JP4092283B2 - Two-dimensional optical scanner and optical device - Google Patents

Description

  The present invention relates to a small and high-speed two-dimensional optical scanner that can be used for optical scanning, such as optical sensors and laser-applied equipment, and more particularly, a piezoelectric-driven micro optical scanner integrally formed by a micromachining process. It is about.

  Currently, an apparatus (optical scanner) that deflects and scans a light beam such as a laser beam is used in an optical device such as a barcode reader or a laser printer. Conventionally, as such an optical scanner, there are a polygon mirror that scans reflected light by rotating a polygonal column mirror by a motor, and a galvano mirror that rotates a plane mirror by an electromagnetic actuator. In such a mechanical structure that is driven by a motor or electromagnetic actuator, there is a limit to miniaturization and high speed.

  Moreover, a certain amount of space is required to assemble each component, and there is a problem that the size of the entire apparatus using the optical scanner is increased. Furthermore, when scanning light two-dimensionally, a combination of two polygon mirrors and galvanometer mirrors is generally used. However, in order to perform accurate two-dimensional light scanning, the scanning direction of each mirror is different. There is also a problem that it is necessary to accurately position and arrange them so as to be orthogonal to each other, and optical adjustment is very complicated.

  On the other hand, a micro optical scanner in which mechanical parts such as a mirror and an elastic beam are integrally formed on a semiconductor substrate using a micromachining technique for finely processing silicon or glass by applying a semiconductor manufacturing technique has been developed (for example, , Patent Document 1 and Patent Document 2).

  FIG. 8 is a perspective view showing an example of such an optical scanner. The upper glass substrate 103 and the lower glass substrate 104 are anodically bonded to the upper and lower sides of the silicon substrate 102, and rectangular recesses 103A and 104A are formed at, for example, ultrasonic processing at the center of both glass substrates 103 and 104. To secure a swinging space for the movable mirror portion 105B.

  In addition, a movable plate 105 is formed on the silicon substrate 102. The movable plate 105 includes a frame 105A formed in a frame shape and a mirror portion 105B that is pivotally supported inside the frame 105A. The frame 105A is elastically supported on the silicon substrate 102 by a torsion bar 106A. The mirror portion 105B is elastically supported by the frame 105A by a second torsion bar 106B whose axial direction is orthogonal to the torsion bar 106A. The frame 105A, the mirror portion 105B, and the torsion bars 106A and 106B are formed physically by etching the silicon substrate 102.

  A planar coil 107A is formed on the frame 105A via an insulating film, and both ends thereof are electrically connected to electrode pads 109A provided on the outer frame of the silicon substrate 102. Similarly, a planar coil 107B is also formed on the mirror portion 105B so as to surround the reflective film 108, and is connected to an electrode pad 109B provided on the outer frame of the silicon substrate 102. Two pairs of permanent magnets 110A to 113A and 110B to 113B are arranged on the upper glass substrate 103 and the lower glass substrate 104 as shown in the figure.

  That is, a magnetic field for driving frame 105A is generated by a pair of permanent magnets 110A and 111A and a pair of permanent magnets 110B and 111B. Further, a magnetic field for driving the mirror portion 105B inside the frame is generated by the pair of permanent magnets 112A and 113A and the pair of permanent magnets 112B and 113B.

  With the above configuration, when a current is passed through the planar coil 107A, it acts on the magnetic field generated by the previous permanent magnet, and the frame 105A rotates according to the current direction with the torsion bar 106A as a fulcrum. At that time, the inner mirror portion 105B also rotates integrally with the frame 105A. On the other hand, when a current is passed through the planar coil 107B, only the mirror portion 105B rotates with the torsion bar 106B as a fulcrum. Therefore, the mirror part 105B can be rotated two-dimensionally by supplying current to the two planar coils 107A and 107B simultaneously. That is, the laser beam can be scanned two-dimensionally.

FIG. 9 is a perspective view showing another example of the above-described optical scanner. This optical scanner includes a vibrator 202 and a small drive source 206 that generates minute vibrations such as a piezoelectric element. The vibrator 202 is provided with a vibration input portion 204 at one end of an elastic deformation portion 203 having two elastic deformation modes, a bending mode θ _B and a torsion deformation mode θ _T , and a mirror support portion 208 and a mirror portion 207 at the other end. A scanning unit 205 is provided.

