JP2009192967A - Optical reflecting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a frequency ratio of vibration of a biaxially driven optical reflecting element. <P>SOLUTION: The optical reflection element is provided with a mirror part 1, a pair of tuning fork type piezoelectric vibrators 3 coupled to the mirror part by first support parts 2, a frame 6 coupled to the center 4 of vibration of the pair of tuning fork type piezoelectric vibrators 3 by second support parts 5 and enclosing an outer circumference of the pair of tuning fork type piezoelectric vibrators 3, a pair of meander type vibrators 8 each having one end 7 coupled to the frame 6, and a support body 10 to which the other end 9 of each of the meander type vibrators 8 is coupled. The pair of tuning fork type piezoelectric vibrators 3 have a first arm 12 and a second arm 13 respectively on both sides of the first support part 2, and the axis of rotation of vibration of the tuning fork type piezoelectric vibrators 3 and the axis of rotation of vibration of the meander type vibrators 8 are orthogonal to each other. Consequently, the frequency ratio of vibration of the biaxially driven optical reflection element can be made large. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  FIG. 8 shows an example of a conventional piezoelectric drive type optical reflection element. The optical reflecting element is connected to the frame body 103 supporting the mirror section 101 and the both ends of the frame body 103 via the mirror section 101 and the first torsion beam 102 connected to both ends of the mirror section 101. And a support body 105 that supports the frame body 103 via a second torsion beam 104 whose axial direction is orthogonal to the first torsion beam 102.

  Further, on both sides of the first torsion beam 102, piezoelectric vibrating bodies 106A and 106B having one end connected to the mirror part 101 and the other end connected to the frame 103 are provided on both sides of the second torsion beam 104. Includes piezoelectric vibrating bodies 107 </ b> A and 107 </ b> B having one end connected to the frame body 103 and the other end connected to the support body 5.

  When positive and negative voltages are applied to the piezoelectric diaphragms 106A and 106B and the piezoelectric diaphragms 107A and 107B, respectively, the first and second torsion beams 102 and 104 rotate about their rotation axes. The vibration energy propagates to the mirror unit 101 and the frame body 103, and the mirror unit 101 repeatedly rotates and vibrates around two axes that are orthogonal to each other. (For example, refer to Patent Document 1).

This optical reflection element reflects light from a laser light source or the like by a mirror unit, and can project a two-dimensional drawing on the screen surface by scanning the light in the vertical and horizontal directions of the screen.
JP 2005-148459 A

  When a conventional optical reflection element is used, the resolution of drawing to be projected may be lowered.

  This is because the frequency ratio of repetitive rotational vibrations about the two axes is small.

  Accordingly, an object of the present invention is to increase the frequency ratio of vibration in a biaxially driven optical reflecting element.

  In order to achieve this object, the present invention provides a pair of tuning fork-shaped piezoelectric vibrators that are opposed to each other via a mirror portion and are connected to the mirror portion by a first support portion. The tuning fork-shaped piezoelectric vibrators are connected to the vibration center by a second support portion, and surround the outer periphery of the pair of tuning-fork piezoelectric vibrators. And a pair of meander-type vibrators, one end of which is connected to each other, and a support body to which the other end of each of these meander-type vibrators is connected. The first arm and the second arm are provided on both sides of the portion, and the rotation axis of the vibration of the tuning fork type piezoelectric vibrator and the rotation axis of the vibration of the meandering vibrator are orthogonal to each other.

  Thereby, the present invention can increase the frequency ratio of vibration in the biaxially driven optical reflecting element.

  The reason is that repetitive rotational vibration around one axis can be driven at a high frequency by a tuning fork-shaped piezoelectric vibrator, and repetitive rotational vibration around the other axis is driven by a meander beam having a large beam length. This is because it can be driven at a low frequency.

  As a result, the frequency ratio of vibration can be increased in the biaxially driven optical reflecting element.

