JP4972781B2 - A micro scanner and an optical scanning device including the same. - Google Patents

Description

  The present invention relates to a micro scanner (optical scanner) that scans light from a light source used in a projector, a laser beam printer, or the like. The present invention also relates to an optical scanning apparatus that can scan light at high speed by including such an optical scanner.

  Conventionally, various compact optical scanners (micro scanners) using MEMS (Micro Electro Mechanical Systems) technology have been developed. For example, an optical scanner 101 of Patent Document 1 as shown in FIG. 11 includes a scanning mirror unit 103, a torsion bar TB that supports the mirror unit 103, and a movable frame 105 connected to the mirror unit 103. A unimorph drive unit 106 for deflecting the mirror unit 103 is disposed above.

  The optical scanner 101 includes a driving frequency of the unimorph driving unit 106 disposed on the movable frame 105 and a mechanical resonance frequency of the mirror unit 103 including the torsion bar TB in order to deflect the mirror unit 103 as much as possible. Are matched. This is because, even if the unimorph drive unit 106 is driven at a low voltage, the mirror unit 103 resonates and deflects relatively large.

  However, the distal end portion 110 of the movable frame 105 connected to the mirror portion 103 is difficult to twist. Therefore, the force generated in the movable frame 105 is unlikely to act on the mirror unit 103 as a rotational torque. Therefore, it cannot be said that the mirror unit 103 is sufficiently deflected.

  Here, an optical scanner 101 in which the distal end portion 110 and the mirror portion 103 are not connected is also conceivable. For example, an optical scanner 101 as shown in FIG. The optical scanner 101 includes a fixed frame 102, a mirror unit 103, a movable frame 105 that is deformed by the unimorph drive units 106 a to 106 d, and a main shaft unit 104 that connects the mirror unit 103 and the movable frame 105.

  Then, the optical scanner 101 rotates the mirror unit 103 forward and backward based on the X direction (rotating in the P direction or rotating in the R direction) according to the bending deformation of the movable frame 105. FIGS. 13A and 13B show the movable frame 105 that is bent and deformed by the deflection operation of the mirror unit 103. These figures are cross-sectional views taken along the line AA ′ of FIG. 12, and FIG. 13A shows a case of forward rotation (rotation in the P direction), and FIG. 13B shows a case of reverse rotation (rotation in the R direction). Indicates.

  For the sake of explanation, the axial direction of the main shaft 104 is the X direction (may be referred to as the X axis), and the extending direction of the movable frame 105 orthogonal to the X direction is the Y direction, the X direction, and the orthogonal direction to the Y direction. Is the Z direction. Also, the upper side of the paper surface in FIG. 12 is the Y direction plus {Y (+)}, the opposite direction to the + direction is the Y direction minus {Y (−)}, and the front side of the paper surface in FIG. Plus {Z (+)}, and the opposite direction to the + direction is the minus Z in the Z direction {Z (-)}.

  In the following, only the movable frame 105a of the two movable frames 105 (movable frames 105a and 105b) will be described. However, when the movable frame 105a attempts to rotate the mirror unit 103 forward or backward, Similarly, the movable frame 105b rotates the mirror unit 103 forward or backward.

  When the mirror unit 103 rotates in the forward direction, as shown in FIG. 13A, the piezoelectric element 108 of the Y (+) side unimorph drive unit 106a extends, so that the main shaft unit 104 side of the movable frame 105a on the Y (+) side is It hangs down to Z (-). On the other hand, when the piezoelectric element 108 of the Y (−) side unimorph drive unit 106b contracts, the main shaft 104 side of the movable frame 105a on the Y (−) side jumps up to Z (+). Then, the movable frame 105a bends like a wave, and the main shaft portion 104 also rotates forward and tilts following the bend.

When the mirror 103 rotates in the reverse direction, as shown in FIG. 13B, the piezoelectric element 108 of the unimorph drive unit 106a on the Y (+) side contracts, so that the main shaft part 104 in the movable frame 105a on the Y (+) side. The side jumps up to Z (+). On the other hand, when the piezoelectric element 108 of the Y (−) side unimorph drive unit 106b extends, the main shaft portion 104 side of the movable frame 105a on the Y (−) side hangs down to Z (−). Then, the movable frame 105a is waved and bent in the direction opposite to that in FIG. 13A, and the main shaft portion 104 is also reversely rotated and tilted following the bending.
JP 2005-128147 A

  When the optical scanner 101 as shown in FIG. 12 is used in a scanning projection apparatus such as a projector, the deflection angle of the mirror unit 103 is a major factor in determining the screen size that can be projected. In addition, when the driving frequency of the unimorph driving unit 106 and the vibration frequency of the mirror unit 103 are matched to cause the mirror unit 103 to resonate, the scanning speed draws a sine waveform. The scanning speed on the side becomes slow and the image pitch fluctuates. Therefore, the coupling portion 107 of the movable frame 105 is more easily curved than the other portions so that a larger deflection angle can be obtained without causing the mirror portion 103 to resonate and with a slight displacement of the unimorph driving portions 106a to 106d. It is desirable to keep it.

As a method for increasing the bendability of the coupling portion 107, a method of reducing the thickness or width of the coupling portion 107 is conceivable, but this method also reduces the strength of the coupling portion 107. Therefore, there is a possibility that the coupling portion 107 may be damaged when a large stress is applied due to the displacement of the unimorph driving portions 106a to 106d. Further, it is difficult to etch the entire thickness of the coupling portion 107 uniformly and accurately because it is easily affected by variations in processing conditions. Further, when an SOI substrate in which SiO ₂ is inserted between the silicon substrate and the surface silicon layer in order to suppress processing variations, the substrate cost increases, which is not practical.

