JP2009217193A - Optical deflector and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical deflector in which a dynamic deflection is minimized by keeping the rigidity of a mirror while reducing the moment of inertia of the mirror. <P>SOLUTION: The optical deflector of one embodiment has: a mirror 2 which has a reflection face which is formed turnably around a predetermined shaft; a recessed part 14 formed on the back face of the reflection face of the mirror 2 for arranging a magnet; and the magnet 22 fixed in the recessed part 14 of the mirror 2. It is preferable that the magnet 22 is fixed to the mirror 2 by an adhesive 23 formed on the side face of the magnet 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical deflector using MEMS (Micro Electro Mechanical System) technology and a driving method thereof.

  In recent years, development of microactuators using MEMS technology has been active. For example, an optical deflector including a mirror supported to be torsionally rotated by a pair of elastic support portions (torsion bars) has been developed as a device capable of forming an image display device with a simple configuration.

  As a method for driving such a mirror, a method using electrostatic attraction, a method using electromagnetic force, and a method using a piezoelectric element are mainly cited.

Among these, in an optical deflector using an electromagnetic force, a magnet for applying a driving force for rotating the mirror is joined to the back side of the reflecting surface of the mirror (see Patent Document 1).
JP 2005-169553 A

  By the way, in order to suppress distortion (dynamic deflection) during high-speed operation of the mirror, it is preferable that the mirror has high rigidity. In order to increase the rigidity of the mirror, the thickness of the mirror may be increased. In this case, however, there is a concern that the driving torque increases. Therefore, there is a need for a structure that suppresses dynamic deflection while maintaining the rigidity of the mirror while reducing the moment of inertia as much as possible in order to suppress the increase in drive torque.

  The present invention has been made in view of the above circumstances, and one of its purposes is an optical deflector capable of suppressing dynamic deflection while maintaining the rigidity of the mirror while reducing the moment of inertia of the mirror as much as possible, and its manufacture. To provide a method.

  In order to achieve the above object, an optical deflector according to the present invention is a mirror having a reflecting surface configured to be rotatable along a predetermined axis, and a magnet arrangement formed on the back surface of the reflecting surface of the mirror. And a magnet fixed to the mirror recess.

  In the above configuration, since the magnet is fixed to the recess for arranging the magnet, the center of gravity of the mirror is closer to the center axis of the rotation than when there is no recess. Thus, by bringing the center of gravity of the mirror closer to the center axis of rotation, the moment of inertia of the mirror is reduced. Moreover, since the magnet is arrange | positioned in the location in which the hollow was formed, the hollow part is reinforced by this magnet and the rigidity of a mirror is maintained as a whole.

  The magnet is preferably bonded to the mirror by an adhesive formed on the side surface of the magnet. Thus, by not providing an adhesive between the magnet and the mirror, the inclination and displacement of the magnet due to the adhesive can be prevented. Moreover, compared with the case where an adhesive is applied to the entire surface between the magnet and the mirror, the stress generated during curing is reduced, and the bending of the mirror is suppressed.

  Furthermore, in order to achieve the above object, the method of manufacturing an optical deflector according to the present invention includes a step of forming a magnet placement recess on the back surface of a portion to be a mirror of the substrate, and a step of fixing the magnet in the recess of the substrate And having.

  In the above configuration, since the recess for magnet arrangement also functions as an alignment mark for fixing the magnet, it is possible to fix the magnet accurately. In addition, since the magnet is fixed to the recess for arranging the magnet, the center of gravity of the mirror is closer to the central axis of rotation than when there is no recess. Thus, by bringing the center of gravity of the mirror closer to the center axis of rotation, the moment of inertia of the mirror is reduced. Moreover, since the magnet is arrange | positioned in the location in which the hollow was formed, the hollow part is reinforced by this magnet and the rigidity of a mirror is maintained as a whole.

  Preferably, the method further includes a step of forming a mask having a predetermined pattern on both sides of the substrate and a step of processing the substrate into a mirror shape by etching the substrate from both sides using the mask. Simultaneously with the step of processing into a shape, a recess for magnet placement is formed. Thereby, compared with the case where a hollow is not provided, the hollow for magnet arrangement | positioning is formed, without increasing a process.

  Preferably, the step of fixing the magnet in the recess of the substrate includes the step of placing the magnet in the recess of the substrate, applying an adhesive on the back surface of the substrate at the outer edge of the magnet, And joining. Thus, by not providing an adhesive between the magnet and the mirror, the inclination and displacement of the magnet due to the adhesive can be prevented. Moreover, compared with the case where an adhesive is applied to the entire surface between the magnet and the mirror, the stress generated during curing is reduced, and the bending of the mirror is suppressed.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view showing the configuration of the optical deflector according to the present embodiment. 2 is a cross-sectional view taken along line II-II in FIG.