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

  In FIG. 1, the optical reflecting element is a pair of tuning fork-shaped piezoelectric vibrators that are opposed to the mirror unit 1 via the mirror unit 1 and are connected to the mirror unit 1 by the respective first support units 2. 3 and a vibration center 4 of these tuning fork-shaped piezoelectric vibrators 3 are connected to each other by a second support portion 5 and enclose the outer periphery of the pair of tuning-fork piezoelectric vibrators 3. And a pair of meander-type vibrators 8 that are connected to the frame body 6 and one end portion 7 respectively, and the other end portions 9 of the meander-type vibrators 8 are connected to each other. The meandering vibrator 8 and a frame-shaped support body 10 surrounding the entire outer periphery of the frame body 6 are provided.

  The opposing meandering vibrators 8 are symmetrical with respect to the first support portion 2, and the end portions 7 are connected to the corners of the frame body 6, and the diaphragm 11 is parallel to the first support portion 2. And meander repeatedly.

  The tuning fork-shaped piezoelectric vibrator 3 has a first arm 12 and a second arm 13 that are substantially parallel to the first support portion on both sides of the first support portion 2.

  Moreover, in this Embodiment, the 1st support part 2 and the 2nd support part 5 were provided on the straight line parallel to the X-axis of FIG. Furthermore, in the present embodiment, the end 9 of the meandering vibrator 8 is provided on the rotation axis of the meandering vibrator 8 in order to drive it more stably.

  In the present embodiment, the tuning fork type piezoelectric vibrator 3 has a rotation axis (28A in FIG. 3) parallel to the Y axis, and the meander vibrator 8 has a rotation axis (28B in FIG. 1) parallel to the X axis. The vibration rotating shaft 28A of the tuning fork type piezoelectric vibrator 3 and the vibration rotating shaft 28B of the meandering vibrator 8 are formed so as to be orthogonal to each other at substantially the center of the mirror portion 1.

  In this embodiment, as shown in FIG. 2, the substrate 14 of the optical reflecting element is made of a material having elasticity, mechanical strength and high Young's modulus such as metal, glass or ceramic substrate. From the viewpoint of mechanical properties and availability, for example, it is preferable to use a metal, quartz, glass, quartz, or ceramic material. 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.

  In the present embodiment, as shown in FIG. 1, the first arm 12, the second arm 13 and the diaphragm of the meandering vibrator 8 made of a base material such as silicon (14 in FIG. 2). Each of 11 is formed with piezoelectric actuators 15, 16, and 17 for causing a flexural vibration on at least one surface.

  Further, in the present embodiment, as shown in FIG. 2, the piezoelectric actuators 15, 16, and 17 are formed by laminating thin films having a laminated structure of a lower electrode layer 18, a piezoelectric layer 19, and upper electrode layers 20 A, 20 B, and 21. The piezoelectric actuators 15, 16, and 17 were used. Thereby, the tuning fork type piezoelectric vibrator 3 and the meander type vibrator 8 can be made thinner. In the present embodiment, the lower electrode layer 18 and the piezoelectric layer 19 are formed in common for the tuning fork type piezoelectric vibrator 3 and the meander vibrator 8, and the upper electrode layers 20A, 20B, and 21 are electrically connected to each other. Formed independently.

  Further, by making the thickness of the tuning fork type piezoelectric vibrator 3 smaller than the width dimension of the first arm 12 and the second arm 13 shown in FIG. 1, the amplitude is increased and a small optical reflecting element is realized. be able to. Similarly, the amplitude is increased by making the thickness of the meandering vibrator 8 smaller than its width.

  The lower electrode layer 18, the piezoelectric layer 19, and the upper electrode layers 20A, 20B, and 21 are sequentially formed on a base material 14 that forms the tuning fork type piezoelectric vibrator 3 and the meander vibrator 8 by a thin film such as a sputtering technique. It can be formed by a process. Therefore, it is preferable from the viewpoint of productivity to form the piezoelectric actuators 15, 16, and 17 on the surfaces of the tuning fork type piezoelectric vibrator 3 and the meandering vibrator 8.

