WO2024084875A1 - 光偏向器 - Google Patents

光偏向器 Download PDF

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Publication number
WO2024084875A1
WO2024084875A1 PCT/JP2023/033853 JP2023033853W WO2024084875A1 WO 2024084875 A1 WO2024084875 A1 WO 2024084875A1 JP 2023033853 W JP2023033853 W JP 2023033853W WO 2024084875 A1 WO2024084875 A1 WO 2024084875A1
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WO
WIPO (PCT)
Prior art keywords
optical deflector
torsion bar
mirror
rotation axis
side edge
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2023/033853
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English (en)
French (fr)
Japanese (ja)
Inventor
春輝 田中
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Stanley Electric Co Ltd
Original Assignee
Stanley Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stanley Electric Co Ltd filed Critical Stanley Electric Co Ltd
Priority to CN202380072580.2A priority Critical patent/CN120077314A/zh
Priority to US19/115,249 priority patent/US20260103376A1/en
Priority to EP23879525.6A priority patent/EP4579311A4/en
Publication of WO2024084875A1 publication Critical patent/WO2024084875A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0035—Constitution or structural means for controlling the movement of the flexible or deformable elements
    • B81B3/004—Angular deflection
    • B81B3/0048—Constitution or structural means for controlling angular deflection not provided for in groups B81B3/0043 - B81B3/0045
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0035—Constitution or structural means for controlling the movement of the flexible or deformable elements
    • B81B3/004—Angular deflection
    • B81B3/0043—Increasing angular deflection
    • 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
    • G02B26/105—Scanning systems with one or more pivoting mirrors or galvano-mirrors
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/04—Optical MEMS
    • B81B2201/042—Micromirrors, not used as optical switches
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2203/00—Basic microelectromechanical structures
    • B81B2203/01—Suspended structures, i.e. structures allowing a movement
    • B81B2203/0145—Flexible holders
    • B81B2203/0154—Torsion bars
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2203/00—Basic microelectromechanical structures
    • B81B2203/05—Type of movement
    • B81B2203/058—Rotation out of a plane parallel to the substrate