  The optical deflector 1 includes a movable plate 11, a support frame 12, and a pair of elastic support portions 13 that support the movable plate 11 so as to be torsionally rotatable with respect to the support frame 12. The movable plate 11, the support frame 12, and the elastic support portion 13 are integrally formed, for example, by etching a silicon substrate. A reflective film 21 is formed on the surface of the movable plate 11. Thereby, the mirror 2 including the movable plate 11 and the reflective film 21 is configured.

  A magnet 22 is joined to the back surface of the movable plate 11. The magnet 22 is magnetized in a direction orthogonal to the axis X that is the rotation center axis of the movable plate 11 when the movable plate 11 is viewed in plan. That is, the magnet 22 has a pair of magnetic poles that are opposed to each other via the axis X and have different polarities. The support frame 12 is joined to the holder 50, and a coil 51 for driving the movable plate 11 is disposed on the holder 50.

  In the oscillating mirror 1, a periodically changing current (AC) is supplied to the coil 51. As a result, the coil 51 alternately generates a magnetic field directed upward (movable plate 11 side) and a magnetic field directed downward. As a result, one of the pair of magnetic poles of the magnet 22 approaches the coil 51 and the other magnetic pole moves away, and the movable plate 11 rotates around the X axis while twisting and deforming the elastic support portion 13. Be moved.

  FIG. 3 is a rear view of the movable plate 11. FIG. 4 is a cross-sectional view showing how the movable plate 11 and the magnet 22 are joined.

  As shown in FIG. 3, the magnet 22 is arranged at the center of the movable plate 11 having a planar outline close to a polygon or a circle. As shown in FIG. 4, a magnet placement recess 14 is formed on the back surface of the movable plate 11, and a magnet 22 is fixed to the recess 14. The depth of the recess 14 is not limited, but it is sufficient that the total thickness of the movable plate 11 and the magnet 22 at least at the site of the recess 14 is equal to or greater than the thickness of the movable plate 11 at the site other than the recess 14. Thereby, it is prevented that the rigidity of the site | part of the hollow 14 becomes low compared with another site | part.

  The method of fixing the magnet 22 to the movable plate 11 is not limited, but preferably, the adhesive 23 is applied to the side surface of the magnet 22, thereby joining the back surface of the movable plate 11 and the side surface of the magnet 22. ing. As the adhesive 23, various adhesives such as a thermosetting adhesive and an ultraviolet curable adhesive can be used. For example, the adhesive 23 may be partially applied to the side surface of the magnet 22 at a plurality of locations, or may be applied in a frame shape covering all the side surfaces of the magnet 22.

  Next, a method for manufacturing the optical deflector 1 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 5, for example, a substrate 10 made of silicon is prepared. Then, as shown in FIG. 6, masks 31 and 32 made of silicon oxide are formed on both surfaces of the substrate 10 by thermal oxidation.

  Next, as shown in FIG. 7, a resist 41 is formed on the mask 31 on the surface side of the substrate 10. The resist may be positive or negative. Subsequently, as shown in FIG. 8, a resist 42 is formed on the mask 32 on the back surface side of the substrate 10.

  Next, as shown in FIG. 9, the resist 42 on the back surface side of the substrate 10 is exposed and developed to form predetermined opening patterns P <b> 2 and P <b> 2 ′ in the resist 42. The opening pattern P <b> 2 is a pattern that opens an area other than the movable plate 11, the support frame 12, and the elastic support portion 13. The opening pattern P <b> 2 ′ is a pattern that opens the recess 14.

  Next, as shown in FIG. 10, the mask 32 on the back surface side is etched using the resist 42 as a mask. As a result, the opening patterns P <b> 2 and P <b> 2 ′ of the resist 42 are transferred to the mask 32. For example, buffered hydrofluoric acid (BHF) is used for etching the mask 32.

  Next, as shown in FIG. 11, the resists 41 and 42 on both sides of the substrate are removed. For removing the resists 41 and 42, sulfuric acid washing or ashing is used.

  Next, as shown in FIG. 12, a resist 43 is formed again on the back side of the substrate 10. Further, as shown in FIG. 13, a resist 44 is formed again on the surface side of the substrate 10.

  Next, as shown in FIG. 14, the resist 44 on the surface side of the substrate 10 is exposed and developed to form a predetermined opening pattern P <b> 1 in the resist 44. The opening pattern P <b> 1 is a pattern that opens an area other than the movable plate 11, the support frame 12, and the elastic support portion 13. The resist 44 covers a region corresponding to the depression 14.

  Next, as shown in FIG. 15, the mask 31 on the surface side is etched using the resist 44 as a mask. Thereby, the opening pattern P1 of the resist 44 is transferred to the mask 31. For the etching of the mask 31, for example, buffered hydrofluoric acid (BHF) is used.

