WO2012176492A1 - Actionneur d'entraînement par résonance, micro-dispositif de balayage et appareil optique - Google Patents

Actionneur d'entraînement par résonance, micro-dispositif de balayage et appareil optique Download PDF

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Publication number
WO2012176492A1
WO2012176492A1 PCT/JP2012/053854 JP2012053854W WO2012176492A1 WO 2012176492 A1 WO2012176492 A1 WO 2012176492A1 JP 2012053854 W JP2012053854 W JP 2012053854W WO 2012176492 A1 WO2012176492 A1 WO 2012176492A1
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WIPO (PCT)
Prior art keywords
resonance
mirror
frequency
excitation source
mode
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PCT/JP2012/053854
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English (en)
Japanese (ja)
Inventor
保孝 中垣
吉田　龍一
野田　哲也
松尾　隆
久保　直樹
Original Assignee
コニカミノルタアドバンストレイヤー株式会社
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Publication of WO2012176492A1 publication Critical patent/WO2012176492A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
    • G02B26/0858—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting means being moved or deformed by piezoelectric means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/101—Scanning systems with both horizontal and vertical deflecting means, e.g. raster or XY scanners
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2041—Beam type
    • H10N30/2042—Cantilevers, i.e. having one fixed end
    • H10N30/2046—Cantilevers, i.e. having one fixed end adapted for multi-directional bending displacement

Definitions

  • the present invention relates to a resonance drive actuator, a micro scanner, and an optical device.
  • resonance drive actuator that includes a drive body that is swingably held and that drives the drive body to resonate.
  • resonance drive actuators are being used in MEMS (Micro Electro Mechanical Systems) devices in which components such as mirrors and elastic beams are integrally formed using micromachining technology for finely processing silicon or glass.
  • an optical scanner that polarizes and scans a light beam such as a laser beam is known, and is used in an optical apparatus such as an image projection apparatus.
  • a two-dimensional scanning optical scanner capable of horizontal scanning and vertical scanning is conventionally known (see, for example, Patent Document 1).
  • Patent Document 1 describes an optical scanner that includes a mirror portion (driving body) that reflects light, and the mirror portion is held so as to be swingable.
  • the mirror part is held on the movable frame part via the mirror shaft part.
  • the movable frame portion is connected to a frame shaft portion extending in a direction orthogonal to the mirror shaft portion. For this reason, the said mirror part is rock
  • the optical scanner described in Patent Document 1 includes a holding unit that holds the movable frame unit by being connected to the frame shaft unit, and a vibration source (driving body) for vibrating (swinging) the mirror unit.
  • the excitation source has a unimorph structure including a piezoelectric element, and is configured by attaching the piezoelectric element on the surface of the holding portion. For this reason, when a voltage is applied to the piezoelectric element, the piezoelectric element expands and contracts, and the holding portion is deformed. Then, the mirror part is swung (driven) by the deformation of the holding part.
  • the swinging (driving) of the mirror portion with respect to the mirror shaft portion is performed by resonance in order to obtain a large displacement.
  • it is comprised so that the resonance frequency of the excitation source in which a deformation
  • the resonance frequency of the excitation source may be substantially symmetric with respect to the resonance frequency of the mirror unit (driving body). That is, the resonance frequency of the excitation source may have frequency characteristics that straddle (pinch) the resonance frequency of the driver. In this case, there is a problem that the phase of the excitation source is reversed, and the driving body (mirror part) is not driven (oscillated) (the driving amount of the driving body cannot be sufficiently secured). In this case, the resonance mode (resonance mode of the driving body) for driving the driving body (mirror part) is not functioning.
  • the present invention has been made to solve the above-described problems, and one object of the present invention is a resonant drive capable of stably driving a drive body even when assembly variations occur. Actuators, microscanners and optical instruments are provided.
  • the inventors of the present invention have made extensive studies, and as a result, two or more resonance modes are generated in the drive body, and the stability of the drive body is greatly improved by utilizing these resonance modes. I found out that it would be possible.
  • the resonance drive actuator includes a drive body that is driven by resonance and has two or more resonance modes that can be used for driving the drive body.
  • the driver is driven to resonate at the frequency of the functioning resonance mode.
  • the resonance mode which can be utilized means the resonance mode which can drive a drive body by a desired speed in a resonance drive actuator, for example.
  • the resonance drive actuator when there are two or more resonance modes that can be used for driving the drive body, for example, when some resonance modes do not function due to assembly variations. However, other resonance modes can be in a functioning state. For this reason, by using a functioning resonance mode, it is possible to drive the drive body even when assembly variations occur (a sufficient driving amount of the drive body can be ensured). Thereby, the stability of the driving body can be significantly improved.
  • the stability of the drive body can be improved by improving production technology and performing high-precision assembly.
  • the configuration having two or more resonance modes that can be used for driving the drive body even when easy and rough assembly is performed, the drive body cannot be driven due to assembly variations. Can be solved. For this reason, cost reduction and productivity improvement can be achieved.
  • the resonance drive actuator preferably includes a vibration source for vibrating the drive body.
  • a vibration source for vibrating the drive body.
  • at least one of the resonance modes has a frequency smaller than the resonance frequency of the excitation source. If comprised in this way, when an assembly variation arises, the resonance mode (resonance frequency of a drive body) which does not straddle (it is not pinched) by the resonance frequency of an excitation source can be generated. For this reason, since the functioning resonance mode can be easily generated, the driver can be driven effectively and stably.