  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).

  Further, the tuning fork-shaped piezoelectric vibrator 3 is designed to vibrate so that the resonant frequency of the tuning fork-shaped piezoelectric vibrator 3 and the resonant frequency of the torsional vibrator constituted by the mirror part 1 and the first support part 2 are substantially the same frequency. When the piezoelectric vibrator 3 is driven to resonate, the torsional vibrator can also resonate, and an optical reflection element that efficiently and repeatedly vibrates the mirror unit 1 can be realized.

  Further, in the present embodiment, the frame 6 can be efficiently and repeatedly oscillated by applying a signal having the resonance frequency to the meandering vibrator 8 and causing it to resonate. Further, by making the vibrator 8 meandered, the resonator length can be increased and the resonator 8 can be driven at a low frequency.

  Furthermore, by setting the widths of the first arm 12, the second arm 13, and the connecting portion 22 thereof, and the meandering vibrator 8 to have the same width, unnecessary vibration modes generated in the optical reflecting element can be reduced. .

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

  In the present embodiment, the piezoelectric actuators 15, 16, 17 formed on the diaphragm 11 of the first arm 12, the second arm 13, and the meandering vibrator 8 of the tuning fork-shaped piezoelectric vibrator 3 shown in FIG. The upper electrode layers (20A, 20B, 21 in FIG. 2) and the lead electrodes of the lower electrode layer (18 in FIG. 2) common to these upper electrode layers individually form lead lines (not shown) and connect the connection terminals 23A to 23A. 23C and 24 are connected. As a result, opposite electrical signals can be applied to the first arm 12 and the second arm 13, and an electrode signal of the resonance frequency can be applied to the meandering vibrator 8 to the piezoelectric actuators 15, 16, and 17. .

  In the present embodiment, monitor electrodes (not shown) are arranged on the first arm 12, the second arm 13, and the vibration plate 11 of the meandering vibrator 8 of the tuning fork type piezoelectric vibrator 3, respectively. Similarly to the upper electrode, it was connected to the connection terminals 25A to 25C while being routed on the element. As a result, the input signal can be adjusted while detecting the respective amplitudes of the first and second arms 12 and 13 of the tuning fork type piezoelectric vibrator 3 and the diaphragm 11 of the meandering vibrator 8. Exciting drive can be realized.

  Note that the lead lines of the above-described piezoelectric actuators 15, 16, and 17, monitor electrodes, and lead lines thereof are omitted in FIG. 2.

  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 layers 20A and 20B shown in FIG. 2, the piezoelectric layer 19 expands and contracts in the plane direction, and the first arm 12 and the second arm 13 bends and vibrates in a direction perpendicular to the substrate 14.

  At this time, if a driving signal opposite to positive and negative is applied to the piezoelectric actuators 15 and 16 formed on the first arm 12 and the second arm 13, respectively, as shown in FIG. The second arm 13 can be flexed and vibrated in a direction (in the directions 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 22 of the tuning fork type piezoelectric vibrator 3. As a result, the tuning fork-shaped piezoelectric vibrator 3 repeats rotational vibration (torsional vibration) at a predetermined frequency about the rotation axis 28A with the straight line passing through the vibration center 4 as the rotation axis 28A.

  Next, the vibration energy of this repetitive rotational vibration is transmitted to the first support part 2 joined to the connecting part 22, and the torsional vibrator composed of the first support part 2 and the mirror part 1 Torsional vibration occurs in the direction of the arrow 29 about the rotation shaft 28A. As a result, repetitive rotational vibration is caused in the mirror section 1 with the rotation axis 28A as the axis center. At this time, the direction of repetitive rotational vibration of the tuning fork-shaped piezoelectric vibrator 3 and the direction of repetitive rotational vibration of the torsional vibrator constituted by the first support portion 2 and the mirror portion 1 vibrate in opposite directions that are 180 degrees out of phase. Will be.

