JP2013190498A - Optical deflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical deflector capable of accurately detecting oscillation around two axes of a reflection surface without reducing a rotational angle in the case of oscillating the reflection surface around the two axes.SOLUTION: An optical deflector 1 includes: a reflection surface 2a which oscillates around two axes X and Y by drive of a first piezoelectric actuator 31 and a second piezoelectric actuator 51; and a first support part 4 having detection parts 71 and 72 which detect oscillation of the reflection surface 2a. In the second piezoelectric actuator 51, two first drive wiring lines Wy1 and Wy2 which are conducted to the first piezoelectric actuator 31, and to which voltages of antiphase with each other are applied, second drive wiring lines Wo and We which are conducted to the second piezoelectric actuator 51, and a detection wiring line Wm which is conducted to the detection part 71 are arranged in parallel with one another. The detection wiring line Wm is arranged between the two first drive wiring lines Wy1 and Wy2.

Description

  The present invention relates to an optical deflector that can swing a reflecting surface about two axes.

  2. Description of the Related Art Conventionally, an optical deflector including a mirror portion having a reflecting surface, a pair of first vibrators, a first support portion, a pair of second vibrators, and a second support portion is known (patent). Reference 1). One end of each of the pair of first vibrators of the optical deflector is coupled to the end portion of the mirror portion so as to face each other through the mirror portion. The first support part is coupled to the other ends of the pair of first vibrators so as to surround the outer circumferences of the pair of first vibrators and the mirror part. One end of each of the pair of second vibrators is coupled to the first support portion so as to face each other via the first support portion. The second support part is connected to the other end of each of the pair of second vibrators so as to surround the outer periphery of the pair of second vibrators and the first support part.

  The first vibrator is formed in a meander shape in which a plurality of diaphragms parallel to an axis perpendicular to the central axis of the first vibrator are folded and connected on the same plane. The second vibrator is formed in a meander shape in which a plurality of diaphragms parallel to an axis perpendicular to the central axis of the second vibrator are connected in a folded manner on the same plane.

  A drive element and a monitor element are disposed on a plurality of diaphragms constituting the first vibrator and the second vibrator, respectively. The drive element is a piezoelectric element for bending and deforming each diaphragm by piezoelectric driving. The monitor element is a piezoelectric element for detecting the amount of bending deformation of each diaphragm. Each of these piezoelectric elements is formed by laminating a lower electrode, a piezoelectric body, and an upper electrode.

  In such an optical deflector, each diaphragm is bent and deformed by the drive elements of the first vibrator and the second vibrator, so that the reflecting surface can be swung around the first axis and the second axis. Further, in such an optical deflector, the actual deformation amount of the bending deformation of each diaphragm when piezoelectrically driven is detected by the monitor element. The optical deflector increases the accuracy of the piezoelectric drive control by feeding back the actual deformation amount.

JP 2010-122480 A

  However, in the optical deflector of Patent Document 1, monitor elements are arranged on a plurality of diaphragms constituting the first vibrator and the second vibrator in addition to the drive elements. For this reason, the area which a drive element occupies on a diaphragm reduces. As a result, the optical deflector has less force to bend a plurality of diaphragms than that in which no monitor element is disposed, and the rotation angle of the reflecting surface of the mirror portion is reduced.

  For this reason, it is desired to be able to detect this swing without reducing the rotation angle when the reflecting surface swings around two axes. When the reflecting surface is swung, vibration due to piezoelectric driving of each vibrator is transmitted to the first support portion to which the first vibrator and the second vibrator are coupled. Therefore, it is conceivable to dispose the monitor element on the first support portion. In this case, it is not necessary to dispose the monitor element on the first vibrator and the second vibrator, and the drive element can occupy a sufficient area on the diaphragm.

  At this time, since it is necessary to acquire a signal detected by the monitor element disposed on the first support portion, in order to electrically connect the monitor element and the electrode pad disposed on the second support portion, It is necessary to arrange the wiring for the monitor element on the second vibrator. For this reason, on each diaphragm of the second vibrator, a driving wiring for swinging the reflecting surface about the first axis, and a driving wiring for swinging the reflecting surface about the second axis, Detecting wiring for detecting the deformation amount of the diaphragm when the reflecting surface is swung around the first axis, and detecting the deformation amount of the diaphragm when the reflecting surface is swung around the second axis Therefore, the detection wiring for this is arranged in parallel.

  In recent years, such optical deflectors have been required to be further miniaturized as equipment to be mounted is miniaturized, and are generally manufactured as MEMS (Micro Electro Mechanical Systems) devices. For this reason, the diaphragm of the second vibrator is formed very thin (for example, several hundred μm). Therefore, it is difficult to provide a sufficient distance between the driving wiring and the detection wiring, and interference (so-called crosstalk) between the driving wiring and the detection wiring may become a problem. For example, when a driving signal interferes with a signal detected by the monitor element, appropriate feedback cannot be performed, and as a result, the accuracy of control of piezoelectric driving is reduced.