  • the resonance mode may be configured to include a first resonance mode having a frequency lower than the resonance frequency of the excitation source and a second resonance mode having a frequency higher than the resonance frequency of the excitation source. it can. Even in such a configuration, the driving body can be driven effectively and stably.
  • At least one of the two or more resonance modes has a frequency that approximates or matches the resonance frequency of the excitation source. If the driving body is driven in such a resonance mode, the displacement (driving amount) of the driving body can be easily increased.
  • a micro scanner according to a second aspect of the present invention is a micro scanner including the resonance drive actuator according to the first aspect. With this configuration, it is possible to easily obtain a micro scanner that can significantly improve the stability of the driving body.
  • the driving body may include a mirror part that reflects light, and may further include a mirror frame that surrounds the mirror part.
  • the resonance mode is configured to include a third resonance mode that vibrates the mirror part and the mirror frame in different directions and a fourth resonance mode that vibrates the mirror part and the mirror frame in the same direction. preferable. With this configuration, it is possible to easily generate two or more resonance modes of the driver.
  • the deflection angle of the mirror part is preferably different from the deflection angle of the mirror frame. If comprised in this way, it can comprise so that the frequency of each resonance mode (resonance frequency of a drive body) may mutually approach. Therefore, it is possible to easily change the resonance mode of the drive body generated two or more to a resonance mode that can be used for driving the drive body. In other words, if configured as described above, it is possible to suppress the frequency of each resonance mode from being too far from a predetermined frequency (for example, a design value). Note that a resonance mode having a frequency far away from a predetermined resonance frequency cannot be used as a resonance mode for driving the driving body (mirror unit).
  • the micro scanner described above can be a micro scanner that performs two-dimensional scanning by two scannings in the first direction and the second direction, which are different directions.
  • a configuration having two or more resonance modes in the first direction can be adopted.
  • f1 and f2 satisfy the following formulas when the frequencies of two adjacent resonance modes are f1 and f2, respectively. f1 ⁇ f2 f1 + 0.2 ⁇ f1 ⁇ f2 With this configuration, the frequencies of the respective resonance modes can be made sufficiently close to each other, so that these resonance modes can be easily made into resonance modes that can be used for driving the driver.
  • An optical instrument according to a third aspect of the present invention is an optical instrument including the micro scanner according to the second aspect and a drive circuit unit that drives and controls the micro scanner. If comprised in this way, the optical apparatus with which the stability of the drive body was improved significantly can be obtained.
  • the drive amount of the drive body is ensured, so that stable product supply is possible.
  • FIG. 6 is an enlarged cross-sectional view showing a part of the optical scanner shown in FIG. 5.
  • FIG. 1 A diagram showing an example of the deformation amount (unimorph displacement) of the excitation source and the rotation angle (mirror deflection angle) of the mirror unit in a general (typical) optical scanner (when an assembly error (assembly variation) occurs) It is the figure which showed the frequency characteristic of the mirror part and the vibration source. It is the figure which showed the relationship between the frequency and phase in the unimorph (excitation source) shown in FIG.
  • FIG. 16 is a perspective view illustrating an example of a driving state of the optical scanner according to the first embodiment of the present invention (a diagram illustrating a driving state in a low-frequency resonance mode (mode A) in FIG. 15).
  • mode A low-frequency resonance mode
  • FIG. 16 is a perspective view illustrating an example of a driving state of the optical scanner according to the first embodiment of the present invention (a diagram illustrating a driving state in a high-frequency resonance mode (mode B) in FIG. 15).
  • 1 is a plan view (a diagram showing a part of an optical scanner) showing an example of an optical scanner according to a first embodiment of the present invention.
  • FIG. It is the top view which expanded and showed a part (part enclosed with the broken line R) of FIG. It is the figure which showed the frequency characteristic of the optical scanner (comparative example) which has one resonance mode.
  • It is a perspective view of the optical scanner which showed the drive state of the mirror part in the resonance mode in FIG.
  • FIG. 1 is a schematic diagram showing a drive signal applied to an excitation source (piezoelectric element) of an optical scanner.
  • FIG. 2 is a schematic view showing a state where scanning projection is performed by a two-dimensional scanning optical scanner.
  • FIG. 3 is a schematic diagram showing the positional relationship between the optical scanner and the light source according to the first embodiment of the present invention.
  • FIG. 4 is a diagram schematically showing an example of the resonance mode of the mirror unit in the optical scanner according to the first embodiment of the present invention.
  • 5 to 21 are views for explaining the optical scanner according to the first embodiment of the present invention.
  • the optical scanner 10 includes a mirror unit 11 that reflects the light beam LT from the light source 30 (see FIGS. 2 and 3).
  • the mirror unit 11 includes a first axis (horizontal torsion bar) parallel to the X axis and a second axis (vertical torsion bar) parallel to the Y axis and intersecting the first axis at a substantially right angle. And can be rotated (swinged) around the center.
  • the mirror unit 11 is two-dimensionally rotated (swinged) about the first axis and the second axis, so that the light beam LT from the light source 30 reflected by the mirror unit 11 is raster-scanned. That is, the optical scanner 10 according to the first embodiment performs a scanning operation by changing (swinging) the mirror unit 11.
  • the mirror unit 11 is an example of the “driving body” in the present invention.
  • the optical scanner 10 is configured to include a resonance driving actuator that resonance-drives the mirror unit 11 that is a driving body. That is, the optical scanner 10 is configured to utilize a resonance drive actuator.