  The present invention has been made in view of such a situation, and by improving the curvature of the coupling portion that couples the mirror portion and the movable frame, the deflection angle of the mirror is increased and the coupling portion due to stress is increased. An object of the present invention is to provide an optical scanner capable of preventing damage and an optical scanning device including the same.

  In order to achieve the above object, a microscanner of the present invention includes a variable portion, a main shaft portion that supports the variable portion so as to be swingable, a deformable movable frame that holds the main shaft portion, and the movable frame. A microscanner including a driving means for bending and tilting the variable part, and a fixed frame that supports the movable frame so as to be bendable. Bending portions comprising a pair of groove portions substantially parallel to the main shaft portion formed on the first shaft portion are formed on both sides of the main shaft portion.

  According to this configuration, since the coupling portion is deformed by a relatively weak force at the bent portion, the amount of rotation of the main shaft portion is also increased. And the fluctuation | variation part rock | fluctuates comparatively largely due to this increased rotation amount. As a result, the microscanner can easily increase the deflection angle of the variable portion. Further, the sum of the depths of the pair of groove portions is larger than the thickness of the coupling portion, and the groove portions are formed at positions that do not overlap in the thickness direction of the coupling portion. As a result, the cross section of the bent portion is formed in a serpentine shape, and the bent portion has sufficient strength in addition to bendability.

  In addition, the groove part which comprises a bending part is provided by etching the front and back of the coupling part which consists of one board | substrate, for example, and the micro scanner itself is formed in one board | substrate. In addition, when the variable part is a mirror part that reflects light by including a metal film, the microscanner can also be referred to as an optical scanner.

  Further, it is desirable that a plurality of bent portions are arranged along the extending direction of the movable frame. With this configuration, the bending deformation of the coupling portion is distributed to the plurality of bending portions arranged in parallel, and the twist applied to each bending portion can be reduced. Therefore, it is particularly effective when the thickness of the substrate is large and the stress dispersion effect is small, or when the driving force generated by the driving means is small. As the driving means, a unimorph driving unit including a piezoelectric element and electrodes sandwiching the piezoelectric element is preferably used.

  However, it is desirable that at least one of the groove widths and depths of the groove portions constituting the bent portions be different in each of the bent portions arranged in a plurality along the extending direction of the movable frame. More specifically, it is desirable that at least one of the groove width and depth of each groove portion becomes smaller as the distance from the main shaft portion increases.

  Usually, the moment applied to each bent portion increases as the distance from the main shaft portion increases. Moreover, the rigidity becomes larger as the bent portion has a smaller groove width and depth. Accordingly, by reducing at least one of the groove width and depth as the distance from the main shaft portion decreases, an appropriate rigidity can be obtained with respect to the magnitude of the moment. There will be no occurrence of torsional deformation.

  Further, an optical scanning device equipped with the above micro scanner can also be said to be the present invention.

  According to the present invention, the connecting portion connecting the variable portion and the movable frame is formed of a pair of groove portions formed on the front and back surfaces and parallel to the rotation shaft, and the sum of the depths of the groove portions is larger than the thickness of the connecting portion. By forming the portion, the variable portion can be rotated at a wide angle even if the amount of bending of the movable frame is slight. This makes it possible to easily increase the deflection angle of the variable part of the micro scanner. In addition, since the stress applied to the joint portion is dispersed by the bending deformation of the movable frame, it is possible to suppress damage due to bending fatigue of the joint portion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In order to facilitate understanding, even plan views are hatched. In addition, for convenience of explanation, member symbols and hatching may be omitted, but in such a case, other drawings are referred to. Moreover, the black circle on the drawing means a direction perpendicular to the paper surface. In the following embodiments, a mirror part is taken as an example of a member (fluctuating part) that fluctuates in a micro scanner, and an optical scanner that performs a scanning operation by reflecting light by changing the mirror part is taken as an example.

  FIG. 1 is a block diagram illustrating an example of an image projection apparatus including a micro scanner and an optical scanning device according to the present invention. In FIG. 1, an image projection apparatus 100 receives an image signal output from, for example, a personal computer or a television, and scans light by receiving a light control unit 20 that performs processing and a signal output from the light control unit 20. For example, the optical scanning device 40 that projects image light onto the screen 30 is included.

  As shown in FIG. 1, the optical scanning device 40 includes three light sources 21 to 23 corresponding to red, green, and blue (hereinafter abbreviated as RGB), a color synthesis prism 24, a collimator lens 25, and light. The scanner (microscanner) 1, a projection optical system 26, a mirror position detection light source 27, a mirror position detection means 28, and an optical scanning control unit 29 are configured.

  Then, light emitted from the three light sources 21 to 23 corresponding to RGB passes through the color synthesis prism 24 and the collimator lens 25 in this order, and after optical scanning with the optical scanner 1, passes through the projection optical system 27. For example, the image is formed on the screen 30.

  Next, details of the optical scanning device 40 will be described. For example, the light source 21 corresponds to a red semiconductor laser diode, the light source 22 corresponds to a green semiconductor laser diode, and the light source 23 corresponds to a blue semiconductor laser diode. The wavelengths of the respective semiconductor laser diodes are set to, for example, 660 nm for red, 532 nm for green, and 450 nm for blue.

