JP6926625B2 - Piezoelectric actuators, optical deflectors and image projection devices - Google Patents

Description

The present invention relates to piezoelectric actuators, light deflectors and image projection devices.

In recent years, the development of piezoelectric actuators including piezoelectric materials has been actively carried out.

For example, Patent Document 1 discloses a piezoelectric actuator in which a first electrode, a piezoelectric body, and a second electrode are provided in this order on a beam whose end is connected to a member.

However, in the conventional piezoelectric actuator such as the piezoelectric actuator disclosed in Patent Document 1, there is room for improvement in obtaining the desired power performance in a stable manner.

The present invention is provided on a beam having an end connected to a member, at least a first electrode provided on the beam, a piezoelectric body provided on the first electrode, and a piezoelectric body provided on the piezoelectric body. The first electrode is provided with a second electrode, the first electrode is projected onto the member , the piezoelectric body is projected on the member, and the second electrode is not projected on the member. It is a piezoelectric actuator characterized by this.

According to the present invention, desired power performance can be stably obtained.

It is the schematic of an example of an optical scanning system. It is a hardware block diagram of an example of an optical scanning system. It is a functional block diagram of an example of a control device. It is a flowchart of an example of the process which concerns on an optical scanning system. It is a schematic diagram of an example of an automobile equipped with a head-up display device. It is the schematic of an example of a head-up display device. It is a schematic diagram of an example of an image forming apparatus equipped with an optical writing apparatus. It is a schematic diagram of an example of an optical writing device. It is a schematic diagram of an example of an automobile equipped with a laser radar device. It is the schematic of an example of a laser radar apparatus. It is a schematic diagram of an example of a packaged movable device. It is a top view when viewed from the + Z direction as an example of a movable device. FIG. 12 is a cross-sectional view taken along the line PP ′ of FIG. 13 (a) and 13 (b) show Comparative Examples 1 and 2, respectively, and FIG. 13 (c) shows an embodiment of the present embodiment. It is a cross-sectional view of QQ'of FIG. FIG. 12 is a cross-sectional view taken along the line RR'of FIG. 15 (a) and 15 (b) show Comparative Examples 1 and 2, respectively, and FIG. 15 (c) shows an embodiment of the present embodiment. It is a top view of the S region of FIG. 16 (a) and 16 (b) show Comparative Examples 1 and 2, respectively, and FIG. 16 (c) shows an embodiment of the present embodiment. It is a top view of the T region of FIG. 17 (a) and 17 (b) show Comparative Examples 1 and 2, respectively, and FIG. 17 (c) shows an embodiment of the present embodiment. 18 (a) to 18 (d) are schematic views (Nos. 1 to 4) for explaining the deformation operation of the second drive unit 130b of the movable device, respectively. FIG. 19A is an example of the waveform of the drive voltage A applied to the piezoelectric drive unit group A of the movable device, and FIG. 19B is an example of the drive voltage B applied to the piezoelectric drive unit group B of the movable device. As an example of the waveform, FIG. 19 (c) is a diagram in which the waveform of the drive voltage of FIG. 19 (a) and the waveform of the drive voltage of FIG. 19 (b) are superimposed. It is a schematic diagram schematically showing the twist deformation of the 2nd piezoelectric drive part 131b to 131e and the 2nd support part 141bc to 141de of the movable device. It is a schematic diagram which schematically represented the optical scanning locus by a biaxial optical deflector. It is a schematic diagram which schematically represented the resonance peak of the reflection mirror of a movable device. It is a figure which shows the resonance peak of the reflection mirror of a movable device. The solid line shows an embodiment of this embodiment, and the broken line shows a conventional example. This is an example of a movable device to which the present invention is applied. This is an example of a movable device for light deflection to which the present invention is applied. This is an example of a movable device for light deflection to which the present invention is applied. This is an example of a movable device for light deflection to which the present invention is applied. 28 (a) and 28 (b) are diagrams for explaining modified examples (No. 1 and No. 2) of the first piezoelectric drive unit. 29 (a) and 29 (b) are diagrams for explaining modified examples (No. 3 and No. 4) of the first piezoelectric drive unit. It is a figure for demonstrating the modification (No. 5) of the 1st piezoelectric drive part. 31 (a) and 31 (b) are diagrams for explaining modified examples (No. 1 and No. 2) of the second piezoelectric drive unit. 32 (a) and 32 (b) are diagrams for explaining modified examples (No. 3 and No. 4) of the second piezoelectric drive unit. It is a figure for demonstrating the modification (6) of the 1st piezoelectric drive part. It is a figure for demonstrating the comparative example with respect to the modification (6) of the 1st piezoelectric drive part.

Hereinafter, embodiments of the present invention will be described in detail.

[Optical scanning system]
First, the optical scanning system to which the control device of the present embodiment is applied will be described in detail with reference to FIGS. 1 to 4.
FIG. 1 shows a schematic diagram of an example of an optical scanning system.
As shown in FIG. 1, the optical scanning system 10 is a system in which the light emitted from the light source device 12 is deflected by the reflecting surface 14 of the movable device 13 under the control of the control device 11 to lightly scan the scanned surface 15. be.

The optical scanning system 10 includes a control device 11, a light source device 12, and a movable device 13 having a reflecting surface 14.

The control device 11 is an electronic circuit unit including, for example, a CPU (Central Processing Unit) and an FPGA (Field-Programmable Gate Array). The movable device 13 is, for example, a MEMS (Micro Electromechanical Systems) device having a reflecting surface 14 and capable of moving the reflecting surface 14. The light source device 12 is, for example, a laser device that irradiates a laser. The surface to be scanned 15 is, for example, a screen.

The control device 11 generates a control command for the light source device 12 and the movable device 13 based on the acquired optical scanning information, and outputs a drive signal to the light source device 12 and the movable device 13 based on the control command.
The light source device 12 irradiates the light source based on the input drive signal. The movable device 13 moves the reflecting surface 14 in at least one of the uniaxial direction and the biaxial direction based on the input drive signal.

As a result, for example, by controlling the control device 11 based on the image information which is an example of the optical scanning information, the reflecting surface 14 of the movable device 13 is reciprocated in a predetermined range in the biaxial direction and is incident on the reflecting surface 14. An arbitrary image can be projected on the surface to be scanned 15 by deflecting the irradiation light from the light source device 12 around a certain axis and scanning the light.
The details of the movable device and the details of the control by the control device of the present embodiment will be described later.

Next, the hardware configuration of an example of the optical scanning system 10 will be described with reference to FIG.
FIG. 2 is a hardware configuration diagram of an example of the optical scanning system 10.
As shown in FIG. 2, the optical scanning system 10 includes a control device 11, a light source device 12, and a movable device 13, each of which is electrically connected.
Of these, the control device 11 includes a CPU 20, a RAM 21 (Random Access Memory), a ROM 22 (Read Only Memory), an FPGA 23, an external I / F 24, a light source device driver 25, and a movable device driver 26.

The CPU 20 is an arithmetic unit that reads programs and data from a storage device such as the ROM 22 onto the RAM 21 and executes processing to realize overall control and functions of the control device 11.

The RAM 21 is a volatile storage device that temporarily holds programs and data.

The ROM 22 is a non-volatile storage device that can retain programs and data even when the power is turned off, and stores processing programs and data executed by the CPU 20 to control each function of the optical scanning system 10. There is.

The FPGA 23 is a circuit that outputs a control signal suitable for the light source device driver 25 and the movable device driver 26 according to the processing of the CPU 20.

The external I / F 24 is, for example, an interface with an external device, a network, or the like. The external device includes, for example, a host device such as a PC (Personal Computer) and a storage device such as a USB memory, an SD card, a CD, a DVD, an HDD, and an SSD. The network is, for example, a CAN (Controller Area Network) of an automobile, a LAN (Local Area Network), the Internet, or the like. The external I / F 24 may have a configuration that enables connection or communication with an external device, and an external I / F 24 may be prepared for each external device.

The light source device triber is an electric circuit that outputs a drive signal such as a drive voltage to the light source device 12 according to an input control signal.

The movable device driver 26 is an electric circuit that outputs a drive signal such as a drive voltage to the movable device 13 according to an input control signal.

In the control device 11, the CPU 20 acquires optical scanning information from the external device or network via the external I / F 24. The configuration may be such that the CPU 20 can acquire the optical scanning information, and the optical scanning information may be stored in the ROM 22 or FPGA 23 in the control device 11, or the SSD or the like may be newly stored in the control device 11. A storage device may be provided and the optical scanning information may be stored in the storage device.

Here, the optical scanning information is information indicating how the surface to be scanned 15 is optical-scanned. For example, when displaying an image by optical scanning, the optical scanning information is image data. Further, for example, when optical writing is performed by optical scanning, the optical scanning information is write data indicating the writing order and the writing location. In addition, for example, when object recognition is performed by optical scanning, the optical scanning information is irradiation data indicating the timing and irradiation range of irradiating the light for object recognition.

