216 on the outer side, and on the inner side is provided with a vibrating body 224 having a reflection mirror part 222 on which a reflection surface 220 is formed.

  Corresponding to the configuration of the main body part 210, the base 212 has a support part 230 to which the fixing frame 216 is to be attached in a state of being attached to the main body part 210, and a concave part 232 facing the vibrating body 224. It is configured. The recess 232 is formed so as to have a shape that does not interfere with the base 212 even when the vibrating body 224 is displaced by vibration in a state where the main body 210 is mounted on the base 212.

  As shown in FIG. 12, the reflection surface 220 of the reflection mirror portion 222 is swung around a swing axis 234 that is also a symmetric center line thereof. The vibrating body 224 further includes a beam portion 240 that extends on the same plane as the reflection mirror portion 222 and joins the reflection mirror portion 222 to the fixed frame 216. In the present embodiment, a pair of beam portions 240 and 240 extend in opposite directions from both sides of the reflection mirror portion 222.

  Each beam portion 240 includes one mirror side leaf spring portion 242, a pair of frame side leaf spring portions 244 and 244, and a connecting portion that connects the mirror side leaf spring portion 242 and the pair of frame side leaf spring portions 244 and 244 to each other. 246.

  In each beam portion 240, the mirror side leaf spring portion 242 extends from one of a pair of edges facing each other on the swing axis 234 of the reflection mirror portion 222 to the corresponding connection portion 246. The connecting portion 246 extends in a direction orthogonal to the swing axis 234. Further, in each beam portion 240, the pair of frame side leaf spring portions 244 are along the swing axis 234 in a posture in which they are offset from the ends of the corresponding connecting portions 246 in the opposite directions with respect to the swing axis 234. Extending to the fixed frame 216.

  In each beam portion 240, strain-generating elements 250, 252, 254, and 256 are attached to the pair of frame-side plate spring portions 244 and 244 in a posture that reaches the fixed frame 216. As shown in FIG. 13, each of the strain generating elements 250, 252, 254, and 256 is configured mainly with a piezoelectric element 260, an upper electrode 262, and a lower electrode 264, as shown in FIG.

  The piezoelectric element 260 has a thin plate shape and is attached to one surface of the vibrating body 224. The piezoelectric element 260 is sandwiched between the upper electrode 262 and the lower electrode 264 in a direction perpendicular to the sticking surface thereof, thereby constituting the strain-generating elements 250, 252, 254, and 256. The upper electrode 262 and the lower electrode 264 are respectively connected to a pair of input terminals 268 and 268 installed on the fixed frame 216 by lead wires 266.

  As shown in FIG. 12, in this embodiment, four strain generating elements 250, 252, 254, and 256 are provided two at a pair of opposed positions with the reflecting mirror portion 222 therebetween, and the swing axis 234. With respect to each other. Of these four strain-generating elements 250, 252, 254, and 256, two strain-generating elements 250 and 254 (located on the right side in FIG. 12) arranged at one opposing position form a first pair. The two strain-generating elements 252 and 256 (located on the left side in FIG. 12) arranged at the other facing position form a second pair. In this embodiment, the pair of strain-generating elements 250 and 254 and the pair of strain-generating elements 252 and 256 are used. However, the present invention is not limited to this. For example, the pair of strain-generating elements 250 and 252 A pair of elements 254 and 256 may be used, and in this case, driving is performed by driving the electrodes in each pair in phase.

  In the present embodiment, the two strain-generating elements 250 and 254 forming the first pair function as drive sources, respectively, and torsionally vibrate the vibrating body 224 around the oscillation axis 234. Therefore, in each of the strain generating elements 250 and 254, a voltage is applied to the upper electrode 262 and the lower electrode 264 (see FIG. 13), thereby causing displacement in the direction perpendicular to the application direction, that is, the length direction. It is generated in the strain elements 250 and 254.

  Due to this displacement, as shown in FIG. 14, the beam 240 is bent or warped. This bending is performed with the connection portion with the fixed frame 216 in the beam portion 240 as a fixed end, and the connection portion with the reflection mirror portion 222 as a free end. As a result, the free end is displaced upward or downward depending on whether the bending direction is upward or downward.

