WO2012133505A1 - Dispositif de lecture optique et procédé de fabrication d'un dispositif de lecture optique - Google Patents

Dispositif de lecture optique et procédé de fabrication d'un dispositif de lecture optique Download PDF

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Publication number
WO2012133505A1
WO2012133505A1 PCT/JP2012/058090 JP2012058090W WO2012133505A1 WO 2012133505 A1 WO2012133505 A1 WO 2012133505A1 JP 2012058090 W JP2012058090 W JP 2012058090W WO 2012133505 A1 WO2012133505 A1 WO 2012133505A1
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Prior art keywords
layer
optical scanner
pedestal
resonance frequency
linear expansion
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PCT/JP2012/058090
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English (en)
Japanese (ja)
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武田　仁志
和浩 中嶋
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ブラザー工業株式会社
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Publication of WO2012133505A1 publication Critical patent/WO2012133505A1/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

Definitions

  • the present invention relates to an optical scanner for scanning light such as a laser and a method for manufacturing the optical scanner.
  • an optical scanner that scans light such as laser light with a vibrating mirror.
  • the optical scanner described in Patent Document 1 scans light incident on a mirror by a mirror supported so as to be swingable by a torsion beam swinging in a resonance state by a driving unit such as a piezoelectric element. To do. And the structure (main-body part) containing a mirror is being fixed to the base (base).
  • the resonance frequency of the optical scanner varies depending on various factors.
  • the resonance frequency of the optical scanner varies depending on the Young's modulus of the structure including the mirror.
  • the horizontal axis indicates the relative value of Young's modulus
  • the vertical axis indicates the amount of fluctuation of the resonance frequency.
  • the horizontal axis in FIG. 10 is shown as a relative value based on the Young's modulus of the middle data point on the horizontal axis among the three data points.
  • the Young's modulus of the structure 110 is basically determined by the type of material constituting the structure 110. However, the Young's modulus of the material generally has temperature dependence. Specifically, even for the same type of material, the Young's modulus decreases as the temperature increases, and the Young's modulus increases as the temperature decreases. Since the resonance frequency depends on the Young's modulus, the resonance frequency also has temperature dependency. Therefore, a change in the ambient temperature in which the optical scanner is placed changes the resonance frequency of the optical scanner.
  • Examples of devices that use optical scanners include laser printers and scanning image display devices.
  • the scanning speed since the change in the scanning speed results in output distortion, it is desirable that the scanning speed be constant. That is, when an optical scanner that is swung in a resonance state is used, the resonance frequency of the optical scanner is required to be maintained at a predetermined value. However, when the ambient temperature in which the optical scanner is placed changes, the resonance frequency of the optical scanner changes. Therefore, in order to obtain an optical scanner that can be driven stably, the temperature dependence of the resonance frequency needs to be reduced. Therefore, an object of the present disclosure is to provide an optical scanner capable of reducing the temperature dependence of the resonance frequency and a method for manufacturing the optical scanner.
  • one aspect of the present disclosure includes a reflecting surface that reflects light and is configured to be swingable about a first axis, and is coupled to both sides of the mirror portion.
  • a pair of torsion beam portions extending from the mirror portion in parallel to the first axis and an end of the pair of torsion beam portions on the opposite side of the mirror portion and extending in a direction intersecting the first axis.
  • a flat plate-like structure body made of a first material, and provided at least in the structure body, and swinging the mirror part around the first axis at a predetermined resonance frequency.
  • a drive unit configured to be configured, and a pedestal formed of a second material and to which the structure is fixed.
  • the structure is a part of the main body portion, the pair of torsion beam portions, and the A pair of objects to be opposed across the mirror
  • the linear expansion coefficient of the second material is greater than the linear expansion coefficient of the first material
  • the absolute value of the temperature dependence of the resonance frequency is such that the pedestal is
  • An optical scanner characterized in that it is set to a value smaller than the absolute value of the temperature dependence of the resonance frequency in the case of being constituted by the first material.
  • the structure is fixed to at least the pedestal in the pair of fixed portions.
  • the pair of fixed parts is a part of the main body part that faces the pair of torsion beam parts and the mirror part.
  • the structure and the base are fixed on both sides of the main body portion with the pair of torsion beam portions and the mirror portion interposed therebetween.
  • the value of the linear expansion coefficient of the 2nd material which comprises a base is set so that the following 2 conditions may be satisfy
  • the linear expansion coefficient of the pedestal is larger than that of the structure, thermal stress is generated in the structure due to temperature change. Specifically, when the temperature rises, the pedestal expands more than the structure. This difference in the amount of expansion applies tension in the longitudinal direction of the torsion beam to the torsion beam part and the mirror part sandwiched between the fixed parts of the base and the structure. When tension is applied to the torsion beam, the rigidity of the torsion beam is apparently increased. The higher the stiffness of the torsion beam, the higher the resonant frequency of the optical scanner. On the other hand, the Young's modulus decreases as the temperature increases. That is, the change in Young's modulus of the first material due to the temperature rise works in the direction of lowering the resonance frequency.
