JP5239382B2 - Optical reflection element - Google Patents

Description

  The present invention relates to an optical reflection element used for a laser display or the like.

  Conventionally, a galvanometer mirror etc. are mentioned as an optical reflective element which sweeps the light emitted from the laser used for a laser display etc.

  The galvano mirror includes a mirror part, a coil arranged on the outer periphery of the mirror part, and a magnet arranged outside the coil, generates a magnetic field inside the magnet, and supplies a current to the coil in the magnetic field. Electromagnetic force is generated by flowing. And a mirror part is driven by this electromagnetic force, and a laser beam is swept on a screen surface by reflecting a laser beam by the rotating mirror part (for example, refer patent document 1).

In recent years, with the miniaturization of such a laser display, miniaturization of the optical reflecting element has become a proposition.
JP 7-218857 A

  Conventional optical reflecting elements have been difficult to downsize.

  This is because a magnet for driving the mirror portion requires a large arrangement area.

  Therefore, an object of the present invention is to reduce the size of the optical reflecting element.

  In order to achieve this object, the present invention provides a pair of first tuning fork-shaped piezoelectric elements that are opposed to each other via a mirror part and are connected to the mirror part by a first support part. The vibrator is connected to the vibration center of each of the first tuning fork-shaped piezoelectric vibrators by the second support portion and surrounds the outer periphery of the pair of first tuning-fork piezoelectric vibrators, And a pair of second tuning-fork type piezoelectric vibrators connected to the frame body by a third support portion, and the vibration centers of the second tuning-fork type piezoelectric vibrators, respectively, Each of the first tuning fork-type piezoelectric vibrators has a first arm and a second arm on both sides of the first support portion, respectively, and a second tuning fork. Each piezoelectric vibrator has a third arm and a fourth arm on both sides of the third support part. The opposing direction of the pair of first tuning fork type piezoelectric vibrators and the opposing direction of the pair of second tuning fork type piezoelectric vibrators are orthogonal to each other, and the third support part and the fourth support part are The bellows shape.

  Thereby, the present invention can reduce the size of the optical reflecting element.

  The reason is that the mirror portion can be excited by bending and vibrating the arm of the tuning fork type piezoelectric vibrator by piezoelectric driving. As a result, the optical reflecting element can be reduced in size.

(Embodiment 1)
Hereinafter, the configuration of the optical reflecting element according to Embodiment 1 of the present invention will be described.

  In FIG. 1, this optical reflecting element is a pair of first tuning forks that are opposed to a mirror portion 1 via the mirror portion 1 and are connected to the mirror portion 1 by a respective first support portion 2. A frame surrounding the outer circumference of the pair of first tuning fork-shaped piezoelectric vibrators 3, which is connected to the vibration center 4 of each of the first tuning-fork type piezoelectric vibrators 3 by the second support portion 5. A pair of second tuning-fork-type piezoelectric vibrators 8 that face the body 6 through the frame body 6 and are connected to the frame body 6 by a third support portion 7, respectively. A vibration center 9 of the tuning-fork type piezoelectric vibrator 8 and a frame-shaped support body 11 each connected by a fourth support portion 10 are provided.

  The first tuning-fork type piezoelectric vibrator 3 has a first arm 12 and a second arm 13 on both sides of the first support part 2, respectively. Each has a third arm 14 and a fourth arm 15 on both sides of the third support portion 7.

  The opposing direction of the pair of first tuning fork type piezoelectric vibrators 3 is parallel to the X axis in FIG. 1, and the opposing direction of the pair of second tuning fork type piezoelectric vibrators 8 is parallel to the Y axis. The facing direction is in a relationship of passing through the center of the mirror unit 1 and orthogonal.

  The first support portion 2, the second support portion 5, and the first tuning fork type piezoelectric vibrator 3 have a common rotation axis, and the rotation axis passes through the center of the mirror portion 1 and is the X axis in FIG. Parallel to

  The third support portion 7, the fourth support portion 10, and the second tuning fork type piezoelectric vibrator 8 have a common rotation axis, and this rotation axis passes through the center of the mirror portion 1 and is parallel to the Y axis. .

  And the 3rd support part 7 and the 4th support part 10 are bellows shapes.