In the above configuration, the elastic deformation portion 203 causes bending vibration and torsional vibration due to vibration from the vibration source 206. Since the elastic deformation portion 203 has a resonance vibration mode that is unique to each of bending and torsion, the elastic deformation portion 203 is generated through the vibration input portion 204 by generating vibrations having the same frequency as these two resonance frequencies by the vibration source 206. 203 resonates at the resonance frequency and rotates the scanning unit 205 in the bending direction (θ _B ) and the twisting direction (θ _T ). Accordingly, when the mirror unit 207 is irradiated with light, the reflected light is scanned two-dimensionally.
Japanese Patent Application Laid-Open No. 07-175005 Japanese Patent Application Laid-Open No. 07-181414

  However, the conventional optical scanner as described above is small and can perform two-dimensional scanning, but has the following problems.

  In the optical scanner shown in FIG. 8, in order to increase the deflection angle of optical scanning, it is necessary to increase the distance between the upper and lower glass substrates 103 and 104 and the mirror portion 105B. As a result, the distance between each of the permanent magnets 110A and 110B; 111A and 111B; 112A and 112B; 113A and 113B is increased, and the magnetic field of the permanent magnet in the planar coils 107A and 107B is weakened. Therefore, in order to drive the frame unit 105A and the mirror unit 105B, it is necessary to pass a large current through the planar coils 107A and 107B, and a power-saving optical scanner with a large deflection angle cannot be configured. Further, in principle, the permanent magnet has to be arranged outside the mirror part, and the planar coil 107B has to be provided inside the mirror part 105B, so that the overall dimensions of the entire element inevitably increase.

  In the optical scanner shown in FIG. 9, two-dimensional light scanning is obtained by simultaneously exciting the bending mode and the torsion mode of the elastic deformation portion 203. However, the bending mode is not rotated by the rotation about the torsion bar axis. Therefore, the center of the mirror unit 207 cannot always hold a fixed position, and the optical scanning accuracy cannot be made very high. In addition, since it is not possible to perform optical scanning by driving at a frequency other than the resonance frequency, the scanning frequency and the scanning waveform are limited. Furthermore, since one elastic deformation portion 203 bears bending vibration and torsion vibration, there is a problem that mechanical stress is concentrated on the elastic deformation portion 203 and is easily damaged. In addition, since the optical scanner is manufactured by bonding the vibrator 202 and the driving source 206, the outer dimensions are larger than those of the element manufactured by the micromachining process.

  The present invention has been made in view of the above problems, and provides an optical scanner that can be integrally formed by a micromachining process and that is small and capable of two-dimensional scanning, and an optical device configured using the optical scanner. The purpose is to do.

As a means for achieving the above object, an optical scanner of the present invention includes a mirror part having a reflecting surface inside a support having a cavity part, and the mirror part surrounding the mirror part via a first torsion bar. The inner movable frame is supported on the support body via a second torsion bar whose axial direction is orthogonal to the first torsion bar, and one end is supported by the first movable torsion bar. A second piezoelectric unimorph diaphragm that is held by the body and connected to the internal movable frame via a tip drive section that extends in parallel with the second torsion bar, and one end that is held by the internal movable frame and a first piezoelectric unimorph diaphragm end is connected to the mirror portion through the distal driving portion extending parallel to said first torsion bar, the piezoelectric unimorph vibrating plate, the first and second torsion It consists diaphragm pair or two pairs arranged symmetrically about the over rotation torque to the inner movable frame and the mirror unit by a phase for each of the vibration plate to apply an AC voltage not unified By rotating the mirror unit about the first and second torsion bars as two axes, the reflected light incident on the reflecting surface of the mirror unit is scanned two-dimensionally. It is what.

Further, the optical scanner of the present invention includes a mirror part having a reflecting surface inside a support having a hollow part, and an internal movable frame that surrounds the mirror part and supports the mirror part via a first torsion bar. The inner movable frame is pivotally supported on the support via a second torsion bar whose axial direction is orthogonal to the first torsion bar, and one end is held by the support and the other end is the A second piezoelectric unimorph diaphragm connected to the second torsion bar via a tip drive section extending in parallel with the second torsion bar and a power plate extending in a direction perpendicular to the second torsion bar; Is held by the internal movable frame and the other end of the first torsion bar extends through a tip drive unit extending in parallel with the first torsion bar and a power plate extending in a direction perpendicular to the first torsion bar. A first piezoelectric unimorph diaphragm connected to the piezoelectric unimorph diaphragm, the piezoelectric unimorph diaphragm including a pair of diaphragms arranged symmetrically with respect to the first and second torsion bars, By applying an alternating voltage whose phase is not unified to the diaphragm, a rotational torque is applied to the inner movable frame and the mirror part, whereby the mirror part is formed with the first and second torsion bars as two axes. The reflected light of the light incident on the reflecting surface of the mirror portion is scanned two-dimensionally by rotating .