  Further, in the meander-shaped vibrator 8 shown in FIG. 1, when a voltage is applied between the lower electrode layer 18 and the upper electrode layer 21 in FIG. Repetitive rotational vibration is generated around the rotation axis (28B in FIG. 1).

  In the present embodiment, a common upper electrode 21 is provided for each adjacent diaphragm 11 and a signal having the same phase is applied. However, an independent upper electrode layer is provided, and the phase of the adjacent diaphragm 11 is shifted. If signals different by 180 degrees are applied, displacement accumulates around the rotation axis 28B, and a larger amplitude can be obtained.

  Then, the end of the frame body 6 can be vibrated in the vertical direction with this vibration energy, and the frame body 6 can be repetitively rotationally oscillated around the rotation shaft 28 </ b> B of the meandering vibrator 8.

  When the frame body 6 vibrates in this way, the mirror unit 1 supported by the frame body 6 can also be repeatedly rotated and oscillated around the rotation shaft 28B of the meandering vibrator 8.

  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 rotating shafts 28A and 28B of the tuning fork type piezoelectric vibrator 3 and the meandering vibrator 8 are orthogonal to each other, the light emitted from the mirror unit 1 is scanned vertically and horizontally on the screen. Can do.

  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 a base material 14 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 changed. The natural frequency can be adjusted by changing the thickness.

  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 improved, and the piezoelectric actuators 15, 16, and 17 having excellent piezoelectric characteristics can be realized.

  Next, a titanium / gold film to be the upper electrode layers 20A, 20B, and 21 is formed on the piezoelectric layer 19.

  At this time, the titanium film under the gold film is formed in order to enhance 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, the piezoelectric actuators 15, 16, and 17 having high adhesion strength can be formed because a diffusion layer that is excellent in adhesion to the piezoelectric layer 19 and is strong with the gold electrode is formed.

  In the present embodiment, the thickness of the lower electrode layer 18 of platinum is 0.2 μm, the piezoelectric layer 19 made of PZT is 3.5 μm, and the titanium portions of the upper electrode layers 20A, 20B, and 21 are 0.01 μm. The gold electrode portion is formed with a thickness of 0.3 μm.

  Next, the lower electrode layer 18, the piezoelectric layer 19, and the upper electrode layers 20A, 20B, and 21 are etched using a photolithographic technique, and the piezoelectric actuators 15, 16, and 17 are patterned.

  At this time, as an etching solution for the upper electrode layers 20A, 20B, and 21, 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.

  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 wet-etched and patterned using a mixed solution of hydrofluoric acid, nitric acid, acetic acid and hydrogen peroxide, and then the lower electrode layer 18 is further etched and patterned by dry etching. is there.

Next, the silicon substrate is isotropically dry-etched using XeF ₂ gas to remove unnecessary silicon portions and patterning to form the base material 14 as shown in FIG. An optical reflection element having a shape as shown 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, 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.

  In the present embodiment, the mirror unit 1, the first support unit 2, the tuning fork type piezoelectric vibrator 3, the second support unit 5, the frame body 6, the end 7, the meandering vibrator 8, and the base of the support body 10. By integrally forming the material 14 from the same base material 14, it is possible to realize an optical reflecting element having stable vibration characteristics and excellent productivity.

  Further, the optical reflecting element in the present embodiment can be manufactured in a lump with high accuracy by applying a semiconductor process such as a thin film process or a photolithographic technique on a base material 14 such as a silicon wafer. 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 be formed by mirror polishing the surface of the substrate 14, but a metal thin film of gold or aluminum having excellent light reflection characteristics can also be formed as a mirror film. In the present embodiment, since gold is used for the upper electrode layers 20A, 20B, and 21, this gold film can be used as a mirror film as it is, and the production efficiency is increased.

  The effect of this embodiment will be described below.

  In the present embodiment, the vibration frequency ratio can be increased in the biaxially driven optical reflecting element.