  • the thermal stress generated in the structure acts in the direction of increasing the resonance frequency as the temperature rises. Therefore, the temperature dependence of the resonance frequency is reduced.
  • the pedestal contracts more than the structure, and thus a force compressing the torsion beam in the longitudinal direction works. That is, the apparent rigidity of the torsion beam is lowered, and the resonance frequency is lowered. Therefore, even when the temperature is lowered, similarly, the change in the resonance frequency due to the change in the Young's modulus of the structure (which works in the direction of increasing) is caused by the difference in the expansion amount between the pedestal and the structure. It is reduced by a change in frequency (which works in the direction of lowering).
  • the pedestal is provided by a first material constituted by the second material, and a third material having a linear expansion coefficient different from that of the second material provided between the first layer and the structure.
  • a second layer configured, and the second layer may be fixed to the fixed portion of the structure, and the first layer may be fixed to the second layer.
  • the pedestal has the first layer and the second layer. Since the first layer and the second layer are made of materials having different linear expansion coefficients, the selection range of the pedestal that can further reduce the temperature dependence of the resonance frequency is expanded depending on the combination of materials.
  • the second layer may be configured so that the thickness in the stacking direction is thinner than the first layer.
  • the second layer in contact with the structure is thinner in the stacking direction than the first layer. Therefore, the linear expansion coefficient of the entire pedestal is roughly determined by the first layer, and can be finely adjusted by selecting the material of the second layer.
  • first material and the second material may be a metal.
  • the structure and the pedestal are both made of a metal that is a ductile material. If the structure or pedestal is made of a brittle material such as silicon, for example, depending on the combination of materials, the structure or pedestal may be damaged due to thermal stress. Therefore, the structure and the pedestal are made of metal, thereby increasing the degree of freedom in combining materials. Further, since it can be manufactured by machining such as a press, an optical scanner can be provided at low cost.
  • the drive unit is provided in the main body portion, and excites plate waves in the main body portion, thereby swinging the mirror portion around the first axis via the main body portion and the pair of torsion beam portions. It may be a piezoelectric element that can be moved.
  • Another aspect of the present disclosure is a method for manufacturing an optical scanner, which includes a reflecting surface that reflects light and is configured to be swingable about a first axis, and is connected to both sides of the mirror portion.
  • a pair of torsion beam portions extending from the mirror portion in parallel to the first axis, and a pair of the torsion beam portions opposite to the mirror portion, and intersecting the first axis.
  • the temperature of the resonance frequency of the scanner The absolute value of the temperature dependency is minimized among the dependency determination step for determining the dependency and the two or more second material candidates whose temperature dependency is determined by the dependency determination step.
  • the pedestal is constituted by the second material that minimizes the temperature dependence of the resonance frequency of the optical scanner. Therefore, an optical scanner in which the temperature dependence of the resonance frequency is reduced can be obtained.
  • the acquisition step of acquiring the linear expansion coefficient of the two or more second material candidates, the value of the linear expansion coefficient of the two or more second material candidates, and the dependency determination step are determined.
  • a material having a linear expansion coefficient corresponding to a value whose absolute value of temperature dependency is close to a minimum is determined as the second material from the population. May be.
  • the second material having the minimum temperature dependence is determined. Therefore, it is possible to determine the second material based on the value of the linear expansion coefficient without determining the temperature dependence of the resonance frequency for all the second material candidates.
  • the second layer constituting the second layer provided between the first layer constituted by the second material of the pedestal and the structure is selected from the population.
  • a third material determination step for determining a material to be used as the three materials, and the creation step is performed when the temperature dependency is determined not to fall within a predetermined range in the determination step.
  • the optical scanner may be manufactured using the pedestal having a material as the first layer of the pedestal and the third material as the second layer.
  • a stacked structure pedestal having a first layer and a second layer is created.
  • the selection range of the pedestal that can further reduce the temperature dependence of the resonance frequency is expanded.
  • the third material determination step when the temperature dependency is a negative value, a material having a linear expansion coefficient larger than that of the second material is determined as the third material, and the temperature dependency is positive. In the case of a value, a material having a smaller linear expansion coefficient than the second material may be determined as the third material.
  • the temperature dependence of the resonance frequency of the pedestal made of only the second material is a positive value, in other words, when the resonance frequency also increases with the temperature rise, the line is smaller than the second material.
  • a material having an expansion coefficient is determined as the third material constituting the second layer.
  • the linear expansion coefficient when it sees with the whole base can be made small, and the temperature dependence of a resonant frequency can be reduced.
  • the temperature dependence of the resonance frequency of the pedestal made of only the second material is negative, in other words, when the resonance frequency decreases with increasing temperature, a linear expansion coefficient larger than that of the second material is obtained.
  • the material having is determined as the third material constituting the second layer. Thereby, the linear expansion coefficient when it sees with the whole base can be enlarged, and the temperature dependence of a resonant frequency can be reduced.
  • an optical scanner capable of reducing the temperature dependence of the resonance frequency and a method for manufacturing the optical scanner are provided.
  • FIG. 1 is a perspective view of an optical scanner 100 according to a first embodiment.
  • the perspective view of the optical scanner 200 based on 2nd Embodiment.