The control device 11 according to the present embodiment can realize the functional configuration described below by the instruction of the CPU 20 and the hardware configuration shown in FIG.

Next, the functional configuration of the control device 11 of the optical scanning system 10 will be described with reference to FIG. FIG. 3 is a functional block diagram of an example of a control device for an optical scanning system.

As shown in FIG. 3, the control device 11 has a control unit 30 and a drive signal output unit 31 as functions.

The control unit 30 is realized by, for example, a CPU 20, an FPGA 23, or the like, acquires optical scanning information from an external device, converts the optical scanning information into a control signal, and outputs the optical scanning information to the drive signal output unit 31. For example, the control unit 30 acquires image data as optical scanning information from an external device or the like, generates a control signal from the image data by a predetermined process, and outputs the control signal to the drive signal output unit 31.
The drive signal output unit 31 is realized by the light source device 12 driver 25, the movable device 13 driver 26, and the like, and outputs a drive signal to the light source device 12 or the movable device 13 based on the input control signal.

The drive signal is a signal for controlling the drive of the light source device 12 or the movable device 13. For example, in the light source device 12, it is a drive voltage that controls the irradiation timing and irradiation intensity of the light source. Further, for example, in the movable device 13, it is a drive voltage that controls the timing and the movable range of moving the reflective surface 14 included in the movable device 13.

Next, the process of optical scanning the surface to be scanned 15 by the optical scanning system 10 will be described with reference to FIG. FIG. 4 is a flowchart of an example of processing related to the optical scanning system.

In step S11, the control unit 30 acquires optical scanning information from an external device or the like.
In step S12, the control unit 30 generates a control signal from the acquired optical scanning information and outputs the control signal to the drive signal output unit 31.
In step S13, the drive signal output unit 31 outputs a drive signal to the light source device 12 and the movable device 13 based on the input control signal.
In step 14, the light source device 12 irradiates light based on the input drive signal. Further, the movable device 13 moves the reflecting surface 14 based on the input drive signal. By driving the light source device 12 and the movable device 13, light is deflected in an arbitrary direction and light-scanned.

In the optical scanning system 10, one control device 11 has a device and a function of controlling the light source device 12 and the movable device 13, but the control device for the light source device and the control device for the movable device It may be provided separately.

Further, in the optical scanning system 10, one control device 11 is provided with the functions of the control unit 30 of the light source device 12 and the movable device 13 and the functions of the drive signal output unit 31, but these functions exist as separate bodies. For example, a drive signal output device having a drive signal output unit 31 may be provided separately from the control device 11 having the control unit 30. In the optical scanning system 10, a movable device 13 having a reflecting surface 14 and a control device 11 may form an optical deflection system that performs optical deflection.

[Image projection device]
Next, the image projection device to which the control device of the present embodiment is applied will be described in detail with reference to FIGS. 5 and 6.

FIG. 5 is a schematic view of an embodiment of an automobile 400 equipped with a head-up display device 500, which is an example of an image projection device. Further, FIG. 6 is a schematic view of an example of the head-up display device 500.

The image projection device is a device that projects an image by optical scanning, for example, a head-up display device.

As shown in FIG. 5, the head-up display device 500 is installed near, for example, a windshield (windshield 401, etc.) of an automobile 400. The projected light L emitted from the head-up display device 500 is reflected by the windshield 401 and heads toward the observer (driver 402) who is the user. As a result, the driver 402 can visually recognize the image or the like projected by the head-up display device 500 as a virtual image. A combiner may be installed on the inner wall surface of the windshield so that the user can visually recognize the virtual image by the projected light reflected by the combiner.

As shown in FIG. 6, in the head-up display device 500, laser light is emitted from red, green, and blue laser light sources 501R, 501G, and 501B. The emitted laser light passes through an incident optical system composed of collimator lenses 502, 503, 504 provided for each laser light source, two dichroic mirrors 505, 506, and a light amount adjusting unit 507. It is deflected by a movable device 13 having a reflecting surface 14. Then, the deflected laser beam is projected onto the screen via a projection optical system composed of a free curved mirror 509, an intermediate screen 510, and a projection mirror 511. In the head-up display device 500, the laser light sources 501R, 501G, 501B, the collimator lenses 502, 503, 504, and the dichroic mirrors 505 and 506 are unitized by an optical housing as a light source unit 530.

The head-up display device 500 projects the intermediate image displayed on the intermediate screen 510 onto the windshield 401 of the automobile 400, so that the driver 402 visually recognizes the intermediate image as a virtual image.

The laser light of each color emitted from the laser light sources 501R, 501G, and 501B is regarded as substantially parallel light by the collimator lenses 502, 503, and 504, respectively, and is combined by two dichroic mirrors 505 and 506. The combined laser light is two-dimensionally scanned by the movable device 13 having the reflecting surface 14 after the light amount is adjusted by the light amount adjusting unit 507. The projected light L two-dimensionally scanned by the movable device 13 is reflected by the free-form surface mirror 509, corrected for distortion, and then condensed on the intermediate screen 510 to display an intermediate image. The intermediate screen 510 is composed of a microlens array in which microlenses are two-dimensionally arranged, and magnifies the projected light L incident on the intermediate screen 510 in microlens units.

The movable device 13 reciprocates the reflecting surface 14 in the biaxial direction, and two-dimensionally scans the projected light L incident on the reflecting surface 14. The drive control of the movable device 13 is performed in synchronization with the light emission timing of the laser light sources 501R, 501G, and 501B.

The head-up display device 500 as an example of the image projection device has been described above, but the image projection device may be a device that projects an image by performing optical scanning by a movable device 13 having a reflecting surface 14. .. For example, it is mounted on a projector that is placed on a desk or the like and projects an image on a display screen, or is mounted on a mounting member mounted on an observer's head or the like, and is projected onto a reflection / transmission screen of the mounting member, or an eyeball is used as a screen. The same can be applied to a head-mounted display device or the like that projects an image.

Further, the image projection device is not only a vehicle or a mounting member, but also, for example, a moving body such as an aircraft, a ship, or a mobile robot, or a work robot that operates a drive target such as a manipulator without moving from the place. It may be mounted on a non-moving body.

[Optical writing device]
Next, an optical writing device as an optical scanning device to which the control device 11 of the present embodiment is applied will be described in detail with reference to FIGS. 7 and 8.

FIG. 7 is an example of an image forming apparatus incorporating the optical writing apparatus 600. Further, FIG. 8 is a schematic view of an example of the optical writing device.

As shown in FIG. 7, the optical writing device 600 is used as a constituent member of an image forming device represented by a laser printer 650 or the like having a printer function using laser light. In the image forming apparatus, the optical writing device 600 performs optical writing on the photoconductor drum by lightly scanning the photoconductor drum which is the surface to be scanned 15 with one or a plurality of laser beams.

As shown in FIG. 8, in the optical writing device 600, the laser light from the light source device 12 such as a laser element passes through an imaging optical system 601 such as a collimator lens and then is transferred by a movable device 13 having a reflecting surface 14. It is deflected in the axial or biaxial direction. Then, the laser beam deflected by the movable device 13 passes through a scanning optical system 602 including a first lens 602a, a second lens 602b, and a reflection mirror portion 602c, and then passes through a surface to be scanned 15 (for example, a photoconductor drum or a photosensitive paper). ) Is irradiated and optical writing is performed. The scanning optical system 602 forms a spot-shaped light beam on the surface to be scanned 15. Further, the movable device 13 having the light source device 12 and the reflecting surface 14 is driven under the control of the control device 11.

As described above, the optical writing device 600 can be used as a constituent member of an image forming device having a printer function by laser light. Further, by making the scanning optical system different so that light scanning can be performed not only in the uniaxial direction but also in the biaxial direction, the laser beam is deflected to the thermal media to scan the light, and the laser label device for printing by heating and the like. It can be used as a constituent member of the image forming apparatus of.

Since the movable device 13 having the reflecting surface 14 applied to the optical writing device consumes less power for driving than the rotating multifaceted mirror using a polygon mirror or the like, the power saving of the optical writing device can be achieved. It is advantageous. Further, since the wind noise when the movable device 13 vibrates is smaller than that of the rotating multifaceted mirror, it is advantageous for improving the quietness of the optical writing device. The optical writing device requires an overwhelmingly smaller installation space than a rotating multifaceted mirror, and the amount of heat generated by the movable device 13 is also small, so that it is easy to miniaturize, which is advantageous for miniaturizing the image forming device. be.

[Object recognition device]
Next, the object recognition device to which the control device of the present embodiment is applied will be described in detail with reference to FIGS. 9 and 10.

FIG. 9 is a schematic view of an automobile equipped with a laser radar device, which is an example of an object recognition device. Further, FIG. 10 is a schematic view of an example of a laser radar device. The laser radar device is also called a lidar (LIDAR: LIGHT Detection And Ranking) device.