  The two strain-generating elements 250 and 254 forming the first pair are bent so that the free ends of the respective piezoelectric elements 260 are displaced in directions opposite to each other. As a result, the reflection mirror unit 222 is rotated around the swing axis 234 as shown in FIG.

  As described above, each frame-side leaf spring portion 244 has a function of converting the linear displacement of the strain-generating elements 250, 252, 254, and 256 affixed thereto into a bending motion, and the connection portion 246 has each frame-side leaf spring portion 244. It has a function to convert the bending motion of the mirror into the rotational motion of the mirror side leaf spring portion 242. The reflection mirror 222 is rotated by the rotational movement of the mirror side leaf spring 242.

  In the present embodiment, the two strain-generating elements 250 and 254 forming the first pair are displaced in opposite directions to cause the reflection mirror unit 222 to reciprocate or swing around its swing axis 234. Is generated. In order to realize this, alternating voltages are applied to the two strain-generating elements 250 and 254 forming the first pair in opposite phases. As a result, when one of the two strain-generating elements 250 and 254 forming the first pair bends downward in FIG. 12, the other bends upward in FIG. That is, an in-phase voltage is applied to the upper electrode 262 in the strain generating element 250. In addition, a reverse phase voltage different from that of the upper electrode 262 in the strain generating element 250 is applied to the upper electrode 262 in the strain generating element 252.

  Each of the strain generating elements 250, 252, 254, and 256 described above is branched into a plurality and arranged in parallel. The strain generating elements 252 and 256 will be described below with reference to FIG.

  As shown in FIG. 15A, a strain generating element 252 is attached to the frame side leaf spring portion 244. As described above, the strain generating element 252 includes the piezoelectric element 260, the upper electrode 262, and the lower electrode 264 (see FIG. 13). As shown in FIG. 15A, the strain generating element 252 has a groove 252c formed in the longitudinal direction (X-axis direction in FIG. 15A), and in the short direction (FIG. 15A). In the Y-axis direction), the plurality of drive units 252a and 252b are branched and arranged in parallel. That is, the plurality of drive units 252a and 252b are perpendicular to the drive surface Q (the surface including the X axis and the Z axis in FIG. 15A) including the drive direction (vertical direction, the Z axis direction in FIG. 15A). Are branched in parallel to each other (short direction, Y-axis direction in FIG. 15A).

Further, the frame-side leaf spring portion 244 is also formed with a groove 270 that is continuous with the groove 252c so as to extend in the longitudinal direction (X-axis direction in FIG. 15A). The groove 270 is formed in a shape longer in the longitudinal direction (X-axis direction in FIG. 15A) than the groove 252c. For this reason, the frame side leaf | plate spring part 244 as an elastic member is also branched and provided in the transversal direction (Y-axis direction in Fig.15 (a)).
That is, the frame side leaf spring portion 244 as an elastic member also has a driving surface Q (a surface including the X axis and the Z axis in FIG. 15A) including the driving direction (vertical direction, Z axis direction in FIG. 15A). Are branched in parallel (a short direction, the Y-axis direction in FIG. 15A).

  Then, an in-phase voltage is applied to the upper electrode 262 in the strain generating element 252, and the upper electrode 262 is driven in the vertical direction (Z-axis direction in FIG. 15A). Of course, the upper electrode 262 in the strain-generating element 252 is out of phase with the upper electrode 262 in the strain-generating element 256, but the same-phase voltage is applied to the upper electrode 262 itself, and the vertical direction (Z-axis direction in FIG. 15A). Will be driven to.