  Next, as shown in FIG. 16, the resists 43 and 44 on both surfaces of the substrate are removed. For removing the resists 43 and 44, sulfuric acid cleaning or ashing is used.

  Next, as shown in FIG. 17, the substrate 10 is etched using masks 31 and 32. Thereby, in the area | region of opening pattern P1, P2, the board | substrate 10 is etched from both surfaces, a through-hole is formed in the board | substrate 10, and the pattern of the movable plate 11, the support frame 12, and the elastic support part 13 is formed. Further, in the region of the opening pattern P2 ', the substrate 10 is etched only from the back surface to form a recess 14 instead of a through hole. For the etching of the substrate 10, either dry etching or wet etching can be applied. For example, wet etching using KOH is used. When wet etching such as KOH is applied to the substrate 10 made of a Si surface orientation (100) wafer, the Si (111) surface appears on the side surface of the recess 14, so the side surface of the recess 14 is tapered. It becomes. Since the side surface of the recess 14 is tapered, the magnet 22 can be disposed in the recess 14 and the adhesive 23 can be accommodated in the recess 14.

  Next, as shown in FIG. 18, after removing the masks 31 and 32, a reflective film 21 is formed on the movable plate 11 by forming a metal film on the surface of the substrate 10 and patterning it. Examples of the method for forming the metal film include vacuum deposition, sputtering, electroplating, electroless plating, and metal foil bonding. Note that the mask 31 and the mask 32 may be left without being removed.

  Next, as shown in FIG. 19, the magnet 22 is placed in the recess 14 of the movable plate 11. Subsequently, as shown in FIG. 20, the adhesive 23 is applied in the recess 14 at the outer edge of the magnet 22, and the adhesive 23 is cured to join the side surface of the magnet 22 and the back surface of the movable plate 11.

  As the subsequent steps, the optical deflector 1 is mounted by attaching the structure including the movable plate 11, the support frame 12, and the elastic support portion 13 manufactured using a single substrate in this manner to the holder 50. Manufactured.

  In the optical deflector 1 and the manufacturing method thereof according to the above-described embodiment, since the magnet 22 is fixed to the recess 14 for magnet arrangement, the center of gravity of the mirror 2 is rotated as compared with the case where there is no recess 14. It will be closer to the center axis. The central axis of rotation is defined by the elastic support portion 13. Thus, by bringing the center of gravity of the mirror closer to the center axis of rotation, the moment of inertia of the mirror is reduced. Since the moment of inertia can be reduced, an increase in driving torque is suppressed. Moreover, since the magnet is arrange | positioned in the location in which the hollow was formed, the hollow part is reinforced by this magnet and the rigidity of a mirror is maintained as a whole. By maintaining the rigidity of the mirror high, dynamic deflection is suppressed. Furthermore, since the magnet placement recess also functions as an alignment mark for fixing the magnet, the placement accuracy of the magnet is improved.

  Furthermore, in this embodiment, the back surface of the movable plate 11 and the side surface of the magnet 22 are joined by the adhesive 23. In this way, by not providing the adhesive 23 between the magnet 22 and the movable plate 11, the inclination and displacement of the magnet due to the adhesive 23 are prevented. Moreover, compared with the case where an adhesive is applied to the entire surface between the magnet 22 and the movable plate 11, the stress generated during curing is reduced, and the bending of the movable plate 11 is suppressed.

  Furthermore, in the manufacturing method of the optical deflector according to the present embodiment, it is possible to provide the recess 14 on the back surface of the movable plate 11 without adding a process as compared with the case where the recess 14 is not provided.

(Second Embodiment)
As an application example of the optical deflector 1 according to the present embodiment, a projection type display device will be described. FIG. 21 is a diagram illustrating a schematic configuration of a projection type display device. The optical scanning device shown in FIG. 21 uses the optical deflector 1 shown in FIG. 1 as a horizontal scanning mirror.

  The optical scanning device shown in FIG. 21 includes a laser light source 101, a dichroic mirror 102, a photodiode 103, and a vertical mirror 104 in addition to the optical deflector 1.

  The laser light source 101 includes a red laser light source 101R that emits red laser light, a blue laser light source 101B that emits blue laser light, and a green laser light source 101G that emits green laser light. However, laser light sources of two colors or less or four colors or more may be used.

  The dichroic mirror 102 includes a dichroic mirror 102R that reflects red laser light from the red laser light source 101R, a dichroic mirror 102B that reflects blue laser light and transmits red laser light, and reflects green laser light and blue laser light and red. A dichroic mirror 102G that transmits laser light. By these three types of dichroic mirrors 102, the combined light of red laser light, blue laser light, and green laser light is incident on the vibrating mirror 1.