The object recognition device is a device that recognizes an object in the target direction, for example, a laser radar device.

As shown in FIG. 9, the laser radar device 700 is mounted on, for example, an automobile 701, and by lightly scanning the target direction and receiving the reflected light from the target object 702 existing in the target direction, the target object is received. Recognize 702.

As shown in FIG. 10, the laser light emitted from the light source device 12 is reflected through an incident optical system composed of a collimating lens 703, which is an optical system in which divergent light is substantially parallel light, and a plane mirror 704. The movable device 13 having the surface 14 scans in one or two axial directions. Then, the object 702 in front of the apparatus is irradiated through the light projecting lens 705 or the like, which is a light projecting optical system. The drive of the light source device 12 and the movable device 13 is controlled by the control device 11. The reflected light reflected by the object 702 is photodetected by the photodetector 709. That is, the reflected light is received by the image pickup device 707 via the condenser lens 706 or the like which is an incident light detection and reception optical system, and the image pickup element 707 outputs the detection signal to the signal processing device 708. The signal processing circuit 708 performs predetermined processing such as binarization and noise processing on the input detection signal, and outputs the result to the distance measuring circuit 710.

In the distance measuring circuit 710, the object is determined by the time difference between the timing when the light source device 12 emits the laser light and the timing when the laser light is received by the photodetector 709, or the phase difference for each pixel of the light receiving image sensor 707. The presence or absence of the 702 is recognized, and the distance information to the object 702 is calculated.

Since the movable device 13 having the reflecting surface 14 is less likely to be damaged and is smaller than the multifaceted mirror, it is possible to provide a compact radar device with high durability. Such a radar A radar device can be attached to, for example, a vehicle, an aircraft, a ship, a robot, or the like, and can lightly scan a predetermined range to recognize the presence or absence of an obstacle and the distance to the obstacle.

In the above-mentioned object recognition device, the laser radar device 700 as an example has been described, but the object recognition device performs optical scanning by controlling the movable device 13 having the reflecting surface 14 by the control device 11, and performs photodetection, and is a photodetector. The device may be any device that recognizes the object 702 by receiving the reflected light, and is not limited to the above-described embodiment.

For example, biometric authentication that recognizes an object by calculating object information such as shape from distance information obtained by light scanning the hand or face and referring to it as a record, or recognizing an intruder by light scanning the target range. It can also be applied to a security sensor, a component of a three-dimensional scanner that calculates and recognizes object information such as a shape from distance information obtained by optical scanning, and outputs it as three-dimensional data.

[Packaging]
Next, the packaging of the movable device controlled by the control device of the present embodiment will be described with reference to FIG.

FIG. 11 is a schematic view of an example of a packaged mobile device.

As shown in FIG. 11, the movable device 13 is attached to the attachment member 802 arranged inside the package member 802, and a part of the package member is covered with the transmission member 803 and sealed to be packaged. NS. Further, the package is sealed with an inert gas such as nitrogen. As a result, deterioration of the movable device 13 due to oxidation is suppressed, and durability against changes in the environment such as temperature is further improved.

The details of the movable device used in the light deflection system, the light scanning system, the image projection device, the light writing device, and the object recognition device described above and the details of the present embodiment will be described with reference to FIGS. 12 to 23. ..

[Movable device]
First, the movable device will be described with reference to FIGS. 12 to 14.

FIG. 12 is a plan view of a cantilever type movable device capable of light deflection in the biaxial direction. FIG. 13 (c) is a cross-sectional view taken along the line PP'of FIG. FIG. 14 is a cross-sectional view taken along the line QQ'of FIG.

As shown in FIG. 12, the movable device 13 has a mirror unit 101 that reflects incident light and a first drive unit 110a that is connected to the mirror unit and drives the mirror unit 101 around a first axis parallel to the Y axis. , 110b, the first support unit 120 that supports the mirror unit 101 and the first drive units 110a, 110b, and the first support unit 120, which are connected to the mirror unit 101, the first drive unit 110a, 110b, and the first support unit. Second drive units 130a and 130b that drive 120 around the second axis parallel to the X axis, second support units 150 that support the second drive units 130a and 130b, and first drive units 110a, 110b and the second. It has drive units 130a and 130b and an electrode connection unit 160 that is electrically connected to the control device 11.

In the movable device 13, for example, one SOI (Silicon On Insulator) substrate is formed by etching or the like, and the reflective surface 14, the first piezoelectric drive units 112a, 112b, and the second piezoelectric drive units 131a to the molded substrate are used. By forming 131f, 132a to 132f, the electrode connecting portion 160, and the like, each constituent portion is integrally formed. The formation of each of the above components may be performed after molding the SOI substrate, or may be performed during molding of the SOI substrate.

In the SOI substrate, a silicon oxide layer 172 is provided on a first silicon layer made of single crystal silicon (Si), and a second silicon layer made of single crystal silicon is further provided on the silicon oxide layer 172. It is a substrate that is used. Hereinafter, the first silicon layer will be referred to as a silicon support layer 171 and the second silicon layer will be referred to as a silicon active layer 173. It is preferable to use the silicon active layer 173 after sintering it. In this case, a thin silicon oxide layer is formed on the surface of the silicon active layer 173, and a short circuit with the electrode can be suppressed.

Since the silicon active layer 173 has a small thickness in the Z-axis direction with respect to the X-axis direction or the Y-axis direction, the member composed of only the silicon active layer 173 has a function as an elastic portion having elasticity.

The SOI substrate does not necessarily have to be flat, and may have a curvature or the like. Further, the member used for forming the movable device 13 is not limited to the SOI substrate as long as it is a substrate that can be integrally molded by etching or the like and can be partially elastic.

The mirror portion 101 is composed of, for example, a circular mirror portion base 102 and a reflection surface 14 formed on the + Z side surface of the mirror portion base. The mirror part substrate 102 is composed of, for example, a silicon active layer 173. The reflective surface 14 is made of, for example, a metal thin film containing aluminum, gold, silver and the like.

The first drive units 110a and 110b have two torsion bars 111a and 112b that are connected to the mirror unit 102 at one end and extend in the first axial direction to movably support the mirror unit 101, and one end is a torsion bar. It is composed of first piezoelectric drive portions 112a and 112b, which are connected and the other end is connected to the inner peripheral portion of the first support portion 120.

As shown in FIG. 13 (c), the torsion bars 111a and 111b are composed of the silicon active layer 173. Further, the first piezoelectric drive portions 112a and 112b are configured by forming the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 in this order on the + Z side surface of the silicon active layer 173, which is an elastic portion that functions as a cantilever. .. The upper electrode 230 and the lower electrode 210 are composed of, for example, gold (Au), platinum (Pt), IrO ₂ (iridium dioxide), SR0 (SrRuO ₃ : strontium ruthenium oxide) and the like. The piezoelectric portion 220 is made of, for example, PZT (lead zirconate titanate), which is a piezoelectric material.

Returning to FIG. 12, the first support portion 120 is a rectangular support formed so as to surround the mirror portion 101, which is composed of, for example, a silicon support layer 171, a silicon oxide layer 172, and a silicon active layer 173.

The second drive units 130a and 130b are composed of, for example, a plurality of second piezoelectric drive units 131a to 131f and 132a to 132f connected so as to be folded back, and one end of the second drive units 130a and 130b is a first support. It is connected to the outer peripheral portion of the portion 120, and the other end is connected to the inner peripheral portion of the second support portion 150. At this time, the connection points between the second drive unit 130a and the first support unit 120, the connection points between the second drive unit 130b and the first support unit 120, the connection points between the second drive unit 130a and the second support unit 150, and the second support unit 150. The connection points between the two drive units 130b and the second support unit 150 are point-symmetrical with respect to the center of the reflection surface 14.

As shown in FIG. 14, the second piezoelectric drive portions 130a and 130b have the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 in this order on the + Z side surface of the silicon active layer 173, which is an elastic portion that functions as a cantilever. It is formed and composed. The upper electrode 230 and the lower electrode 210 are made of, for example, gold (Au) or platinum (Pt). The piezoelectric portion 220 is made of, for example, PZT (lead zirconate titanate), which is a piezoelectric material.

Returning to FIG. 12, the second support portion 150 is composed of, for example, a silicon support layer 171, a silicon oxide layer 172, and a silicon active layer 173, and includes a mirror portion 101, first drive portions 110a and 110b, and a first support portion 120. It is a rectangular support formed so as to surround the second drive units 130a and 130b.

The electrode connection portion 160 is formed, for example, on the + Z side surface of the second support portion 150, and the upper electrodes 230 of the first piezoelectric drive portions 112a and 112b, the second piezoelectric drive portions 131a to 131f, and 132a to 132f are formed. It is electrically connected to each lower electrode 210 and the control device 11 via electrode wiring such as aluminum (Al). The upper electrode 230 or the lower electrode 210 may be directly connected to the electrode connecting portion, or may be indirectly connected by connecting the electrodes to each other.