  The reason is that repetitive rotational vibration about one axis can be driven at a high frequency by the tuning-fork type piezoelectric vibrator 3, and repetitive rotational vibration about the other axis is meander-shaped vibration with a large beam length. This is because it can be driven by the meander beam of the child 8 and driven at a low frequency.

  As a result, the frequency ratio can be increased in the biaxially driven optical reflecting element.

  Particularly when an image is projected, in order to increase the resolution of the image, it is desirable that the scanning speed in the horizontal direction of the screen is larger than the scanning speed in the vertical direction.

  In the present embodiment, since the vibrator for scanning light in the vertical direction is the meander type vibrator 8, the beam length can be easily designed even in a small element, and the biaxial drive optical The frequency ratio of the reflective element can be increased.

  Further, in the present embodiment, the vibrator arranged at the inner side of the meander-shaped vibrator 8 and having a smaller size is made into a tuning fork shape, thereby forming a simple pattern and increasing the production efficiency.

  Further, since the tip of the arm becomes a free end by making the tuning fork type piezoelectric vibrator 3 into a tuning fork shape, the deflection angle of the mirror unit 1 can be efficiently increased even if it is small. If the tuning fork type piezoelectric vibrator 3 is driven at a high frequency, the amplitude becomes small. If the amplitude can be obtained efficiently as described above, a highly accurate optical reflecting element can be realized.

  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 tuning fork type piezoelectric vibrator 3 and the meander type vibrator 8, the reflection angle of the output light can be changed greatly so that the input light such as a laser beam becomes a predetermined design value. An optical reflecting element that can be swept can be realized.

  Further, in the embodiment, the mirror unit 1 is surrounded by a pair of tuning fork type piezoelectric vibrators 3 from both sides thereof, and the outer periphery of these tuning fork type piezoelectric vibrators 3 is surrounded by a frame body 6, and the frame body 6 is paired from both sides thereof. Therefore, the area of the element can be used effectively, and the element can be miniaturized.

  In the present embodiment, since the first and second arms 12 and 13 are each linear, processing is easy.

  In the present embodiment, the tuning fork-shaped piezoelectric vibrators 3 are symmetrically arranged on both sides of the mirror unit 1, so that the mirror unit 1 can be stably excited in the left-right direction. The center becomes a fixed point, and 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 meandering vibrator 8 is symmetrically disposed on both sides of the frame body 6, it can be excited with the center of the frame body 6 as a fixed point.

  Further, since the frame body 6 has a both-end support structure in which both ends are supported by the meander-type vibrator 8, 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 15 and 16 are formed on both the first arm 12 and the second arm 13, but the piezoelectric actuator may be formed on at least one of them. This utilizes the characteristics of a tuning fork type piezoelectric vibrator. When one of the arms vibrates, kinetic energy propagates to the other arm via the connecting portion 22, and this other arm can also be excited. Because it can.

  In the meandering vibrator 8, even if the piezoelectric actuator 17 is formed only on one of the paired meandering vibrators 8, the other meandering vibrator 8 is connected via the frame 6. The vibration propagates and can be operated in the same manner as when formed on both sides.

  In the present embodiment, the piezoelectric actuators 15, 16, and 17 are formed only on one side of the arm in each of the tuning fork type piezoelectric element 3 and the meander type vibrator 8, but may be formed on both sides. Since the tuning fork type piezoelectric vibrator 3 has a smaller area than the meander type vibrator 8 and has a weak driving force, only the tuning fork type piezoelectric vibrator 3 has piezoelectric actuators 15 and 16 formed on both surfaces of the base material 14. Also good.

  In addition, if each cross-sectional shape of the 1st support part 2 and the 2nd support part 5 is circular, the vibration mode of a torsional vibration will be stabilized, an unnecessary resonance can also be suppressed, and it will be influenced by disturbance vibration. A difficult optical reflecting element can be realized.