  As shown in FIGS. 2A and 2B, in the two third support portions 7 that form a pair, one third support portion 7 is rotationally symmetric with respect to the other third support portion 7. is there. In other words, in the present embodiment, when one third support portion 7 is rotated 180 degrees in the horizontal plane of the optical reflecting element, the same shape as the other third support portion 7 is obtained.

  Of the two fourth support portions 10 to be paired, one fourth support portion 10 is rotationally symmetric with respect to the other fourth support portion 10. By adopting such a rotationally symmetric shape, it is possible to increase the weight balance of the entire element and reduce the occurrence of unnecessary vibration.

  In the present embodiment, both ends of the third support portion 7 are arranged on the rotation axis of the second tuning-fork type piezoelectric vibrator 8. Thereby, unnecessary vibration can be suppressed. For the same reason, both ends of the fourth support portion 10 are arranged on the rotation axis of the second tuning-fork type piezoelectric vibrator 8.

  Further, in the present embodiment, the third support portion 7 and the fourth support portion 10 have the same shape and are rotationally symmetric. With the same shape, the beam lengths of the third support portion 7 and the fourth support portion 10 are matched, and the natural vibration frequencies of the third support portion 7 and the fourth support portion 10 can be matched, It can be driven efficiently. Moreover, unnecessary vibration can be reduced by using a rotationally symmetric shape.

  As shown in FIG. 3, the substrate 16 of the optical reflecting element in the present embodiment is made of a material having elasticity, mechanical strength and high Young's modulus such as metal, glass or ceramic substrate. From the viewpoint, it is preferable to use a metal, quartz, glass, quartz, or ceramic material from the viewpoint of mechanical properties and availability. Furthermore, if a metal such as silicon, titanium, stainless steel, Elinvar, or a brass alloy is used, an optical reflecting element having excellent vibration characteristics and workability can be realized.

  And in this Embodiment, as shown in FIG. 1, the 1st arm 12, the 2nd arm 13, the 3rd arm 14, and the 4th comprised with base materials, such as a silicon | silicone (16 of FIG. 3). Each of the arms 15 is formed with a piezoelectric actuator 17 for causing flexural vibration on at least one surface.

  In this embodiment, the piezoelectric actuator 17 is a thin film laminated piezoelectric actuator 17 having a laminated structure of a lower electrode layer 18, a piezoelectric layer 19, and an upper electrode layer 20, as shown in FIG. Thereby, the first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8 can be made thinner. In the present embodiment, the lower electrode layer 18 and the piezoelectric layer 19 are formed in common by the first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8, and the upper electrode layer 20 is respectively formed. It was formed so as to be electrically independent.

  Further, by making the thickness of the first tuning-fork type piezoelectric vibrator 3 smaller than the width dimension of the first arm 12 and the second arm 13 shown in FIG. Can be realized. Similarly, by making the thickness of the second tuning-fork type piezoelectric vibrator 8 smaller than the width dimension of the third arm 14 and the fourth arm 15 shown in FIG. 1, it contributes to miniaturization of the optical reflecting element.

  Further, the lower electrode layer 18, the piezoelectric layer 19 and the upper electrode layer 20 shown in FIG. 3 are sequentially formed on the base material 16 forming the first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8. It can be formed by a thin film process such as a sputtering technique. Therefore, the piezoelectric actuator 17 is preferably formed on the surfaces of the first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8 from the viewpoint of productivity.

  The piezoelectric material used for the piezoelectric layer 19 is preferably a piezoelectric material having a high piezoelectric constant such as lead zirconate titanate (PZT).

  The resonance frequency of the first tuning-fork type piezoelectric vibrator 3 vibrates so as to be substantially the same as the resonance frequency of the torsional vibrator formed by the mirror part 1 and the first support part (2 in FIG. 1). By designing, the mirror unit 1 can be repeatedly rotated and vibrated efficiently.

  Similarly, the resonance frequency of the second tuning-fork type piezoelectric vibrator 8 can be designed to be substantially the same as the resonance frequency of the torsional vibrator constituted by the frame body 6 and the third support portion 7. preferable.

  In the present embodiment, as shown in FIG. 1, the third support portion 7 is formed so as to enter the frame body 6 and the second tuning-fork type piezoelectric vibrator 8 side. As a result, even if the resonator length of the third support portion 7 is increased, the third support portion 7 can be disposed in a space-saving manner, contributing to downsizing.