In the present embodiment, the case where the piezoelectric portion 220 is formed only on one surface (the surface on the + Z side) of the silicon active layer 173 which is the elastic portion has been described as an example, but the other surface of the elastic portion (for example, −Z) has been described as an example. It may be provided on the side surface), or may be provided on both one surface and the other surface of the elastic portion.

Further, the shape of each component is not limited to the shape of the embodiment as long as the mirror portion can be driven around the first axis or the second axis. For example, the torsion bars 111a and 111b and the first piezoelectric drive units 112a and 112b may have a shape having a curvature.

Further, on the + Z side surface of the upper electrodes 230 of the first drive units 110a and 110b, on the + Z side surface of the first support portion, on the + Z side surface of the upper electrodes 230 of the second drive units 130a and 130b, and so on. An insulating layer made of a silicon oxide film may be formed on at least one of the + Z-side surfaces of the support portion. At this time, the electrode wiring is provided on the insulating layer, and the insulating layer is partially removed or the insulating layer is not formed as an opening only in the connection spot where the upper electrode 230 or the lower electrode 210 and the electrode wiring are connected. This makes it possible to increase the degree of design freedom of the first drive units 110a and 110b, the second drive units 130a and 130b, and the electrode wiring, and further suppress short circuits due to contact between the electrodes. The silicon oxide film also has a function as an antireflection material.

[Details of control device control]
Next, the details of the control of the control device for driving the first drive unit and the second drive unit of the movable device will be described.

When a positive or negative voltage is applied in the polarization direction, the piezoelectric portion 220 included in the first drive units 110a and 110b and the second drive units 130a and 130b undergoes deformation (for example, expansion and contraction) proportional to the potential of the applied voltage. , So-called inverse piezoelectric effect is exhibited. The first drive units 110a and 110b and the second drive units 130a and 130b move the mirror unit 101 by utilizing the above-mentioned inverse piezoelectric effect.

At this time, the angle at which the light flux incident on the reflecting surface 14 of the mirror portion 101 is deflected (deflection angle) is called a deflection angle. This runout angle is set to zero when no voltage is applied to the piezoelectric portion, a positive runout angle when the deflection angle is larger than that angle, and a negative runout angle when the deflection angle is smaller than that angle.

First, the control of the control device for driving the first drive unit will be described.
In the first drive units 110a and 110b, when a drive voltage is applied in parallel to the piezoelectric units 220 of the first piezoelectric drive units 112a and 112b via the upper electrode 230 and the lower electrode 210, the respective piezoelectric units 220 Deform. Due to the action of the deformation of the piezoelectric portion 220, the first piezoelectric driving portions 112a and 112b are bent and deformed. As a result, a driving force around the first axis acts on the mirror portion 101 through the twist of the two torsion bars 111a and 111b, and the mirror portion 101 moves around the first axis. The drive voltage applied to the first drive units 110a and 110b is controlled by the control device 11.

Therefore, the control device 11 applies a drive voltage having a predetermined sine waveform to the first piezoelectric drive units 112a and 112b of the first drive units 110a and 110b in parallel to move the mirror unit 101 around the first axis. It can be moved in a cycle of a drive voltage having a predetermined sinusoidal waveform.

In particular, for example, when the frequency of the sinusoidal waveform voltage is set to about 20 kHz, which is about the same as the resonance frequency of the torsion bars 111a and 111b, mechanical resonance due to the twist of the torsion bars 111a and 111b is utilized. The mirror unit 101 can be resonated and vibrated at about 20 kHz.

[Details of movable device]
FIG. 13 (a) is a cross-sectional view of Comparative Example 1 corresponding to FIG. 13 (c), which is a cross-sectional view taken along the line PP'of FIG. 12 of the present embodiment. FIG. 13 (b) is a cross-sectional view of Comparative Example 2 corresponding to FIG. 13 (c) of the present embodiment. Here, for convenience, in Comparative Examples 1 and 2, the members having the same configuration and function as the movable device 13 of the present embodiment are designated by the same reference numerals as those of the movable device 13.

In Comparative Example 1 shown in FIG. 13A, the lower electrode 210 and the piezoelectric portion 220 are formed on the silicon active layer 173 between the first support portion 120 and the torsion bar 111b in the first piezoelectric drive portion 112b. There is. Similarly, in Comparative Example 1, in the first piezoelectric drive portion 112a, the lower electrode 210 and the piezoelectric portion 220 are formed on the silicon active layer 173 between the first support portion 120 and the torsion bar 111b.

In Comparative Example 2 shown in FIG. 13 (b), in the first piezoelectric drive unit 112b, the lower electrode 210, the piezoelectric unit 220, and the upper electrode 230 have a silicon active layer 173 between the first support portion 120 and the torsion bar 111b. It is formed on the upper and the silicon active layer 173 of the first support portion 120. That is, in Comparative Example 2, the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 of the first piezoelectric drive portion 112b project onto the first support portion 120. Similarly, in Comparative Example 2, the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 of the first piezoelectric drive portion 112a project onto the first support portion 120.

In the present embodiment shown in FIG. 13 (c), in the first piezoelectric drive portion 112b, the lower electrode 210 and the piezoelectric portion 220 are placed on the silicon active layer 173 between the first support portion 120 and the torsion bar 111b and first. It is formed on the silicon active layer 173 of the support portion 120. That is, in the present embodiment, the lower electrode 210 and the piezoelectric portion 220 of the first piezoelectric drive portion 112b project onto the first support portion 120. In FIG. 13C, a reference numeral 211 is attached to a portion on the first support portion 120 of the lower electrode 210 (hereinafter, also referred to as “lower electrode protrusion 1”), and a portion on the first support portion 120 of the piezoelectric portion 220. (Hereinafter, also referred to as “piezoelectric portion protruding portion 1”) is designated by reference numeral 221. Similarly, in the present embodiment, the lower electrode 210 and the piezoelectric portion 220 of the first piezoelectric drive portion 112b project onto the first support portion 120.

Here, in both Comparative Examples 1, 2 and the present embodiment, the first piezoelectric hole or notch for connecting the other end of the wiring to which one end is connected to the electrode connecting portion 160 to the lower electrode 210 is provided. It needs to be formed in the drive unit.

16 (a) to 16 (c) are top views of the S region (the region surrounded by the broken line with the symbol S) in FIGS. 1 and 2 and FIG. 12 of the present embodiment, respectively. Here, for convenience, in Comparative Examples 1 and 2, the members having the same configuration and function as the movable device 13 of the present embodiment are designated by the same reference numerals as those of the movable device 13.

In Comparative Example 1, a part of the upper electrode 230 and the piezoelectric portion 220 on the silicon active layer 173 between the first support portion 120 and the torsion bar is removed by, for example, etching to form the contact hole and the notch portion. This is the case (see FIG. 16 (a)). However, in this case, there is a concern that the driving force of the first piezoelectric driving unit is reduced.

In Comparative Example 2, a part of the upper electrode 230 and the piezoelectric portion 220 on the silicon active layer 173 of the first support portion 120 can be removed by, for example, etching to form the contact hole or the notch portion (FIG. 16). (B)). However, in this case, since the drive source including the upper electrode 230, the piezoelectric portion 220, and the lower electrode 210 is on the first support portion 120, the piezoelectric portion is formed when a voltage is applied between the upper electrode 230 and the lower electrode 210. There is a concern that the driving force of 220 acts on the first support portion 120 and unnecessary excitation vibration is generated.

In the present embodiment, a part of the piezoelectric portion 220 (piezoelectric portion protruding portion 1) on the silicon active layer 173 of the first support portion 120 is removed by etching, for example, and the contact hole or notch is formed on the lower electrode protruding portion 1. The portions can be formed (see FIG. 16 (c)). In this case, it is possible to suppress a decrease in the driving force as in Comparative Example 1 and the generation of unnecessary excitation vibration as in Comparative Example 2. In FIG. 16C, the shape of the lower electrode protruding portion 1 and the piezoelectric portion protruding portion 1 is a rectangle, but other shapes such as a polygon other than the rectangle may be used.

FIG. 15 (c) is a cross-sectional view taken along the line RR of FIG. 12 of the present embodiment. 15 (a) is a cross-sectional view corresponding to FIG. 15 (c) of Comparative Example 1, and FIG. 15 (b) is a cross-sectional view corresponding to FIG. 15 (c) of Comparative Example 2. Here, for convenience, in Comparative Examples 1 and 2, the members having the same configuration and function as the movable device 13 of the present embodiment are designated by the same reference numerals as those of the movable device 13.