  • the optical scanner 10 (resonance drive actuator) has two or more resonance modes for resonance driving the mirror unit 11 (drive body). That is, as shown in FIG. 4, the optical scanner 10 has two or more resonance modes having a frequency (resonance frequency) at which the deflection angle of the mirror portion 11 becomes large.
  • FIG. 4 shows an example in which two resonance modes are provided.
  • the resonance modes are all resonance modes that can be used for driving the mirror unit 11. That is, the optical scanner 10 (resonance driving actuator) utilizes (uses) any of two or more resonance modes.
  • the resonance mode that can be used means a resonance mode in which a desired operation (for example, a swinging operation of the mirror unit 11 at a desired speed) can be performed in driving the optical scanner 10 (resonance drive actuator).
  • the usable resonance mode is a resonance mode that can be used inherently, and can be used to drive the mirror unit 11 as long as there is no characteristic variation in the excitation source, as will be described later. It is a resonance mode.
  • the mirror unit 11 when the mirror unit 11 is resonantly driven in one resonance mode of two or more resonance modes, other resonance modes other than the resonance mode are used. However, similarly, the mirror unit 11 can be driven to resonate. Therefore, all of the resonance modes have the same or close frequency as a predetermined frequency (for example, a design value). For this reason, the resonance frequency of each resonance mode is adjusted so that it may mutually approach. More specifically, the frequency difference ⁇ f (see FIG. 4), which is the difference between the frequencies of two adjacent resonance modes, is adjusted to be small, and both resonance modes can be utilized.
  • ⁇ f see FIG. 4
  • the optical scanner 10 includes a structure (MEMS structure) obtained by performing an etching process or the like on a deformable silicon substrate serving as a base.
  • the optical scanner 10 includes a fixed frame 12, an excitation source (drive unit) 13, a mirror frame (movable frame unit) 14, a vertical torsion bar (frame axis) in addition to the mirror unit 11 described above. Part) 15 and a horizontal torsion bar (mirror shaft part) 16.
  • the axis that crosses the center of the mirror unit 11 in the vertical direction in FIG. 5 is the X axis, and the center of the mirror unit 11 is illustrated.
  • An axis that traverses 5 in the horizontal direction is defined as a Y axis.
  • the point where the X axis and the Y axis are orthogonal to each other is the center of the mirror unit 11.
  • the fixed frame 12 is a portion corresponding to the outer edge of the optical scanner 10 and surrounds other portions (the mirror unit 11, the excitation source 13, the mirror frame 14, and the like).
  • the vibration source 13 is connected to the fixed frame 12 in the X-axis direction and separated from the fixed frame 12 in the Y-axis direction. Further, the excitation source 13 includes four unimorph structures, and the four unimorph structures are arranged so as to be symmetric with respect to the X axis and the Y axis, respectively, and separated from each other. Yes. Further, as shown in FIG. 6, the unimorph structure as the excitation source 13 is a piezoelectric element in which a piezoelectric body 13a (for example, a sintered body made of PZT or the like as a raw material is polarized) is sandwiched between a pair of electrodes 13b.
  • a piezoelectric body 13a for example, a sintered body made of PZT or the like as a raw material is polarized
  • the holding unit 19 constituting the excitation source 13 holds the mirror frame 14 by holding the vertical torsion bar 15 (connected to the vertical torsion bar 15).
  • the mirror frame 14 is a substantially rhombus-shaped frame located inside the excitation source 13.
  • a pair of vertical torsion bars 15 extending along the Y-axis direction is provided between the mirror frame 14 and the fixed frame 12.
  • the pair of vertical torsion bars 15 are arranged so as to overlap with the Y axis and be symmetric with respect to the X axis.
  • one end of each of the pair of vertical torsion bars 15 is connected to an end portion of the fixed frame 12 on the Y axis.
  • the mirror frame 14 is disposed between the other ends of the pair of vertical torsion bars 15 and is supported (clamped) by the other end (the pair of vertical torsion bars 15). For this reason, the mirror frame 14 can be rotated around the Y axis with the vertical torsion bar 15 as a rotation axis (center axis).
  • the mirror frame 14 is a frame that surrounds the mirror unit 11, and in addition to the mirror unit 11, a pair of horizontal torsion bars 16 extending along the X-axis direction are provided inside the mirror frame 14.
  • the pair of horizontal torsion bars 16 are arranged so as to overlap the X axis and be symmetric with respect to the Y axis. Further, one end of each of the pair of horizontal torsion bars 16 is connected to an end portion on the X axis of the mirror frame 14.
  • the mirror portion 11 is disposed between the other ends of the pair of horizontal torsion bars 16 and is supported (sandwiched) by the other end (the pair of horizontal torsion bars 16). For this reason, the mirror part 11 is rotated around the Y axis together with the mirror frame 14, and is also rotated around the X axis about the horizontal torsion bar 16 as a rotation axis (center axis).
  • the mirror part 11 is formed, for example, in a substantially circular shape, and is obtained by sticking a reflective film made of gold, aluminum or the like on a region to be the mirror part 11 of the silicon substrate.
  • a reflective film such as gold or aluminum can be formed on a part of the silicon substrate by vapor deposition or sputtering. It is also possible to improve the reflectivity by forming a dielectric multilayer film on gold or aluminum.
  • a part of the four excitation sources 13 is connected to the vertical torsion bar 15 by a connecting portion 17.
  • the connecting portion 17 is formed integrally with the region (holding portion 19) that becomes the vibration source 13 of the silicon substrate and the vertical torsion bar 15.
  • a strain sensor 18a for detecting the twist angle of the vertical torsion bar 15 is provided.