  An object of the present invention is to provide an optical deflector that can accurately detect the swing of the reflecting surface about two axes without reducing the rotation angle when the reflecting surface is swung about two axes.

  The present invention provides a mirror part having a reflective surface, a first support part for supporting the mirror part, one end connected to the mirror part, the other end connected to the first support part, and the mirror driven by piezoelectric drive. A first piezoelectric actuator that swings a portion about the first axis relative to the first support portion, a second support portion that supports the first support portion, and one end connected to the first support portion, A second piezoelectric actuator, the other end of which is connected to the second support portion, and causes the first support portion to swing about a second axis intersecting the first axis with respect to the second support portion by piezoelectric driving; The first deflector is transmitted to the first support portion by the piezoelectric drive of the first piezoelectric actuator, and the second vibration is transmitted to the first support portion by the piezoelectric drive of the second piezoelectric actuator. The detection piezoelectric element that detects The second support portion is provided with a connection portion for electrically connecting to the outside of the optical deflector, and the second piezoelectric actuator electrically connects the first piezoelectric actuator and the connection portion. A first drive wiring to be connected; a second drive wiring to electrically connect the second piezoelectric actuator to the connection portion; and a detection wiring to electrically connect the detection piezoelectric element to the connection portion. Arranged in parallel, a voltage of a first frequency is applied to the first drive wiring, a voltage of a second frequency different from the first frequency is applied to the second drive wiring, and the first drive Of the wiring and the second driving wiring, the driving wiring to which a high frequency voltage is applied is composed of two driving wirings to which voltages having opposite phases are applied, and the detection wiring is between the two driving wirings. Characterized by being placed

  According to the present invention, the mirror portion swings around the first axis by the piezoelectric drive of the first piezoelectric actuator, and the first support portion swings around the second axis by the piezoelectric drive of the second piezoelectric actuator. Oscillate the reflecting surface about two axes. Since the first piezoelectric actuator and the second piezoelectric actuator are connected to the first support portion, vibration due to the piezoelectric driving of these piezoelectric actuators is transmitted. These vibrations, that is, the first vibration transmitted by the piezoelectric drive of the first piezoelectric actuator and the second vibration transmitted by the piezoelectric drive of the second piezoelectric actuator are the detection piezoelectric elements arranged on the first support portion. Detected by the element.

  Therefore, the first piezoelectric actuator and the second piezoelectric actuator need not be provided with a detecting piezoelectric element. As a result, the optical deflector can obtain a larger rotation angle of the reflecting surface than a piezoelectric actuator (corresponding to the vibrator in Patent Document 1) in which the monitor element is arranged.

  Further, it is known that as the frequency of the voltage applied to the wiring increases, the influence (so-called voltage leaks) on the wiring arranged in the vicinity of the wiring increases. Therefore, among the first drive wiring and the second drive wiring that are piezoelectric drive wiring, the drive wiring to which a high frequency voltage is applied is configured by two drive wirings. At this time, voltages having opposite phases are applied to the two drive wirings. The detection wiring is disposed between the two drive wirings. For this reason, the leaked voltage is canceled out by applying a high frequency voltage to the two drive wirings. As a result, the signal passing through the detection wiring is not affected, or the effect is negligibly small.

  Therefore, this optical deflector can accurately detect the swing of the reflecting surface about the two axes without reducing the rotation angle when the reflecting surface is swung about the two axes.

  In the present invention, it is preferable that a frequency filter that separates an output signal of the detection piezoelectric element into a first signal due to the first vibration and a second signal due to the second vibration is provided. Since the first vibration and the second vibration are transmitted to the first support portion, the detection piezoelectric element disposed on the first support portion outputs a signal in which the first signal and the second signal are superimposed. The frequency filter can separate the superimposed and output signal into a first signal and a second signal. Accordingly, the detection piezoelectric element for detecting the first vibration and the detection piezoelectric element for detecting the second vibration are not provided separately, and even if only one type of detection piezoelectric element is provided, the first Both vibration and second vibration can be detected. As a result, the number of wirings (first driving wiring, second driving wiring, and detection wiring) can be reduced.

  In the present invention, the second piezoelectric actuator includes a piezoelectric body that bends and deforms when a driving voltage is applied, and a plurality of piezoelectric cantilevers that support the piezoelectric body and bend and deform together when the piezoelectric body is bent and deformed. The plurality of piezoelectric cantilevers are arranged side by side so that both ends of each piezoelectric cantilever are adjacent to each other, and end portions thereof are folded back with respect to the adjacent piezoelectric cantilevers so as to accumulate each bending deformation. It is preferable that the piezoelectric cantilevers be mechanically connected and be formed to bend and deform in a direction perpendicular to the direction in which the piezoelectric cantilevers are arranged.

  As a result, even if the deformation amount of the bending deformation of each piezoelectric cantilever is small, the first supporting portion can be swung greatly by accumulating the bending deformation of each of the plurality of piezoelectric cantilevers, and thus reflecting. The surface can be swung greatly.