As shown in FIG. 15, each second piezoelectric drive portion is formed in the order of the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 on the + Z side surface of the silicon active layer 173, which is an elastic portion that functions as a cantilever. It is composed of. The connecting portions 141ab to 141ef and 142ab to 142ef that connect the second piezoelectric drive portions 131a to 131f and 132a to 132f in a folded shape are formed of, for example, a silicon active layer 173. It may be composed of a silicon support layer and a silicon oxide layer.

In Comparative Example 1 shown in FIG. 15 (a), in the second piezoelectric drive unit 131c, the lower electrode 210 and the piezoelectric unit 220 are formed on the silicon active layer 173 between the two corresponding connecting portions 141bc and 141cd. Similarly, in Comparative Example 1, in the other second piezoelectric drive portion, the lower electrode 210 and the piezoelectric portion 220 are formed on the silicon active layer 173 between the corresponding two connecting portions.

In Comparative Example 2 shown in FIG. 15B, in the second piezoelectric drive unit 131c, the lower electrode 210, the piezoelectric unit 220, and the upper electrode 230 correspond to each other on the silicon active layer 173 and between the two connecting portions 141bc and 141cd. It is formed on the silicon active layer 173 of the portion 141bc and on the silicon active layer 173 of the connecting portion 141cd. That is, in Comparative Example 2, the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 of the second piezoelectric drive unit 131c project onto the corresponding two connecting portions 141bc and 141cd. Similarly, in Comparative Example 2, the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 of the other second piezoelectric drive unit project onto the corresponding two connecting portions.

In the present embodiment shown in FIG. 15 (c), in the second piezoelectric drive unit 131c, the lower electrode 210 and the piezoelectric portion 220 are formed on the silicon active layer 173 between the two corresponding connecting portions 141bc and 141cd and the connecting portion 141bc. It is formed on the silicon active layer 173 and on the silicon active layer 173 of the connecting portion 141cd. That is, in the present embodiment, the lower electrode 210 and the piezoelectric portion 220 of the second piezoelectric drive portion 131c project onto the corresponding two connecting portions 141bc and 141cd. In FIG. 15C, a reference numeral 211 is attached to a portion on the connecting portion of the lower electrode 210 (hereinafter, also referred to as “lower electrode protruding portion 2”), and a portion on the connecting portion of the piezoelectric portion 220 (“piezoelectric portion in the following”). Reference numeral 221 is attached to (also referred to as a protruding portion 2). Similarly, in Comparative Example 3, the lower electrode 210 and the piezoelectric portion 220 of the other second piezoelectric drive portion project onto the corresponding two connecting portions.

Here, in both Comparative Examples 1, 2 and this embodiment, the second piezoelectric hole or notch for connecting the other end of the wiring to which one end is connected to the electrode connecting portion 160 to the lower electrode 210 is provided. It needs to be formed in the drive unit.

16 (a) to 16 (c) are top views of the T region (the region surrounded by the broken line with the reference numeral T) in FIGS. 1 and 2 and FIG. 12 of the present embodiment, respectively. Here, for convenience, in Comparative Examples 1 and 2, the members having the same configuration and function as the movable device 13 of the present embodiment are designated by the same reference numerals as those of the movable device 13.

In Comparative Example 1, a part of the upper electrode 230 and the piezoelectric portion 220 on the silicon active layer 173 between the two connecting portions is removed to form the contact hole and the notch portion (FIG. 17 (a)). reference). However, in this case, there is a concern that the driving force of the second piezoelectric driving unit is reduced.

In Comparative Example 2, the contact hole and the notch portion can be formed by removing a part of the upper electrode 230 and the piezoelectric portion 220 on the silicon active layer 173 of the two connecting portions (see FIG. 17B). ). However, in this case, since the drive source including the upper electrode 230, the piezoelectric portion 220, and the lower electrode 210 is located on each connecting portion, the piezoelectric portion 220 of the piezoelectric portion 220 when a voltage is applied between the upper electrode 230 and the lower electrode 210. There is a concern that the driving force acts on the connecting portion and unnecessary excitation vibration is generated.

In the present embodiment, a part of the piezoelectric portion 220 (piezoelectric portion protruding portion 2) on the silicon active layer 173 of the two connecting portions is removed to form the contact hole and the notch portion on the lower electrode protruding portion 2. Can be done (see FIG. 17 (c)). In this case, it is possible to suppress a decrease in the driving force as in Comparative Example 1 and the generation of unnecessary excitation vibration as in Comparative Example 2. In FIG. 17C, the shape of the lower electrode protruding portion 2 and the piezoelectric portion protruding portion 2 is a rectangle, but other shapes such as a polygon other than the rectangle may be used. In FIG. 17, the wiring connected to the upper electrode 230 is omitted.

The surface of the upper electrode 230 of the first piezoelectric drive unit on the + Z side, the surface of the first support portion on the + Z side, the surface of the upper electrode 230 of the second piezoelectric drive unit on the + Z side, and the + Z side of the connecting portion. An insulating layer made of a silicon oxide film may be formed on at least one of the + Z-side surfaces of the third support portion. At this time, the electrode wiring is provided on the insulating layer, and the insulating layer is partially removed or the insulating layer is not formed as an opening only in the connection spot where the upper electrode 230 or the lower electrode 210 and the electrode wiring are connected. This makes it possible to increase the degree of freedom in designing the first piezoelectric drive unit, the second piezoelectric drive unit, and the electrode wiring, and further suppress short circuits due to contact between the electrodes. The silicon oxide film as an insulating layer also has a function as an antireflection material.

In the present embodiment, the case where the piezoelectric portion 220 is formed only on one surface (the surface on the + Z side) of the silicon active layer 173 which is the elastic portion has been described as an example, but the other surface of the elastic portion (for example, −Z) has been described as an example. It may be provided on the side surface), or may be provided on both one surface and the other surface of the elastic portion.

Further, the shape of each component is not limited to the shape of the embodiment as long as the mirror portion can be driven around the first axis or the second axis. For example, the torsion bars 111a and 111b and the first piezoelectric drive units 112a and 112b may have a shape having a curvature.

[Details of operation and action / effect of movable device]
Next, a driving method, a rotating state, and actions / effects of the first piezoelectric driving unit and the second piezoelectric driving unit of the movable device 13 will be described.

When a positive or negative voltage is applied in the polarization direction, the piezoelectric portion 220 included in the first drive units 110a and 110b and the second drive units 130a and 130b undergoes deformation (for example, expansion and contraction) proportional to the potential of the applied voltage. , So-called inverse piezoelectric effect is exhibited. The first drive units 110a and 110b and the second drive units 130a and 130b have a Z-direction layer structure of the first piezoelectric drive unit and the second piezoelectric drive unit in conjunction with the piezoelectric unit 220 by utilizing the above-mentioned inverse piezoelectric effect. The silicon active layer 173 contained in the above deforms and expands and contracts. As a result, the mirror portion 101 is moved.

The first piezoelectric drive unit realizes that the reflection mirror reciprocates and rotates around the Y axis in FIG. This is the rotation around the first axis. In the first drive units 110a and 110b, when a drive voltage is applied in parallel to the piezoelectric units 220 of the first piezoelectric drive units 112a and 112b via the upper electrode 230 and the lower electrode 210, the respective piezoelectric units 220 Deform. Due to the action of the deformation of the piezoelectric portion 220, the first piezoelectric driving portions 112a and 112b are bent and deformed. As a result, a driving force around the first axis acts on the mirror portion 101 through the twist of the two torsion bars 111a and 111b, and the mirror portion 101 moves around the first axis. The drive voltage applied to the first drive units 110a and 110b is often a sine wave, and at this time, the mirror unit 101 is rotated by a resonance operation in a cycle of a sine wave drive voltage.

In particular, for example, when the frequency of the sinusoidal waveform voltage is set to about 20 kHz, which is about the same as the resonance frequency of the torsion bars 111a and 111b, mechanical resonance due to the twist of the torsion bars 111a and 111b is utilized. The mirror unit 101 can be resonated and vibrated at about 20 kHz.

When the first drive units 110a and 110b are driven and the mirror unit 101 is rotated, the first support unit 120 serves as a fixed end of the first piezoelectric drive unit. Since the first support portion 120 has a layer continuous with the second piezoelectric drive portion, it is not desirable that the drive source of the first piezoelectric drive portion exists on the first support portion 120. This is because the silicon active layer 173 of the first support portion 120 is continuous with the silicon active layer 173 of the second piezoelectric drive unit. During biaxial operation, the vibration of the first piezoelectric drive unit becomes a vibration crosstalk with respect to the vibration of the second piezoelectric drive unit.

FIG. 18 is a schematic view schematically showing the driving of the second driving unit 130b of the movable device 13. The broken line represents a system that includes the mirror unit 101, the first drive units 110a and 110b, and the first support unit 120 and is movable around the second axis (hereinafter, also referred to as a "movable system around the second axis"). be.