  An optical device according to the present invention includes the above-described optical scanner.

  According to the present invention, it is possible to realize an optical scanner that can be integrally formed by a micromachining process and that is small and capable of two-dimensional scanning, and an optical device configured using the optical scanner.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a configuration of a two-dimensional optical scanner (optical deflector) according to the present invention, FIGS. 2 and 3 are side sectional views thereof, and FIG. 2 is a sectional view taken along line AA ′ in FIG. 3 shows a cross section taken along line BB 'in FIG.

  An internal movable frame 3 formed in a frame shape as a movable part inside a support substrate (support) 11 having a gap (cavity) 11 ′ formed from a silicon substrate, and a rectangular shape formed inside the internal movable frame 3 The mirror unit 1 has a reflective film (reflective surface) 2 and is surrounded by an internal movable frame 3. The mirror portion 1 is elastically supported by the internal movable frame 3 via first torsion bars 4a and 4b extending outward from the center position of the pair of sides, and at the same time, the first torsion bar First diaphragms (piezoelectric unimorph diaphragms) 6a, 6b, 6c, one end of which is supported by the inner movable frame 3 by the four first tip driving units 5a, 5b, 5c, 5d with the bars 4a, 4b sandwiched therebetween. , 6d are also elastically supported.

  The inner movable frame 3 is elastically supported by the support substrate 11 from both sides via the second torsion bars 12a and 12b at the center positions of the pair of opposite sides in the direction orthogonal to the first torsion bars 4a and 4b. Has been. Further, a second diaphragm (piezoelectric unimorph diaphragm) whose one end is supported on the support substrate 11 by the four second tip drive units 13a, 13b, 13c, and 13d with the second torsion bars 12a and 12b interposed therebetween. 14a, 14b, 14c, and 14d are also elastically supported.

  These mirror part 1, internal movable frame 3, first torsion bars 4a, 4b, first diaphragms 6a, 6b, 6c, 6d, second torsion bars 12a, 12b, second diaphragm 14a, 14b, 14c, 14d, the first tip driving portions 5a, 5b, 5c, 5d and the second tip driving portions 13a, 13b, 13c, 13d are integrally formed by etching the silicon substrate. In addition, a gap 11 ′ is formed at the same time so as not to hinder the mirror 1 and the inner movable frame 3 from rotating at a predetermined displacement angle.

  A reflection film 2 made of a metal thin film such as gold (Au) or aluminum (Al) is formed on the upper surface of the mirror portion 1 so as to increase the reflectance of incident light. Further, as shown in FIGS. 2 and 3, each of the above-described etched components is thinner than the thickness of the support substrate 11, and can be easily bent and twisted. .

  On the first diaphragm 6a, 6b, 6c, 6d, the first lower electrodes 7a, 7b, 7c, 7d, the first piezoelectric films 8a, 8b, 8c, 8d, and the first upper electrode The first piezoelectric actuators 10a, 10b, 10c, and 10d are formed by laminating 9a, 9b, 9c, and 9d, respectively. Similarly, on the second diaphragms 14a, 14b, 14c, and 14d, the second lower electrodes 15a, 15b, 15c, and 15d, the second piezoelectric films 16a, 16b, 16c, and 16d, and the second The upper electrodes 17a, 17b, 17c, and 17d are laminated to form second piezoelectric actuators 18a, 18b, 18c, and 18d.