  • FIG. 12 is a flowchart for explaining a manufacturing process of the optical scanners 100 and 200 according to the third embodiment.
  • the flowchart explaining the manufacturing process of the optical scanner in the flowchart of FIG. The figure explaining the change of the temperature dependence of the resonant frequency when the thickness of the 2nd layer 222 of the base 220 changes.
  • FIG. 6 is a diagram for explaining the correlation between the Young's modulus of the structure 110 and the resonance frequency of the optical scanner 100.
  • the optical scanner 100 includes a structure 110 and a pedestal 120.
  • the mirror portion 111 of the structure 110 is swung around the first axis a by the piezoelectric element 114. By this oscillation, the light incident on the mirror portion 111 is scanned.
  • the structure 110 is a plate-like structure having a rectangular shape in plan view, which includes a pair of short sides parallel to the first axis a and a pair of long sides orthogonal to the first axis a.
  • the structure 110 includes a mirror portion 111, a pair of torsion beam portions 112, and a main body portion 113.
  • a piezoelectric element 114 is provided on one surface (for example, the upper surface) of the main body portion 113.
  • the structure 110 is made of, for example, a first material that is a metal.
  • the structure 110 will be described.
  • Mirror portion 111 includes a reflective surface that reflects light such as a laser.
  • the shape of the mirror portion 111 is rectangular in plan view.
  • the shape of the mirror portion 111 is not limited to this, and may be any shape such as a circle, an ellipse, or a polygon in plan view.
  • the reflecting surface is provided by, for example, a method in which the surface of the mirror portion 111 is mirror-polished, or a dielectric such as sapphire or a diamond on which a metal thin film such as aluminum or silver is formed is attached to the mirror portion 111.
  • One end of the pair of torsion beam portions 112 is connected to both sides of the mirror portion 111.
  • the pair of torsion beam portions 112 each extend in a direction away from the mirror portion 111.
  • the extending direction of the pair of torsion beam portions 112 is parallel to the first axis a.
  • the first axis a passes through the centers of the pair of torsion beam portions 112.
  • the main body portion 113 is connected to the other end of the pair of torsion beam portions 112, that is, the end portion on the opposite side to the mirror portion 111.
  • the main body portion 113 is separated from the mirror portion 111 and extends in a direction intersecting the first axis a.
  • the main body portion 113 extends from the connecting portion with the pair of torsion beam portions 112 to both sides in the direction orthogonal to the first axis a.
  • the main body portion 113 includes a fixed portion 113a and a node coupling portion 113b.
  • a pair of fixed portions 113a is provided with a pair of torsion beam portions 112 and a mirror portion 111 interposed therebetween.
  • a rectangular through hole is provided at the end of the main body portion 113 in the first axis a direction along a long side orthogonal to the first axis a.
  • the region of the main body portion that is located farther from the mirror portion 111 than the through hole is the fixed portion 113a.
  • the structure 110 and the pedestal 120 are fixed.
  • the node fixing portion 113b is provided at a central portion in a direction orthogonal to the first axis a of the rectangular through hole. The node fixing portion 113b extends in the first axis a direction.
  • the node fixing portion 113b connects the body portion 113 closer to the mirror portion 113 than the rectangular through hole and the fixed portion 113a. More specifically, the node fixing portion 113b is positioned in the same straight line as the pair of torsion beam portions 112. Thereby, the thermal stress due to the difference in linear expansion coefficient between the structure 110 and the pedestal 120 is efficiently converted into tension / contraction of the pair of torsion beam portions 112 via the node fixing portion 113b.
  • a piezoelectric element 114 as a driving unit is provided on the upper surface of the main body portion 113.
  • a pair of the piezoelectric elements 114 is provided at both ends of the main body portion 113 in the first axis a direction and in the direction orthogonal to the first axis a.
  • the piezoelectric element 114 is formed by laminating 0.2 ⁇ m to 0.6 ⁇ m of gold, platinum, or the like as an electrode layer on both surfaces of a piezoelectric material such as lead zirconate titanate formed into a flat plate having a thickness of 30 ⁇ m to 100 ⁇ m. It is formed by doing.
  • the piezoelectric element 114 and the main body portion 113 are bonded with a conductive adhesive.
  • a thin metal wire (not shown) such as gold is connected to the upper surface of the piezoelectric element 114 by wire bonding or the like.
  • the pedestal 120 has a rectangular shape in plan view.
  • the pedestal 120 has a rectangular hole that is hollowed out in a rectangular shape at the center.
  • the fixed portion 113 a of the structure 110 is fixed to an adjacent portion of the rectangular hole of the pedestal 120.
  • the thickness of the pedestal 120 is sufficiently larger than the thickness of the structure 110. Therefore, even if the structure 110 swings, the pedestal 120 hardly deforms.
  • the pedestal 120 has a single layer structure including only the first layer 121.
  • the second material constituting the first layer 121 is, for example, a metal having a linear expansion coefficient different from that of the first material constituting the structure 110. More specifically, the value of the linear expansion coefficient of the second material is set so as to satisfy the following two conditions. (1) A value greater than the linear expansion coefficient of the first material, (2) the temperature of the resonance frequency when the pedestal 120 is made of the same first material as the structure 110, and the absolute value of the temperature dependence of the resonance frequency. A value that is smaller than the absolute value of the dependency.