  Conventionally, as shown in FIG. 15B, the strain-generating element 298 is not branched into a plurality, but is integrated. Also in this embodiment, as in the above-described embodiment, a frame-side leaf spring portion using a plurality of drive units 252a and 252b to which in-phase voltages are applied as an elastic member even if the volume is the same as in the conventional case. Since it is arranged in parallel with H.244, for example, compared with the conventional case where the strain generating element 298 is provided as one drive unit, the stress in the short direction is released, and unnecessary due to driving of the drive units 252a and 252b of the strain generating element 252 is unnecessary. Unnecessary stress can be reduced, and unnecessary strain can be suppressed. Further, since the plurality of driving units 252a and 252b are arranged in parallel in a direction (horizontal direction) parallel to a driving surface (for example, vertical surface) including the driving direction (for example, vertical direction), the strain generating element Unnecessary stress generated by driving the driving units 252a and 252b of 252 can be further efficiently reduced, and unnecessary distortion can be suppressed. Note that, for example, a plurality of drive units 252a and 252b that are fixed at one end in the longitudinal direction and are driven in the vertical direction (drive direction) with respect to the longitudinal direction are arranged in parallel in the short direction parallel to the vertical direction. In other words, it can be paraphrased. In addition, a groove 252c is formed in each of the upper electrode 262 and the piezoelectric element 260 (for example, the lower electrode 264 may be included), and a plurality of upper electrodes and a plurality of piezoelectric elements (for example, a plurality of lower electrodes) are formed. Therefore, unnecessary stress generated by driving the driving portions 252a and 252b of the strain generating element 252 can be more efficiently reduced, and unnecessary distortion can be suppressed. .

  Further, since the frame side leaf springs 244 are arranged in parallel in a branched state, unnecessary stress caused by driving of the drive parts 252a and 252b of the strain generating element 252 can be more efficiently reduced, which is not necessary. Necessary distortion can be suppressed. The groove 270 in the frame side leaf spring portion 244 is formed longer in the longitudinal direction than the groove 252c in the drive portions 252a and 252b. For this reason, unnecessary stress generated by driving the drive units 252a and 252b of the strain generating element 252 can be more efficiently reduced, and unnecessary strain can be suppressed.

  Similarly, a strain generating element 256 is attached to the frame side leaf spring portion 244. As described above, the strain generating element 256 includes the piezoelectric element 260, the upper electrode 262, and the lower electrode 264 (see FIG. 13). As shown in FIG. 15A, the strain generating elements 252 and 256 are formed with grooves 256c in the longitudinal direction, and are branched as a plurality of drive units 256a and 256b. Further, the frame side leaf spring portion 244 is also formed with a groove 274 that is continuous with the groove 256c. Further, the groove 274 is formed in a shape longer in the longitudinal direction than the groove 256c. For this reason, the same effect as described above can be obtained.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and various embodiments can be made based on the knowledge of those skilled in the art including the aspects described in the section of the disclosure of the invention. The present invention can be implemented in other forms that have been modified or improved. For example, it goes without saying that the optical scanning apparatus to which the present invention is applied can also be applied to an optical scanning apparatus that scans a laser beam in a laser printer. The focus changing apparatus to which the present invention is applied is a mechanism for adjusting the focus by moving a lens or a mirror in an optical mechanism such as an image projection apparatus (for example, a projector) or various imaging apparatuses (for example, a digital camera), or a mechanism for performing a zoom adjustment. It can also be applied to.

It is explanatory drawing which shows the retinal scanning display 1 in this embodiment. It is explanatory drawing which shows the wavefront curvature modulation system 100 in this embodiment. It is a perspective view which shows the movable mirrors 103 and 143 in this embodiment, and the movable mirror 183 in the past. It is explanatory drawing which shows the piezoelectric actuator 109 in this embodiment. It is explanatory drawing which looked at the piezoelectric actuator 109 in this embodiment from the longitudinal direction. It is explanatory drawing which shows the piezoelectric actuator 109 in this embodiment. It is explanatory drawing which shows the simulation result which computed the piezoelectric actuator 109 in this embodiment, and the stress with respect to the displacement. It is explanatory drawing which shows the manufacturing method of the piezoelectric actuator 109 in this embodiment. It is explanatory drawing which shows the manufacturing method of the piezoelectric actuator 109 in this embodiment. It is explanatory drawing which shows the manufacturing method of the piezoelectric actuator 109 in this embodiment. It is explanatory drawing which shows the piezoelectric actuator 109 in this embodiment. It is a perspective view which shows the optical scanner 204 in this embodiment. It is explanatory drawing which shows the vibrating body 224 in this embodiment. It is a perspective view which shows the vibrating body 224 in this embodiment. It is a perspective view which shows the vibrating body 224 in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Retina scanning display 19 Horizontal scanning system 20 1st relay optical system 21 Vertical scanning system 22 2nd relay optical system 24 Pupil 100 Wavefront curvature modulation system 101 Beam splitter 102 Convex lens 103 Movable mirror 106 Driving circuit 108, 222 Reflecting mirror part 108a , 220 Reflecting surface 109 Piezoelectric actuator 111, 112, 250, 252, 254, 256 Strain generating element 111a, 112a Fixed part 111b, 111c, 111d, 112b, 112c, 112d, 252a, 252b, 256a, 256b Drive part 111e, 112e 113a, 113b, 252c, 256c, 270, 274 Groove 113 Elastic member 114 Frame 131, 264 Lower electrode 132, 260 Piezoelectric element 133, 262 Upper electrode 204 Optical scanner 224 Vibration body 244 Frame side leaf spring