  Further, since the second piezoelectric actuator is configured as described above, each wiring (first driving wiring, second driving wiring, and detection wiring) arranged in the second piezoelectric actuator becomes long. As the distance in which the wirings are arranged in parallel is longer, interference between the wirings is more likely to occur. However, in the optical deflector, since the detection wiring is arranged between two drive wirings to which a high frequency voltage is applied, the influence of interference between the wirings can be reduced to a negligible level.

  In this way, even when the piezoelectric cantilever is configured to accumulate bending deformation in order to increase the rotation angle of the reflecting portion, it is possible to accurately detect the swing of the reflecting surface about two axes.

  In the present invention, the first frequency is a resonance frequency of the first piezoelectric actuator and the mirror part, and is preferably higher than the second frequency. In general, when the first piezoelectric actuator is driven at a resonance frequency, the frequency tends to increase. When a high-frequency voltage passes through the drive wiring, the signal of the drive wiring arranged in parallel with the drive wiring is easily affected. Even in such a case, the influence of the first drive wiring on the detection wiring is ignored by configuring the first drive wiring with two drive wirings and disposing the detection wiring between the two drive wirings. It can be reduced as much as possible.

The figure which shows the structure of the optical deflector of embodiment of this invention. The figure which shows the left side in the end surface which follows the II-II line | wire of FIG. The figure which shows the right side in the end surface which follows the II-II line | wire of FIG. (A) shows the voltage waveform applied to the second piezoelectric actuator, (b) shows the voltage waveform applied to the first piezoelectric actuator, (c) shows the voltage waveform detected by the detector, (d) shows a voltage waveform when the voltage waveform of (c) is passed through a high-pass filter, and (e) is a diagram showing a voltage waveform when the voltage waveform of (c) is passed through a low-pass filter. (A) shows the state where the piezoelectric actuator of the optical deflector is not operating, (b) is a diagram showing the state where the piezoelectric actuator is operating.

  The configuration of the optical deflector according to the embodiment of the present invention will be described. The optical deflector 1 of this embodiment includes a mirror unit 2, a pair of first piezoelectric actuators 31 and 32, a first support unit 4, a pair of second piezoelectric actuators 51 and 52, and a second support unit 6. Is provided.

  The mirror unit 2 includes a circular reflection surface 2a that reflects incident light and a circular reflection surface support 2b that supports the reflection surface 2a. The reflecting surface 2a is formed by processing a metal thin film (one metal thin film in this embodiment) on the reflecting surface support 2b using a semiconductor planar process. As a material for the metal thin film, for example, gold (Au), platinum (Pt), silver (Ag), aluminum (Al), or the like is used.

  The thickness of the metal thin film is set to about 100 to 500 nm, for example. The metal thin film is formed by, for example, a sputtering method or an electron beam evaporation method. The reflective surface support 2b is formed of a silicon substrate. A pair of torsion bars 21 and 22 extending outward from both ends thereof are connected to the reflecting surface support 2b.

  The first piezoelectric actuators 31 and 32 are each formed in a semicircular arc shape, and are arranged with a gap therebetween so as to surround the mirror part 2. The first piezoelectric actuators 31, 32 are arranged such that one end of each is opposed to sandwich one torsion bar 21, and the other end of each is opposed to sandwich the other torsion bar 22. ing.

  The first support portion 4 is formed in a rectangular frame shape, and is provided so as to surround the mirror portion 2 and the first piezoelectric actuators 31 and 32. The first support part 4 is connected to the outside of the center position of the arc part of the first piezoelectric actuators 31 and 32, and supports the mirror part 2 via the first piezoelectric actuators 31 and 32.

  Each of the first piezoelectric actuators 31 and 32 includes first piezoelectric cantilevers 31A and 32A configured to bend and deform by piezoelectric driving. Specifically, one of the first piezoelectric actuators 31, 32 includes one first piezoelectric cantilever 31 A, and the other of the first piezoelectric actuators 31, 32 has the other first piezoelectric actuator 32. The other first piezoelectric cantilever 32A is provided. The first piezoelectric actuators 31 and 32 swing the mirror part 2 around the first axis Y with respect to the first support part 4 via the torsion bars 21 and 22 by bending deformation of the first piezoelectric cantilevers 31A and 32A. It is possible.

  The second piezoelectric actuators 51 and 52 are disposed to face each other with the first support portion 4 interposed therebetween. The tip ends of the second piezoelectric actuators 51 and 52 are respectively connected to a pair of both sides in a direction orthogonal to the torsion bars 21 and 22 of the first support portion 4.

  The second support portion 6 is formed in a rectangular frame shape, and is provided so as to surround the first support portion 4 and the second piezoelectric actuators 51 and 52. The second support portion 6 is connected to a pair of other ends of the second piezoelectric actuators 51 and 52 that are not connected to the first support portion 4. As a result, the second support portion 6 supports the first support portion 4 via the second piezoelectric actuators 51 and 52.