  • the piezoelectric element 114 can be deformed by applying a voltage between the structure 110 and the electrode layer on the upper surface of the piezoelectric element 114.
  • An AC voltage is applied to the piezoelectric element 114 provided on one side with respect to the first axis a and the piezoelectric element 114 provided on the other side so as to be in opposite phases.
  • the frequency of the AC voltage corresponds to the resonance frequency of the optical scanner 100, a plate wave is excited in the main body portion 114 as the piezoelectric element 114 is deformed.
  • the plate wave is transmitted to the mirror portion 111 through the main body portion 113 and the pair of torsion beam portions 112, so that the mirror portion 111 swings around the first axis a at a predetermined resonance frequency. That is, since the optical scanner 100 is a so-called external excitation type optical scanner, a large deflection angle can be obtained.
  • the structure 110 is fixed to the pedestal 120 at the fixed portion 113a, and the main body portion 113 sandwiched between the fixed portions 113a is in a state of being suspended in the air by the pedestal 120. Therefore, when the optical scanner 100 is driven, the main body portion 113 is displaced in the vertical direction.
  • the torsion beam portion 112 is provided at a position that becomes a vibration node of the main body portion 113, even if the main body portion 113 is displaced up and down, the torsion beam portion 112 is not displaced up and down. Further, a node fixing portion 113 b provided on the same straight line as the torsion beam portion 112 connects the fixed portion 113 a and the torsion beam portion 112. Therefore, the torsion beam portion 112 is further suppressed from being displaced in the vertical direction. Therefore, when the mirror portion 111 is swung around the first axis a, the vertical displacement is suppressed. Accordingly, the light incident on the mirror portion 111 is always incident on the same position on the mirror portion 111, so that stable light scanning is possible.
  • the linear expansion coefficient of the pedestal 120 is larger than that of the structure 110, thermal stress is generated in the structure 110 due to temperature change. Specifically, when the temperature rises, the pedestal 120 expands more than the structure. This difference in expansion amount applies tension in the direction of the first axis a to the pair of torsion beam portions 112 and the mirror portion 111 sandwiched between the fixed portions of the base 120 and the structure 110. When tension is applied to the pair of torsion beam portions 112, the rigidity of the pair of torsion beam portions 112 is apparently increased. The higher the rigidity of the pair of torsion beam portions 112 is, the higher the resonance frequency of the optical scanner 100 is. On the other hand, the Young's modulus decreases as the temperature increases.
  • the change in Young's modulus of the first material due to the temperature rise works in the direction of lowering the resonance frequency.
  • the linear expansion coefficient of the second material is larger than the linear expansion coefficient of the first material, the thermal stress generated in the structure 110 acts in the direction of increasing the resonance frequency as the temperature rises. Therefore, the temperature dependence of the resonance frequency is reduced. Note that, when the temperature is lowered, the pedestal 120 contracts more than the structure 110, and thus a force that compresses the pair of torsion beam portions 112 in the longitudinal direction acts. That is, the apparent rigidity of the pair of torsion beam portions 112 decreases, and the resonance frequency decreases.
  • the change in the resonance frequency caused by the change in the Young's modulus of the structure 110 (which works in the direction of increasing) is caused by the difference in expansion amount between the pedestal 120 and the structure 110. It is reduced by the change in the resonance frequency (which works in the direction of lowering).
  • Both the structure 110 and the pedestal 120 are made of a metal that is a ductile material. If the structure 110 or the pedestal 120 is made of a brittle material such as silicon, the structure 110 or the pedestal 120 may be damaged due to thermal stress depending on the combination of materials. Therefore, the structure 110 and the pedestal 120 are made of metal, so that the degree of freedom in combining materials increases. Further, since it can be manufactured by machining such as a press, the optical scanner 100 can be provided at low cost.
  • the temperature dependence of the resonance frequency is shown in units of the amount of change in the resonance frequency (Hz / ° C.) with respect to a temperature increase of 1 ° C.
  • the absolute value of the temperature dependence differs even for the same material due to various indeterminates such as the bonding conditions between the pedestal 120 and the structure 110 and the size variation in manufacturing. .
  • the tendency was found that the greater the linear expansion coefficient of the material of the pedestal 120, the greater the temperature dependence of the resonance frequency. More specifically, when the pedestal 120 is configured by SUS420, the temperature dependence of the resonance frequency is ⁇ 0.5 to ⁇ 0.6 [Hz / ° C.] in both simulation and measurement.
  • the temperature dependence of the resonance frequency when the pedestal 120 is formed of SUS420 can be regarded as a value when the linear expansion coefficients of the structure 110 and the pedestal 120 are substantially the same. Since the Young's modulus decreases with increasing temperature, when the linear expansion coefficient of the structure 110 and the pedestal 120 is substantially the same, the temperature dependence of the resonance frequency shows a negative value (the higher the temperature, the lower the resonance frequency). ).