  Furthermore, it is preferable that the third support portion 7 is allowed to enter the frame body 6 longer than the second tuning fork-shaped piezoelectric vibrator 8 side. Conversely, if the second tuning fork type piezoelectric vibrator 8 is inserted long, the shape in the vicinity of the vibration center 9 becomes complicated, and an unnecessary vibration mode may occur in the second tuning fork type piezoelectric vibrator 8 in some cases. It is. In particular, in the present embodiment, since the third support portion 7 has an accordion shape, the area to be entered increases, and thus it is possible to suppress an unnecessary vibration mode when entering the frame body 6 side in this way. .

  Furthermore, the 4th support part 10 is formed so that it may enter into the support body 11 side. That is, in order to efficiently torsionally vibrate the frame body 6 and the third support portion 7, it is necessary to make the resonator lengths of the third support portion 7 and the fourth support portion 10 as equal as possible. By inserting the fourth support portion 10 toward the support body 11, the fourth support portion 10 can be disposed in a space-saving manner even if the fourth support portion 10 is long, and the optical reflecting element can be miniaturized.

  Moreover, in this Embodiment, since the 2nd support part 5 is formed so that it may enter into the frame 6 side, size reduction can be achieved. Since the second support portion 5 is inserted into the frame body 6 side, the width of the frame body 6 is narrow, but the width of the first tuning fork type piezoelectric vibrator 3 is not changed. That is, in a narrow region, stress concentrates locally and an unnecessary vibration mode may occur. However, in the present embodiment, the first tuning-fork type piezoelectric vibrator 3 has substantially the same width as a whole. Therefore, the stress can be evenly distributed and can be vibrated stably.

  Furthermore, by making the widths of the first arm 12, the second arm 13, and their connecting portions 21 and the third arm 14, the fourth arm 15 and their connecting portions 22 equal, Unnecessary vibration modes generated in the reflective element can be reduced.

  Unnecessary vibration modes can also be suppressed by making the first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8 U-shaped.

  In the present embodiment, the upper electrode layers 20 of the piezoelectric actuators 17 formed on the first arm 12, the second arm 13, the third arm 14, and the fourth arm 15 shown in FIG. The lead electrodes of the common lower electrode layer 18 are connected to the connection terminals 23A to 23D and 24 while individually forming lead lines (not shown). As a result, opposite electrical signals can be applied to the first arm 12 and the second arm 13, and opposite electrode signals can be applied to the respective piezoelectric actuators 17 to the third arm 14 and the fourth arm 15. it can.

  In the present embodiment, monitor electrodes (not shown) are arranged on the first arm 12, the second arm 13, the third arm 14, and the fourth arm 15, respectively, and these are also the same as the upper electrode. It was connected to connection terminals 25A to 25D while being routed on the element. As a result, the input signal can be adjusted while detecting the amplitude of each of the first, second, third, and fourth arms 12, 13, 14, and 15, and stable self-excited drive can be realized.

  Note that the lead lines of the piezoelectric actuator 17 and the monitor electrodes and the lead lines thereof are not shown in FIG.

  Next, the operation principle of the optical reflecting element having such a configuration will be described.

  When an alternating drive voltage is applied between the lower electrode layer 18 and the upper electrode layer 20 shown in FIG. 3, the piezoelectric layer 19 expands and contracts in the plane direction, and the first arm (12 in FIG. 1) and the first The second arm 13 bends and vibrates in the direction perpendicular to the substrate 16.

  At this time, if a drive signal opposite to the positive and negative is applied to each piezoelectric actuator 17 formed on the first arm 12 and the second arm 13, as shown in FIG. The arm 13 can be flexibly vibrated in a direction (in the direction of arrows 26 and 27) that is 180 degrees out of phase, that is, in the opposite direction. Here, in the present embodiment, the first and second arms 12 and 13 can be greatly bent and vibrated because of the cantilever structure having the distal ends thereof as free ends.

  The vibration energy of the first arm 12 and the second arm 13 is propagated to the connecting portion of the first tuning-fork type piezoelectric vibrator 3. As a result, the first tuning-fork type piezoelectric vibrator 3 repeats rotational vibration (torsional vibration) at a predetermined frequency about the rotation axis 28 with the straight line passing through the vibration center 4 as the rotation axis 28.