  Then, by applying a predetermined voltage between the lower electrodes 7a, 7b, 7c, and 7d and the upper electrodes 9a, 9b, 9c, and 9d, the piezoelectric actuator 10a is used with the end connected to the inner movable frame 3 as a fulcrum. Due to the displacement of 10b, 10c, and 10d, the first diaphragms 6a, 6b, 6c, and 6d are unimorphally displaced in the substrate thickness direction. At this time, the tip driving units 5a, 5b, 5c, and 5d are also displaced in the same direction as the diaphragms 6a, 6b, 6c, and 6d. Similarly, due to the displacement of the piezoelectric actuators 18a, 18b, 18c, 18d, the second diaphragms 14a, 14b, 14c, 14d are displaced in the substrate thickness direction with the end connected to the support substrate 11 as a fulcrum. Thus, the tip driving units 13a, 13b, 13c, and 13d are also displaced in the same direction.

  Note that the first piezoelectric actuators 10a, 10b, 10c, and 10d and the second piezoelectric actuators 18a, 18b, 18c, and 18d react using CSD, MOCVD, sputtering, and arc discharge plasma before etching the silicon substrate. The film is formed by a technique such as reactive ion plating, and is formed by patterning by wet or dry etching.

  Next, the operation of the two-dimensional optical scanner having the above configuration will be described. FIG. 4 is a cross-sectional view taken along the line CC 'in FIG.

  The second diaphragms 14a, 14b and 14c, 14d are vibrated by applying an alternating voltage (for example, a sine wave) having the same phase to the piezoelectric actuators 18a, 18b and an opposite phase or phase shift to the piezoelectric actuators 18c, 18d. Since one end of each diaphragm is fixed and held on the support substrate 11, the diaphragm vibrates up and down in the thickness direction of the substrate, and the second tip drive unit also vibrates in the same manner. However, there is a phase difference in the vibrations of the tip driving units 13a, 13b and 13c, 13d. In particular, when the phase of the applied voltage is opposite, the vibration directions of the tip driving units 13a, 13b and 13c, 13d are opposite to each other.

  That is, when the tip driving units 13a and 13b move in the upward direction, the tip driving units 13c and 13d move in the downward direction. At this time, rotational torque about the second torsion bars 12a and 12b acts on the inner movable frame 3 and tilts about the torsion bars 12a and 12b as the central axis. When each tip drive unit follows the alternating voltage and repeats vibration in the vertical direction of the substrate, a seesaw-like rotational torque acts on the internal movable frame 3 according to the above principle, and the internal movable frame 3 is moved to a predetermined displacement angle. Repeat rotational vibration. Even in the case of vibration with a phase difference instead of an antiphase, the internal movable frame 3 vibrates in the same manner as described above. FIG. 4 shows a state in which the inner movable frame 3 is tilted with the movement of the diaphragms 14b and 14d and the tip driving units 13b and 13d.

  Based on the same principle as described above, by applying an AC voltage to the first piezoelectric actuator to vibrate the first diaphragm, the mirror unit 1 rotates to a predetermined angle about the first torsion bars 4a and 4b. Vibrate. By simultaneously applying an alternating voltage to the first and second piezoelectric actuators, the internal movable frame 3 and the mirror unit 1 rotate and vibrate in directions orthogonal to each other, so that the light incident on the reflecting surface 2 of the mirror unit 1 The reflected light is scanned two-dimensionally.

  When the driving frequency of the first piezoelectric actuator is equal to or close to the mechanical resonance frequency of the combined structure of the mirror unit 1, the first torsion bar, and the first tip driving unit, the rotational vibration of the mirror unit 1 is The maximum displacement angle is obtained. If the mechanical resonance frequency of the diaphragm 6 is set to be close to or close to the resonance frequency of the structure, a large rotation angle of the mirror unit 1 can be obtained even if the driving force of the first piezoelectric actuator is small. Is possible. Of course, although the rotation angle is small, it is needless to say that the mirror unit 1 can be rotated and vibrated at the drive frequency of the first piezoelectric actuator.

  Similarly, when the driving frequency of the second piezoelectric actuator matches or is close to the mechanical resonance frequency of the structure in which the internal movable frame 3, the second torsion bar, and the second tip driving unit are combined, the internal movement is possible. The rotational vibration of the frame 3 is maximized, and the maximum displacement angle is obtained. Further, when the resonance frequency of the second diaphragm is set to be close to or close to the resonance frequency of the structure, the energy efficiency of the second piezoelectric actuator is highest. Similarly, the internal movable frame 3 can be rotated and oscillated at the drive frequency of the second piezoelectric actuator without necessarily using resonance.