  • the temperature dependence of the resonant frequency will be relieved. As described above, this is because the pair of torsion beam portions 112 are pulled by the thermal stress acting on the structure 110 due to the difference in the linear expansion coefficient between the structure 110 and the pedestal 120, and apparently a pair of torsion. This is because the rigidity of the beam portion 112 increases. According to the result of FIG. 2, when SECC and SUS309 are used for the pedestal 120, the temperature dependence of the resonance frequency is alleviated as compared to the case where the pedestal 120 is made of the same material as the structure 110.
  • the material that minimizes the absolute value of the temperature dependence of the resonance frequency may be determined as a constituent material of the pedestal 120 based on this result.
  • the pedestal 120 is formed using SECC.
  • the base 120 is formed using SECC or SUS309. Thereby, the optical scanner 100 in which the temperature dependency of the resonance frequency is reduced is obtained.
  • the correlation between the two is examined by taking the linear expansion coefficient of the material of the pedestal 120 on the horizontal axis and the temperature dependence of the resonance frequency on the vertical axis.
  • FIG. 3 there is a positive correlation, more specifically, a linear relationship between the linear expansion coefficient of the constituent material of the pedestal 120 and the temperature dependence of the resonance frequency.
  • the difference in the temperature dependence of the resonance frequency between the simulation and the actual measurement is shown in FIG. 3 as a difference in proportionality coefficient.
  • a material that minimizes the absolute value of the temperature dependence of the resonance frequency can be selected as the material of the pedestal 120.
  • the proportionality coefficient between the linear expansion coefficient and the temperature dependence of the resonance frequency can be determined.
  • this proportionality factor is used, the material whose resonance frequency temperature dependency is minimized can be obtained only for the material whose resonance frequency temperature dependency is not determined, based only on the value of the linear expansion coefficient. Selection becomes possible.
  • Second Embodiment 4A and 4B show another preferred embodiment of the present invention.
  • the optical scanner 200 includes a structure 210 and a pedestal 220.
  • the optical scanner 200 is different from the optical scanner 100 described above in the configuration of the base 220.
  • the structure 210 includes a mirror portion 211, a pair of torsion beam portions 212, and a main body portion 213.
  • a piezoelectric element 214 is provided on the upper surface of the main body portion 213.
  • the pedestal 220 has a first layer 221 and a second layer 222.
  • the constituent material of the first layer 221 and the constituent material of the second layer 222 are metals having different linear expansion coefficients. Therefore, the selection range of the pedestal 220 that can further reduce the temperature dependence of the resonance frequency is expanded depending on the combination of materials.
  • the second layer 222 has a rectangular shape in plan view, and has a rectangular hole cut out in a rectangular shape at the center.
  • the second layer 222 is fixed to the fixed portion 213a of the structure 210, similarly to the first layer 121 in the above-described embodiment.
  • the first layer 221 is formed in the same manner as the second layer 222 in plan view.
  • the first layer 221 is fixed to the lower surface of the second layer 222.
  • one surface (upper surface) of the second layer 222 is fixed to the structure 210, and the other surface (lower surface) is fixed to the first layer 221.
  • the thickness of the second layer 222 is thinner than the thickness of the first layer 221.
  • the thickness of the first layer 221 is about 2 mm
  • the thickness of the second layer 222 is set to about 0.4 mm.
  • the thickness of the structure 210 is about 0.1 mm, for example.
  • FIG. 5 shows the temperature dependence of the resonance frequency obtained by simulation when the material of the second layer 222 is combined with the material of the first layer 221 in the optical scanner 200 shown in FIGS. 4A and 4B. It is a figure which shows a result.
  • SUS420 10.3 ⁇ 10 -6 [/°C]
  • SECC 11.7 ⁇ 10 -6 [/ °C]
  • the structure 210 is formed of SUS430 as in the case of the optical scanner 100.
  • high function spring steel for example, HT2000 manufactured by Nisshin Steel Co., Ltd. can be used.
  • the temperature dependency of the resonance frequency changes when the material of the first layer 221 is fixed and the material of the second layer 222 is changed.
  • the temperature dependence of the resonance frequency of both is about 0.2 [Hz / ° C.] regardless of the material of the first layer 221.
  • the temperature dependence of the resonance frequency tends to increase as a material having a large linear expansion coefficient is used for the second layer 222.
  • the temperature dependence of both resonance frequencies is about 0.5 to 0.8 [Hz. / ° C].
  • the linear expansion coefficient of the entire pedestal 220 is roughly determined by the first layer 221 having a large thickness, and can be finely adjusted by selecting the material of the second layer 222.
  • the material of the first layer 221 is selected so that the absolute value of the temperature dependency of the resonance frequency is minimized, and then the material of the second layer 222 is selected, so that the temperature of the resonance frequency is selected.
  • the dependency can be made closer to 0.
  • the temperature dependency of the resonance frequency is a negative value, and thus the second layer 222 is configured with a material having a larger linear expansion coefficient than the first layer 221.
  • the temperature dependency of the resonance frequency can be further reduced.
  • the temperature dependency of the resonance frequency is a positive value, and therefore the second layer 222 is configured with a material having a smaller linear expansion coefficient than the first layer 221. By doing so, the temperature dependence of the resonance frequency can be further reduced.