As shown in FIG. 18A, when the drive voltage is not applied to the second drive unit 130b, the runout angle by the second drive unit 130b is zero.

Of the plurality of second piezoelectric drive units 131a to 131f included in the second drive unit 130a of FIG. 12, the second piezoelectric drive unit is even-numbered from the second piezoelectric drive unit (131a) that is closest to the mirror unit 101. That is, the second piezoelectric drive units 131b, 131d, and 131f are designated as the piezoelectric drive unit group A. Further, among the plurality of second piezoelectric drive units 132a to 132f of the second drive unit 130b, the odd-numbered second piezoelectric drive unit counted from the second piezoelectric drive unit (132a) having the closest distance to the mirror unit 101. That is, the second piezoelectric drive units 132a, 132c, and 132e are similarly designated as the piezoelectric drive unit group A. When the drive voltage is applied in parallel to the piezoelectric drive unit group A, as shown in FIG. 18B, the piezoelectric drive unit group A is bent and deformed in the same direction, and the mirror unit 101 is second in the −Z direction. Movable around the axis.

Further, among the plurality of second piezoelectric drive units 131a to 131f included in the second drive unit 130a, the second piezoelectric drive unit, which is an odd number counting from the second piezoelectric drive unit (131a) having the closest distance to the mirror unit 101, That is, the second piezoelectric drive units 131a, 131c, and 131e are designated as the piezoelectric drive unit group B. Further, among the plurality of second piezoelectric drive units 132a to 132f of the second drive unit 130b, the second piezoelectric drive unit, which is an even number from the second piezoelectric drive unit (132a) having the closest distance to the mirror unit, That is, 132b, 132d, and 132f are similarly designated as the piezoelectric drive unit group B. When the drive voltage is applied in parallel to the piezoelectric drive unit group B, as shown in FIG. 18D, the piezoelectric drive unit group B is bent and deformed in the same direction, and the mirror unit 101 is displaced in the + Z direction by the second axis. Movable around.

As shown in FIGS. 18B and 18D, in the second drive unit 130a or the second drive unit 130b, a plurality of piezoelectric units 220 included in the piezoelectric drive unit group A or a plurality of piezoelectric units 220 included in the piezoelectric drive unit group B. By simultaneously bending and deforming the piezoelectric portion 220 of the above, the amount of movement due to the bending deformation can be accumulated, and the runout angle around the X axis by the mirror portion 101 can be increased. This is the rotation around the second axis. For example, as shown in FIG. 12, the second drive units 130a and 130b are connected to the first support unit 120 point-symmetrically with respect to the center point of the first support unit 120. Therefore, when a drive voltage is applied to the piezoelectric drive unit group A, a driving force is generated at the connection portion between the first support unit 120 and the second drive unit 130a in the second drive unit 130a, and a driving force is generated in the second drive unit 130b to move in the + Z direction. A driving force that moves in the −Z direction is generated at the connection portion between the first support portion 120 and the second drive portion 130b, and the amount of movement is accumulated so that the swing angle around the second axis by the mirror portion 101 can be increased.

Further, as shown in FIG. 18C, when the movable amount of the mirror portion 101 by the piezoelectric drive group A due to the voltage application and the movable amount of the mirror portion 101 by the piezoelectric drive group B due to the voltage application are balanced, the runout occurs. The angle is zero.

By applying a drive voltage to the second piezoelectric drive unit so as to continuously repeat FIGS. 18 (b) to 18 (d), the mirror unit 101 can be driven around the second axis. In this case, the drive is not limited to the operation at the resonance frequency peculiar to the structure.

The drive voltage applied to the second piezoelectric drive unit includes a drive voltage applied to the piezoelectric drive unit group A (hereinafter, drive voltage A) and a drive voltage applied to the piezoelectric drive unit group B (hereinafter, drive voltage B). ).

FIG. 19A is an example of the waveform of the drive voltage A applied to the piezoelectric drive unit group A of the movable device 13. FIG. 19B is an example of the waveform B of the drive voltage applied to the piezoelectric drive unit group B of the movable device 13. FIG. 19C is a diagram in which the waveform of the drive voltage A and the waveform of the drive voltage B are superimposed.

As shown in FIG. 19A, the drive voltage A applied to the piezoelectric drive unit group A is, for example, a drive voltage having a sawtooth waveform, and the frequency is, for example, 60 Hz. Further, in the waveform of the drive voltage A, the time width of the rising period in which the voltage value increases from the minimum value to the next maximum value is TrA, and the falling period in which the voltage value decreases from the maximum value to the next minimum value. When the time width of is TfA, for example, the ratio of TrA: TfA = 9: 1 is preset. At this time, the ratio of TrA to one cycle is called the symmetry of the drive voltage A.

As shown in FIG. 19B, the drive voltage B applied to the piezoelectric drive unit group B is, for example, a drive voltage having a sawtooth waveform, and the frequency is, for example, 60 Hz. Further, in the waveform of the drive voltage B, the time width of the rising period in which the voltage value increases from the minimum value to the next maximum value is TrB, and the falling period in which the voltage value decreases from the maximum value to the next minimum value. When the time width of is TfB, for example, the ratio of TfB: TrB = 9: 1 is preset. At this time, the ratio of TfB to one cycle is called the symmetry of the drive voltage B. Further, as shown in FIG. 19C, for example, the period TA of the waveform of the drive voltage A and the period TB of the waveform of the drive voltage B are set to be the same.

The sawtooth waveforms of the drive voltage A and the drive voltage B are generated by superimposing sinusoidal waves. Further, in the present embodiment, the drive voltage of the sawtooth waveform is used as the drive voltages A and B, but the present invention is not limited to this, and the drive voltage of the waveform in which the apex of the sawtooth waveform is rounded and the sawtooth waveform are not limited to this. It is also possible to change the waveform according to the device characteristics of the mobile device, such as the drive voltage of the waveform with the linear region of.

As described above, the second drive unit flexes and deforms a plurality of cantilever levers at the same time to accumulate the amount of movement due to the flexion deformation, and further controls the drive signal waveforms input to the piezoelectric drive unit group A and the piezoelectric drive unit group B. This enables non-resonant drive in which a desired runout angle can be obtained.

However, the second drive unit also has a unique resonance frequency of the structure itself. In particular, for example, it is a vibration mode in which the cantilever levers of the second piezoelectric drive units 131a to 131f and 132a to 132f are twisted with the Y axis as the rotation axis. As shown in FIG. 20, each cantilever of the silicon active layer constituting the second piezoelectric drive unit twists around the Y axis. This movement is strengthened by the connecting portions 141ab to 141ef and 142ab to 142ef, which serve as support ends of the second piezoelectric drive portion, vibrating in the + Z direction.

The torsional vibration mode of the second drive unit is superimposed on the rotation around the Y axis, that is, the rotation around the first axis by the first drive unit, and this becomes the vibration crosstalk of the two-axis operation.

As shown in FIG. 21, by operating the first drive unit and the second drive unit at the same time, the light reflected by the mirror unit 101 draws a two-dimensional scanning locus, and an optical scanning device as shown in FIG. 1 is provided. It will be possible to realize. In designing a movable device as a higher-performance optical deflector, it is desirable that the runout angle of the mirror unit 101 has higher sensitivity to voltage and a large runout angle is possible. On the other hand, the above-mentioned problem related to crosstalk during biaxial operation becomes more remarkable as the deflection angle due to the mirror portion is increased. As a result, there are adverse effects such as deterioration of image quality due to unintended fluctuation of scanning lines, optical axis deviation of irradiation light, and vulnerability to environmental vibration. In order to realize a high-quality and highly reliable optical deflector, optical scanning device, image projection device, optical writing device, image forming device, and object recognition device, the movements intended in the first drive unit and the second drive unit are performed. It is desirable to reduce vibration components other than.

In the first piezoelectric drive unit and the second piezoelectric drive unit, the piezoelectric portion is sandwiched between the upper electrode and the lower electrode, and this serves as a drive source. Then, by connecting the electric wiring to the drive source, the function as a piezoelectric actuator is realized. At this time, it is desirable that the drive source composed of the piezoelectric portion 220, the upper electrode 230, and the lower electrode 210 has a large area, but the presence of the drive source in the member that originally corresponds to the support frame of the drive portion is the first. Unintended vibrations can be induced in the drive unit and the second drive unit, and vibration crosstalk associated therewith can be generated.

FIG. 22 shows a schematic diagram of the peak of the resonance sensitivity corresponding to the rotation of the mirror unit 101 by the first drive unit and the crosstalk peak due to the torsional vibration in the second drive unit. The resonance frequency observed with the deflection angle by the mirror unit 101 when fm drives the first drive unit as the vertical axis, and fd is the vibration crosstalk due to the torsional vibration when the second drive unit is driven, and the mirror unit 101. It is a resonance frequency observed with the deflection angle due to the vertical axis.