Definitions

  • the present invention relates to an optical deflector that is installed in a scanning device and emits scanning light.
  • Optical deflectors manufactured as MEMS (Micro Electro Mechanical Systems) devices reflect an incoming laser beam onto a mirror that rotates back and forth around a rotation axis, and emit the reflected light from the mirror as scanning light (e.g., Patent Documents 1 to 3).
  • MEMS Micro Electro Mechanical Systems
  • the optical deflector of Patent Document 1 comprises a mirror section, a pair of torsion bars extending from the mirror section along the rotation axis, one on each side of the mirror section in the extension direction of the rotation axis of the mirror section, and a piezoelectric actuator coupled to the tip end of each torsion bar to rotate the torsion bar back and forth around the rotation axis.
  • the optical deflector in Patent Document 2 comprises a mirror section, a total of four torsion bars, two on each side of the mirror section in the extension direction of the rotation axis of the mirror section, extending parallel to the rotation axis with equal gaps between them, and a piezoelectric actuator that is connected to the tip end of each torsion bar and rotates the torsion bar back and forth around the rotation axis.
  • the optical deflector in Patent Document 3 is equipped with a mirror section, four torsion bars, two on each side of the mirror section in the direction of extension of the rotation axis, with holes drilled so that the distance between the two becomes narrower toward the tip (i.e., in a figure of eight), and an electrostatic actuator that rotates the mirror section back and forth around the rotation axis from both sides perpendicular to the rotation axis.
  • an optical deflector it is desirable for an optical deflector to have a large scanning angle, which corresponds to the reciprocating rotation angle of the mirror part around the axis of rotation.
  • the maximum reciprocating rotation angle of the mirror part is limited by the maximum allowable stress of the torsion bar to prevent the torsion bar from being damaged as it rotates reciprocatingly.
  • the ratio of the width of the torsion bar in the front view to the thickness of the torsion bar is defined as the aspect ratio A.R. (Aspect Ratio).
  • A.R. Aspect Ratio
  • A.R. ⁇ 1 it is the corner, which is the point farthest from the axis of rotation in the cross section of the torsion bar.
  • the optical deflector in Patent Document 1 has an A.R. ⁇ 1, and the points of maximum stress in the mirror are the four corners of the mirror's cross section.
  • the only way is to narrow the width or thickness of the torsion bar. Reducing the width or thickness of the torsion bar increases the harmonics generated in the mirror, inducing abnormal vibrations in the mirror (such as vibrations in the extension direction of the rotation axis or perpendicular to the rotation axis).
  • the two torsion bars on each side of the mirror are completely open at the end opposite the mirror, with gaps extending in the width direction, reducing the transmission efficiency of the rotational force transmitted from the piezoelectric actuator to the torsion bars.
  • the two torsion bars on each side of the mirror section are connected to the mirror section at two points separated in a direction perpendicular to the axis of rotation, so compared to when there is only one point, the rotational driving force of the torsion bars or the reversal driving force when the rotation is reversed is increased, and the load on the actuator is increased.
  • the object of the present invention is to provide an optical deflector that overcomes the above-mentioned problems of the prior art and can increase the maximum allowable rotation angle of the torsion bar when the aspect ratio A.R. of the torsion bar is A.R. ⁇ 1.
  • the optical deflector of the present invention comprises: A mirror portion having a mirror surface on one side in a thickness direction and reciprocatingly rotating around a rotation axis (Da) perpendicular to the thickness direction; a pair of torsion bars extending along the rotation axis from inner joining positions at both ends of the mirror part in an extension direction of the rotation axis; an actuator that couples the torsion bar from both sides in a width direction at an outer coupling position separated from the inner coupling position in the extension direction, and rotates the torsion bar reciprocally around the rotation axis at the outer coupling position; a slit formed in the torsion bar such that, in a front view as a direction when the mirror surface is viewed from the one side in the thickness direction, both ends in the extension direction are closed, and the both ends extend along the rotation axis within a range of lengths reaching the inner coupling position and the outer coupling position; Equipped with The torsion bar has a dimension between both ends of Wa and a thickness of Ta when viewed
  • slits are formed in the torsion bar so that, when viewed from the front, both ends in the extension direction are closed, and the slits extend along the rotation axis over a length range that reaches the inner and outer bonding regions at both ends.
  • the stress acting on each torsion bar during reciprocal rotation around the rotation axis is distributed to four areas: the side surfaces of the torsion bar and the inner surfaces of the slits, so that the reciprocal rotation angle when the maximum allowable stress is generated in the torsion bar can be increased.