  Here, since the above-described two-dimensional optical scanner of the present invention drives the mirror unit 1 and the internal movable frame 3 by two independent piezoelectric actuators, there is no restriction on the driving frequency and 2 in the orthogonal direction. The problem of interference between two rotating vibrations is less likely to occur. In addition, since a piezoelectric film is directly formed on a structure integrally formed from a silicon substrate to form a piezoelectric actuator, it is easy to reduce the size of the element, and the silicon substrate must be bonded to form a laminated structure. There is an advantage that

  Next, the present inventor actually produced the above-described two-dimensional optical scanner and conducted an evaluation experiment. Hereinafter, this will be described as Examples 1 and 2.

Example 1
In Example 1, the optical deflector shown in FIG. 1 was produced. The manufacturing method is shown in FIG. As the support substrate 11, a single crystal silicon (top layer) / silicon oxide (intermediate oxide film layer) / single crystal silicon (base layer) bonded substrate (SOI substrate) having a thickness of 552 μm was used. The thickness of each layer is 25 μm / 2 μm / 525 μm, and the surface of the top layer is subjected to optical polishing treatment.

  First, as shown in FIG. 5A, a thermal silicon oxide film having a thickness of 500 to 1000 nm was formed on the surface of the SOI substrate using a diffusion furnace. Next, as shown in FIG. 5B, Ti and Pt are sequentially formed on the top layer side (substrate surface) by sputtering so that the respective thicknesses become 50 and 150 nm, thereby forming the lower electrode. did. A film of lead zirconate titanate (PZT), which is a piezoelectric material, is formed by a reactive arc discharge ion plating method (see Japanese Patent Application Laid-Open No. 2001-234331, Japanese Patent Laid-Open No. 2002-177765, and Japanese Patent Laid-Open No. 2003-81694). A film was formed on the Pt electrode at 3 μm to form a piezoelectric film. Thereafter, Pt was deposited on the piezoelectric film with a thickness of 150 nm by sputtering to form an upper electrode.

  Next, as shown in FIG. 5C, patterning of the upper electrode of Pt is performed on the substrate surface by a photolithography technique and a dry etching technique, and the upper electrodes 9a, 9b, 9c, 9d and 17a, 17b, 17c, 17d was formed. At the same time, a wiring / electrode pad 19a that combines the upper electrodes 9a and 9b into one, and a wiring / electrode pad 19b that combines the upper electrodes 9c and 9d into one are also formed.

  Similarly, PZT piezoelectric films were also patterned to form piezoelectric films 8a, 8b, 8c, 8d and 16a, 16b, 16c, 16d. Further, the lower electrode of Ti / Pt is also patterned to form the lower electrodes 7a, 7b, 7c, 7d and 15a, 15b, 15c, 15d, and the piezoelectric actuators 10a, 10b, 10c, 10d and 18a, 18b, 18c. , 18d was produced. At the same time, the wiring / electrode pad 20a that combines the lower electrodes 7a and 7b into one, and the wiring / electrode pad 20b that combines the upper electrodes 7c and 7d into one are also formed.

  Thereafter, as shown in FIG. 5D, Al or Au was formed by sputtering, and the reflective film 2 was patterned on the mirror portion 1 by using a photolithography technique and a dry etching technique.

  Next, as shown in FIG. 5E, the entire substrate surface is protected with a thick film resist, and the thermal oxide film on the base layer surface on the back side is removed with buffered hydrofluoric acid (BHF). Al was sputtered and patterned by photolithography and wet etching techniques to form an ICP-RIE hard mask. Thereafter, as shown in FIG. 5F, the protective resist on the surface of the substrate is peeled off, and photolithography is performed again, using the resist pattern as a mask, and the top layer thermal oxide film and single crystal silicon are formed using an ICP-RIE apparatus. Is removed by dry etching, and the mirror unit 1, the inner movable frame 3, the first torsion bar, the first diaphragm, the second torsion bar, the second diaphragm, the first and second tip driving units. Finally, a groove to be a gap 11 ′ of the support substrate 11 was formed.

  Thereafter, as shown in FIG. 5G, the single crystal silicon of the base layer was dry-etched from the back side by an ICP-RIE apparatus to form a deep groove to be a gap 11 ′ of the support substrate 11. Finally, as shown in FIG. 5H, the intermediate oxide film layer was removed using BHF to form a gap 11 ′ of the support substrate 11, thereby completing the two-dimensional optical scanner of FIG.