  • step S1 the linear expansion coefficient of the first material constituting the optical scanner structure (structure 110 or structure 210 of the above-described embodiment) is acquired.
  • the material constituting the structure is selected in advance according to, for example, the design value of the resonance frequency of the optical scanner.
  • the linear expansion coefficient may be obtained by directly measuring the material, or may be obtained by utilizing an existing value such as a data sheet.
  • step S2 the temperature dependence of the Young's modulus of the material constituting the structure is obtained.
  • the Young's modulus of the structure affects the resonance frequency of the optical scanner.
  • the higher the Young's modulus the higher the resonant frequency. Therefore, by obtaining the temperature dependence of the Young's modulus, the temperature dependence of the resonance frequency of the optical scanner caused only by the structure can be understood.
  • the temperature dependence of the Young's modulus may be acquired by any method such as application of a mathematical formula using an existing value such as a data sheet as a coefficient, actual measurement, or the like.
  • a candidate for the second material constituting the pedestal is determined, and its linear expansion coefficient is acquired.
  • a plurality of materials having different linear expansion coefficient values exist as a candidate population as the second material.
  • This population includes a material having a linear expansion coefficient larger than that of the first material constituting the structure.
  • a material having a linear expansion coefficient smaller than that of the first material may be included in this population.
  • one material for example, SUS420
  • acquisition of a linear expansion coefficient may be achieved by arbitrary methods, such as using measurement and the value of a data sheet.
  • step S4 the temperature dependence of the Young's modulus of the second material candidate determined in step S3 is acquired.
  • the temperature dependence of the Young's modulus may be obtained by any method such as a mathematical expression using an existing value such as a data sheet as a coefficient, or actual measurement.
  • step S5 the temperature dependence of the resonance frequency in the optical scanner in which the second material candidate is used for the pedestal is determined.
  • This step is achieved, for example, by actually creating an optical scanner and measuring the resonance frequency of the optical scanner while changing the ambient temperature in which the optical scanner is placed.
  • the resonance frequency may be determined from, for example, the timing of the scanning light detected by the optical sensor disposed at the position where the light scanned by the optical scanner enters.
  • the temperature dependence of the resonance frequency of the optical scanner may be obtained using simulation.
  • the temperature dependency of the resonance frequency is obtained for two or more second material candidates, based on the correlation between the temperature dependency of the resonance frequency and the linear expansion coefficient of the material.
  • the temperature dependence of the resonance frequency is obtained from the value of the linear expansion coefficient.
  • FIG. 2A or FIG. 2B it is assumed that the temperature dependence of the resonance frequency is obtained by actual measurement when a pedestal is constituted by SUS420 and SUS304.
  • a proportional coefficient between the linear expansion coefficient and the temperature dependence of the resonance frequency is determined using the linear expansion coefficients of SUS420 and SUS304 obtained in step S3. If this proportionality coefficient is used, for example, the temperature dependence of the resonance frequency can be determined when the pedestal is constituted by SECC, SUS309, and SUS316 that are not actually measured.
  • the temperature dependence of the resonance frequency when the material is used for the pedestal can be determined based only on the value of the linear expansion coefficient of the material. If further expanding, even if the material is not included in the population as a candidate for the second material (for example, a material not shown in FIG. 2), only the value of the linear expansion coefficient of the material is used. Based on this, the temperature dependence of the resonance frequency can be determined.
  • step S6 it is determined whether or not the absolute value of the temperature dependence of the resonance frequency of the second material candidate determined in step S3 is the minimum. If the absolute value of the temperature dependence of the resonance frequency of the second material candidate is minimum (S6: Y), after the second material candidate is determined as the second material constituting the pedestal in step S7. The process proceeds to step S8. On the other hand, when the absolute value of the temperature dependence of the resonance frequency of the second material candidate is not minimum (S6: N), the process proceeds to step S8. For example, in the case where SUS420 is first determined as the second material candidate in FIG. 2A or FIG. 2B, there is no second material candidate determined before that, so the absolute frequency dependence of the resonance frequency of SUS420 is absolute.
  • step S6: Y The value is minimized (step S6: Y). Therefore, SUS420 is determined as the second material constituting the pedestal (S7).
  • SECC is determined as the second material candidate after SUS420, the absolute value of the temperature dependence of the resonance frequency of SECC is smaller than the absolute value of the temperature dependence of the resonance frequency of SUS420. Therefore, the absolute value of the temperature dependence of the SECC resonance frequency is minimized (step S6: Y). Therefore, instead of SUS420, SECC is determined as the second material constituting the pedestal (S7).
  • SUS309 is determined as the second material candidate after SECC, the absolute value of the temperature dependence of the resonance frequency of SUS309 is larger than the absolute value of the temperature dependence of the resonance frequency of SECC. For this reason, the absolute value of the temperature dependence of the resonance frequency of SECC remains minimal (step S6: N). In this case, since step S7 is not performed, the second material constituting the pedestal remains SECC.