  • FIG. 1 is a schematic diagram of a light deflector as viewed obliquely from the front.
  • FIG. 2 is an enlarged front view of the torsion bar and its surroundings in FIG. 1 .
  • FIG. 2B is an enlarged view of the outer bond area of FIG. 2A.
  • FIG. 2B is an enlarged view of the inner bond area of FIG. 2A.
  • FIG. 2B is a front view showing an area having an inner extension portion with a shape different from that of the inner extension portion of FIG. 2A together with the inner ends of the torsion bars on both sides thereof.
  • FIG. 3B is a close-up of the inner bond area of FIG. 3A.
  • 2 is a cross-sectional view of the optical deflector cut in the thickness direction along the axis Ax in FIG.
  • FIG. 1 is a cross-sectional view taken along a plane parallel to the cross section of FIG. 4 at the position of the equal-width extension portion of the torsion bar.
  • FIG. FIG. 4 is an explanatory diagram of the aspect ratio of a torsion bar.
  • FIG. 13 is a stress distribution diagram around a slit when the slit is composed only of an equal-width extension portion.
  • optical deflector/overall 1 is a schematic diagram of an optical deflector 10 as viewed obliquely from the front.
  • the optical deflector 10 is manufactured as a MEMS (Micro Electro Mechanical Systems) device from an SOI substrate.
  • MEMS Micro Electro Mechanical Systems
  • a view in a thickness direction of the optical deflector 10 (which is also the thickness direction of the mirror section 11) from the incident side of the incident light La (the mirror surface side in the thickness direction of the mirror section 11) is referred to as a "front view.”
  • the overall configuration of the optical deflector 10 will be described briefly with reference to FIG. 1. Details of the overall configuration of the optical deflector 10 are as described, for example, in JP 2012-201386 A of the present applicant.
  • the optical deflector 10 is installed in any device equipped as an optical scanner, such as a projector (including a picoprojector), a head-up display, an automobile headlamp, or eyewear.
  • the optical deflector 10 has a symmetrical structure when viewed from the front, and includes a mirror section 11, upper and lower torsion bars 12a, 12b, left and right inner actuators 13a, 13b, a movable frame 14, left and right outer actuators 15a, 15b, and a fixed frame 16.
  • the inner actuators 13a, 13b and the outer actuators 15a, 15b are all piezoelectric actuators.
  • orthogonal axes Ax and Ay are defined at the center O of the mirror section 11.
  • the axes Ax and Ay are defined as coordinate axes parallel to the mirror surface (reflective film 64 in FIG. 4) of the mirror section 11, and are also two orthogonal rotation axes of the mirror section 11.
  • the sides closer to and farther from the center O are referred to as the inside and outside, respectively.
  • the circular mirror section 11 has a reflective film 64 ( Figure 4) on the front side (one side in the thickness direction of the mirror section 11) that acts as a mirror surface.
  • Incident light La is emitted from a laser light source (not shown), enters the mirror section 11, is reflected by the mirror section 11, and is emitted from the mirror section 11 as scanning light Lb.
  • the torsion bars 12a, 12b extend along the axis Ay and interconnect the mirror section 11 and the movable frame 14.
  • the inner actuators 13a, 13b have a peripheral contour shape that is long from top to bottom when viewed from the front when interconnected from the left and right, and each has an elliptical arc shape that is a semi-ellipse on the left and right.
  • the torsion bars 12a and 12b extend from the mirror section 11, pass beyond the joints with the inner actuators 13a and 13b, reach the movable frame 14, and are joined to the inner circumference of the movable frame 14.
  • the torsion bars 12a and 12b can also be structured so that they remain at the joints with the inner actuators 13a and 13b without reaching the inner circumference of the movable frame 14.
  • the movable frame 14 When viewed from the front, the movable frame 14 has a vertically elongated elliptical contour shape similar to the overall shape of the left and right inner actuators 13a, 13b connected to each other, and surrounds the mirror part 11, the torsion bars 12a, 12b, and the inner actuators 13a, 13b from the outside.
  • the inner actuators 13a, 13b are interposed between the torsion bars 12a, 12b and the movable frame 14.
  • the inner actuators 13a and 13b are supplied with sinusoidal drive voltages of opposite phases and resonant frequency Fy from a drive device (not shown), causing the torsion bars 12a and 12b to rotate back and forth around the axis Ay at the resonant frequency Fy.
  • the outer actuators 15a and 15b are disposed on the left and right sides of the movable frame 14, and are interposed between the outer circumference of the movable frame 14 and the inner circumference of the fixed frame 16.
  • the outer actuators 15a and 15b are composed of multiple linear piezoelectric cantilevers connected in series in a meandering pattern.
  • the outer actuators 15a and 15b are numbered in sequence from the outside to the inside in the horizontal direction (parallel to the long side of the rectangular fixed frame 16)