  In this embodiment, the semiconductor laser diode is used as the light source. However, the present invention is not limited to this, and can be changed without departing from the object of the present invention. In particular, since a green semiconductor laser diode is difficult to obtain, a DPSS (Diode Pomping Solid State) laser that excites a crystal with a semiconductor laser only in green may be modulated with an external modulator. Further, for all colors of red, green, and blue, a light emitting diode (LED), a solid state laser, or the like may be used as a light source instead of the semiconductor laser diode. However, the size of the light source is preferably small, and a semiconductor laser diode is preferable in that respect.

  The color synthesizing prism 24 plays a role of synthesizing the laser beams emitted from the light sources 21 to 23, and the laser beams emitted from the light sources 21 to 23 are synthesized here, and the synthesized color is displayed on the screen 30. In the present embodiment, a color synthesis prism is used, but the present invention is not limited to this. For example, as shown in FIG. 2, two dichroic mirrors 31a and 31b are used to synthesize laser beams emitted from red and green light sources 21 and 22 with a dichroic mirror 31a that reflects red light and transmits green light. Then, using the dichroic mirror 31b that reflects blue light and transmits red light and green light, the laser light emitted from the blue light source 23 is combined with the previously synthesized laser light. I do not care. However, it is preferable to use the color synthesizing prism 24 in terms of reducing the number of parts of the apparatus and reducing the size of the entire apparatus.

  The collimator lens 25 is a lens that converts divergent light emitted from the light sources 21 to 23 and passing through the color synthesis prism 24 into parallel light. The collimator lens 25 is adjusted in focus so as to correct chromatic aberration generated in the projection optical system 27. The optical scanner 1 can scan the laser light transmitted through the collimator lens 25, and in this embodiment, the horizontal direction (left-right direction in FIG. 1) and the vertical direction (paper surface direction in FIG. 1) with respect to the screen 30. ) Is scanned with a laser beam.

  FIG. 3 is a plan view showing the optical scanner according to the first embodiment of the present invention. The optical scanner 1 of this embodiment is a one-dimensional scanning type optical scanner that performs only scanning around the X axis (vertical rotation in FIG. 3), and includes a fixed frame 2, a mirror unit 3, main shaft units 4a and 4b, and a movable frame. 5a, 5b and unimorph drive units 6a-6d. Note that these members are integrally formed by etching a deformable silicon substrate or the like.

  The mirror unit 3 is a member that reflects light from a light source or the like. Such a mirror unit 3 is formed by arranging openings H (first opening H1 and second opening H2) side by side on a rectangular substrate in plan view so that the fixed frame 2 as shown in FIG. The resulting island-shaped portion (the remaining portion located between the first opening H1 and the second opening H2) is formed, and a reflective film such as gold or aluminum is attached to the island-shaped portion.

  The direction in which the first opening H1 and the second opening H2 are arranged is referred to as the Y direction, the Y direction on the first opening H1 side is the Y direction plus {Y (+)}, and the direction opposite to the + direction. Is negative {Y (−)} in the Y direction. Further, a direction extending in the Y direction from the center of the mirror unit 3 is referred to as a Y axis.

  The main shaft portions 4 a and 4 b are members that support the mirror portion 3 by sandwiching the mirror portion 3 by extending outward from one end and the other end facing each other at the outer edge of the mirror portion 3. The main shaft portions 4a and 4b are formed by making a part of the substrate into a rod shape by bringing both corners of the first opening H1 and the second opening H2 in contact with the mirror portion 3 close to each other.

  The main shaft portions 4a and 4b extend in a direction intersecting the Y direction (for example, an orthogonal direction). Therefore, this direction is referred to as the X direction, the X direction on the main shaft portion 4b side is defined as the plus X in the X direction, and the opposite direction to the + direction is defined as the minus X in the X direction {X (−)}. Furthermore, a direction extending in the X direction so as to overlap the main shaft portions 4a and 4b is referred to as an X axis (main axis direction / X axis direction).

  The movable frames 5a and 5b are members that hold the mirror portion 3 by holding the main shaft portions 4a and 4b (connected to the main shaft portions 4a and 4b). The movable frames 5a and 5b remain in a bridging manner between the opening H (third opening H3 and fourth opening H4) extending in the Y direction and the first opening H1 and second opening H2. It is formed with the remainder of the substrate.

  That is, between the remaining portion of the substrate located between the third opening H3 and the first opening H1 and the second opening H2, and between the fourth opening H4 and the first opening H1 and the second opening H2. The remaining portions of the substrate located at the positions are movable frames 5a and 5b. The movable frames 5a and 5b made of such remaining portions are easily bent because they have a shape (linear shape) extending in the Y direction (that is, the Y direction is the extending direction of the movable frames 5a and 5b).

  The unimorph drive units 6a to 6d function as actuators that convert voltage into force, and include a piezoelectric element 61 such as PZT, ZnO, or BST that has been subjected to polarization processing, and an electrode 62 that sandwiches the piezoelectric element 61. (Refer to FIG. 4 described later). And the unimorph drive parts 6a-6d are formed by affixing this piezoelectric element 61 and the electrode 62 on the surface of movable frame 5a, 5b.