  Examples of the application of the optical reflection element as described above include an image projection apparatus and a laser exposure machine. The image projection apparatus can project a two-dimensional image on a screen by irradiating the mirror unit 1 with light while rotating the mirror unit 1 in two axial directions, for example, and reflecting the light on the mirror unit 1. It can be done.

(Embodiment 2)
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 actuators 15 and 16 as shown in FIG.

  That is, in the present embodiment, in the tuning fork type piezoelectric vibrator 3, the piezoelectric actuators 15 and 16 are extended to the connecting portion 22 between the first arm 12 and the second arm 13, and are configured in an L shape. Thus, a large driving force can be generated by increasing the area of the piezoelectric actuators 15 and 16. 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 actuators 15 and 16 formed thereon are not electrically short-circuited with each other. It is intermittent at the vibration center 4 of the vibrator 3.

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

(Embodiment 3)
The main difference between the present embodiment and the first embodiment is that, as shown in FIG. 5, each tuning fork type piezoelectric vibrator 3 includes a first arm 12, a second arm 13, and a first support. The third support part 30 is provided between the part 2 and the part 2.

  Moreover, in this Embodiment, the 3rd support part 30 and the 1st support part 2 shall be orthogonally crossed.

  In the present embodiment, the energy of repetitive rotational vibration of the tuning fork-shaped piezoelectric vibrator 3 propagates to the first support portion 2 via the third support portion 30, and the first support portion 2 is efficiently transmitted. Torsional vibration can be achieved, which contributes to downsizing of the optical reflecting element.

  The third support portion 30 is preferably provided in a vibration node portion of a higher-order standing wave having a resonance frequency of the torsional vibrator constituted by the first support portion 2 and the mirror portion 1. In other words, this standing wave appears as an integral fraction as indicated by 1/2, 1/3, and 1/4, and a third support portion is added to the vibration node of the predetermined standing wave. By providing 30, vibration energy can be propagated more efficiently.

  Further, the third support portion 30 is closer to the fixed end side than the free end sides of the first arm 12 and the second arm 13, that is, closer to the vibration center 4 of the tuning fork-shaped piezoelectric vibrator 3 than the mirror portion 1. It is more preferable to form it. This is because if the third support portion 30 is formed on the free end side, the flexural vibrations of the first arm 12 and the second arm 13 are constrained and the amplitude is reduced.

  As described above, in the present embodiment, the tuning fork-shaped piezoelectric vibrator 3 can be greatly oscillated while being driven at a high frequency by the third support portion 30, which contributes to downsizing of the element.

  In addition, when providing the 3rd support part 30, it is desirable to form in both the tuning fork type piezoelectric vibrators 3 used as a pair. Thereby, it can be rotated symmetrically by making the center of the mirror part 1 into a fixed point.

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

(Embodiment 4)
The main difference between the present embodiment and the first embodiment is that, as shown in FIG. 6, the pair of tuning fork-shaped piezoelectric vibrators 3 are arranged between the opposed first arms 12 and the opposed second arms 13. The points are connected by elastic bodies 31.

  The elastic body 31 has a smaller elasticity (softer) than the base material of the optical reflecting element, and is formed of a stretchable resin film in the present embodiment, and is formed by the first arm 12 or the second arm 13. Is pasted.

  As this resin film, a material having higher elasticity in the direction parallel to the extending direction of the first arm 12 and the second arm 13 is preferable.

  In this embodiment, a resin is used as the elastic body, but other materials such as a rubber material or a metal having a small elasticity and a small thickness may be used.

  By connecting the first arm 12 and the second arm 13 with the elastic body 31 in this way, a slight deviation in the resonance frequency of the tuning fork-shaped piezoelectric vibrator 3 facing each other can be corrected. Further, the symmetry of flexural vibration is increased, unnecessary vibration at the free end of the arm can be suppressed, and the driving force is increased.