  • the odd-numbered piezoelectric cantilevers and the even-numbered piezoelectric cantilevers are supplied with sawtooth or triangular wave drive voltages of mutually opposite phase non-resonant frequency Fx (Fx ⁇ Fy) from a control device (not shown).
  • Fx phase non-resonant frequency
  • optical deflector 10 The overall general function of the optical deflector 10 is explained below.
  • a drive voltage is supplied to the torsion bar 12 (general term for the torsion bars 12a and 12b) and the outer actuator 15 (general term for the outer actuators 15a and 15b) from a drive device (not shown).
  • This causes the mirror section 11 to rotate back and forth around the axes Ax and Ay at the non-resonant frequency Fx and the resonant frequency Fy, respectively.
  • Fx and Fy are, for example, 60 Hz and 25 kHz, respectively.
  • incident light La of a laser beam from a laser light source is incident on the mirror section 11 which rotates back and forth around the axes Ax and Ay.
  • scanning light Lb which is the reflected light of the incident light La, is emitted from the mirror section 11 as a two-dimensional scanning beam.
  • the incident light La may be three laser beams of different colors, red, green, and blue, or may be a single predetermined color.
  • the light source control device (not shown) is capable of controlling the brightness (intensity) of the incident light La emitted from the laser light source for each color.
  • Fig. 2A is an enlarged front view of the range including the torsion bars 12a, 12b and their surroundings in Fig. 1.
  • Da is the vertical rotation axis of the mirror part 11, which extends on the axis Ay in Fig. 1.
  • the outer ends (ends farther from the center O) of the torsion bars 12a, 12b do not reach the inner periphery of the movable frame 14, and remain at the joint positions with the torsion bars 12a, 12b.
  • Slits 20a and 20b are formed in the torsion bars 12a and 12b, respectively.
  • the structure is vertically symmetrical with respect to the axis Ax (Fig. 1) when viewed from the front. For this reason, the structure and function of the upper torsion bar 12a and slit 20a will be explained, and an explanation of the structure and function of the lower torsion bar 12b and slit 20b will be omitted.
  • the slit 20a is formed in the torsion bar 12a so as to extend along the rotation axis Da and penetrate in the thickness direction.
  • the slit 20a has an equal-width extension portion 22 that extends along the rotation axis Da with an equal width, and an outer extension end 24a and an inner extension end 24b that are connected to the outer and inner ends of the equal-width extension portion 22, respectively.
  • the circumference of the mirror part 11 disappears at the joint between the mirror part 11 and the torsion bar 12a. If the boundary line between the mirror part 11 and the torsion bar 12a is set on the disappeared circumference line, the equal-width extension part 22 of the slit 20 reaches at least the boundary line inward, and typically crosses the boundary line and enters the mirror part 11. Note that the boundary line means the joint position between the mirror part 11 and the torsion bar 12a.
  • the torsion bar 12a and the inner actuators 13a, 13b are bonded to each other in the outer bonding region 36.
  • the outer bonding region 36 is defined as the region inside the left and right ends of the left and right curved outer corners (first corners) 30a, 30b in the width direction, outside the ends of the left and right curved outer corners 30a, 30b on the center O side in the extension direction, and inside the outer peripheral contours of the inner actuators 13a, 13b in the extension direction.
  • the outer bonding region 36 refers to the bonding position between the torsion bar 12a and the mirror section 11 as a whole.
  • the mirror section 11 and the torsion bar 12a are bonded to each other at the inner bonding region 38.
  • the inner bonding region 38 is defined as a region that is inside the left and right ends of the left and right curved inner corners (second corners) 32a, 32b in the width direction, and is closer to the center O than the ends of the left and right curved inner corners 32a, 32b farther from the center O in the extension direction. Furthermore, the inner bonding region 38 is defined as a region in the mirror section 11 where a predetermined stress is generated when the mirror section 11 rotates back and forth around the rotation axis Da.
  • the inner bonding region 38 as a whole refers to the bonding position between the torsion bar 12a and the mirror section 11.
  • the curved outer corners 30a, 30b are formed at the corners between the side edges of the torsion bar 12a and the inner circumferential edges of the inner actuators 13a, 13b as first curved lines that extend outward from the side edges of the torsion bar 12a in the width direction of the torsion bar 12a (perpendicular to the extension direction of the rotation axis Da and the thickness direction) and are curved inwardly of the outer bonding region 36.
  • the curved inner corners (second corners) 32a, 32b are formed at the corners between the periphery of the mirror section 11 and the side edges of the torsion bar 12a as second curved lines that extend outward from the side edges of the torsion bar 12a in the width direction and are curved inwardly of the inner bonding region 38.
  • FIG. 2B and 2C are enlarged views of the outer bonded region 36 and inner bonded region 38 of FIG. 2A, respectively.