  Next, a sine wave bias with a voltage of 10 Vpp and 500 Hz having the same phase is applied to the piezoelectric actuators 18 a and 18 b, and a sine wave bias with a voltage of 10 Vpp and 500 Hz having the same phase opposite to the above phase is applied to the piezoelectric actuators 18 c and 18 d, An attempt was made to rotate the internal movable frame 3. The He—Ne laser light is incident on the reflective film 2 on the mirror unit 1 and the reflected light is observed on a screen arranged at a predetermined distance, thereby rotating the internal movable frame 3 integral with the mirror unit 1. When the rotation angle was measured, a rotation angle of ± 10 ° was obtained.

  At this time, when the deflected optical scanning was observed over time, stable optical scanning with good linearity could be confirmed. Further, a sine wave bias having a voltage of 10 Vpp and 30 kHz having the same phase is applied to the piezoelectric actuators 10 a and 10 b, and a sine wave bias having a voltage of 10 Vpp and 30 kHz having the same phase opposite to the above phase is applied to the piezoelectric actuators 10 c and 10 d. When rotational vibration of the part 1 was tried, a rotation angle of ± 8 ° was measured.

  Also in this case, stable optical scanning with good linearity could be confirmed. The direction of optical scanning deflected by the mirror unit 1 was orthogonal to the direction of optical scanning deflected by the rotation of the internal movable frame 3. Thereafter, two-dimensional optical scanning was observed by applying the sine wave bias to each of the two systems of the first and second piezoelectric actuators.

  The rotation angles in the two orthogonal directions were the same as the rotation angles observed when the inner movable frame 3 and the mirror unit 1 were independently rotated.

  As described above, in the two-dimensional optical scanner according to the present embodiment, a large rotation angle can be obtained even in low voltage driving by matching the driving frequency of the two piezoelectric actuators with the mechanical resonance frequency of the mirror unit 1 and the internal movable frame 3. It was confirmed that it was obtained. In addition, since the rotary torque acting point from the piezoelectric unimorph diaphragm and the rotating shaft are separated, it is confirmed that only the rotational motion around the torsion bar is excited and stable optical scanning can be performed. did it.

(Example 2)
In Example 2, the optical deflector shown in FIG. 6 was produced. The manufacturing method is basically the same as that shown in Example 1, but the element structure is slightly different. In the first embodiment, the rotational torque generated by the piezoelectric unimorph diaphragm is transmitted to the mirror unit 1 and the inner movable frame 3 via the four tip drive units. In this embodiment, as shown in FIG. The two front end drive parts are not connected to the mirror part 1 and the internal movable frame 3, respectively, and are respectively held by the first power plates 21a and 21b and the second power plates 22a and 22b for applying rotational torque. .

  6 are connected to the power plate 21a, and the first torsion bar 4a is supported by the internal movable frame 3 via the power plate 21a. Similarly, the tip driving portions 5b and 5d are connected to the power plate 21b, and the first torsion bar 4b is supported by the internal movable frame 3 via the power plate 21b. The method for supporting the internal movable frame 3 is also the same as described above. The tip driving units 13a and 13c are connected to the power plate 22a, and the second torsion bar 12a is supported on the support substrate 11 via the power plate 22a. The tip driving units 13b and 13d are connected to the power plate 22b, and the second torsion bar 12b is supported by the support substrate 11 through the power plate 22b. Other configurations are the same as those of the first embodiment.

  Similarly to the first embodiment, a sine wave bias having a voltage of 10 Vpp and 300 Hz having the same phase is applied to the piezoelectric actuators 18 a and 18 b, and a sine wave having a voltage of 10 Vpp and 300 Hz having a phase opposite to the above-described phase is applied to the piezoelectric actuators 18 c and 18 d. When a bias was applied and rotational vibration of the internal movable frame 3 was tried, stable optical scanning with good linearity could be confirmed.

  When the rotation angle of the internal movable frame 3 was measured in the same manner as in Example 1, a rotation angle greater than ± 12 ° and Example 1 was obtained. This is because the rotational torque acting on the power plates 22a and 22b is directly converted into the torsional deformation of the second torsion bars 12a and 12b, and the energy efficiency is improved, and the tip driving units 13a and 13b in the first embodiment. , 13c and 13d are effective for applying a rotational torque, but act as a resistance component for suppressing the displacement angle against the rotational vibration of the internal movable frame 3, whereas in the second embodiment, This is because the resistance component is reduced because there is no portion connected to the mirror unit 1 other than the second torsion bars 12a and 12b which are shafts. However, the mechanical resonance frequency of the internal movable frame 3 decreased from 500 Hz to 300 Hz because the structure was mechanically softer than the two-dimensional optical scanner of Example 1.