  The photodiode 103 detects the amounts of red laser light, green laser light, and blue laser light that are transmitted without being reflected by the dichroic mirrors 102R, 102G, and 102B.

  The optical deflector 1 scans the laser beam sent from the dichroic mirror 102 in the horizontal direction (the vertical direction of the axis X). As described above, the optical deflector 1 is a resonant mirror formed by MEMS.

  The vertical mirror 104 scans the laser beam reflected by the optical deflector 1 in the vertical direction. The vertical mirror 104 is configured by a galvanometer mirror, for example. A galvanometer mirror is a deflector in which a mirror is provided with an axis so that the rotation angle of the mirror can be changed according to electric vibration. An image is displayed by horizontal scanning of the laser light by the optical deflector 1 and vertical scanning of the laser light by the vertical mirror 104.

  The optical scanning device according to the present embodiment further drives a laser driving unit 110 that drives the laser light source 101 and the optical deflector 1 as a drive control system for the laser light source 101, the vibrating mirror 1, and the vertical mirror 104. It has a horizontal mirror driving means 111, a vertical mirror driving means 112 for driving the vertical mirror 104, a control means 113 for controlling the overall operation, and a storage means 114.

  The control means 113 is based on image information sent from various video sources 115 such as a personal computer or a mobile phone, and displays these images by means of a laser drive means 110, a horizontal mirror drive means 111, a vertical mirror drive means. The operation of 112 is controlled.

  The storage unit 114 includes, for example, a ROM that stores various programs, a RAM that stores variables, and the like, and a nonvolatile memory.

  By applying the optical deflector 1 according to the present embodiment to a display device, a display device with good display performance can be realized.

The present invention is not limited to the description of the above embodiment.
For example, the movable plate 11 may be a polygon other than a circle. Further, in the present embodiment, the movable plate 11 of a type that is driven in a one-dimensional one degree of freedom is illustrated, but the movable plate 11 may be a type of a movable plate 11 that is driven in two dimensions, and is driven in a one-dimensional two degrees of freedom. The type of movable plate 11 may be used. When a two-dimensional driving type oscillating mirror is used, the vertical mirror 104 is not necessary. The adhesive 23 may be applied to the bottom surface of the magnet 22 instead of the side surface of the magnet 22.
The optical deflector 1 can be applied to a laser printer or the like other than the display device.
In addition, various modifications can be made without departing from the scope of the present invention.

It is a top view of the optical deflector which concerns on 1st Embodiment. It is sectional drawing of the II-II line | wire of FIG. It is a reverse view of a movable plate. FIG. 6 is a cross-sectional view in the vicinity of the joint between the movable plate and the magnet 22. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is process sectional drawing which shows the manufacturing method of the optical deflector which concerns on 1st Embodiment. It is a schematic block diagram of the display apparatus using the optical deflector based on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical deflector, 2 ... Mirror, 10 ... Board | substrate, 11 ... Movable plate, 12 ... Support frame, 13 ... Elastic support part, 14 ... Depression, 50 ... Holder, 21 ... Reflective film, 22 ... Magnet, 23 ... Adhesion Agent, 31, 32 ... Mask, 41, 42, 43, 44 ... Resist, 50 ... Holder, 51 ... Coil, 100 ... Display device, 101 ... Laser light source, 101R ... Red laser light source, 101G ... Green laser light source, 101B ... Blue laser light source, 102, 102R, 102G, 102B ... Dichroic mirror, 103, 103R, 103G, 103B ... Photodiode, 104 ... Vertical mirror, 110 ... Laser drive means, 111 ... Horizontal mirror drive means, 112 ... Vertical mirror drive means , 113 ... control means, 114 ... storage means, 115 ... video source, P1, P2 ... opening pattern

Claims (5)

A mirror having a reflecting surface, configured to be rotatable along a predetermined axis;
A recess for magnet arrangement formed on the back surface of the reflecting surface of the mirror;
A magnet fixed in the recess of the mirror;
An optical deflector. The magnet is joined to the mirror by an adhesive formed on a side surface of the magnet.
The optical deflector according to claim 1. Forming a recess for magnet placement on the back surface of the portion to be a mirror of the substrate;
Fixing a magnet in the recess of the substrate;
The manufacturing method of the optical deflector which has. Forming a mask having a predetermined pattern on both sides of the substrate;
Further processing the substrate into a mirror shape by etching the substrate from both sides using the mask,
Simultaneously with the step of processing the substrate into a mirror shape, the recess for magnet placement is formed.
The manufacturing method of the optical deflector of Claim 3. The step of fixing a magnet in the depression of the substrate includes
Placing a magnet in the recess of the substrate;
Applying an adhesive on the back surface of the substrate at the outer edge of the magnet, and joining the back surface of the substrate and the side surface of the magnet;
The method of manufacturing an optical deflector according to claim 3.

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