  Here, the unimorph drive portions 6a and 6b are formed so as to sandwich the main shaft portion 4a on the movable frame 5a, and the unimorph drive portions 6c and 6d are also formed so as to sandwich the main shaft portion 4b on the movable frame 5b. Is done. And the area | region between the unimorph drive parts 6a and 6b and the area | region between the unimorph drive parts 6c and 6d becomes the coupling | bond part 7 connected with the end of the main shaft parts 4a and 4b. Therefore, the movable frames 5a and 5b are also deformed (flexure deformation / bending deformation) in accordance with the expansion and contraction of the piezoelectric element 61 in the unimorph drive units 6a and 6b and the unimorph drive units 6c and 6d. In the optical scanner 1, using the deformation of the movable frames 5a and 5b, the mirror portion 3 is tilted (can be swung) in the forward and reverse rotation directions with respect to the main shaft portions 4a and 4b (main shaft direction). Details will be described later.

  The coupling portion 7 is provided with a bent portion 8 parallel to the mirror rotation axis. The bent portions 8 are composed of a pair of groove portions 81 and 82 (see FIG. 4) provided on the front and back surfaces of the coupling portion 7, and are provided in pairs at symmetrical positions with the main shaft portions 4a and 4b interposed therebetween. . Further, the groove portions 81 and 82 constituting the bent portion 8 are formed at positions that do not overlap with the thickness direction of the coupling portion 7. In addition, the groove part formed in the surface side {Z (+) side of FIG. 4} of the coupling part 7 is the groove part 81, and the groove part formed on the back surface side {Z (−) side of FIG. 4} of the coupling part 7 is the groove part. 82.

  Next, an example of a method for manufacturing the optical scanner 1 will be described. The optical scanner 1 is manufactured using, for example, a silicon substrate having a thickness of about 100 μm. First, the silicon substrate is processed by photoresist and etching to form openings H1 to H4, thereby integrally forming the fixed frame 2, the mirror portion 3, the main shaft portions 4a and 4b, and the movable frames 5a and 5b shown in FIG. To do. At this time, groove portions 81 and 82 are simultaneously formed in the coupling portion 7 of the movable frames 5a and 5b to form the bent portion 8. Next, the electrode 62, the piezoelectric element 61, and the electrode 62 are affixed in order on the surface side of a silicon substrate, and the unimorph drive parts 6a-6d are formed. Then, the optical scanner 1 is manufactured by attaching a metal film serving as a reflective film to the mirror unit 3.

  Note that the piezoelectric element 61, the electrode 62, and the metal film of the mirror unit 3 can be directly formed on the silicon substrate as a thin film. Examples of the thin film forming method include a sputtering method, a chemical vapor deposition method (CVD method), a sol-gel method, and an aerosol deposition method (AD method). The aerosol deposition method is preferable. According to this, compared with sputtering method, CVD method, sol-gel method, an etching process etc. can be omitted, and the film-forming speed can be improved and the process can be shortened. The aerosol deposition method is a technology that forms fine particles and ultrafine particles prepared in advance by other methods in advance by mixing them with gas to form an aerosol, which is then sprayed onto a substrate through a nozzle under a reduced pressure atmosphere to form a film. Show.

  Next, the deflection operation of the mirror unit 3 in the optical scanner 1 of the present embodiment will be described with reference to FIGS. 4A and 4B. 4A and 4B are cross-sectional views taken along line A-A 'in FIG.

  The optical scanner 1 in FIG. 3 rotates the mirror unit 3 with respect to the main shaft portions 4a and 4b (main shaft direction). Therefore, one direction around the main axis direction (clockwise rotation from X (+) to X (-)) is normal rotation, and reverse rotation (counterclockwise rotation) is normal rotation. 4A shows the main shaft portion 4a that rotates in the forward direction, and FIG. 4B shows the main shaft portion 4a that rotates in the reverse direction (P indicates the normal rotation direction and R indicates the reverse rotation direction).

  In addition, the direction perpendicular to the X direction and the Y direction is illustrated as the Z direction (deflection direction), and for convenience, the light receiving side of the mirror unit 3 is the Z direction plus {Z (+)}, this + direction. The opposite direction to the negative is Z direction minus {Z (−)}. Furthermore, the direction extending in the Z direction from the intersection of the X axis and the Y axis is referred to as the Z axis.

  In the following, only the movable frame 5a of the two movable frames 5a and 5b will be described, and description of the movable frame 5b will be omitted. However, the movable frame 5a tries to rotate the mirror unit 3 forward or backward. In the case of the movable frame 5b, the mirror unit 3 is also rotated forward or backward in the same manner.

  As shown in FIGS. 4A and 4B, the unimorph drive units 6a and 6b include a piezoelectric element 61 and an electrode 62 facing each other with the piezoelectric element 61 interposed therebetween. The piezoelectric element 61 expands and contracts by applying a ± voltage (alternating voltage) between the two electrodes 62 within a range that does not cause polarization reversal, and the unimorph drive units 6a and 6b move according to the expansion and contraction. Bend.

  Specifically, when the mirror unit 3 rotates in the forward direction, as shown in FIG. 4A, a voltage for extending the piezoelectric element 61 of the unimorph driving unit 6a is applied and a voltage for contracting the piezoelectric element 61 of the unimorph driving unit 6b. (Voltage having an opposite phase to the voltage applied to the unimorph drive unit 6a side) is applied.