  Next, the vibration energy of this repetitive rotational vibration is transmitted to the first support part 2 joined to the connecting part 21, and the torsional vibrator constituted by the first support part 2 and the mirror part 1 The torsional vibration is caused in the arrow direction 29 around the rotation shaft 28. As a result, repetitive rotational vibration is caused in the mirror unit 1 with the rotation shaft 28 as the axis. At this time, the direction of the repetitive rotational vibration of the first tuning-fork type piezoelectric vibrator 3 and the direction of the repetitive rotational vibration of the torsional vibrator composed of the first support part 2 and the mirror part 1 are opposite to each other by 180 degrees. It will vibrate in the direction.

  As shown in FIG. 5, the second tuning-fork type piezoelectric vibrator 8 also applies a voltage between the lower electrode layer and the upper electrode layer, and the third arm 14 and the fourth arm 15 have a phase of 180 respectively. By bending and vibrating in different directions, torsional vibration is caused about the rotation axis 30 passing through the vibration center 9.

  When this vibration energy propagates to the third support portion 7 via the connecting portion 22, the torsional vibrator composed of the third support portion 7 and the frame body (6 in FIG. 1) is connected to the rotating shaft 30. In the center, the second tuning fork-shaped piezoelectric vibrator 8 can be repeatedly rotated and oscillated in the opposite phase.

  When the frame 6 in FIG. 1 is tilted, the mirror unit 1 supported by the frame 6 is also tilted, and the mirror unit 1 can be repeatedly rotated and vibrated.

  In the present embodiment, the third support portion 7 has a bellows shape, so that the spring constant in the third support portion 7 is reduced, and the frame 6 connected to the third support portion 7 is repeated. The amplitude of the rotational vibration can be increased.

  In addition, the fourth support portion 10 that repeatedly rotates and vibrates in the opposite direction to the third support portion 7 is also formed in a bellows shape so that the resonator lengths of the third support portion 7 and the fourth support portion 10 are matched. And can be driven efficiently.

  A light beam generated from, for example, a laser light source or an LED light source is input to the mirror unit 1 and reflected by the vibrating mirror unit 1 to scan the light beam on the screen. In the present embodiment, since the rotation axes of the first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8 are orthogonal, the light emitted from the mirror unit 1 is scanned in the horizontal and vertical directions. be able to.

  Next, a method for manufacturing the optical reflecting element in the first embodiment will be described with reference to FIG.

  First, a silicon substrate having a thickness of about 0.3 mm to be the base material 16 is prepared, and a lower electrode layer 18 made of a platinum electrode is formed thereon using a thin film process such as sputtering or vapor deposition. At this time, the thickness of the silicon substrate may be greater than 0.3 mm.

  Thereafter, a piezoelectric layer 19 is formed on the lower electrode layer 18 by a sputtering method or the like using a piezoelectric material such as lead zirconate titanate (PZT). At this time, an oxide dielectric containing Pb and Ti is preferably used as the orientation control layer between the piezoelectric layer 19 and the lower electrode layer 18, and an orientation control layer made of PLMT is more preferably formed. . Thereby, the crystal orientation of the piezoelectric layer 19 is further increased, and the piezoelectric actuator 17 having excellent piezoelectric characteristics can be realized.

  Next, an upper electrode layer 20 made of titanium / gold is formed on the piezoelectric layer 19.

  At this time, titanium below the upper electrode layer 20 is formed in order to increase the adhesion with the piezoelectric layer 19 such as a PZT thin film, and a metal such as chromium can be used in addition to titanium. As a result, since a diffusion layer that is excellent in adhesion to the piezoelectric layer 19 and is strong with the gold electrode is formed, the piezoelectric actuator 17 having high adhesion strength can be formed. In this embodiment, the thickness of the platinum lower electrode layer 18 is 0.2 μm, the piezoelectric layer 19 made of PZT is 3.5 μm, the titanium portion of the upper electrode layer 20 is 0.01 μm, and the gold electrode portion. Is formed at 0.3 μm.

  Next, the lower electrode layer 18, the piezoelectric layer 19, and the upper electrode layer 20 are etched using a photolithographic technique, and the piezoelectric actuator 17 is patterned.

  At this time, a predetermined electrode pattern was formed using an etching solution composed of an iodine / potassium iodide mixed solution, ammonium hydroxide, and hydrogen peroxide mixed solution as an etching solution for the upper electrode layer 20.