  Each of the second piezoelectric actuators 51 and 52 includes second piezoelectric cantilevers 51A to 51D and 52A to 52D configured to bend and deform by piezoelectric driving. Specifically, one second piezoelectric actuator 51 of the pair of second piezoelectric actuators 51 and 52 includes one second piezoelectric cantilever 51A to 51D including four piezoelectric cantilevers. The other second piezoelectric actuator 52 of the pair of second piezoelectric actuators 51 and 52 is composed of the other second piezoelectric cantilevers 52A to 52D including four piezoelectric cantilevers.

  One of the second piezoelectric cantilevers 51A to 51D is adjacent to each other so that the length directions thereof are the same, and the mirror portion 2 is arranged on the second axis X (an axis orthogonal to the first axis Y. However, (It is not necessary to be orthogonal at right angles.)) It is arranged at predetermined intervals so as to be able to swing around. And one 2nd piezoelectric cantilever 51A-51D is connected so that it may return with respect to an adjacent piezoelectric cantilever.

  Similarly to the second piezoelectric cantilevers 51A to 51D, the other second piezoelectric cantilevers 52A to 52D are adjacent to each other so that the length directions thereof are the same, and the mirror portion 2 is moved to the second axis. They are arranged side by side at a predetermined interval so as to be swingable around X. The other second piezoelectric cantilevers 52 </ b> A to 52 </ b> D are connected so as to be folded back with respect to the adjacent piezoelectric cantilevers.

  In this way, one second piezoelectric actuator 51 and the other second piezoelectric actuator 52 are formed so that one of the second piezoelectric cantilevers 51A to 51D and the other second piezoelectric cantilever 52A to 52D form a so-called meander shape. Is formed.

  In addition, one of the second piezoelectric cantilevers 51 </ b> A to 51 </ b> D and the other second piezoelectric cantilever 52 </ b> A to 52 </ b> D can be disposed on the mirror part 2 side (the first support part 4 side). 51A and 52A are adjacent to the second piezoelectric cantilevers adjacent to each other (hereinafter referred to as “second second piezoelectric cantilevers”) 51B and 52B. 4 is connected to the outer peripheral portion.

  One of the second piezoelectric cantilevers 51A to 51D and the other of the second piezoelectric cantilevers 52A to 52D, the piezoelectric cantilever (hereinafter referred to as the “fourth second piezoelectric cantilever”) 51D disposed on the second support portion 6 side. , 52D are connected to the inner peripheral portion of the second support portion 6 at one end on the side not connected to the adjacent second piezoelectric cantilever (hereinafter referred to as “third second piezoelectric cantilever”) 51C, 52C. Has been.

  As a result, the first support portion 4 moves around the second axis X with respect to the second support portion 6 by bending deformation of the second piezoelectric cantilevers 51A to 51D and 52A to 52D constituting the second piezoelectric actuators 51 and 52. It can swing.

  As described above, the second piezoelectric actuators 51 and 52 are formed in a meander shape, one end is connected to the first support portion 4, and the other end is connected to the second support portion 6. The plurality of piezoelectric cantilevers are arranged side by side so that both ends of each piezoelectric cantilever are adjacent to each other, and the ends are mechanically connected so as to be folded back to the adjacent piezoelectric cantilevers so as to accumulate each bending deformation. Each piezoelectric cantilever is formed to bend and deform in a direction perpendicular to the direction in which the piezoelectric cantilevers are arranged.

  Thereafter, out of the pair of second piezoelectric cantilevers 51A to 51D and 52A to 52D, each piezoelectric cantilever (the first second piezoelectric cantilever 51A, 52A and the third first cantilever 51A, 52A, 52A and 52D) which are arranged oddly from the mirror unit 2 is arranged. 2 piezoelectric cantilevers 51C, 52C) are referred to as odd-numbered second piezoelectric cantilevers 51A, 51C, 52A, 52C. Among the odd-numbered second piezoelectric cantilevers 51A, 51C, 52A, and 52C, the one included in one of the second piezoelectric cantilevers 51A to 51D is referred to as one odd-numbered second piezoelectric cantilever 51A, 51C, and the other. Those included in the second piezoelectric cantilevers 52A to 52D are referred to as the other odd-numbered second piezoelectric cantilevers 52A and 52C.

  Similarly, among the pair of second piezoelectric cantilevers 51A to 51D and 52A to 52D, each piezoelectric cantilever (second second piezoelectric cantilevers 51B, 52B and fourth ones arranged evenly from the mirror part 2). The second piezoelectric cantilevers 51D, 52D) are referred to as even-numbered second piezoelectric cantilevers 51B, 51D, 52B, 52D. Among the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, and 52D, one included in the second piezoelectric cantilevers 51A to 51D is referred to as one even-numbered second piezoelectric cantilever 51B, 51D, and the other. Those included in the second piezoelectric cantilevers 52A to 52D are referred to as the other even-numbered second piezoelectric cantilevers 52B and 52D.