  When such a voltage is applied, the portion of the movable frame 5a (movable piece 5aa) to which the unimorph drive unit 6a is attached bends in a convex manner on the Z (+) side. As a result, the main shaft portion 4a side of the movable piece 5aa hangs down to Z (−). On the other hand, the portion (movable piece 5ab) of the movable frame 5a to which the unimorph drive unit 6b is attached bends in the Z (−) side so as to protrude. As a result, the main shaft portion 4a side of the movable piece 5ab jumps up to Z (+). As the movable pieces 5aa and 5bb are bent, the Y (+) side of the main shaft portion 4a is pushed down and the Y (−) side is pushed up via the coupling portion 7, and the main shaft portion 4a rotates forward.

  On the contrary, when the mirror unit 3 rotates in reverse, as shown in FIG. 4B, a voltage for contracting the piezoelectric element 61 of the unimorph driving unit 6a is applied and a voltage for extending the piezoelectric element 61 of the unimorph driving unit 6b is applied. Is done. When such a voltage is applied, the movable piece 5aa is bent convexly on the Z (−) side, and the main shaft portion 4a side of the movable piece 5aa jumps up to Z (+). On the other hand, the movable piece 5ab bends convexly on the Z (+) side, and the main shaft portion 4a side of the movable piece 5ab hangs down to Z (−).

  As the movable pieces 5aa and 5bb are bent, the Y (+) side of the main shaft portion 4a is pushed up and the Y (−) side is pushed down through the coupling portion 7. That is, the main shaft portion 4a rotates in the reverse direction by moving the Y (+) side and the Y (−) side of the main shaft portion 4a in the reverse direction to the normal rotation.

  Here, since the bent portion 8 including the groove portions 81 and 82 is formed in the connecting portion 7, the connecting portion 7 can be sharply bent at the bent portion 8 portion, and the unimorph drive portions 6 a and 6 b can be bent in the Z-axis direction. Even if the displacement is slight, it can be largely rotated around the mirror rotation axis (X axis). Further, since the stress applied to the joint portion 7 by the groove portions 81 and 82 is dispersed, the breakage of the joint portion 7 due to bending fatigue can be suppressed. At this time, if the bent portion 8 is provided as close as possible to the main shaft portion 4a, the rotation angle (deflection angle) θ of the main shaft portion 4a with respect to the displacement amount of the unimorph drive portions 6a and 6b can be further increased.

  Note that the rotation angle θ is an angle generated between the mirror unit 3 that is stationary without being affected by the unimorph drive units 6a and 6b and the mirror unit 3 that fluctuates.

  The groove portions 81 and 82 constituting the bent portion 8 are easily etched by etching simultaneously with other portions such as the fixed frame 2, the mirror portion 3, the main shaft portions 4 a and 4 b, and the movable frames 5 a and 5 b constituting the optical scanner 1. Therefore, it is not necessary to provide a separate process with high accuracy in order to form the groove portions 81 and 82.

  About the depth and arrangement | positioning of the groove parts 81 and 82, it can set suitably according to the thickness of the silicon substrate used as the material of the optical scanner 1, and the curvature requested | required of the coupling | bond part 7. FIG. For example, when the grooves 81 and 82 are formed by etching as described above, it is sufficiently possible to process with an aspect ratio of about 20, and therefore, when the thickness of the silicon substrate is about several tens to several hundreds μm, the groove width The groove portions 81 and 82 can be formed with a thickness of 10 μm or less. Therefore, the bent portion 8 can be easily formed even if the optical scanner 1 is small in distance from the connecting portions of the main shaft portions 4a and 4b to the unimorph drive portions 6a to 6d.

  In addition, in order to give sufficient curvature to the coupling portion 7, as shown in FIG. 5, a pair of groove portions 81 and 82 constituting the bending portion 8 are provided so as not to overlap in the thickness direction of the coupling portion 7. When the depth of the groove portions 8a and 8b is D and the thickness of the coupling portion 7 (= silicon substrate thickness) is T, in other words, the groove depth is set so as to satisfy the relationship of 0.5 <D / T <1. The sum (2D) is set to be larger than the silicon substrate thickness T. As a result, the cross section of the bent portion 8 has a serpentine shape (bellows shape), and the bent portion 8 has sufficient strength in addition to bendability. In order to further enhance the bendability of the bent portion 8, it is desirable to make the depth D of the groove as deep as possible (D / T close to 1). Here, the depths D of the grooves 81 and 82 are the same, but the depths of the grooves 81 and 82 may be different as long as the sum of the depths of the grooves is larger than the silicon substrate thickness T.

  FIG. 6 is an enlarged cross-sectional view showing another example of the bent portion 8 provided in the coupling portion 7. In FIG. 6A, a plurality of bent portions (here, three bent portions 8a, 8b, 8c) are provided on both sides of the main shaft portion 4a. With this configuration, the twist applied to the coupling portion 7 is dispersed at the three portions of the bent portions 8a to 8c, so that the twist applied to each bent portion is small. Therefore, it is particularly effective when the thickness of the silicon substrate is large and the stress dispersion effect is small, or when the driving force generated by the unimorph driving units 6a to 6d is small.

  Further, since the moment applied to each bent portion increases as the distance from the mirror rotation axis (= main shaft portion 4a) increases, the bent portion that is farther from the mirror rotation axis when a groove having the same shape as shown in FIG. 6A is provided. Large torsional deformation occurs in the order of 8a, 8b, and 8c. Therefore, in FIG. 6B, the depths of the groove portions 81 and 82 are made smaller in the order of the bent portions 8a, 8b, and 8c. Thereby, the torsional rigidity becomes higher as the groove portion is farther from the mirror rotation axis, and the torsional angle can be balanced as compared with the configuration of FIG.