  • a strain sensor 18b for detecting the twist angle of the horizontal torsion bar 16 is provided.
  • Each of the strain sensors 18a and 18b has a piezoresistive element 20, and detects a shear stress generated when the vertical torsion bar 15 and the horizontal torsion bar 16 are deformed by a resistance value.
  • the piezoresistive element 20 (strain sensors 18a and 18b) is generated by partially doping an impurity such as boron or arsenic into a silicon substrate.
  • the strain sensor 18a is arranged on the axis of the vertical torsion bar 15 (on the Y axis) (the root portion of the vertical torsion bar 15), and the strain sensor 18b is on the axis of the horizontal torsion bar 16 (on the X axis). ) (The root portion of the horizontal torsion bar 16).
  • the term “on the axis” includes not only on the vertical torsion bar 15 and the horizontal torsion bar 16 but also on the extension line of the vertical torsion bar 15 and the extension line of the horizontal torsion bar 16.
  • the scanning operation (drive control) of the optical scanner 10 is performed by adjusting the timing of driving (stretching) the four excitation sources 13 and vibrating the mirror unit 11 around the X axis and the Y axis.
  • the frequency when vibrating around the Y axis is set to 60 Hz
  • the frequency when vibrating around the X axis is set to 30 kHz. That is, it is driven at 60 Hz (design value) in the vertical direction V, and is driven at 30 kHz (design value) in the horizontal direction H.
  • the vertical direction is DC driven
  • the horizontal direction is resonance driven.
  • the movement of the mirror unit 11 is detected by the distortion sensor 18 in both the vertical direction and the horizontal direction.
  • the horizontal direction H is an example of the “first direction” in the present invention
  • the vertical direction V is an example of the “second direction” in the present invention.
  • the four excitation sources 13 will be described in detail with reference numerals 13-1 to 13-4.
  • the excitation sources 13-1 and 13-3 are set as one set, and the excitation sources 13-2 and 13-4 are set as the other set.
  • the polarity of the voltage applied to each of the set and the other set is reversed.
  • the other excitation source 13-2 and 13-4 is deformed in a contracting direction.
  • the excitation sources 13-1 and 13-3 that are one set are deformed in a contracting direction
  • the excitation sources 13-2 and 13-4 that are the other set are deformed in an extending direction.
  • the mirror unit 11 vibrates around the Y axis together with the mirror frame 14, and the inclination (angle) of the mirror unit 11 varies around the Y axis.
  • the excitation sources 13-1 and 13-2 are set as one set, and the excitation sources 13-3 and 13-4 are set as the other set.
  • the polarity of the voltage applied to one set and the other set is reversed.
  • the other excitation source 13-3 and 13-4 is deformed in a contracting direction.
  • the excitation sources 13-1 and 13-2 that are one set are deformed in a contracting direction
  • the excitation sources 13-3 and 13-4 that are the other set are deformed in an extending direction.
  • the frequency of the voltage applied to the excitation source 13 is set so that the mirror unit 11 resonates with the frequency of the voltage applied to the excitation source 13.
  • the mirror unit 11 By operating the mirror unit 11 as described above, the mirror unit 11 can be rotated about two axes orthogonal to each other, and two-dimensional scanning can be performed by the single mirror unit 11.
  • the horizontal torsion bar 16 is moved as described above.
  • a horizontal resonance drive as a fulcrum and a vertical drive (DC drive) for driving the entire mirror frame 14 are realized.
  • the vertical drive signal is, for example, a triangular wave of 60 Hz
  • the horizontal drive signal is, for example, a sine wave.
  • the frequency of the horizontal drive signal is the horizontal resonance frequency of the mirror unit 11.
  • FIG. 9 shows an example of a deformation amount (unimorph displacement) of a vibration source and a rotation angle (mirror deflection angle) of a mirror unit in a general (typical) optical scanner.
  • the unimorph displacement ( ⁇ m) on the vertical axis indicates the amount of displacement in the bending direction (protrusion direction (height direction)) of the vibration source when the vibration source is bent due to deformation.
  • the mirror deflection angle (°) indicates a deflection angle (rotation angle) when the mirror unit is driven (oscillated) by vibration from a state where the mirror unit is not excited.
  • the broken line J indicates the deflection angle of the mirror portion
  • the solid line K indicates the displacement of the unimorph (excitation source).
  • the resonance frequency of the mirror part which is the frequency at which the mirror deflection angle increases, is smaller than the resonance frequency of the excitation source, which is the frequency at which the unimorph displacement increases, but the resonance frequency of the mirror part is used as the excitation source.
  • FIG. 9 shows the frequency characteristics of a general (typical) optical scanner. That is, FIG. 9 shows frequency characteristics when no assembly error (assembly variation) or the like occurs in the optical scanner. For this reason, since the four excitation sources all show the same displacement (frequency characteristics), the displacements (unimorph displacement) of the four excitation sources overlap. For this reason, the displacement (unimorph displacement) of the four excitation sources is indicated by a solid line K.
  • FIG. 10 is a graph showing the relationship between frequency and phase in the unimorph (excitation source) shown in FIG.
  • the displacements (unimorph displacements) of the four excitation sources are the same. Therefore, as shown in FIG. 10, the phases of the four excitation sources (unimorphs) are also the same.
  • the dashed-dotted line e in FIG. 10 has shown the resonant frequency of the mirror part shown in FIG.
  • the excitation source 13 of the optical scanner 10 is configured by attaching a piezoelectric element 13 c on the holding portion 19, as in the conventional structure described above. For this reason, characteristic variation is likely to occur in the vibration source 13 due to a pasting error (for example, positional deviation) of the piezoelectric element 13c.