  FIG. 2 is a diagram schematically showing one second piezoelectric actuator 51 in the end view taken along the line II-II of the optical deflector 1 of FIG. FIG. 3 is a view schematically showing the other second piezoelectric actuator 52 in the end view taken along the line II-II of the optical deflector 1 of FIG. However, in FIG.2 and FIG.3, the 2nd support part 6 is abbreviate | omitted and shown.

  Each of the first piezoelectric cantilevers 31A and 32A constituting the first piezoelectric actuators 31 and 32 and each of the pair of second piezoelectric cantilevers 51A to 51D and 52A to 52D constituting the second piezoelectric actuators 51 and 52 are This is a piezoelectric cantilever having a structure in which a lower electrode L1, a piezoelectric body L2, and an upper electrode L3 are stacked on a layer of a support B serving as a strained body (cantilever body). Specifically, in the piezoelectric cantilever, the lower electrode L1, the piezoelectric body L2, and the upper electrode L3 are laminated on the layer of the support B, and surround the lower electrode L1, the piezoelectric body L2, and the upper electrode L3. Thus, an interlayer insulating film M1 is provided. An upper electrode wiring W is stacked on the interlayer insulating film M1, and a passivation film M2 is provided so as to surround the upper electrode wiring W.

  Here, the upper electrode wiring W includes a first positive phase driving wiring Wy1, a first reverse phase driving wiring Wy2, a second odd driving wiring Wo, a second even driving wiring We, and a detection wiring Wm. When these wirings do not need to be particularly distinguished, they are referred to as upper electrode wirings W. Here, “two first drive wires Wy1, Wy2” correspond to “first drive wires” in the present invention, and “two second drive wires Wo, We” correspond to “second drive wires” in the present invention. The “detection wiring Wm” corresponds to the “detection wiring” in the present invention.

  The piezoelectric bodies L2 of the piezoelectric cantilevers 31A, 32A, 51A to 51D, and 52A to 52D are bent and deformed by piezoelectric driving when a driving voltage is applied between the upper electrode L3 and the lower electrode L1. These piezoelectric cantilevers 31A, 32A, 51A to 51D, and 52A to 52D are bent and deformed as the piezoelectric body L2 is bent.

  The connecting portions of the adjacent piezoelectric cantilevers in each of the pair of second piezoelectric cantilevers 51A to 51D and 52A to 52D constituting the second piezoelectric actuators 51 and 52 are integrated with the support bodies B of the adjacent piezoelectric cantilevers. It is a part connected to. The connecting portion is not provided with the layers of the piezoelectric body L2 and the upper electrode L3.

  The first support unit 4 is provided with detection units 71 and 72. The detection units 71 and 72 are arranged at the center of the first support unit 4 along the side parallel to the first axis Y of the first support unit 4. The detection units 71 and 72 are provided as sensors for detecting the following two vibrations. First, when the mirror unit 2 swings around the first axis Y with respect to the first support unit 4 by the piezoelectric drive of the first piezoelectric actuators 31 and 32, the first support unit 4 is transmitted to the first support unit 4. One vibration. The other is transmitted to the first support portion 4 when the first support portion 4 swings around the second axis X with respect to the second support portion 6 by the piezoelectric drive of the second piezoelectric actuators 51 and 52. Is the second vibration.

  Similar to the first piezoelectric cantilevers 31A and 32A and the second piezoelectric cantilevers 51A to 51D and 52A to 52D, the detectors 71 and 72 are provided on the lower electrode L1 on the layer of the support B constituting the first support 4. The piezoelectric body L2 and the upper electrode L3 are stacked. In the detection units 71 and 72, the interlayer insulating film M1, the upper electrode wiring W, and the passivation film M2 are provided as in the piezoelectric cantilevers 31A, 32A, 51A to 51D, and 52A to 52D. Here, the detection units 71 and 72 (specifically, these piezoelectric bodies L2) correspond to the detection piezoelectric elements in the present invention.

  And when the 1st vibration or the 2nd vibration is transmitted to the 1st support part 4, when the 1st support part 4 bends and deforms, piezoelectric material L2 of detection parts 71 and 72 is the amount of deformation of this bending deformation. The voltage according to is output. The optical deflector 1 can detect the vibration transmitted to the first support portion 4 based on the voltage value at this time.

  The optical deflector 1 includes lower electrode pads 61a and 62a, normal phase first upper electrode pads 61b and 62b, reverse phase first upper electrode pads 61c and 62c, and odd-numbered second upper portions on the second support portion 6. Electrode pads 61d and 62d, even-numbered second upper electrode pads 61e and 62e, and detection electrode pads 61f and 62f are provided.