  Moreover, as an etching method used for the lower electrode layer 18 and the piezoelectric layer 19, any one of a dry etching method and a wet etching method, or a combination of these methods can be used.

For example, in the case of a dry etching method, a fluorocarbon-based etching gas or SF ₆ gas can be used.

  In addition, there is a method in which the piezoelectric layer 19 is patterned by wet etching using a mixed solution of hydrofluoric acid, nitric acid, acetic acid and hydrogen peroxide, and then further patterned by etching the lower electrode layer 18 by dry etching. .

Next, if the silicon substrate (base material 16) isotropically dry-etched using XeF ₂ gas to remove unnecessary silicon portions and patterning, the optical reflection having the shape shown in FIG. An element can be formed.

In addition, when etching a silicon substrate with higher accuracy, dry etching utilizing the anisotropy of silicon is preferable. In this case, the etching can be performed more linearly by using a mixed gas of SF ₆ gas that promotes etching and C ₄ F ₈ gas that suppresses etching, or by alternately switching these gases.

  By the manufacturing method as described above, it is possible to efficiently produce a small and highly accurate optical reflecting element collectively.

By the manufacturing process as described above, for example, the size of the mirror portion 1 is 1.0 mm × 1.0 mm, the size of the support 11 is 5.8 mm × 5.8 mm, the thickness is 0.03 mm, the driving frequency; f _H (Horizontal) 22 kHz, f _V (vertical) 0.8 kHz, deflection angle of the mirror portion 1; θ _H (horizontal) ± 5 degrees, θ _V (vertical) ± 10 degrees optical reflection element having characteristics Can do.

  In the present embodiment, the mirror part 1, the first support part 2, the first tuning fork-shaped piezoelectric vibrator 3, the second support part 5, the frame 6, the third support part 7, and the second tuning fork form. By integrating the piezoelectric vibrator 8, the fourth support portion 10, and the base material 16 of the support body 11 from the same base material 16, a stable vibration characteristic and an optical reflective element with excellent productivity can be realized. can do.

  Further, the optical reflecting element in the present embodiment can be manufactured in a lump with high precision by applying a semiconductor process such as a thin film process or a photolithographic technique on the base material 16 such as a silicon wafer, and the optical reflecting element. It is possible to realize an optical reflective element that is small in size, high in accuracy, and excellent in production efficiency.

  The mirror portion 1 can also be formed by mirror polishing the surface of the substrate 16, but a gold or aluminum metal thin film having excellent light reflection characteristics can also be formed as a mirror film. In this embodiment, since gold is used as the upper electrode layer 20, this gold film can be used as a mirror film as it is, and the production efficiency is also increased.

  The effect of this embodiment will be described below.

  In the present embodiment, the optical reflecting element can be reduced in size.

  The first tuning fork type piezoelectric vibrator 3 and the second tuning fork type piezoelectric vibrator 8 as shown in FIG. 1 are used, so that the first arm 12, the second arm 13, and the third arm are respectively used. 14 because the mirror unit 1 can be repeatedly rotated and vibrated by utilizing the flexural vibration of the fourth arm 15.

  Therefore, the mirror unit 1 can be excited without using a magnet having a large arrangement area, which contributes to miniaturization of the element.

  Further, since the tip of the arm becomes a free end by making the drive source a tuning fork, the deflection angle (amplitude) of the mirror portion 1 can be efficiently increased even if it is small.

  Further, by making the vibration source a tuning fork having a high Q value, a large vibration energy can be obtained with a small energy, which contributes to the miniaturization of the element.

  Further, by designing the vibration of the first tuning-fork type piezoelectric vibrator 3 and the second tuning-fork type piezoelectric vibrator 8, the reflection angle of the output light can be greatly changed, and the input light such as a laser beam is predetermined. It is possible to realize an optical reflecting element that can be swept so that the design value becomes.

  In the present embodiment, the third support portion 7 and the fourth support portion 10 have a bellows shape, so that the spring constant of the third support portion 7 is reduced. It is possible to increase the amplitude of repeated rotational vibration of the frame body 6 connected to, and to obtain a large driving force with a small energy.

Furthermore, in the present embodiment, only the third support portion 7 and the fourth support portion 10 are formed in a bellows shape, so that the mirror portion 1 can be vibrated in the vertical direction by the second tuning fork-shaped piezoelectric vibrator 8. Only the vibration frequency f _V in the vertical direction can be reduced, and the frequency ratio of the vibration in the horizontal direction and the vertical direction can be increased in this secondary drive type optical reflecting element.