FIG. 23 compares the resonance peaks of the conventional optical deflector and the movable device 13 as the optical deflector of the present embodiment when the vibration mode and frequency as shown in FIG. 22 exist. Similar to FIG. 22, FIG. 23 shows the resonance frequency characteristic of the deflection angle due to the mirror portion. The solid line is the frequency dependence of the resonance runout angle in one embodiment of the present embodiment, and the broken line is the frequency dependence of the resonance runout angle in the conventional example. In one embodiment of the present embodiment, the peak value of fd was reduced, and the vibration crosstalk generated during the biaxial operation of the optical deflector could be reduced.

By obtaining the results shown in FIG. 23, the optical deflectors can ensure the rotational operation in the two-dimensional directions independent of each other, and the piezoelectric cantilever region of the drive unit can be fully utilized.

The piezoelectric actuators (first piezoelectric drive unit and second piezoelectric drive unit) of the present embodiment described above have a cantilever (beam) in which one end and the other end are connected to the first and second members, respectively, and at least on the cantilever. The lower electrode 210 (first electrode) provided on the lower electrode 210, the piezoelectric portion 220 (piezoelectric body) provided on the lower electrode 210, and the upper electrode 230 (second electrode) provided on the piezoelectric portion 220. The lower electrode 210 projects above at least one of the first and second members. Examples of the first and second members include torsion bars 111a and 111b, a first support portion 120, a connecting portion, and a second support portion 150.

In this case, the lower electrode 210 projecting above at least one of the first and second members without providing a drive source including the lower electrode 210, the piezoelectric portion 220, and the upper electrode 230 on the first and second members. Wiring can be connected.

As a result, the generation of unnecessary excitation vibration can be suppressed, and a desired driving force can be obtained.

As a result, according to the piezoelectric actuator of the present embodiment, desired power performance (driving performance) can be stably obtained.

Further, the piezoelectric portion 220 projects above at least one of the first and second members, and the second electrode does not project above at least one of the first and second members.

Further, the protruding portion of the lower electrode 210 (protruding portion of the lower electrode) has a region in which the protruding portion of the piezoelectric portion 220 (protruding portion of the piezoelectric portion) is not provided, and it is preferable that the wiring is connected to this region.

Further, the upper electrode 230, the lower electrode 210, and the piezoelectric portion 220 have dissimilar shapes.

Further, the portion provided on the cantilever of the piezoelectric portion 220 is larger than the protruding portion (protruding portion of the piezoelectric portion) of the piezoelectric portion 220.

Further, the portion provided on the cantilever of the lower electrode 210 is larger than the protruding portion (lower electrode protruding portion) of the lower electrode 210.

Further, it is preferable that the cantilever is provided with a vibration sensor for detecting the vibration of the cantilever. This vibration sensor can be realized by the same configuration as the piezoelectric actuator of the present embodiment.

The piezoelectric actuator of the present embodiment can be applied not only to an optical deflector and a vibration sensor, but also to all devices that utilize the piezoelectric effect.

Further, the piezoelectric actuator of the present embodiment, a torsion bar connected to one end of the cantilever of the piezoelectric actuator, a support portion 120 for supporting the other end of the cantilever, and a mirror portion 101 connected to the torsion bar are provided. According to the movable device 13, a desired swing angle can be obtained, and an optical deflector with high operation reliability can be realized.

Further, a drive system including a plurality of piezoelectric actuators of the present embodiment in which cantilever levers are connected to each other via a connecting portion so as to form a meandering structure (manda shape) as a whole, and a drive system including one end of the drive system. According to the movable device 13 including the movable system around the second axis (movable system) including the mirror portion 101 and the second support portion 150 that supports the other end of the drive system, a desired deflection angle can be obtained and An optical deflector with high operational reliability can be realized.

Further, the movable system further includes a torsion bar connected to the mirror portion 101, a piezoelectric actuator of the present embodiment in which one end of the cantilever is connected to the torsion bar, and a support portion 120 for supporting the other end of the cantilever. Is preferable. In this case, a biaxial optical deflector having a desired deflection angle and high operational reliability can be realized.

Further, the optical scanning device (for example, the optical writing device 600) of the present embodiment is an optical scanning device that scans an object with light, and is a light source device 12 and a light deflection that deflects light from the light source device 12. It includes a movable device 13 as an element.
In this case, the object can be stably and accurately scanned by light.

Further, the laser printer 650 as the image forming apparatus of the present embodiment includes a photoconductor drum (image carrier), an optical writing device 600 that scans the surface to be scanned 15 which is the surface of the photoconductor drum with light. It has.
In this case, the quality of the image formed on the surface to be scanned 15 can be improved.

The optical writing device 600 can also be applied to an image forming device such as a color printer or a color copier provided with a plurality of photosensitive drums. In such a color-compatible image forming device, for example, a plurality of movable devices 13 may be provided corresponding to a plurality of photoconductor drums.

Further, the head-up display device 500 as an image projection device of the present embodiment includes an intermediate screen 510 on which an image is formed by being irradiated with light from an optical scanning device including a light source device 12 and a movable device 13, and the intermediate screen 510. It includes a projection mirror 511 (optical system) that projects light that forms an image through the image.
In this case, the quality of the projected image can be improved.

Further, the object recognition device (laser radar device) of the present embodiment includes a light projection system including a light scanning device having a light source device 12 and a movable device 13, and an object 702 (object) projected from the light projection system. It is equipped with a light receiving system that receives the light reflected or scattered by the light source.
In this case, the object 702 can be recognized stably and accurately.

It is also possible to realize a mobile device including at least one of the image projection device and the object recognition device of the present embodiment and a mobile body on which at least one of the image projection device and the object recognition device is mounted.

Although the embodiment of the present invention has been described above, the above-described embodiment shows an application example of the present invention. The present invention is not limited to the above-described embodiment as it is, and can be embodied by making various modifications and changes at the implementation stage without departing from the gist thereof.

For example, by irradiating a heat-reversible recording medium (for example, a rewritable label) with light from an optical scanning device including a light source device 12 and a movable device 13, the heat-reversible recording medium is light-scanned to record and erase an image. May be done.

Such an image recording / erasing device can be used as an image rewriting device, an image recording device, or an image erasing device for a thermoreversible recording medium as an object.
In this case, images can be recorded and erased stably and accurately with respect to the heat reversible recording medium.

Further, the fundus may be light-scanned by irradiating the fundus with light from an optical scanning device including the light source device 12 and the movable device 13, and the light reflected or scattered by the fundus may be analyzed by an analysis means.

By irradiating the fundus with light (for example, weak infrared rays) and analyzing the returned light, it is possible to depict a tomography of the retina. Such a device is called an "optical coherence tomography" and is used for diagnosing age-related macular degeneration, macular edema, and macular hole, and for examining the condition of optic nerve fibers in glaucoma.

Further, in the above embodiment, as shown in FIG. 12, the movable device 13 uses a cantilever type movable device in which the first piezoelectric drive units 112a and 112b extend from the torsion bars 111a and 111b in the + X direction. However, the present invention is not limited to this as long as the piezoelectric portion to which the voltage is applied is movable. For example, as in the example shown in FIG. 24, a movable device in which one end of a beam of the drive unit 240 as a piezoelectric actuator is connected to a support portion 250 as a fixed end may be used. Further, as shown in FIG. 25, a dual-holding type movable device having drive units 241a and 241b extending in the + X direction and drive units 241c and 241d extending in the −X direction from the torsion bars 211a and 211b is used. May be good. Further, when the reflecting surface is moved only around one axis, as shown in FIG. 26, the reflecting surface 14 may be provided on the movable portion 260. Further, as shown in FIG. 27, a movable device may be used in which the reflecting surface 14 is moved only around one axis by the mirror unit 101, the first drive units 110a and 110b, and the support unit 120.

Further, the mirror portion 101 may have ribs for reinforcing the mirror portion formed on the surface of the mirror portion base 102 on the −Z side. The rib is composed of, for example, a silicon support layer 171 and a silicon oxide layer 172, and can suppress distortion of the reflective surface 14 caused by movement.

In the above embodiment, in order to suppress unnecessary excitation vibration, it is avoided that a drive source including a piezoelectric body and two electrodes sandwiching the piezoelectric body is provided on the first support portion 120 or the connecting portion. Even when such a drive source is provided on the torsion bar, there is a concern that unnecessary excitation vibration may occur.

However, even if at least one of the lower electrode 210 and the piezoelectric portion 220 protrudes on the torsion bar, there is no problem because the drive source is not formed on the torsion bar.

Further, in the above embodiment, in the first piezoelectric drive portion, the lower electrode 210 and the piezoelectric portion 220 project only on the support portion 120, but in addition to this, for example, as shown in FIG. 28A, the lower portion The electrode 210 and the piezoelectric portion 220 may also project on the torsion bar, or only the lower electrode 210 may project on the torsion bar, for example, as shown in FIG. 28 (b).