  • the outer expanded end 24a and inner expanded end 24b of the slit 20a are formed in the outer bonded region 36 and inner bonded region 38, respectively.
  • the stress relaxation effect of the outer expanded end 24a and inner expanded end 24b will be described in detail in FIG. 7 below.
  • FIG. 7 Only the configuration of the outer expanded end 24a and inner expanded end 24b will be described with reference to FIG. 2B and FIG. 2C.
  • the outer extension end 24a is circular (an example of a first curved contour shape) in front view, except for the boundary between the outer extension end 24a and the equal-width extension 22.
  • the contour of the boundary is set to a contour that extends parallel to the first curved line of the curved outer corners 30a, 30b with approximately equal width.
  • the diameter of the outer expansion end 24a is larger than the width of the uniform width extension 22 (Wb in FIG. 6 described below), and the outer expansion end 24a is wider in the width direction of the slit 20a than the uniform width extension 22.
  • the curved outer corners 30a, 30b serve to reinforce the outer expansion end 24a against widthwise expansion.
  • the inner extension end 24b is formed in a shape (an example of a second curved contour shape) that is symmetrical with respect to the rotation axis Da when viewed from the front.
  • the inner extension end 24b is formed as a through hole defined by the outer curved contour portions 44a, 44b closer to the periphery of the mirror portion 11 and the inner curved contour portion 46 closer to the center O.
  • the outer curved contour portions 44a, 44b are set to contour lines that are parallel and of approximately equal width from the second curved lines of the curved inner corner portions 32a, 32b. The significance of such contour lines of the inner extension end 24b will be described later in comparison with the inner extension end 24c of the cylindrical hole in FIG. 3A and FIG. 3C.
  • the inner curved contour portion 46 is set to the contour line of a circular arc concentric with the circle of the mirror portion 11.
  • the width of the inner extension end 24b is greater than the width of the equal-width extension portion 22, and the inner extension end 24b is wider in the width direction of the slit 20a than the equal-width extension portion 22.
  • the curved inner corners 32a, 32b serve to reinforce the inner extension end 24b against widthwise expansion.
  • Figure 3A is a front view of the range including the mirror portion 11 and the inner ends of the torsion bars 12a, 12b in the extension direction of the rotation axis Da.
  • Figure 3B is an enlarged view of the inner bonding region 38.
  • the inner extension end 24c has the same cylindrical hole shape (another example of the second curved contour shape) as the outer extension end 24a, and is formed in the inner bonding region 38 symmetrically with respect to the rotation axis Da, penetrating the mirror portion 11.
  • the boundary between the equal-width extension portion 22 and the inner extension end 24c is set to a contour line extending parallel to the second curved line.
  • the diameter of the inner expansion end 24c is larger than the width of the uniform width extension 22, and the inner expansion end 24c is wider in the width direction of the slit 20a than the uniform width extension 22.
  • the curved outer corners 30a and 30b serve to reinforce the inner expansion end 24c against widthwise expansion.
  • FIG. 4 is a cross-sectional view taken along the axis Ax in FIG. 1 in the thickness direction of the optical deflector 10 with the mirror portion 11 in a stationary state
  • FIG. 5 is a cross-sectional view taken along a plane parallel to the cross section of FIG. 4 at the position of the equal-width extension portion 22 of the torsion bar 12a.
  • the SOI substrate 50 has a five-layered structure of, from the top, an oxide film layer 51, an active layer 52, an oxide film layer 53, a handling layer 54, and an oxide film layer 55.
  • the oxide film layers 51, 53, and 55 are made of SiO2.
  • the active layer 52 and the handling layer 54 are made of Si.
  • the piezoelectric element 58 has a three-layered structure of, from the top, an upper electrode layer 59, a PZT (lead zirconate titanate) film layer 60, and a lower electrode layer 61.
  • the mirror section 11, torsion bar 12a and fixed frame 16 are composed of all layers of the SOI substrate 50.
  • the inner actuators 13a, 13b and the outer actuators 15a, 15b are composed of two oxide film layers 51 and an active layer 52 from the top of the SOI substrate 50, and a three-layer laminate of a piezoelectric element 58 stacked on top of that.
  • the surface of the mirror section 11 is covered with a reflective film 64 made of a metal component.
  • the reflective film 64 acts as a mirror surface that reflects the incident light La ( Figure 1).
  • the equal-width extension 22 of the slit 20a penetrates the torsion bar 12a in the thickness direction.
  • the outer extension end 24a and the inner extension end 24b of the slit 20a also penetrate the outer extension end 24a of the torsion bar 12a and the inner extension end 24b of the mirror portion 11 in the thickness direction, just like the equal-width extension 22.
  • the slits 20a in the torsion bar 12a are manufactured by deep RIE.
  • Typical deep RIE methods include using high-density plasma to cool the sample to a low temperature, using an etching technique called the Bosch process, or using both.