  In FIG. 6B, the depths of the groove portions 81 and 82 are changed stepwise according to the distance from the mirror rotation axis. However, the groove widths of the groove portions 81 and 82 are adjusted according to the distance from the mirror rotation axis. It may be changed in stages. Further, the cross-sectional shape of the bent portion 8 can be arbitrarily set. For example, as shown in FIG. 7A, a bent portion 8 made up of groove portions 81 and 82 having a sawtooth cross section may be provided, or a bent portion 8 made up of groove portions 81 and 82 having a stepped cross section as shown in FIG. May be provided.

  FIG. 8 is a plan view of an optical scanner according to the second embodiment of the present invention. The optical scanner 1 of the present embodiment is a two-dimensional scanning type optical scanner that performs scanning around the X axis (vertical direction in FIG. 8) and around the Y axis (horizontal direction in FIG. 8). In the one-dimensional scanning type optical scanner 1 shown in FIG. 3, the main shaft portions 4a and 4b, the movable frames 5a and 5b, the unimorph drive portions 6a to 6d and the like are the same, and only the configuration of the mirror portion 3 is different. Therefore, the mirror unit 3 will be mainly described, and the same reference numerals are given to the parts common to the first embodiment, and the description will be omitted. Each member included in the mirror unit 3 is formed by etching a deformable silicon substrate or the like, as in the first embodiment.

  The mirror unit 3 includes a mirror frame 3a, a mirror piece 3b, and mirror piece torsion bars (sub-shaft portions) 9a and 9b. The mirror frame 3a is a member surrounding the mirror piece 3b. More specifically, the mirror frame 3a is connected to mirror piece torsion bars 9a and 9b extending so as to sandwich the mirror piece 3b while positioning the mirror piece 3b in the frame. The mirror frame 3a is supported by the movable frames 5a and 5b by the main shaft portions 4a and 4b. Therefore, like the mirror part 3 of the first embodiment, the mirror frame 3a can be rotated forward and backward with reference to the main shaft parts 4a and 4b using the deformation of the movable frames 5a and 5b.

  The mirror piece 3b is an island-shaped portion (the remaining part located between the fifth opening H5 and the sixth opening H6) generated by the opening H (fifth opening H5, sixth opening H6) arranged in parallel in the mirror frame 3a. Further, it is formed by attaching a metal such as aluminum or gold as a reflective film. That is, the mirror piece 3b is a piece of material that reflects light.

  The mirror piece torsion bars 9a and 9b are members that extend outward from one end and the other end that face each other on the outer edge of the mirror piece 3b, and support the mirror piece 3b so as to be swingable. The mirror piece torsion bars 9a and 9b are formed by extending both ends of the fifth opening H5 and the sixth opening H6 in contact with the mirror piece 3b in a straight line along the Y direction.

  Next, the deflection operation of the mirror unit 3 in the optical scanner 1 of the present embodiment will be described. The deflection operation of the mirror unit 3 with respect to the directions of the main shafts 4a and 4b (X-axis direction) is the same as that of the optical scanner 1 of the first embodiment shown in FIGS. .

  9A and 9C show cross-sectional views taken along the line B-B 'of FIG. 8, and FIGS. 9B and 9D show cross-sectional views taken along the line C-C' of FIG. A rotation operation based on the Y axis of the optical scanner 1 of the present embodiment will be described with reference to FIGS. 9A to 9D. 9A and 9B show a forward rotation operation based on the Y direction, while FIGS. 9C and 9D show a reverse rotation operation based on the Y direction. Here, the normal rotation with respect to the Y axis is a clockwise rotation from Y (+) to Y (−), and the reverse rotation is a rotation in the opposite direction to the normal rotation. (The forward rotation direction is indicated by P and the reverse rotation direction is indicated by R).

  When the mirror unit 3 rotates forward with respect to the Y direction, as shown in FIG. 9A, a voltage is applied to extend the piezoelectric element 61 that constitutes the unimorph drive units 6a and 6b of the movable frame 5a (movable pieces 5aa and 5ab). The When such a voltage is applied, the movable pieces 5aa and 5ab to which the unimorph drive units 6a and 6b are attached are bent convexly on the Z (+) side by the extending piezoelectric element 61. As a result, the main shaft portion 4a side of the movable pieces 5aa and 5ab hangs down to Z (−), and the main shaft portion 4a is also displaced toward Z (−).

  On the other hand, as shown in FIG. 9B, a voltage for contracting the piezoelectric elements 61 constituting the unimorph drive units 6c, 6d of the movable frame 5b (movable pieces 5ba, 5bb) is applied. When such a voltage is applied, the contracting piezoelectric element 61 causes the movable pieces 5ba and 5bb to which the unimorph driving units 6c and 6d are attached to bend in the Z (−) side convexly. As a result, the main shaft portion 4b side of the movable pieces 5ba and 5bb jumps up to Z (+), and the main shaft portion 4b is also displaced toward Z (+).

  As described above, when the movable frame 5a displaces the main shaft portion 4a toward Z (-) and the movable frame 5b displaces the main shaft portion 4b toward Z (+), the movable frame 5a is sandwiched between the main shaft portions 4a and 4b. The mirror frame 3a is tilted. Along with this, the mirror piece 3b provided in the mirror frame 3a also tilts. This inclination is an inclination generated by the displacement of the main shaft portion 4a and the main shaft portion 4b that are deviated from the Y axis at substantially equal intervals. For this reason, considering the Y axis as a reference, the mirror piece 3b rotates forward with respect to the Y axis.