  • step S8 it is determined whether other second material candidates still remain in the population. If other second material candidates still remain (S8: Y), the process returns to step S3, and steps S3 to S7 are performed on the other second material candidates. On the other hand, when no other second material candidates remain, in other words, when the study on all second material candidates included in the population is completed (S8: N), the process proceeds to step S9.
  • step S9 it is determined whether or not the temperature dependency of the resonance frequency when using the pedestal material determined in step S7 is within the specification range.
  • the range of this specification may be determined based on the performance of a printer such as a printer that uses an optical scanner or a scanning image display device. Alternatively, the performance of the optical scanner alone may be set to a predetermined value.
  • an optical scanner is created using the base material (S11). That is, in this case, the above-described optical scanner 100 having a pedestal formed of a single layer is produced.
  • the temperature dependency of the resonance frequency does not fall within the specification range (S9: N)
  • the temperature dependency of the resonance frequency is further reduced by forming the pedestal in a laminated structure as in the optical scanner 200 described above. Consideration is made (S10).
  • step S100 it is determined whether or not the temperature dependence (obtained in step S5) of the resonance frequency of the second material determined in step S7 is a positive value.
  • SECC is determined as the second material.
  • the temperature dependence of the resonance frequency is negative ( ⁇ 0.162 [Hz / ° C. in simulation, ⁇ 0.323 [Hz / ° C.] in actual measurement). Is denied (S100: N).
  • step S102 is performed.
  • step S110 is affirmed (S100: Y).
  • step S101 is performed.
  • step S101 a material having a smaller linear expansion coefficient than the material of the first layer 221 is selected as the material of the second layer 222 of the base 220.
  • the substantial linear expansion coefficient of the entire pedestal 220 can be reduced, and the temperature dependence of the resonance frequency can be brought close to zero.
  • SUS304 is determined as the material of the first layer 221
  • high-function spring steel or SUS430 which is a material having a smaller coefficient of linear expansion than SUS304, is determined as the material of the second layer 222. (See FIG. 5).
  • SUS304 is determined as the material of the first layer 221
  • SUS430 which is a material having a smaller coefficient of linear expansion than SUS304
  • step S102 a material having a larger linear expansion coefficient than the material of the first layer 221 is selected as the material of the second layer 222 of the base 220.
  • the substantial linear expansion coefficient of the entire pedestal 220 can be increased, and the temperature dependence of the resonance frequency can be brought close to zero.
  • SECC is determined as the material of the first layer 221
  • high-function spring steel or SUS304 which is a material having a larger linear expansion coefficient than SECC
  • step S11 of FIG. 6 an optical scanner is created.
  • the optical scanner 100 including the pedestal 120 made of a single layer is formed.
  • the optical scanner 200 including the base 220 having the first layer 221 and the second layer 222 is formed. Details of step S11 are shown in FIG.
  • a structure is formed by a predetermined removal process.
  • wet etching is employed as an example of removal processing.
  • a metal plate (for example, SUS430) constituting the structure is divided into a size equal to the outer shape of the structure.
  • a resist film for masking is formed at positions corresponding to the mirror portion, the torsion beam portion, and the main body portion of the divided metal plate.
  • the resist film is removed.
  • the structure may be formed not by wet etching but by mechanical processing such as press processing.
  • a bulk piezoelectric material provided with electrode layers on both surfaces of the piezoelectric element in advance is mounted on the structure.
  • This mounting is performed using, for example, a conductive adhesive containing a conductive material such as a metal filler in a synthetic resin material such as epoxy, acrylic or silicon.
  • a bulk piezoelectric material is placed on a conductive adhesive applied to the main body portion of the structure.
  • the conductive adhesive is cured by placing the structure in a heating furnace maintained at 100 to 200 ° C. for 30 to 60 minutes. This completes the mounting of the piezoelectric element.
  • a pedestal is created.
  • the outer shape of the pedestal can be obtained by performing removal processing such as etching or pressing on the metal plate that is a constituent material of the pedestal, as in the case of the structure.
  • the metal plate for constituting the first layer and the metal plate for constituting the second layer are respectively subjected to removal processing. Is done. Note that the thicknesses of the first layer and the second layer are automatically set by processing a metal plate having a corresponding thickness. Thereafter, the first layer and the second layer are fixed by adhesion, welding, or the like.
  • step S113 the base and the structure are fixed.
  • This fixing is performed, for example, by welding the fixed portion of the structure and the pedestal by laser welding or the like.
  • the structure and the base may be fixed by other fixing methods such as bonding using a thermosetting adhesive.
  • step S114 the signal line is connected to the piezoelectric element and the structure by wire bonding.
  • This signal line is connected to an AC power source (not shown). Since the structure and the piezoelectric element are bonded by a conductive adhesive, a voltage is applied between the piezoelectric element and the structure via the signal line. This completes the optical scanner manufacturing process.
  • the pedestal 220 has a first layer 221 and a second layer 222.
  • this embodiment does not exclude a configuration in which the pedestal has a laminated structure of three or more layers.
  • the materials for the third and subsequent layers may be determined after the materials for the first layer and the second layer are determined as described above.
  • the material of the second layer 222 is determined to reduce the temperature dependence of the resonance frequency using the type of the constituent material, more specifically, the linear expansion coefficient of the constituent material as a variable.