Further, in the above embodiment, in the first piezoelectric drive portion, the lower electrode 210 and the piezoelectric portion 220 project only on the support portion 120, but instead of this, as shown in FIG. 29 (a), the lower portion Only the electrode 210 may protrude only on the support portion 120, or for example, as shown in FIG. 29 (b), only the lower electrode 210 may protrude on the support portion 120 and the torsion bar.

Further, in the above embodiment, in the first piezoelectric drive unit, the lower electrode 210 and the piezoelectric portion 220 project only on the support portion 120, but instead, only the lower electrode 210 is projected as shown in FIG. 30, for example. May project onto the support portion 120, and the lower electrode 210 and the piezoelectric portion 220 may project onto the torsion bar.

Further, in the above embodiment, in the second piezoelectric drive portion, the lower electrode 210 and the piezoelectric portion 220 project on the two connecting portions on both sides, but instead of this, as shown in FIG. 31 (a), for example. Only the lower electrode 210 may protrude above the connecting portions on both sides, or, for example, as shown in FIG. 31 (b), only the lower electrode 210 may protrude only onto the connecting portion on one side.

Further, in the above embodiment, in the second piezoelectric drive portion, the lower electrode 210 and the piezoelectric portion 220 project on the two connecting portions on both sides, but instead of this, as shown in FIG. 32 (a), for example. The lower electrode 210 and the piezoelectric portion 220 may protrude only on the connecting portion on one side. For example, as shown in FIG. 32 (b), the lower electrode 210 protrudes on the connecting portions on both sides and the piezoelectric portion 220. May project only on one side of the connection.

Further, as shown in FIG. 33, the lower electrode and the piezoelectric portion of the first piezoelectric drive portion may be provided so as to project onto the first support portion. At this time, as shown in FIG. 33, it is preferable to project the lower electrode and the piezoelectric portion onto the first support portion so as to be line-symmetrical with respect to the second axis. In this case, since there is no difference in the distance from the second axis regarding the position where the distortion occurs, the balance is maintained, and the excitation by the rotation component around the second axis perpendicular to the first axis as the rotation axis of the mirror portion is generated. It is possible to suppress the occurrence in the mirror portion. In FIG. 33, only the lower electrode may be projected onto the first support portion.

On the other hand, as in the comparative example shown in FIG. 34, when the lower electrode and the piezoelectric portion are projected onto the first support portion so as to be asymmetric with respect to the second axis, the position where distortion occurs is set to the distance from the second axis. Since there is a difference, the balance is lost, and excitation by the rotational component around the second axis is likely to occur in the mirror portion.

The thinking process that led to the invention of the above embodiment by the inventors will be described above.

In recent years, small optical deflection mirrors manufactured by micromachining technology applying semiconductor manufacturing technology have been developed. This light deflection mirror is a MEMS (Micro Electro Mechanical Systems) device manufactured by microfabrication of silicon or glass, and is formed by integrally forming a movable part and an elastic beam-like part having a reflective surface on a substrate. Deflection and scan the beam.

As such a light deflection mirror, there is a piezoelectric actuator type in which a thin-film piezoelectric material is superposed on a beam-shaped elastic member for driving the mirror. In this configuration, the expansion and contraction of the piezoelectric material due to the piezoelectric effect is transmitted to the support that becomes the beam, and the reflecting surface rotates as the beam vibrates up and down.

Two-dimensional optical scanning is possible by rotating the optical deflection mirrors around two axes, the first axis (horizontal direction) and the second axis (vertical direction), which are orthogonal to each other, and the optical scanning in the horizontal direction is mechanical. It is customary to use a resonance drive that uses a different resonance frequency and to use a non-resonance drive for optical scanning in the vertical direction.

At this time, the vibrating beam that realizes the non-resonant drive usually has a plurality of folded portions and a plurality of connecting portions, and is often formed into a meander shape substantially composed of a plurality of continuous folded shapes. ..

When superimposing the bending displacement of such a meander-shaped connecting portion, there is a problem that a large stress applied to the vibrating beam causes stress migration of the electrodes on the entire upper surface of the piezoelectric film, resulting in disconnection. In particular, torsional stress is applied to the vicinity of the midpoint of the inner circumference of the folded portion due to vertical vibration of the connecting portion, and bending stress is applied to the vicinity of the curvature change point due to bending deformation of the connecting portion. Therefore, there is a problem that a particularly large stress is applied to the piezoelectric film or the electrode provided near the midpoint of the inner circumference of the folded portion or the vicinity of the curvature change point.

Therefore, in Patent Document 1 (WO2012-11133), the curvature change in which the curvature of the inner circumference of each of the inner circumferences of the plurality of folded portions and the vicinity thereof or the plurality of folded shapes in the meander structure changes. It is said that the above problem can be solved by providing an absent region in which the piezoelectric film does not exist at least one of the point and its vicinity.

However, in the conventional optical deflector as disclosed in Patent Document 1, by providing a region in the vicinity of the curvature change point where the piezoelectric film does not exist, the shape becomes complicated due to a decrease in the degree of freedom in electrode design.

As a result, in Patent Document 1, the degree of freedom in designing the optical deflector is reduced, the image quality is deteriorated due to unintended fluctuation of the scanning line due to the complexity of the electrode design, the optical axis of the irradiation light is deviated, and the vulnerability to environmental vibration is adversely affected. There was a problem of inviting.

Therefore, in order to solve such a problem, the inventors can reduce unnecessary excitation vibration that may be excited during the operation of the movable device while simplifying the electrode shape, and stabilize the rotation operation of the mirror portion. In order to realize a movable device (optical deflector) capable of improving the above-mentioned embodiment, the above embodiment was proposed.

12 ... Light source device, 13 ... Movable device (optical deflector), 101 ... Mirror unit, 111a, 111b ... Torsion bar, 112a, 112b ... First piezoelectric drive unit (piezoelectric actuator), 120 ... First support unit (support unit) ), 131a to 131f, 132a to 132f ... Second piezoelectric drive unit (piezoelectric actuator), 141ab to 141ef, 142ab to 142ef ... Connecting portion, 150 ... Second support portion (another support portion), 210 ... Lower electrode (No. 1) 1 electrode), 211 ... Lower electrode protruding part (first electrode protruding part), 220 ... Piezoelectric part (piezoelectric body), 221 ... Piezoelectric part protruding part (piezoelectric body protruding part), 230 ... Upper electrode (first electrode) 2 electrodes), 500 ... head-up display device (image projection device), 600 ... optical writing device, 650 ... laser printer (image forming device), 700 ... laser radar device (object recognition device).

WO2012-11133A

Claims (10)

With the beam whose end is connected to the member,
At least with the first electrode provided on the beam,
With the piezoelectric body provided on the first electrode,
A second electrode provided on the piezoelectric body is provided.
The first electrode projects onto the member and
The piezoelectric body protrudes on the member and
The second electrode is a piezoelectric actuator characterized in that it does not project onto the member. The protruding portion of the first electrode projecting onto the member has a region in which the protruding portion of the piezoelectric body is not provided.
The piezoelectric actuator according to claim 1 , wherein the wiring is connected to the region. The piezoelectric actuator according to claim 2 , wherein the first electrode and the piezoelectric body have dissimilar shapes. The piezoelectric actuator according to any one of claims 1 to 3 , wherein the portion of the piezoelectric body provided on the beam is larger than the protruding portion of the piezoelectric body. The piezoelectric actuator according to any one of claims 1 to 4 , wherein the portion of the first electrode provided on the beam is larger than the protruding portion of the first electrode. The piezoelectric actuator according to any one of claims 1 to 5,
A torsion bar connected to one end of the beam of the piezoelectric actuator,
A support portion connected to the other end of the beam and a support portion
An optical deflector including a mirror portion connected to the torsion bar. The mirror portion rotates about the axis of the torsion bar by driving the piezoelectric actuator.
A claim that the piezoelectric actuator is characterized in that the first electrode projects onto the support portion so as to be orthogonal to the axis and line-symmetrical with respect to an axis passing through the center of the mirror portion. The light deflector according to 6. A drive system including the piezoelectric actuator according to any one of claims 1 to 5 , wherein the beams are connected to each other via a connecting portion so as to form a meandering structure as a whole.
A movable system including a mirror unit connected to one end of the drive system,
An optical deflector including a support portion that supports the other end of the drive system. The movable system is
A torsion bar connected to the mirror unit and
The piezoelectric actuator according to any one of claims 1 to 5 , wherein one end of a beam included in the piezoelectric actuator is connected to the torsion bar.
The light deflector according to claim 8 , further comprising another support portion connected to the other end of the beam. Light source device and
The light deflector according to any one of claims 6 to 9 , which deflects the light from the light source device.
A screen on which an image is formed by irradiating light through the light deflector,
An image projection device including an optical system that projects light through the screen.

Images