  Next, when the mirror unit 3 rotates reversely with respect to the Y direction, as shown in FIG. 9C, a voltage is applied to contract the piezoelectric elements 61 that constitute the unimorph drive units 6a and 6b of the movable frame 5a. When such a voltage is applied, the movable pieces 5aa and 5ab are bent so as to protrude to Z (−) by the contracting piezoelectric element 61. As a result, the main shaft portion 4a side of the movable pieces 5aa and 5ab jumps up to Z (+), and the main shaft portion 4a is also displaced toward Z (+).

  On the other hand, as shown to FIG. 9D, the voltage which extends the piezoelectric element 61 which comprises the unimorph drive parts 6c and 6d of the movable frame 5b is applied. When such a voltage is applied, the movable pieces 5ba and 5bb bend the Z (+) side convexly by the extending piezoelectric element 61. As a result, the main shaft portion 4b side of the movable pieces 5ba and 5bb hangs down to Z (-), and the main shaft portion 4b is also displaced toward Z (-).

  As described above, when the movable frame 5a displaces the main shaft portion 4a toward Z (+) and the movable frame 5b displaces the main shaft portion 4b toward Z (-), the mirror is reversed in the reverse direction to the case of forward rotation. The piece 3b is inclined, and as a result, the mirror piece 3b rotates in reverse with respect to the Y axis.

  However, the rotation angle θ (deflection angle θ) of forward / reverse rotation of the mirror piece 3b with respect to the Y axis as described above is relatively small. However, when the mirror frame 3a tilts, the mirror piece torsion bars 9a and 9b extending along the Y-axis (Y-axis direction) tend to rotate following the tilt.

  Therefore, in the optical scanner 1 of the present embodiment, the frequency of the voltage applied to the piezoelectric element 61 used to tilt the mirror frame 3a is the mirror piece 3b based on the mirror piece torsion bars 9a and 9b (Y-axis direction). The frequency is near the resonance frequency of the rotational vibration. This is because, even if the tilt amount of the mirror frame 3a is relatively small, the mirror piece 3b resonates with the frequency of the voltage applied to the piezoelectric element 61 and rotates relatively large.

  The voltage signal actually applied to the piezoelectric element 61 is a combination of a signal for rotating the mirror unit 3 with respect to the X direction and a signal for rotating the mirror unit 3 with respect to the Y direction. .

  Also in this embodiment, since the bent portion 8 including the pair of groove portions 81 and 82 (see FIG. 5) is formed in the connecting portion 7, the connecting portion 7 can be bent sharply at the bent portion 8 portion, and unimorph drive is performed. Even if the displacements in the Z-axis direction of the parts 6a and 6b are slight, the mirror part 3 can be largely rotated around the X-axis and the Y-axis. Further, since the stress applied to the joint portion 7 by the groove portions 81 and 82 is dispersed, the breakage of the joint portion 7 due to bending fatigue can be suppressed.

  The depth, groove width and shape of the groove portions 81 and 82 constituting the bent portion 8 and the number of the bent portions 8 can be set as in the first embodiment. Further, the manufacturing method of the optical scanner 1 is also the same as that of the first embodiment, so that the description thereof is omitted.

  The optical scanner 1 of the first and second embodiments has been described above, but the configuration of the optical scanner is not limited to the configuration of the present embodiment, and various modifications can be made without departing from the object of the present invention. . For example, the shape and size (area) of the unimorph drive units 6a to 6d are not particularly limited. For example, as shown in FIGS. 3 and 8, rectangular unimorph drive units 6 a to 6 d may be used, or other shapes such as a trapezoidal shape may be used.

  Further, the size of the unimorph drive units 6a to 6d may be an area included in one surface of the movable frames 5a and 5b (an area smaller than the areas of the movable frames 5a and 5b; FIG. 3 and FIG. 3). 8), the area may be larger than one surface of the movable frames 5a and 5b. However, it can be said that the larger the size of the unimorph drive units 6a to 6d, the greater the force to bend the movable frames 5a and 5b.

  Moreover, in the said embodiment, although the unimorph drive part which has a piezoelectric unimorph structure was mentioned as an example as a drive means which drives movable frame 5a, 5b, the member (drive part) which deform | transforms movable frames 5a, 5b is described. A drive unit having a bimorph structure in which the piezoelectric element 61 and the electrode 62 are laminated on both surfaces of the movable frames 5a and 5b may be used. Further, the driving method of the mirror unit is not limited to the piezoelectric driving method using the piezoelectric element, and other driving methods such as an electromagnetic method and an electrostatic method can be used.

  For example, as shown in FIG. 10, an electromagnetic unit 13 including an electromagnetic coil 10 and a permanent magnet 11 may be used as a driving unit instead of the unimorph driving units 6 a to 6 d. In such an electromagnetic unit 13, the electromagnetic coil 10 is formed on the movable frames 5a and 5b (movable pieces 5aa to 5ad), and the permanent magnet 11 is provided above, below, or above and below the movable frame 5a (5b). Electromagnetic force is generated between the coil 10 and the permanent magnet 11 to bend the movable frames 5a and 5b and rotate the mirror unit 3. Although only one end (movable piece 5aa) of the movable frame 5a is shown here, the other end of the movable frame 5a and the movable frame 5b have the same configuration.