  • FIG. 11 is a graph showing an example of the deformation amount (unimorph displacement) of the vibration source and the rotation angle of the mirror part (mirror deflection angle) when an assembly error (assembly variation) occurs in the optical scanner.
  • FIG. 12 is a graph showing the relationship between frequency and phase in the unimorph (excitation source) shown in FIG.
  • FIG. 11 shows a graph corresponding to FIG. That is, FIG. 9 shows a case where there is no variation in the frequency characteristics of the excitation source (unimorph), and FIG. 11 shows a case where there is a variation in the frequency characteristics of the excitation source (unimorph). Therefore, also in FIG. 11, the case where the resonance mode of the mirror part is one is shown.
  • the resonance frequency of the excitation source may have a frequency characteristic that straddles (sandwiches) the resonance frequency of the mirror part (between the two resonance frequencies of the excitation source (unimorph) (between ⁇ P). Resonance frequency may be located).
  • the two resonance frequencies of the excitation source (unimorph) may be substantially symmetrical about the resonance frequency of the mirror part.
  • the phase difference K3 between the right unimorph K1 and the left unimorph K2 is 100 ° or more at the resonance frequency (one-dot chain line e) of the mirror portion. Therefore, for example, in the optical scanner 10 shown in FIG. 8, the right unimorph (excitation sources 13-3 and 13-4) and the left unimorph (excitation sources 13-1 and 13-2) bend in the same direction. (Deform). Thereby, the drive amount (mirror deflection angle) of the mirror part 11 becomes very small.
  • the phase difference K3 in FIG. 12 is 180 °, the phase of the excitation source (unimorph) is completely reversed.
  • FIG. 8 shows a case where there is no variation in the frequency characteristics of the excitation source (unimorph). Therefore, since there is no phase difference between the right unimorph (excitation sources 13-3 and 13-4) and the left unimorph (excitation sources 13-1 and 13-2), the right unimorph (excitation sources 13-3 and 13-4) -4) and the left unimorph (excitation sources 13-1 and 13-2) are bent (deformed) in opposite directions.
  • the resonance (resonance mode) of the mirror portion 11 does not function.
  • the mirror unit 11 is configured to have two or more resonance modes (resonance modes in the horizontal direction) for resonance driving.
  • the mirror unit 11 is moved with a predetermined drive amount (mirror deflection angle) using one of the remaining resonance modes. It can be driven in the horizontal direction (rotated around the X axis).
  • FIG. 13 and 14 show a conventional structure having one resonance mode as a comparative example.
  • the frequency characteristic according to the example of the first embodiment having two resonance modes is indicated by a solid line D
  • the frequency characteristic according to the comparative example is indicated by a one-dot chain line E
  • an excitation source (unimorph) The frequency characteristic is indicated by a broken line F.
  • the low-frequency side resonance mode is mode A
  • the high-frequency side resonance mode is mode B.
  • One resonance mode according to the comparative example is modeG.
  • the resonance mode (mode G) of the comparative example and the two resonance modes (mode A, mode B) of the first embodiment are both functioning. That is, regardless of which resonance mode is used, the mirror unit can be driven horizontally (rotated around the X axis) with a predetermined drive amount (mirror deflection angle) (can be used for driving the mirror unit). It has become.
  • the frequency characteristics of the excitation source are the right unimorph F1 (excitation source on the right side with respect to the X axis) and the left unimorph F2 (on the X axis).
  • the frequency characteristics differ depending on the left excitation source).
  • the resonance frequency of the excitation source has frequency characteristics that straddle (interpose) the resonance mode (mode G) according to the comparative example and one resonance mode (mode B) according to the first embodiment. Thereby, the resonance mode (mode G) according to the comparative example and one resonance mode (mode B) according to the first embodiment do not function.
  • the first embodiment has two or more resonance modes (two in FIGS. 13 and 14). Therefore, even when one resonance mode (mode B) stops functioning, the remaining other resonance mode (mode A) is in a functioning state.
  • the resonance mode (mode A) is a resonance mode that can be used for driving the mirror unit 11 as described above. Therefore, in the first embodiment, even when characteristic variation occurs in the excitation source, a predetermined drive amount (mirror deflection angle) is obtained by using the other resonance mode (mode A) (functional resonance mode). Thus, the mirror unit 11 can be driven in the horizontal direction (rotated around the X axis).
  • the stability of the mirror unit 11 can be significantly improved.
  • the above-mentioned “no function” is a state in which it is difficult to use the available resonance mode for driving the mirror unit 11 due to characteristic variations in the excitation source.
  • the “functional resonance mode” is a resonance mode that does not impede the drive function of deflecting the mirror unit 11 due to the influence of assembly variation among the available resonance modes.
  • the mirror frame 14 (FIG. 5, 7 and 8) may be configured to be twisted in the horizontal direction (horizontal scanning direction).
  • a resonance mode based on vibrations based on the horizontal torsion bar 16 and a resonance mode based on vibrations based on the mirror frame 14.
  • these resonance modes are a resonance mode (third resonance mode) in which the mirror unit 11 and the mirror frame 14 vibrate (oscillate) in different directions, and as shown in FIG.
  • a resonance mode in which the mirror unit 11 and the mirror frame 14 are vibrated (oscillated) in the same direction.
  • the resonance mode (resonance mode in which the mirror unit 11 and the mirror frame 14 vibrate (swing) in the same direction) shown in FIG. 16 corresponds to the low-frequency side resonance mode (for example, mode A) in FIG.