  • other variables that determine the structure of the second layer 222 may be further introduced to reduce the temperature dependence of the resonance frequency.
  • the structure 210 is made of SUS430
  • the first layer 221 of the base 220 is made of SECC
  • the second layer 222 is made of SUS304.
  • the thickness of the structure 210 is set to 100 ⁇ m
  • the thickness of the first layer 221 is set to 2000 ⁇ m.
  • the temperature dependence of the resonance frequency increases as the second layer 222 becomes thicker. That is, for example, a step of determining the thickness of the second layer 222 may be performed after step S101 or step S102 shown in FIG. This makes it possible to determine the structure of the pedestal so that the absolute value of the temperature dependence of the resonance frequency is further reduced by using the variable of the pedestal thickness in addition to the variable of the linear expansion coefficient.
  • the structure and the base are made of metal.
  • the present disclosure is characterized in that the temperature dependence of the resonance frequency is mitigated by making the linear expansion coefficients of the structure and the pedestal different. Therefore, even if the base and the structure are made of a nonmetal such as silicon, the scope of the present disclosure is included.
  • the shapes of the structure and the pedestal are not limited to the above-described embodiments. Any type of optical scanner in which a flat plate-like structure having a mirror portion, a torsion beam portion, and a main body portion is fixed to a pedestal is included in the scope of the present invention.
  • a piezoelectric element is used as the drive unit.
  • an optical scanner that employs another driving method such as an electromagnetic driving method using a combination of a magnet and a coil pattern or an electrostatic driving method using an electrostatic force acting between electrode plates, is included in the scope of the present disclosure. .
  • Optical scanner 110 210 Structure 111, 211 Mirror part 112, 212 Torsion beam part 113, 213 Body part 113a, 213a Fixed part 113b, 213b Node connecting part 114, 214 Piezoelectric element 120, 220 Base 121, 221 First layer 222 second layer

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Optical Scanning Systems (AREA)
  • Micromachines (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)

Abstract

La présente invention se rapporte à un dispositif de lecture optique qui comprend une structure tabulaire constituée d'un premier matériau et d'un socle. La structure présente une section de miroir, une paire de barres de torsion dont une extrémité est couplée aux deux côtés de la section de miroir, et une section de corps principal couplée à l'autre extrémité de la paire de barres de torsion. La structure est pourvue d'une section d'entraînement qui peut faire osciller la section de miroir selon une fréquence de résonance prescrite. Au niveau d'une paire opposée de sections non fixées formant une partie de la section de corps principal et qui prend en sandwich la paire de barres de torsion et la section de miroir, la structure est fixée au moins au socle. Le coefficient de dilatation linéaire d'un second matériau qui constitue le socle, présente une valeur plus élevée que le coefficient de dilatation linéaire du premier matériau et est déterminé de telle sorte que la valeur absolue de la dépendance en température de la fréquence de résonance soit plus petite que la valeur absolue de la dépendance en température de la fréquence de résonance dans le cas où le socle est composé du premier matériau.
PCT/JP2012/058090 2011-03-31 2012-03-28 Dispositif de lecture optique et procédé de fabrication d'un dispositif de lecture optique WO2012133505A1 (fr)

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IT201600079604A1 (it) * 2016-07-28 2018-01-28 St Microelectronics Srl Struttura oscillante con attuazione piezoelettrica, sistema e metodo di fabbricazione

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JP6024269B2 (ja) * 2011-09-20 2016-11-16 株式会社デンソー 光走査装置
CN117716272A (zh) * 2021-08-19 2024-03-15 松下知识产权经营株式会社 驱动元件

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JP2001523350A (ja) * 1994-10-26 2001-11-20 ボード オブ リージェンツ オブ ザ ユニバーシティ オブ ワシントン ２軸スキャニングシステム用の小型光学式スキャナー
JP2002321195A (ja) * 2001-04-20 2002-11-05 Olympus Optical Co Ltd 振動体およびその製造方法
WO2008041585A1 (fr) * 2006-09-27 2008-04-10 National Institute Of Advanced Industrial Science And Technology Dispositif de balayage optique

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JP5267370B2 (ja) * 2009-07-23 2013-08-21 ブラザー工業株式会社 光スキャナ

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JP2002321195A (ja) * 2001-04-20 2002-11-05 Olympus Optical Co Ltd 振動体およびその製造方法
WO2008041585A1 (fr) * 2006-09-27 2008-04-10 National Institute Of Advanced Industrial Science And Technology Dispositif de balayage optique

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT201600079604A1 (it) * 2016-07-28 2018-01-28 St Microelectronics Srl Struttura oscillante con attuazione piezoelettrica, sistema e metodo di fabbricazione
EP3276391A1 (fr) * 2016-07-28 2018-01-31 STMicroelectronics S.r.l. Structure oscillante à actionnement piézo-électrique, système et procédé de fabrication
US10365475B2 (en) 2016-07-28 2019-07-30 Stmicroelectronics S.R.L. Oscillating structure with piezoelectric actuation, system and manufacturing method

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