  One lower electrode pad 61a of the lower electrode pads 61a and 62a includes a lower electrode L1 of one first piezoelectric cantilever 31A, a lower electrode L1 of one second piezoelectric cantilever 51A to 51D, and one detection unit 71. It is electrically connected to the lower electrode L1. Of the lower electrode pads 61a and 62a, the other lower electrode pad 62a includes the lower electrode L1 of the other first piezoelectric cantilever 32A, the lower electrode L1 of the other second piezoelectric cantilever 52A to 52D, and the other detector 72. It is electrically connected to the lower electrode L1.

  Thus, the lower electrode pads 61a and 62a are electrode pads common to the first piezoelectric actuators 31 and 32, the second piezoelectric actuators 51 and 52, and the detection units 71 and 72.

  The lower electrode pads 61a and 62a are connected (grounded) to a reference potential point of a device in which the optical deflector 1 is mounted. For this reason, each lower electrode L1 electrically connected to the lower electrode pads 61a and 62a is also connected (grounded) to the reference potential point.

  One positive phase first upper electrode pad 61b of the positive phase first upper electrode pads 61b and 62b is electrically connected to the upper electrode L3 of one of the first piezoelectric cantilevers 31A via the first positive phase drive wiring Wy1. It is connected. The other positive-phase first upper electrode pad 62b out of the positive-phase first upper electrode pads 61b and 62b is electrically connected to the upper electrode L3 of the first piezoelectric cantilever 31A via the first positive-phase drive wiring Wy1. It is connected.

  One of the negative-phase first upper electrode pads 61c, 62c is electrically connected to the upper electrode L3 of the other first piezoelectric cantilever 32A via the first negative-phase drive wiring Wy2. It is connected. The other negative-phase first upper electrode pad 62c out of the negative-phase first upper electrode pads 61c and 62c is electrically connected to the upper electrode L3 of the other first piezoelectric cantilever 32A via the first negative-phase drive wiring Wy2. It is connected.

  One of the odd second upper electrode pads 61d and 62d is connected to the upper electrode L3 of one of the odd second piezoelectric cantilevers 51A and 51C via the second odd drive wiring Wo. Is electrically connected. The other odd second upper electrode pad 62d out of the odd second upper electrode pads 61d and 62d is connected to the upper electrode L3 of the other odd second piezoelectric cantilevers 52A and 52C via the second odd drive wiring Wo. Is electrically connected.

  One of the even-numbered second upper electrode pads 61e, 62e is connected to the upper electrode L3 of the even-numbered second piezoelectric cantilever 51B, 51D via the second even-numbered drive wiring We. Is electrically connected. The other even-numbered second upper electrode pad 62e out of the even-numbered second upper electrode pads 61e, 62e is the upper electrode L3 of the other even-numbered second piezoelectric cantilever 52B, 52D via the second even-numbered drive wiring We. Is electrically connected.

  One of the detection electrode pads 61f, 62f is electrically connected to the upper electrode L3 of the one detection unit 71 through the detection wiring Wm. Of the detection electrode pads 61f and 62f, the other detection electrode pad 62f is electrically connected to the upper electrode L3 of the other detection unit 72 via the detection wiring Wm.

  When a drive voltage is applied between the upper electrode L3 and the lower electrode L1 by the electrical connection as described above, the piezoelectric body L2 stacked between the applied upper electrode L3 and the lower electrode L1. Are bent and deformed by piezoelectric driving. As a result, the support B (piezoelectric cantilever) corresponding to the bent piezoelectric body L2 is bent and deformed.

  Further, as will be described later, the voltage generated from the detection units 71 and 72 due to the piezoelectric effect caused by the bending deformation of the first support unit 4 due to the transmitted vibration causes the detection electrode pads 61f and 62f and the lower electrode pads 61a and 62a to Is output as a potential difference between them. At this time, the first support portion 4 is transmitted with two vibrations, namely, vibration caused by the piezoelectric drive of the first piezoelectric actuators 31 and 32 and vibration caused by the piezoelectric drive of the second piezoelectric actuators 51 and 52. Therefore, the voltage waveform output as the potential difference between the detection electrode pads 61f and 62f and the lower electrode pads 61a and 62a includes bending deformation of the first support portion 4 due to these two vibrations.

  Here, “lower electrode pads 61a, 62a, positive phase first upper electrode pads 61b, 62b, reverse phase first upper electrode pads 61c, 62c, odd second upper electrode pads 61d, 62d, even second upper electrode. The pads 61e and 62e and the detection electrode pads 61f and 62f ”correspond to the“ connection portion ”in the present invention.

  Hereinafter, details of the above-described upper electrode wiring W, upper electrode L3, piezoelectric body L2, and lower electrode L1 will be described.

“The pair of lower electrode pads 61a and 62a” and “the first piezoelectric cantilevers 31A and 32A, the second piezoelectric cantilevers 51A to 51D and 52A to 52D, and the lower electrodes L1 of the detectors 71 and 72” are on the silicon substrate. This metal thin film (in this embodiment, two metal thin films, hereinafter also referred to as a lower electrode layer) is formed by shape processing using a semiconductor planar process. As a material of the metal thin film, for example, titanium (Ti), titanium dioxide (TiO ₂ ), or titanium oxide (TiOx) whose oxidation amount is adjusted is used for the first layer (lower layer), and the second layer (upper layer). ) Is platinum (Pt), LaNiO ₃ or SrRuO ₃ .