Claims (14)

In the actuator in which the elastic member can be deformed by driving the drive unit of the strain element by applying a voltage to the strain element supported by the elastic member.
An actuator characterized in that a plurality of drive units to which in-phase voltages are applied in the strain generating element are arranged in parallel with the elastic member.   2. The actuator according to claim 1, wherein the plurality of driving units are formed by branching the strain generating element into a plurality of parts.   The actuator according to claim 1, wherein the plurality of driving units are arranged in parallel to a driving surface including a driving direction. The strain generating element is:
An upper electrode to which the in-phase voltage is applied;
A lower electrode supported by the elastic member and applied with a voltage different from the in-phase voltage;
A piezoelectric element sandwiched between the upper electrode and the lower electrode,
A groove is formed in each of the upper electrode and the piezoelectric element, or the upper electrode, the piezoelectric element, and the lower electrode, and a plurality of upper electrodes and a plurality of piezoelectric elements, or a plurality of upper electrodes, a plurality of The actuator according to claim 1, wherein the actuator is branched as a piezoelectric element and a plurality of lower electrodes.   The actuator according to claim 4, wherein the elastic members are juxtaposed in a state of being branched into a plurality of branches.   The actuator according to claim 4 or 5, wherein the plurality of driving units in the strain-generating element are driven by applying a voltage between the upper electrode and the lower electrode. In the method of manufacturing an actuator in which the elastic member is deformable by driving a driving unit of the strain generating element by applying a voltage to the strain generating element supported by the elastic member.
A method for manufacturing an actuator, comprising: a plurality of driving units to which in-phase voltages are applied in the strain generating element; The elastic member is branched into a plurality by etching,
8. A plurality of lower electrodes, a plurality of piezoelectric elements, and a plurality of upper electrodes are sequentially formed on the elastic member by sequentially laminating a lower electrode layer, a piezoelectric element layer, and an upper electrode layer. A manufacturing method of the actuator described in 1. On the elastic member, a lower electrode layer, a piezoelectric element layer, and an upper electrode layer are sequentially laminated to form a lower electrode, a piezoelectric element, and an upper electrode in order,
The actuator manufacturing method according to claim 7, wherein a plurality of upper electrodes and a plurality of piezoelectric elements are formed by forming grooves in at least the upper electrode and the piezoelectric elements. By laminating a lower electrode layer on the elastic member, a lower electrode is formed,
A plurality of piezoelectric elements are formed by performing masking at a predetermined interval on the lower electrode and laminating piezoelectric element layers,
The method for manufacturing an actuator according to claim 7, wherein a plurality of upper electrodes are formed by laminating an upper electrode layer on the plurality of piezoelectric element layers.   11. The plurality of upper electrodes are formed by masking each edge on the plurality of piezoelectric elements and laminating an upper electrode layer on the plurality of piezoelectric elements. A manufacturing method of the actuator described in 1.   A focus variable apparatus comprising the actuator according to claim 1.   An optical scanning device comprising the actuator according to claim 1.   An image display device comprising either or both of the variable focus device according to claim 12 and the optical scanning device according to claim 13.

Images