  Further, a sine wave bias having a voltage of 10 Vpp and 20 kHz having the same phase is applied to the piezoelectric actuators 10 a and 10 b, and a sine wave bias having a voltage of 10 Vpp and 20 kHz having the same phase opposite to the above phase is applied to the piezoelectric actuators 10 c and 10 d. When rotational vibration of the part 1 was tried, a larger rotation angle than that of Example 1 was obtained, which was ± 10 °. Also in this case, stable optical scanning with good linearity could be confirmed in the direction orthogonal to the optical scanning direction by the rotation of the internal movable frame 3. Thereafter, the two-dimensional optical scanning was confirmed by applying the sine wave bias to the two systems of the first and second piezoelectric actuators in the same manner as in Example 1.

  Thus, also in Example 2, the rotation angles in the two orthogonal directions were the same as the rotation angles observed when the internal movable frame 3 and the mirror unit 1 were independently rotated. Also in the two-dimensional optical scanner of the second embodiment, the driving frequencies of the two piezoelectric actuators are matched to the mechanical resonance frequencies of the mirror unit 1 and the internal movable frame 3 in the same manner as in the first embodiment. It was confirmed that a large rotation angle could be obtained.

(Example 3)
Next, application to an optical apparatus (apparatus) including the two-dimensional optical scanner (optical deflector) shown in FIGS. 1 and 6 will be described. FIG. 7 is a diagram illustrating an example of an image display device as an optical apparatus.

  In the figure, reference numeral 31 denotes the two-dimensional optical scanner shown in FIG. 1 or FIG. 6, which can raster scan incident light in the horizontal and vertical directions with one element. The laser light incident from the laser light source 32 is subjected to predetermined intensity modulation related to the timing of optical scanning, passes through the condenser lens or the lens group 33, and is then scanned two-dimensionally by the two-dimensional optical scanner 31. The scanned laser light forms an image on the projection surface 35 through the projection lens or lens group 34.

  Unlike the conventional case where a polygon mirror or a galvanometer mirror is used with two orthogonal axes, this optical apparatus does not need to align the optical axes in the orthogonal direction, and can perform raster scanning very easily.

  As described above, the embodiments of the present invention have been described. In the present invention, an optical scanner which can be integrally formed by a micromachining process and which can be two-dimensionally scanned and an optical apparatus configured using the optical scanner are realized. Can do.

That is, the following effects can be obtained.
(1) The support substrate, the piezoelectric element, the elastic body, and the mirror substrate can be integrally formed (no need for bonding / bonding).
(2) The translational movement of the mirror due to the influence of piezoelectric vibration can be suppressed.
(3) Since a piezoelectric film directly formed on the support is used as the piezoelectric element, batch processing in units of Si wafers is possible.
(4) Smaller, thinner, and lighter than conventional elements.
(5) Optical axis adjustment between two orthogonal axes is unnecessary.
(6) There is no interference between two orthogonal axes, and each can be controlled independently.
(7) Due to the miniaturization of the element, higher speed operation is possible than before.
(8) Since the generated force of the piezoelectric film actuator is large, a large deflection angle can be obtained for both axes.
(9) Since the piezoelectric film actuator is directly driven, the operation is possible even in the non-resonant mode.

  The present invention also relates to a general apparatus that deflects and scans a light beam such as a laser beam, an electrophotographic copying machine, a laser beam printer, a barcode reader, a display device that scans a laser beam and projects an image, and a head-up display. (For automobiles and consumer devices), raster scan displays for portable devices, distance measuring sensors, shape measuring sensors, optical space communication units, and the like.

  The present invention can also be applied to an optical scanning device for forming an image on a photoconductor of an electrophotographic copying machine or a laser printer, an optical scanning device of a barcode reader, or a three-dimensional distance measuring sensor.