  In this case, the lower electrodes L1 of the first piezoelectric cantilevers 31A and 32A are formed on almost the entire surface of the support B of the first piezoelectric cantilevers 31A and 32A. The lower electrodes L1 of the second piezoelectric cantilevers 51A to 51D and 52A to 52D are arranged on the support B of the second piezoelectric cantilevers 51A to 51D and 52A to 52D (the linear portion and the connecting portion where each piezoelectric cantilever extends are aligned. Formed on almost the entire surface.

  The lower electrode L1 of the detection units 71 and 72 is formed in a portion where the detection units 71 and 72 on the support B of the first support unit 4 are arranged. Similarly, the lower electrode L1, the interlayer insulating film M1, the upper electrode wiring W, and the passivation film M2 are also provided on the support B of the second support portion 6.

  The lower electrode pads 61a and 62a are connected to the first piezoelectric cantilevers 31A and 32A and the second piezoelectric cantilevers 51A via the lower electrode L1 formed on the support B of the second support portion 6 and the first support portion 4, respectively. To 51D, 52A to 52D and the lower electrodes L1 of the detectors 71 and 72 are electrically connected.

  The piezoelectric bodies L2 of the first piezoelectric cantilevers 31A and 32A, the second piezoelectric cantilevers 51A to 51D, 52A to 52D, and the detectors 71 and 72 are formed of a single piezoelectric film (on the lower electrode layer) using a semiconductor planar process. (Hereinafter, also referred to as a piezoelectric layer) are formed separately from each other on the lower electrode L1 of each piezoelectric cantilever. As a material of this piezoelectric film, for example, lead zirconate titanate (PZT) which is a piezoelectric material is used.

  In this case, the piezoelectric bodies L2 of the first piezoelectric cantilevers 31A and 32A are formed on almost the entire surface of the lower electrodes L1 of the piezoelectric cantilevers 31A and 32A. The piezoelectric bodies L2 of the second piezoelectric cantilevers 51A to 51D and 52A to 52D are formed on substantially the entire surface of the lower electrode L1 in the extending portions (straight portions) of the second piezoelectric cantilevers 51A to 51D and 52A to 52D. Yes. The piezoelectric body L2 of the detection units 71 and 72 is formed on almost the entire surface of the lower electrode L1 of the detection units 71 and 72.

  “Normal-phase first upper electrode pads 61b and 62b, negative-phase first upper electrode pads 61c and 62c, odd-numbered second upper electrode pads 61d and 62d, even-numbered second upper electrode pads 61e and 62e, and detection electrode pad 61f. , 62f ”,“ the first piezoelectric cantilevers 31A and 32A, the second piezoelectric cantilevers 51A to 51D, 52A to 52D, and the upper electrodes L3 of the detectors 71 and 72 ”, and the“ upper electrode wiring W ”that conducts them. Is formed by shape-processing a metal thin film (in this embodiment, one metal thin film; hereinafter also referred to as an upper electrode layer) using a semiconductor planar process. As a material of the metal thin film, for example, platinum (Pt), gold (Au), aluminum (Al), aluminum alloy (Al alloy), or the like is used. At this time, an interlayer insulating film M1 is formed between the upper electrode L3 and the upper electrode wiring W.

  The first piezoelectric cantilevers 31A and 32A, the second piezoelectric cantilevers 51A to 51D, 52A to 52D, and the upper electrodes L3 of the detection units 71 and 72 are provided on almost the entire surface of the piezoelectric body L2 for each piezoelectric cantilever or each detection unit. Is formed.

  On the interlayer insulating film M1 provided in the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, and 52D, as shown in FIGS. 2 and 3, the upper electrode wiring W is provided from the first support portion 4 side. Toward the opposite side, the planes are separated from each other in the order of “first negative phase drive wiring Wy2 → detection wiring Wm → first positive phase drive wiring Wy1 → second even drive wiring We → second odd drive wiring Wo”. Is provided.

  At this time, the second even-numbered drive wirings We are formed above the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, and 52D by a conductive material (metal or the like) disposed in the electrode via provided in the interlayer insulating film M1. It is electrically connected to the electrode L3. Further, the second even drive wirings We provided in the second second piezoelectric cantilevers 51B and 52B are provided up to the electrode vias corresponding to each, and are not provided thereafter.

  In addition, an upper electrode wiring W is provided on the interlayer insulating film M1 provided in the connection portion between the second support portion 6 and the fourth second piezoelectric cantilevers 51D and 52D, The upper electrode wiring W of the second support portion 6 is electrically connected to the upper electrode wiring W provided on the fourth second piezoelectric cantilevers 51D and 52D.