  Thus, when the frequency ratio of vibration in the biaxial direction is increased, the scanning speed in the horizontal direction is relatively higher than the scanning speed in the vertical direction on the screen when the light beam is scanned using this optical reflecting element. Thus, the resolution of the projected image can be improved, and a highly accurate image projection apparatus can be realized.

  Further, in the embodiment, the mirror unit 1 is surrounded by a pair of first tuning fork type piezoelectric vibrators 3 from both sides thereof, and the outer periphery of these first tuning fork type piezoelectric vibrators 3 is surrounded by a frame body 6. 6 is surrounded by a pair of second tuning fork type piezoelectric vibrators 8 from both sides, and the outer periphery of these second tuning fork type piezoelectric vibrators 8 is surrounded by a support 11, so that each member is interposed through a small gap. The structure is such that it is wound in several layers, reducing the dead space of the entire device and reducing the size of the device.

  In the present embodiment, the first, second, third, and fourth arms 12, 13, 14, and 15 are easy to process because they are each linear.

  In the present embodiment, since the first tuning fork-shaped piezoelectric vibrator 3 is symmetrically disposed on both sides of the mirror unit 1, the mirror unit 1 can be excited stably and bilaterally. Since the center is a fixed point, light can be scanned stably.

  Moreover, since the mirror part 1 has a both-end support structure in which both ends are supported by the first support part 2, unnecessary resonance of the mirror part 1 can be suppressed, and the influence of disturbance vibration can be reduced.

  Further, in the present embodiment, since the second tuning fork-shaped piezoelectric vibrator 8 is symmetrically disposed on both sides of the frame body 6, the center of the frame body 6 can be excited with the fixed point.

  Further, since the frame body 6 has a both-end support structure in which both ends are supported by the third support portion 7, unnecessary resonance of the frame body 6 can be suppressed, and the influence of disturbance vibration can be reduced.

  In the above embodiment, the piezoelectric actuators 17 are formed on both the first arm 12 and the second arm 13, but the piezoelectric actuators 17 may be formed only on at least one of them. This utilizes the characteristics of a tuning fork type piezoelectric vibrator. When one of the arms vibrates, the kinetic energy propagates to the other arm via the connecting portion 21, and the other arm can be excited. Because.

  Similarly, the second tuning-fork type piezoelectric vibrator 8 is operated in the same manner as when the piezoelectric actuator 17 is formed only on one of the third arm 14 and the fourth arm 15. be able to.

  In the present embodiment, the piezoelectric actuator 17 is formed only on one side of the arm in both the first and second tuning-fork type piezoelectric vibrators 3 and 8, but may be formed on both sides. Further, since the first tuning fork type piezoelectric vibrator 3 has a smaller area than the second tuning fork type piezoelectric vibrator 8 and a weak driving force, only the first tuning fork type piezoelectric vibrator 3 is provided on both surfaces of the substrate 16. The piezoelectric actuator 17 may be formed.

  Examples of the application of the optical reflection element as described above include an image projection apparatus and a laser exposure machine, and these apparatuses can be miniaturized.

  In addition, if each cross-sectional shape of the 1st support part 2, the 2nd support part 5, the 3rd support part 7, and the 4th support part 10 is circular, the vibration mode of torsional vibration will be stabilized, Unnecessary resonance can also be suppressed, and an optical reflection element that is hardly affected by disturbance vibration can be realized.

(Embodiment 2)
The main difference between the optical reflecting element in the present embodiment and the optical reflecting element in the first embodiment is that, as shown in FIG. 6, the first support portion 2 and the second support portion 5 are also meandered. Is a point.

  Thereby, in this Embodiment, the spring constant of the 1st support part 2 becomes small, and can drive the mirror part 1 efficiently with small energy. Further, since the resonator length of the first support portion 2 is increased, the amplitude of the repetitive rotational vibration of the mirror portion 1 around the rotation axis of the first support portion 2 can be increased.

  Moreover, in this Embodiment, in the two 1st support parts 2 used as a pair, one 1st support part 2 was made into the rotational symmetry form of the other 1st support part 2. As shown in FIG. As a result, the gravity balance of the entire element is increased, generation of unnecessary vibration is suppressed, and light can be scanned with high accuracy using this optical reflecting element. For the same reason, the second support portion 5 is also rotationally symmetric with the other second support portion 5 in a pair.