  The electrostatic unit composed of two electrodes may be the drive unit. In such an electrostatic unit, one electrode is disposed on one surface of the movable frames 5a and 5b, and the other electrode is disposed at a predetermined interval from the movable frames 5a and 5b. The movable frames 5a and 5b are bent.

  In each of the above embodiments, the members of the optical scanner 1 are integrally formed by masking and etching from a single silicon substrate. However, the manufacturing method of the optical scanner 1 is not limited to the above-described method, and the fixed frame 2, Each member such as the mirror unit 3 and the movable frames 5a and 5b can be separately formed and then joined.

  Note that various types of optical devices equipped with the optical scanner 1 described above are assumed. For example, in addition to the projector (image projection apparatus) shown in FIG. 1, an image forming apparatus such as a copier or a printer can be cited as an example. Further, examples of micro scanners other than the optical scanner include those equipped with a lens (bending optical system) instead of the mirror unit 3 and those equipped with a light source (light emitting element).

  As described above, according to the microscanner of the present invention, the coupling portion that couples the variable portion and the movable frame includes a pair of groove portions parallel to the rotation axis, and the sum of the depths of the groove portions is larger than the thickness of the coupling portion. A large bent portion is formed. For this reason, the variable part can be rotated at a high speed and a wide angle with a simple configuration, and has sufficient durability even when used under such conditions. Application to an image display device such as a projector or a high-speed LBP that needs to be performed is possible. It also contributes to the downsizing and cost reduction of the optical scanning device and the image display device on which it is mounted.

These are block diagrams which show schematic structure of the image display apparatus of this invention. These are explanatory drawings which show the structural example of the image display apparatus which does not use a color synthetic | combination prism. These are top views which show the structure of the optical scanner which concerns on 1st Embodiment of this invention. FIG. 4 is a cross-sectional view taken along the line AA ′ in FIG. 3, FIG. 4A shows a state of normal rotation with reference to the X direction, and FIG. 4B shows a state of reverse rotation with reference to the X direction. Indicates. These are the expanded sectional views of the coupling | bond part in the optical scanner of 1st Embodiment. These are the expanded sectional views which show the example which provided several pairs of bending parts in the both sides of the main-shaft part. These are the expanded sectional views which show the other shape of the bending part provided in a coupling | bond part. These are the top views of the optical scanner which concerns on 2nd Embodiment of this invention. FIG. 9 is a cross-sectional view taken along the line BB ′ in FIG. 8 (FIGS. 9A and 9C) and a cross-sectional view taken along the line CC ′ in FIG. 9 (FIGS. 9B and 9D). FIGS. 9A and 9B show the forward rotation operation based on the Y direction, and FIGS. 9C and 9D show the reverse rotation operation based on the Y direction. These are the partial top views of the optical scanner which employ | adopted the electromagnetic system as a drive means. FIG. 3 is a perspective view of a conventional optical scanner. These are the top views of the conventional optical scanner different from FIG. FIG. 13 is a cross-sectional view taken along line A-A ′ of FIG. 12.

Explanation of symbols

1 Optical scanner (micro scanner)
2 Fixed frame 3 Mirror part (variable part)
3a Mirror frame 3b Mirror piece 4a, 4b Main shaft part 5a, 5b Movable frame 6a-6d Unimorph drive part (drive means)
7 Coupling portion 8 Bending portion 9a, 9b Mirror piece torsion bar 10 Electromagnetic coil (driving means)
11 Permanent magnet (drive means)
21-23 Light source 24 Color synthesis prism 40 Optical scanning device 61 Piezoelectric element 62 Electrode 81 Groove (front side)
82 Groove (Back side)
100 projector

Claims (8)

Variable part,
A main shaft portion that swingably supports the variable portion;
A deformable movable frame extending in a direction perpendicular to the main shaft portion and holding the main shaft portion ;
Provided on the movable frame, and drive means for tilting the variable portion by curving the movable frame,
A fixed frame that supports the movable frame in a bendable manner;
Including a micro scanner,
The movable frame has a coupling portion to which the main shaft portion is coupled to a portion where the driving means is not provided,
In the coupling portion , a bent portion composed of a pair of groove portions substantially parallel to the main shaft portion formed on the front surface side and the back surface side is formed on both sides of the connection position of the main shaft portion,
The sum of the depth of a pair of said groove part is larger than the thickness of the said connection part, The micro scanner characterized by the above-mentioned.   2. The micro scanner according to claim 1, wherein a plurality of the bent portions are formed on both sides of the main shaft portion along the extending direction of the movable frame.   The micro scanner according to claim 2, wherein each of the bent portions is different in at least one of a groove width and a depth of a groove portion constituting the bent portion.   4. The micro of claim 3, wherein each of the bent portions is formed such that at least one of a groove width and a depth of a groove portion constituting the bent portion decreases stepwise as the distance from the main shaft portion increases. Scanner.   5. The micro scanner according to claim 1, wherein the variable portion is a mirror portion that reflects light by including a metal film. 6.   The variable portion, the main shaft portion, the movable frame, and the fixed frame are integrally formed using a silicon substrate, and the groove portion is provided by an etching method. The micro scanner according to claim 1.   The said drive means is a unimorph drive part by which the piezoelectric element and the electrode which pinches | interposes this piezoelectric element are arrange | positioned on the said movable frame, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. Micro scanner.   An optical scanning device on which the micro scanner according to claim 1 is mounted.

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