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

(Embodiment 5)
As shown in FIG. 7, the main difference between the present embodiment and the first embodiment is that the tuning fork-shaped piezoelectric vibrator 3 has a distance d ₁ between the tips of the first arm 12 and the second arm 13. This 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 tuning fork-shaped piezoelectric vibrator 3 do not surround the outer periphery of the mirror unit 1 and are included on the inner side or flush with the side of the mirror unit 1. Therefore, the frame 6 can be made small, and as a result, it contributes to miniaturization of the optical reflecting element.

  In the present embodiment, the resonator lengths of the first and second arms 12 and 13 are shortened, the resonance frequency of the tuning fork type piezoelectric vibrator 3 is further increased, and the frequency ratio with the meandering vibrator 8 is further increased. Can be bigger.

  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 particularly useful for electrophotographic copying machines, laser printers, and optical scanners.

The top view of the optical reflection element in Embodiment 1 of this invention Sectional view of the optical reflecting element (cross section AA in FIG. 1) Schematic diagram showing the operating state of the optical reflection element 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 Plan view of an optical reflecting element in Embodiment 5 of the present invention Plan view of a conventional optical reflecting element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mirror part 2 1st support part 3 Tuning fork type piezoelectric vibrator 4 Center of vibration 5 Second support part 6 Frame body 7 End part 8 Meander type vibrator 9 End part 10 Support body 11 Diaphragm 12 First arm 13 Second arm 14 Base material 15, 16, 17 Piezoelectric actuator 18 Lower electrode layer 19 Piezoelectric layer 20A, 20B Upper electrode layer 21 Upper electrode layer 22 Connecting portion 23A-23C Connection terminal 24 Connection terminal 25A-25C Connection terminal 26 27 Arrow 28A Rotating shaft 28B Rotating shaft 29 Arrow 30 Third support portion 31 Elastic body

Claims (9)

Mirror part,
A pair of tuning fork-shaped piezoelectric vibrators facing each other through the mirror part and connected to the mirror part by a first support part,
A frame that is connected to a vibration center of each of these tuning fork-shaped piezoelectric vibrators by a second support portion and surrounds an outer periphery of the pair of tuning-fork piezoelectric vibrators;
A pair of meander-shaped vibrators that are opposed to each other through the frame and each end of which is connected to the frame,
A support body connected to the other end of each of these meander-shaped vibrators,
The tuning fork type piezoelectric vibrator has a first arm and a second arm on both sides of the first support part, respectively.
An optical reflecting element in which a rotation axis of vibration of the tuning fork type piezoelectric vibrator is orthogonal to a rotation axis of vibration of the meandering vibrator. The tuning fork type piezoelectric vibrator is
2. The optical reflecting element according to claim 1, wherein the first arm and the second arm are driven to bend and vibrate in directions different in phase by 180 degrees and torsionally vibrate about a rotation axis thereof. The optical reflection element according to claim 1, wherein a resonance frequency of the tuning fork-shaped piezoelectric vibrator and a resonance frequency of a 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 piezoelectric actuator is provided on at least one of the first arm and the second arm. At least one of the first arm and the second arm is provided with a piezoelectric actuator,
This piezoelectric actuator
The optical reflection element according to claim 1, wherein the optical reflection element extends to a connecting portion between the first arm and the second arm. Each of the tuning fork type piezoelectric vibrators
The optical reflective element according to claim 1 which has a 3rd support part between said 1st arm and 2nd arm, and the 1st support part. The third support part according to claim 6, wherein the third support part is provided in a vibration node part of a higher-order standing wave having a resonance frequency of a torsional vibrator constituted by the mirror part and the first support part. Optical reflective element. The pair of tuning fork-shaped piezoelectric vibrators are:
The optical reflective element according to claim 1, wherein the first arm facing each other and the second arm facing each other are connected by an elastic body. The tuning fork type piezoelectric vibrator is
The distance between the tips of the first arm and the second arm is
The optical reflecting element according to claim 1, wherein the optical reflecting element is shorter than a maximum length of a mirror portion perpendicular to the first arm and the second arm.

Images