  • the cross-sectional laminated structure in the outer bonding region 36 will be described.
  • the upper electrode layer 59 and PZT film layer 60 of the three-layer laminate of the piezoelectric element 58 are removed by etching, and only the lower electrode layer 61, the bottom layer, remains without being removed.
  • the lower electrode layer 61 is a layer of earth voltage, and as a result of the lower electrode layer 61 remaining in the outer bonding region 36, the lower electrode layers 61 of the left and right inner actuators 13a, 13b are electrically connected to each other in the outer bonding region 36. Meanwhile, the left and right inner actuators 13a, 13b are separated in the outer bonding region 36 by the upper electrode layer 59 and the PZT film layer 60, so that they can be individually driven by being supplied with individual drive voltages.
  • (aspect ratio) 6 is an explanatory diagram of the aspect ratio A.R. of the torsion bar 12a.
  • the definitions of the symbols are as follows: Wa: Width of both ends of the torsion bar 12a in front view Wb: Width of the equal-width extension portion 22 in front view Wc: Width of the left and right portions of the torsion bar 12a divided left and right by the equal-width extension portion 22 in front view Ta: Thickness of the torsion bar 12a
  • the significance of formula (5) is that although the slits 20a, 20b are originally formed to prevent damage from occurring at the corners of the cross sections of the torsion bars 12a, 12b, if Wa/Ta ⁇ 1, damage may occur first on the rotation axis of the torsion bars 12a, 12b, which may defeat the purpose of forming the slits 20a, 20b.
  • the significance of formula (6) is that if Wb>2 ⁇ Wc, the oscillation (pumping) of the mirror part 11 in the extension direction of the rotation axis Da becomes dominant. It is also advantageous for Wb to be 25 ⁇ m or more.
  • the torsion bar is subjected to stress when it rotates back and forth around the axis of rotation, but by providing the slits of the present invention in the torsion bar, it is possible to alleviate the stress.
  • the torsion bar 12 has slits 20 (a collective term for slits 20a and 20b) with equal-width extensions 22, so that the total area of the side surface is the area of the outer side surface in the width direction plus the area of the inner surface of the slit 20 as the inner side surface.
  • the area of the side surface increases, dispersing the stress acting on the side surface. This leads to a reduction in the stress in the torsion bar 12, and increases the maximum allowable rotation angle of the torsion bar 12 around the rotation axis Da without breaking.
  • the lateral scanning angle of the scanning light Lb around the rotation axis Da increases.
  • the stress dispersion effect of the inner surface of the slit 20 reduced the unit rotation angle (unit deflection angle: Mpa/deg) of the torsion bar 12 around the rotation axis Da by 25%. This means that the limit deflection angle of the torsion bar 12 around the rotation axis Da became 1.33 times larger.
  • Fig. 7 is a stress distribution diagram around the slit 20a when the slits 20a and 20b of the optical deflector 10 do not have the outer extended end portion 24a and the inner extended end portions 24b and 24c, but have only the equal-width extension portion 22.
  • Fig. 7 is a diagram showing a screen display based on the analysis results of the simulation, and shows that the stress increases from the dark areas to the light areas.
  • the maximum stress points appear at both ends of the equal-width extension portion 22.
  • the white dashed circles Ca and Cb are shown as circles centered on the outer end and inner end of the equal-width extension portion 22 of the slit 20a. It can be seen that the areas of high stress extend outward and inward from the outer end and inner end of the equal-width extension portion 22, respectively, in the extension direction of the equal-width extension portion 22.
  • the circumferential line of the mirror portion 11 disappears at the bonding portion between the mirror portion 11 and the torsion bar 12a.
  • the inner bonding region 38 is set as the region on the mirror portion 11 side of the boundary line where a stress equal to or greater than a predetermined value is generated in the mirror portion 11.
  • the equal-width extension portion 22 is connected to both ends with an outer extension end 24a and an inner extension end 24b or an inner extension end 24c, so that the maximum stress in the torsion bars 12a and 12b is equal to or less than a predetermined upper limit.
  • the stress transmitted from the mirror portion 11 to the torsion bars 12a, 12b in the outward direction along the rotation axis Da is split into left and right portions of the torsion bars 12a, 12b on both sides of the slit 20 in the width direction and transmitted in parallel to the outer bonding region 36.
  • the circular shape of the outer extension end 24a in front view has the effect of appropriately dispersing the stress transmitted in parallel to the left and right, making the stress in the outer bonding region 36 uniform and reducing the maximum stress.
  • the reduction in maximum stress leads to an increase in the maximum allowable reciprocating angle of the mirror portion 11 around the rotation axis Da.
  • the effect of the inner extension end 24c will be described before the effect of the inner extension end 24b.