  • the resonance mode (resonance mode in which the mirror unit 11 and the mirror frame 14 are vibrated (oscillated) in different directions) shown in FIG. 17 corresponds to the high-frequency side resonance mode (for example, mode B) in FIG.
  • the frequency characteristics of the mirror unit 11 are indicated by a solid line D
  • the frequency characteristics of the four excitation sources are indicated by a broken line F.
  • modeA and modeB can be interchanged.
  • the deflection angle (rotation angle) of the mirror unit 11 is It is preferable that the deflection angle (rotation angle) of the frame 14 is different (for example, the deflection angle of the mirror frame 14 is smaller).
  • At least one of the two or more resonance modes has a frequency smaller than the resonance frequency of the excitation source 13. Moreover, it is preferable that at least one of the two or more resonance modes has a frequency that approximates or matches the resonance frequency of the excitation source 13.
  • f1 and f2 are configured to satisfy the following expressions (1) and (2). f1 ⁇ f2 (1) f1 + 0.2 ⁇ f1 ⁇ f2 (2)
  • the resonance modes are set so that f1 and f2 satisfy the above equations (1) and (2). It is preferable.
  • the resonance frequency of the optical scanner 10 is clarified in terms of conditions such as Young's modulus, Poisson's ratio, and density of the substrate (silicon substrate), the shape of the mirror portion 11, the fixing conditions, and the piezoelectric constant of the piezoelectric element 13c. Then, it can be calculated by commercially available simulation software. Therefore, it is possible to easily obtain a configuration capable of generating two or more resonance modes in the mirror unit 11 (driving body) by simulation.
  • the distance L (see FIG. 18) from the excitation source 13 to the mirror frame 14 is shortened, and the displacement expanding portion 21 provided in the vertical torsion bar 15 is shortened.
  • the width W (see FIG. 19) may be increased.
  • the displacement enlarging unit 21 has a function of enlarging the displacement during DC driving. Then, by adjusting the distance L and the width W, the rigidity of the portion between the excitation source 13 and the mirror frame 14 can be adjusted. Thereby, it is possible to easily generate two or more resonance modes for resonantly driving the mirror unit 11 (driving body), and adjust the two resonance modes so as to approach each other ( ⁇ f in FIG. 4 becomes small). be able to.
  • the above is one example in which the resonance mode can be adjusted by changing the rigidity of this portion, and the method for adjusting the resonance mode may be other than the above.
  • the displacement enlarged portion 21 is formed on the holding portion 19 and the vertical torsion bar 15. If comprised in this way, it will become possible to change a deformation
  • the displacement enlarging portion 21 may be formed on either the holding portion 19 or the vertical torsion bar 15.
  • the frequency characteristics of an optical scanner (comparative example) having one resonance mode are shown in FIG. 20, and the drive state of the mirror unit 11 in the resonance mode is shown in FIG. 20 corresponds to FIG. 15 described above.
  • the frequency characteristic of the mirror unit 11 having one resonance mode is indicated by a solid line E
  • the frequency characteristics of four excitation sources are indicated by a broken line F.
  • the mirror unit 11 when two or more resonance modes that can be used for driving the mirror unit 11 are provided, for example, some resonance modes stop functioning due to assembly variations of the optical scanner 10. However, other resonance modes can be in a functioning state. For this reason, by using a functioning resonance mode, the mirror unit 11 can be driven even when assembly variations occur (a sufficient driving amount of the mirror unit 11 can be ensured). Thereby, the stability of the mirror part 11 can be improved significantly.
  • the stability of the mirror unit 11 can be improved by improving production technology and performing high-precision assembly.
  • the configuration having two or more resonance modes that can be used for driving the mirror unit 11 even when easy and rough assembly is performed, the mirror unit 11 is not driven due to assembly variations. Can be solved. For this reason, cost reduction and productivity improvement can be achieved.
  • At least one of the two or more resonance modes is configured to have a frequency smaller than the resonance frequency of the vibration source 13, it does not straddle with the resonance frequency of the vibration source 13 when an assembly variation occurs.
  • a resonance mode (not sandwiched) (resonance frequency of the mirror portion 11) can be generated. For this reason, since the functioning resonance mode can be easily generated, the mirror part 11 can be driven effectively and stably. That is, the stability of the mirror part 11 can be easily improved remarkably.
  • the displacement (driving amount) of the mirror unit 11 can be easily increased. .
  • the resonance mode includes a resonance mode that causes the mirror unit 11 and the mirror frame 14 to vibrate in different directions, and a resonance mode that causes the mirror unit 11 and the mirror frame 14 to vibrate in the same direction.
  • each resonance mode is configured so that the deflection angle of the mirror unit 11 is different from the deflection angle of the mirror frame 14. Since the frequencies of (the resonance frequency of the mirror unit 11) are close to each other, two or more generated resonance modes can be easily made a resonance mode that can be used for driving the mirror unit 11. In other words, if configured as described above, it is possible to suppress the frequency of each resonance mode from being too far from a predetermined frequency (for example, a design value). Note that a resonance mode having a frequency far away from a predetermined resonance frequency cannot be used as a resonance mode for driving the mirror unit 11.
  • the frequencies of two adjacent resonance modes are f1 and f2, respectively, if f1 and f2 are configured so as to satisfy the above expressions (1) and (2), the frequencies of the respective resonance modes are set to each other. It can be close enough. That is, ⁇ f shown in FIG. 4 can be reduced. For this reason, it is possible to easily set these resonance modes to resonance modes that can be used for driving the mirror unit 11.