  Furthermore, in the present embodiment, both ends of the first support portion 2 and the second support portion 5 are formed so as to be positioned on the rotation axis of the first tuning-fork type piezoelectric vibrator 3. Thereby, in this Embodiment, generation | occurrence | production of an unnecessary vibration can be suppressed and the rotational vibration energy of the 1st support part 2 and the 2nd support part 5 can be transmitted efficiently.

  As described above, in this embodiment, the amplitude can be increased in both the horizontal direction and the vertical direction. Therefore, a large driving force can be generated with a small energy, which contributes to the miniaturization of the optical reflecting element.

  In addition, if the 1st support part 2 and the 2nd support part 5 are made into the same shape, the natural vibration frequency of the 1st support part 2 and the 2nd support part 5 can be united, and it drives efficiently. can do. Moreover, if the 1st support part 2 and the 2nd support part 5 are made into a rotational symmetry type, generation | occurrence | production of an unnecessary vibration can be reduced.

  Further, when it is desired to further increase the frequency ratio of vibration in the biaxial direction, for example, the beam lengths of the third support portion 7 and the fourth support portion 10 are set to be equal to those of the first support portion 2 and the second support portion 5. It may be longer than the beam length. The beam length can be easily adjusted by changing the number of turns of the meandering region.

  Description of other configurations and effects similar to those of the first embodiment is omitted.

(Embodiment 3)
The main difference between the optical reflecting element in the present embodiment and the optical reflecting element in the first embodiment is the shape and location of the piezoelectric actuator 17 as shown in FIG.

  That is, in the present embodiment, in the first tuning-fork type piezoelectric vibrator 3, the piezoelectric actuator 17 is extended to the connecting portion 21 between the first arm 12 and the second arm 13 and configured in an L shape. . The first arm 12 and the second arm 13 are applied with signals having opposite phases, respectively, so that the drive electrodes of the piezoelectric actuator 17 formed thereon are not electrically short-circuited with each other. The vibration is interrupted at the vibration center 4 of the piezoelectric vibrator 3. Thus, by forming the piezoelectric actuator 17 up to the connecting portion 21, the area can be effectively used and a large drive source can be obtained.

  Similarly, in the second tuning-fork type piezoelectric vibrator 8, the piezoelectric actuator 17 may be extended to the connecting portion 22 between the third arm 14 and the fourth arm 15. In this case, the piezoelectric actuators 17 may be electrically disconnected at the vibration center 9.

  Either one of the first and second tuning-fork type piezoelectric vibrators 3 and 8 may be L-shaped as described above, or both piezoelectric actuators 17 may be L-shaped as described above. Further, the tuning fork-type piezoelectric vibrators that are paired with each other preferably have the same shape of the piezoelectric actuator 17, so that the mirror unit 1 can be stably excited with its center as a fixed point.

  Description of other configurations and effects similar to those of the first embodiment will be omitted.

(Embodiment 4)
As shown in FIG. 8, the main difference between the present embodiment and the first embodiment is that the first tuning fork type piezoelectric vibrator 3 has an interval between the tips of the first arm 12 and the second arm 13. d ₁ is a point shorter than the maximum length d ₂ (diameter) of the mirror portion 1 perpendicular to the first and second arms 12 and 13.

  That is, in the present embodiment, the first and second arms 12 and 13 of the first tuning fork-shaped piezoelectric vibrator 3 do not surround the outer periphery of the mirror portion 1 and are enclosed more inside. As a result, the optical reflecting element can be reduced in size.

  In the present embodiment, since the first arm 12 and the second arm 13 are shortened, the resonance frequency in the first tuning-fork type piezoelectric vibrator 3 is increased, and the resonance frequency in the biaxial direction of the optical reflecting element is increased. The ratio can be made larger.

  Description of other configurations and effects similar to those of the first embodiment will be omitted.

  The present invention has an effect that the optical reflecting element can be miniaturized, and is useful for applications such as an image projection apparatus such as a laser display apparatus and other laser exposure machines.