  • the effect of the inner extension end 24c is the same as that of the outer extension end 24a. That is, the stress transmitted inward from the torsion bars 12a, 12b along the rotation axis Da in the mirror part 11 is divided into the left and right parts of the torsion bars 12a, 12b on both sides of the slit 20 in the width direction and transmitted in parallel to the mirror part 11.
  • the circular shape of the inner extension end 24c in front view like the outer extension end 24a, appropriately distributes the stress that is divided into the left and right and transmitted in parallel to the left and right, uniformizing the stress in the inner joint region 38 and reducing the maximum stress.
  • the inner extension end 24c has a simpler shape than the inner extension end 24b, and therefore has the advantage of being less expensive to manufacture.
  • the outer end and/or the inner end of the slit 20 may be advantageous in some cases to move the outer end and/or the inner end of the slit 20 slightly outward and inward along the rotation axis Da from that shown in FIG. 7, and then connect the outer extension end 24a and the inner extension end 24b, 24c.
  • the outer end and/or the inner end of the slit 20 are not fixed to that shown in FIG. 7, but are appropriately advanced deeply into the outer bonded region 36 and the inner bonded region 38 along the rotation axis Da, and the positions of the outer extension end 24a and the inner extension end 24b, 24c are then set.
  • the inner end of the inner extension end 24b is located outward in the extension direction of the rotation axis Da from the inner end of the inner extension end 24c. This means that the beam cross section of the incident light La is irradiated onto the entire surface of the mirror section 11, which is approximately circular.
  • the closest point to the center O penetrates deep into the mirror part 11 toward the center O.
  • the effective diameter of the mirror part 11 in the extension direction of the rotation axis Da is reduced, which causes a decrease in the resolution of the image generated by the scanning light Lb in the irradiation area of a screen or the like.
  • the inner extension end 24b is formed along the circumferential contour of the mirror part 11, and the closest point to the center O can be moved sufficiently farther away than the inner extension end 24c. Therefore, the torsion bar 12a relieves the stress on the inner ends of the torsion bars 12a and 12b while minimizing the reduction in the effective diameter of the mirror part 11. This makes it possible to increase the reciprocating rotation angle of the mirror part 11 around the rotation axis Da while avoiding the reduction in the effective diameter of the mirror part 11.
  • the slits 20a, 20b are closed at both ends in the direction in which the rotation axis extends, so that the torsion bars 12a, 12b, in which the slits 20a, 20b are formed on the inner periphery, do not separate into two, but maintain a single torsion bar, and the optical deflector 10 is configured to have only one torsion bar on each side of the mirror section 11.
  • the optical deflector 10 is a two-axis scanning type optical deflector, but the optical deflector of the present invention may be a one-axis scanning type optical deflector as long as it has a configuration in which an actuator rotates the mirror portion back and forth around a rotation axis via a torsion bar.
  • the outer extension end 24a and the inner extension end 24c of the slits 20a, 20b are substantially circular in front view.
  • the outer end and the inner end of the slit of the present invention may be through holes that are symmetrical with respect to the rotation axis Da and have a regular polygonal shape (e.g., an equilateral triangle, a square, a regular pentagon, etc.) in front view.
  • the equal-width extension 22 has been described as being of equal width, but in the present invention, the extension at the location where the equal-width extension 22 of the optical deflector 10 is formed does not have to be of equal width over the entire length when viewed from the front.
  • both ends of the extension may be of the same width when viewed from the front, and the middle may be wider or narrower, or the widths of both ends of the extension may be different from each other, so long as the driving force of the inner actuators 13a, 13b is not significantly increased.
  • 10 optical deflector
  • 11 mirror portion
  • 12a, 12b torsion bars
  • 13a, 13b inner actuator
  • 14 movable frame
  • 20a, 20b slit
  • 22 equal width extension portion
  • 24a outer extension end (outer end)
  • 24b, 24c inner extension end (inner end)
  • 30a, 30b curved outer corner (first corner)
  • 32a, 32b curved inner corner (second corner)
  • 36 outer bonding region
  • 38 inner bonding region
  • 44 outer curved contour portion
  • 46 inner curved contour portion
  • Da rotation axis.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Mechanical Optical Scanning Systems (AREA)
  • Micromachines (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
PCT/JP2023/033853 2022-10-20 2023-09-19 光偏向器 Ceased WO2024084875A1 (ja)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN202380072580.2A CN120077314A (zh) 2022-10-20 2023-09-19 光偏转器
US19/115,249 US20260103376A1 (en) 2022-10-20 2023-09-19 Light deflector
EP23879525.6A EP4579311A4 (en) 2022-10-20 2023-09-19 Light deflector