  • the rigidity of the portion between the excitation source 13 and the mirror frame 14 is adjusted by adjusting the distance L (see FIG. 18) and the width W (see FIG. 19).
  • the two resonance modes can be easily adjusted ( ⁇ f in FIG. 4 is reduced).
  • FIG. 22 is a diagram for explaining a resonance mode of the optical scanner according to the second embodiment of the present invention.
  • an optical scanner 10 according to a second embodiment of the present invention will be described with reference to FIGS.
  • corresponding components are denoted by the same reference numerals, and redundant description is omitted as appropriate.
  • the optical scanner 10 has two or more resonance modes that can be used for driving the mirror unit 11 as in the first embodiment shown in FIG.
  • the resonance mode is a resonance mode having a frequency smaller than the resonance frequency of the excitation source (first resonance mode (modeA)) and greater than the resonance frequency of the excitation source.
  • a resonance mode having a frequency (second resonance mode (mode B)).
  • FIG. 22 shows a case where there are two resonance modes as an example of the second embodiment.
  • FIG. 22 shows a conventional structure having one resonance mode as a comparative example, similar to FIGS. 13 and 14 described above.
  • the frequency characteristic according to the example of the second embodiment having two resonance modes is indicated by a solid line D
  • the frequency characteristic according to the comparative example is indicated by a dashed line E
  • the frequency characteristic of the excitation source (unimorph) is shown. Is indicated by a broken line F.
  • the low-frequency side resonance mode is mode A
  • the high-frequency side resonance mode is mode B.
  • One resonance mode according to the comparative example is modeG.
  • FIG. 22 shows a state in which there is no characteristic variation in the excitation source.
  • the resonance mode is divided into a resonance mode having a frequency lower than the resonance frequency of the excitation source (first resonance mode) and a resonance mode having a frequency higher than the resonance frequency of the excitation source ( 2nd resonance mode). And also by comprising in this way, the mirror part 11 (driving body) can be driven stably stably.
  • FIG. 23 is a block diagram showing a configuration of an image projection apparatus according to the third embodiment of the present invention.
  • an image projection apparatus 100 according to the third embodiment of the present invention will be described with reference to FIGS.
  • the image projection apparatus 100 is an example of the “optical apparatus” in the present invention.
  • the image projection apparatus 100 is equipped with the optical scanner 10 shown in the first or second embodiment.
  • the optical scanner 10 is mounted on the image projection apparatus 100 and functions as a scanning unit that scans light from the light source 30.
  • the image projection apparatus 100 can display a two-dimensional image on the projection plane 200 by performing a raster scan of light rays emitted toward the projection plane 200.
  • a projector apparatus etc. are mentioned, for example.
  • the light source 30 is provided in the image projection apparatus 100 together with the optical scanner 10, and emits a light beam (for example, laser light) LT toward the optical scanner 10.
  • a light beam for example, laser light
  • the image projecting device 100 drives the optical scanner control unit 40 that controls the driving of the optical scanner 10 and the light source that drives the light source 30 and can modulate the light beam LT.
  • a circuit 70 and an image signal control unit 80 that controls the light source driving circuit 70 are provided.
  • the optical scanner 10 has a strain sensor 18.
  • the strain sensor 18 has a piezoresistive element as an angle detection sensor that detects the angle (rotation angle (deflection angle)) of the mirror unit 11.
  • the optical scanner control unit 40 is related to the mirror unit 11 and a horizontal drive control unit 50 that controls rotation around the X axis, that is, driving in the horizontal direction (H direction), with respect to the mirror unit 11 (see FIG. 5) of the optical scanner 10. And a vertical drive control unit 60 that controls rotation around the Y axis, that is, drive in the vertical direction (V direction).
  • the optical scanner control unit 40 (the horizontal drive control unit 50 and the vertical drive control unit 60) is an example of the “drive circuit unit” in the present invention.
  • the image signal control unit 80 generates a control signal for controlling the light source 30 based on, for example, an image signal input from the outside of the image projection apparatus 100. Based on this control signal, the light source 30 is controlled (for example, lighting / extinguishing control or emission intensity control) via the light source driving circuit 70.
  • the optical scanner control unit 40 receives a synchronization signal for synchronizing the driving timing of the mirror unit 11 with the image signal. Thus, appropriate image display based on the input image signal is performed on the projection plane 200 (see FIG. 2).
  • a triangular wave scan of 60 Hz is performed in the vertical direction (V direction), and a sine wave scan, for example, is performed at the resonance frequency in the horizontal direction (H direction). Done.
  • the optical scanner 10 having two or more resonance modes that can be used for driving the mirror unit 11 (driving body) (see FIG. 5) from the light source 30.
  • the image projection device 100 By mounting as a scanning unit that scans the light, the image projection device 100 in which the stability of the mirror unit 11 (driving body) (see FIG. 5) is significantly improved can be obtained.
  • the present invention is applied to an optical scanner which is an example of a micro scanner.
  • the present invention is not limited to this, and the present invention is applied to a micro scanner other than an optical scanner. It can also be applied.
  • the micro scanner other than the optical scanner include a micro scanner on which a lens (bending optical system) is mounted instead of a mirror portion, and a micro scanner on which a light source (light emitting element or the like) is mounted.
  • the resonance drive actuator of the present invention may be an actuator other than the MEMS device.
  • a unimorph-structured excitation source In the first to third embodiments, an example using a unimorph-structured excitation source has been described.
  • a piezoelectric excitation source is not limited to a unimorph, and may be, for example, a bimorph. .