The top view of the optical reflection element in Embodiment 1 of this invention (A) The principal part enlarged plan view which shows the P section of FIG. 1, (b) The principal part enlarged plan view which shows the Q part of FIG. AA sectional view of FIG. Schematic diagram showing the operating state of the optical reflecting element according to Embodiment 1 of the present invention. Schematic diagram showing the operating state of the optical reflecting element according to Embodiment 1 of the present invention. The top view of the optical reflective element in Embodiment 2 of this invention The top view of the optical reflective element in Embodiment 3 of this invention The top view of the optical reflective element in Embodiment 4 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mirror part 2 1st support part 3 1st tuning fork type piezoelectric vibrator 4 center of vibration 5 2nd support part 6 Frame 7 3rd support part 8 2nd tuning fork type piezoelectric vibrator 9 center of vibration 10 1st Four support portions 11 Support body 12 First arm 13 Second arm 14 Third arm 15 Fourth arm 16 Base material 17 Piezoelectric actuator 18 Lower electrode layer 19 Piezoelectric layer 20 Upper electrode layer 21 Connection portion 22 Connection Portion 23A-23D Connection terminal 24 Connection terminal 25A-25D Connection terminal 26, 27 Arrow 28 Rotating shaft 29 Arrow 30 Rotating shaft

Claims (11)

A pair of first tuning-fork type piezoelectric vibrators that face each other through the mirror part and are connected to the mirror part by a first support part, and these first tuning-fork type piezoelectric vibrations A frame that is connected to the vibration center of each child by a second support and surrounds the outer periphery of the pair of first tuning fork-shaped piezoelectric vibrators, is opposed to the frame through the frame, and A pair of second tuning-fork type piezoelectric vibrators connected by three support parts, and a support center connected by a fourth support part and a vibration center of each of these second tuning-fork type piezoelectric vibrators ,
Each of the first tuning fork type piezoelectric vibrators has a first arm and a second arm on both sides of the first support portion, and each of the second tuning fork type piezoelectric vibrators is provided with the third tuning fork type piezoelectric vibrator. A third arm and a fourth arm on both sides of the support portion of the
The opposing direction of the first tuning fork type piezoelectric vibrator of the pair and the opposing direction of the second tuning fork type piezoelectric vibrator of the pair are orthogonal to each other,
The third support part and the fourth support part are optical reflecting elements having a bellows shape. The first tuning-fork type piezoelectric vibrator is
The first arm and the second arm are flexibly oscillated in directions different in phase by 180 degrees, and driven to torsionally oscillate around the rotation axis,
The second tuning-fork type piezoelectric vibrator is
The third arm and the fourth arm are flexed and vibrated in directions different in phase by 180 degrees,
The optical reflecting element according to claim 1, wherein the optical reflecting element is driven to torsionally vibrate about the rotation axis. The optical reflection element according to claim 1, wherein the resonance frequency of the first tuning-fork type piezoelectric vibrator and the resonance frequency of the torsional vibrator constituted by the mirror part and the first support part are substantially the same frequency. . The optical reflection element according to claim 1, wherein a resonance frequency of the second tuning-fork type piezoelectric vibrator and a resonance frequency of a torsional vibrator constituted by the frame and the third support part are set to substantially the same frequency. . At least one of the first arm and the second arm;
The optical reflecting element according to claim 1, wherein a piezoelectric actuator is provided on at least one of the third arm and the fourth arm. One of the third support portions is
And the rotationally symmetrical shape of the other third support part in the pair,
One of the fourth support parts is
The optical reflection element according to claim 1, wherein the other fourth support portion in a pair has a rotationally symmetric shape. Both ends of the third support part and the fourth support part are
The optical reflection element according to claim 1, wherein the optical reflection element is formed on a rotation axis of the second tuning-fork type piezoelectric vibrator. 2. The optical reflecting element according to claim 1, wherein the third support portion enters at least one of the frame body side and the second tuning fork-shaped piezoelectric vibrator side. The third support portion enters both the frame body side and the second tuning fork-shaped piezoelectric vibrator side, and
The length of the third support part that has entered the frame body side is:
The optical reflection element according to claim 1, wherein the optical reflection element is longer than a length of the second tuning fork-shaped piezoelectric vibrator. The third support part enters the second tuning-fork type piezoelectric vibrator side,
The optical reflection element according to claim 1, wherein the fourth support portion has a shape that enters the support side. The first support part and the second support part are:
The optical reflective element according to claim 1, which has a bellows shape.

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