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022-168099 2022-10-20
JP2022168099A JP2024060686A (ja) 2022-10-20 2022-10-20 光偏向器

Publications (1)

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WO2024084875A1 true WO2024084875A1 (ja) 2024-04-25

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EP (1) EP4579311A4 (cg-RX-API-DMAC7.html)
JP (1) JP2024060686A (cg-RX-API-DMAC7.html)
CN (1) CN120077314A (cg-RX-API-DMAC7.html)
WO (1) WO2024084875A1 (cg-RX-API-DMAC7.html)

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US20240027746A1 (en) * 2022-07-25 2024-01-25 Ricoh Company, Ltd. Movable device, projection apparatus, head-up display, laser headlamp, head-mounted display, and object recognition apparatus

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JP3905539B2 (ja) 2002-08-14 2007-04-18 富士通株式会社 トーションバーを備えるマイクロ揺動素子
JP2009169290A (ja) 2008-01-18 2009-07-30 Stanley Electric Co Ltd 光偏向器
JP2012063413A (ja) * 2010-09-14 2012-03-29 Ricoh Co Ltd 光走査装置およびこの光走査装置を組み込んだ画像形成装置ならびに投影装置
JP2012163939A (ja) * 2011-01-21 2012-08-30 Olympus Corp 光偏向器
JP2012201386A (ja) 2011-03-24 2012-10-22 Toshiba Lighting & Technology Corp 密閉容器及び照明器具
WO2013046612A1 (ja) * 2011-09-30 2013-04-04 パナソニック株式会社 光学反射素子
JP2016151681A (ja) 2015-02-18 2016-08-22 株式会社Ｊｖｃケンウッド Ｍｅｍｓ光スキャナ
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JP5736766B2 (ja) * 2010-12-22 2015-06-17 ミツミ電機株式会社 光走査装置
JP2015152869A (ja) * 2014-02-18 2015-08-24 パナソニックＩｐマネジメント株式会社 可動板構造体及びそれを用いた光走査装置

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JP3905539B2 (ja) 2002-08-14 2007-04-18 富士通株式会社 トーションバーを備えるマイクロ揺動素子
JP2009169290A (ja) 2008-01-18 2009-07-30 Stanley Electric Co Ltd 光偏向器
JP2012063413A (ja) * 2010-09-14 2012-03-29 Ricoh Co Ltd 光走査装置およびこの光走査装置を組み込んだ画像形成装置ならびに投影装置
JP2012163939A (ja) * 2011-01-21 2012-08-30 Olympus Corp 光偏向器
JP2012201386A (ja) 2011-03-24 2012-10-22 Toshiba Lighting & Technology Corp 密閉容器及び照明器具
WO2013046612A1 (ja) * 2011-09-30 2013-04-04 パナソニック株式会社 光学反射素子
JP2016151681A (ja) 2015-02-18 2016-08-22 株式会社Ｊｖｃケンウッド Ｍｅｍｓ光スキャナ
WO2020045152A1 (ja) * 2018-08-31 2020-03-05 パナソニックＩｐマネジメント株式会社 光学反射素子

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20240027746A1 (en) * 2022-07-25 2024-01-25 Ricoh Company, Ltd. Movable device, projection apparatus, head-up display, laser headlamp, head-mounted display, and object recognition apparatus
US12572008B2 (en) * 2022-07-25 2026-03-10 Ricoh Company, Ltd. Movable device, projection apparatus, head-up display, laser headlamp, head-mounted display, and object recognition apparatus

Also Published As

Publication number Publication date
CN120077314A (zh) 2025-05-30
EP4579311A4 (en) 2025-12-03
EP4579311A1 (en) 2025-07-02
JP2024060686A (ja) 2024-05-07
US20260103376A1 (en) 2026-04-16

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