  • the excitation source for driving the mirror unit is configured as a piezoelectric driving system including a piezoelectric element.
  • the present invention is not limited to this, and the mirror unit is driven.
  • the excitation source to be used may be other than the piezoelectric drive system.
  • it may be electrostatic or electromagnetic.
  • an example of an optical scanner capable of two-dimensional scanning is shown as an example of an optical scanner.
  • the present invention is not limited to this, and may be a one-dimensional optical scanner, for example. .
  • the resonance mode that can be used for driving the mirror unit is a resonance mode (first resonance mode (modeA)) having a frequency smaller than the resonance frequency of the excitation source, and the resonance of the excitation source.
  • first resonance mode (modeA) having a frequency smaller than the resonance frequency of the excitation source
  • second resonance mode (mode B) An example in which a resonance mode having a frequency larger than the frequency (second resonance mode (mode B)) is included is shown.
  • the present invention is not limited to such a configuration.
  • each of the resonance modes may be configured to have a frequency equal to or lower than the resonance frequency of the excitation source, or a frequency equal to or higher than the resonance frequency of the excitation source. You may be comprised so that it may have.
  • the present invention is not limited thereto, and the present invention is applied to optical apparatuses other than the image projection apparatus.
  • the optical apparatus may be an image forming apparatus such as a copying machine or a printer other than the image projecting apparatus such as a projector.
  • other scanning devices for example, devices that scan light may be used.
  • the resonance drive actuator (optical scanner 10) demonstrated above can also be expressed as follows. That is, the resonance drive actuator includes a drive body (mirror unit 10) driven by resonance and a plurality of vibration sources (vibration source 13) that vibrate the drive body, for driving the drive body. There are two or more resonance modes that can be used, and the frequency of at least one resonance mode is outside the frequency region between the maximum resonance frequency and the minimum resonance frequency among the resonance frequencies of the respective excitation sources.
  • the driving body is configured to be resonantly driven by a resonance mode having a frequency outside the frequency region among the two or more resonance modes.
  • the two or more resonance modes are a first resonance mode having a frequency lower than the minimum resonance frequency of the excitation source and a second resonance mode having a frequency higher than the maximum resonance frequency of the excitation source. At least one of them may be included. Further, the two or more resonance modes may include a resonance mode having a frequency that approximates or matches one of the resonance frequencies of each excitation source.
  • the resonance drive actuator of the present invention can be used for optical devices such as a micro scanner that performs one-dimensional or two-dimensional scanning, an image projection apparatus, and an image forming apparatus.
  • Optical scanner (micro scanner) 11 Mirror (Driver) 12 Fixed Frame 13 Excitation Source 13a Piezoelectric 13b Electrode 13c Piezoelectric Element 14 Mirror Frame 15 Vertical Torsion Bar (Frame Shaft) 16 Horizontal torsion bar (mirror shaft) 17 connecting portion 18, 18a, 18b strain sensor 19 holding portion 20 piezoresistive element 21 displacement enlargement portion 30 light source 40 optical scanner control portion (drive circuit portion) 50 Horizontal drive control unit (drive circuit unit) 60 Vertical drive control unit (drive circuit unit) Reference Signs List 70 light source drive circuit 80 image signal control unit 100 image projection device (optical apparatus)

Abstract

La présente invention concerne un dispositif (10) de balayage optique muni d'un miroir (11) entraîné par résonance, et comportant au moins deux moteurs à résonance qui peuvent être utilisés pour l'entraînement du miroir (11). Le miroir (11) est également soumis à un entraînement par résonance par la fréquence des moteurs à résonance qui fonctionnent. De ce fait, il est possible d'entraîner de manière stable le miroir (11) même s'il existe des variations sur l'assemblage.
PCT/JP2012/053854 2011-06-21 2012-02-17 Actionneur d'entraînement par résonance, micro-dispositif de balayage et appareil optique WO2012176492A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2808719A1 (fr) * 2013-05-28 2014-12-03 Stanley Electric Co., Ltd. Déflecteur optique comprenant des parties piézoélectriques séparées sur des actionneurs piézoélectriques et son procédé de conception
WO2020219232A1 (fr) * 2019-04-25 2020-10-29 Microsoft Technology Licensing, Llc Scanner de systèmes microélectromécaniques non résonants avec actionneurs piézoélectriques

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JP2005181394A (ja) * 2003-12-16 2005-07-07 Canon Inc ねじり振動子、光偏向器および画像形成装置
WO2009087883A1 (fr) * 2008-01-10 2009-07-16 Konica Minolta Opto, Inc. Micro-scanner et procede de commande associe

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JP2005181394A (ja) * 2003-12-16 2005-07-07 Canon Inc ねじり振動子、光偏向器および画像形成装置
WO2009087883A1 (fr) * 2008-01-10 2009-07-16 Konica Minolta Opto, Inc. Micro-scanner et procede de commande associe

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2808719A1 (fr) * 2013-05-28 2014-12-03 Stanley Electric Co., Ltd. Déflecteur optique comprenant des parties piézoélectriques séparées sur des actionneurs piézoélectriques et son procédé de conception
US9395536B2 (en) 2013-05-28 2016-07-19 Stanley Electric Co., Ltd. Optical deflector including separated piezoelectric portions on piezoelectric actuators and its designing method
WO2020219232A1 (fr) * 2019-04-25 2020-10-29 Microsoft Technology Licensing, Llc Scanner de systèmes microélectromécaniques non résonants avec actionneurs piézoélectriques
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