The top view which shows the structure of the two-dimensional optical scanner which concerns on this invention Side sectional view of the two-dimensional optical scanner of FIG. Side sectional view of the two-dimensional optical scanner of FIG. CC 'sectional view of FIG. Explanatory drawing which shows the preparation methods of Example 1 The top view which shows the structure of Example 2 Explanatory drawing which shows the structure of Example 3. Perspective view showing a conventional example Perspective view showing another conventional example

Explanation of symbols

1 Mirror part 2 Reflective film (reflective surface)
3 Internal movable frames 4a, 4b First torsion bars 5a, 5b, 5c, 5d First tip driving units 6a, 6b, 6c, 6d First diaphragm (piezoelectric unimorph diaphragm)
7a, 7b, 7c, 7d 1st lower electrode 8a, 8b, 8c, 8d 1st piezoelectric film 9a, 9b, 9c, 9d 1st upper electrode 10a, 10b, 10c, 10d 1st piezoelectric actuator 11 Support Substrate (support)
11 'gap (cavity)
12a, 12b Second torsion bars 13a, 13b, 13c, 13d Second tip drive units 14a, 14b, 14c, 14d Second diaphragm (piezoelectric unimorph diaphragm)
15a, 15b, 15c, 15d Second lower electrodes 16a, 16b, 16c, 16d Second piezoelectric films 17a, 17b, 17c, 17d Second upper electrodes 18a, 18b, 18c, 18d Second piezoelectric actuator 312 Dimensional optical scanner 32 Laser light source 33 Lens group 34 Lens group 35 Projection surface

Claims (7)

The first torsion bar includes a mirror part having a reflecting surface and an internal movable frame that surrounds the mirror part and supports the mirror part via a first torsion bar inside a support having a hollow part. The inner movable frame is pivotally supported by the support via a second torsion bar whose axial direction is orthogonal to the support, and one end is held by the support and the other end extends in parallel with the second torsion bar. A second piezoelectric unimorph diaphragm connected to the internal movable frame via a tip drive unit, and a tip drive unit having one end held by the internal movable frame and the other end extending in parallel with the first torsion bar. A first piezoelectric unimorph diaphragm connected to the mirror portion, and the piezoelectric unimorph diaphragm comprises a pair of diaphragms arranged symmetrically with the first and second torsion bars interposed therebetween. Constitution Is the by the action of torque inside the movable frame and the mirror portion, two axes of the first and second torsion bars by applying an AC voltage to the phase with respect to each of the vibration plate is not uniform A two-dimensional optical scanner characterized by rotating the mirror unit and scanning the reflected light of the light incident on the reflecting surface of the mirror unit two-dimensionally. The first torsion bar includes a mirror part having a reflecting surface and an internal movable frame that surrounds the mirror part and supports the mirror part via a first torsion bar inside a support having a hollow part. The inner movable frame is pivotally supported by the support via a second torsion bar whose axial direction is orthogonal to the support, and one end is held by the support and the other end extends in parallel with the second torsion bar. A second piezoelectric unimorph diaphragm connected to the second torsion bar through a power plate extending in a direction orthogonal to the tip drive unit and the second torsion bar, and one end held by the inner movable frame A first piezoelectric unimo connected to the first torsion bar through a tip drive unit extending in parallel with the first torsion bar and a power plate extending in a direction perpendicular to the first torsion bar The piezoelectric unimorph diaphragm is composed of one or two pairs of diaphragms arranged symmetrically across the first and second torsion bars, the phase of each diaphragm being By applying a non-unified AC voltage to the internal movable frame and the mirror portion to cause a rotational torque to act, the mirror portion is rotated about the first and second torsion bars as two axes, and the mirror A two-dimensional optical scanner characterized by two-dimensionally scanning reflected light of light incident on a reflection surface of a part . The AC voltage, the optical scanner according to claim 1 or 2, characterized in that the 180 ° out of phase with each other are two different AC voltages.   A semiconductor substrate is used as the support, mechanical components including a mirror part, an internal movable frame, and a torsion bar are formed by etching the semiconductor substrate, and a metal reflective film is formed on the mirror part to form a reflective surface. The two-dimensional optical scanner according to claim 1, wherein the two-dimensional optical scanner is provided.   5. The two-dimensional optical scanner according to claim 1, wherein the piezoelectric element constituting the piezoelectric unimorph is a piezoelectric film directly formed on a support.   6. The two-dimensional optical scanner according to claim 5, wherein the piezoelectric film is a film formed by a reactive ion plating method using arc discharge plasma.   An optical apparatus comprising the two-dimensional optical scanner according to claim 1.

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