  The upper electrode wiring W provided in the second support portion 6 includes the first positive phase driving wiring Wy1 as the positive phase first upper electrode pads 61b and 62b, and the first negative phase driving wiring Wy2 as the reverse phase first upper electrode pad. 61c, 62c, the second odd drive wiring Wo is the odd second upper electrode pads 61d, 62d, the second even drive wiring We is the even second upper electrode pads 61e, 62e, and the detection wiring Wm is the detection electrode. The pads 61f and 62f are electrically connected to each other.

  On the interlayer insulating film M1 provided on the third second piezoelectric cantilevers 51C and 52C, the upper electrode wiring W is “second odd-numbered driving wiring Wo → second number” from the first support portion 4 side toward the opposite side. 2 even drive lines We → first normal phase drive lines Wy1 → detection lines Wm → first reverse phase drive lines Wy2 ”are provided separately in a plane.

  At this time, the second odd drive wiring Wo is electrically connected to the upper electrode L3 of the third second piezoelectric cantilevers 51C and 52C by a conductive material disposed in the electrode via provided in the interlayer insulating film M1. ing.

  On the interlayer insulating film M1 provided on the first second piezoelectric cantilevers 51A and 52A, the upper electrode wiring W is “second odd-numbered driving wiring Wo → second number” from the first support portion 4 side toward the opposite side. In this order, “1 normal phase drive wiring Wy1 → detection wiring Wm → first reverse phase drive wiring Wy2”, they are provided separately from each other in a plane.

  At this time, the second odd-number drive wiring Wo is electrically connected to the upper electrode L3 of the first second piezoelectric cantilevers 51A and 52A by the conductive material disposed in the electrode via provided in the interlayer insulating film M1. ing. In addition, the second odd-number drive wiring Wo provided in the first second piezoelectric cantilevers 51A and 52A is provided up to the corresponding electrode via, and is not provided thereafter.

  Further, the intervals between adjacent wirings among the upper electrode wirings W are set to be equal. For the first second piezoelectric cantilevers 51A and 52A, since the second even drive wiring We is not arranged, the distance between the second odd drive wiring Wo and the first positive phase drive wiring Wy1 is adjacent to the other. It is different from the distance to the wiring.

  Further, “the connecting portion between the fourth second piezoelectric cantilevers 51D, 52D and the third second piezoelectric cantilevers 51C, 52C”, “the third second piezoelectric cantilevers 51C, 52C and the second second piezoelectric cantilevers 51C, 52C”. The “connection portion between the cantilevers 51B and 52B” and the “connection portion between the second second piezoelectric cantilevers 51B and 52B and the first second piezoelectric cantilevers 51A and 52A” are provided in the connection portion. The upper electrode wiring W is provided on the interlayer insulating film M1, and the upper electrode wiring W is electrically connected to the upper electrode wiring W provided on the second piezoelectric cantilever connected via the connecting portion. Connected to.

  In addition, each upper electrode wiring W (specifically, Wy1, Wy2, Wo, We, Wm) provided in each of the second piezoelectric cantilevers 51A to 51D and 52A to 52D is parallel to the longitudinal direction of the piezoelectric cantilever. Each is provided. That is, the upper electrode wirings W are arranged in parallel with each other. This means that “the second piezoelectric actuator is electrically connected to the first drive wiring for electrically connecting the first piezoelectric actuator and the connecting portion, and to the second piezoelectric actuator and the connecting portion. This corresponds to the fact that the second drive wiring that is electrically connected and the detection wiring that electrically connects the detecting piezoelectric element and the connecting portion are arranged in parallel.

  In addition, the upper electrode wirings W are arranged at the connecting portions that connect the adjacent second piezoelectric cantilevers with a space so as not to cross each other so as to follow the shape of the connecting portions. Each of these upper electrode wirings W is not formed in a straight line, but it is “disposed in parallel” according to the present invention with respect to such an arrangement, because it is arranged while maintaining a distance from each other. To include.

  As shown in FIG. 2, the upper electrode wiring W is formed on the interlayer insulating film M <b> 1 provided on the one detection unit 71 from the mirror unit 2 side toward the first one second piezoelectric cantilever 51 </ b> A side. They are separated from each other in the order of “detection wiring Wm → first positive phase drive wiring Wy1”. At this time, the detection wiring Wm is electrically connected to the upper electrode L3 of one of the detection units 71 by a conductive material disposed in the electrode via provided in the interlayer insulating film M1.

  On the interlayer insulating film M1 provided in the other detection unit 72, as shown in FIG. 3, the upper electrode wiring W is directed from the mirror unit 2 side to the first second piezoelectric cantilever 52A side. The first reverse-phase drive wiring Wy2 → the detection wiring Wm → the first normal-phase drive wiring Wy1 are provided separately from each other in the order of plane. At this time, the detection wiring Wm is electrically connected to the upper electrode L3 of the other detection unit 72 by a conductive material disposed in the electrode via provided in the interlayer insulating film M1. Further, the detection wiring Wm provided in the detection units 71 and 72 is provided up to the electrode via corresponding to each, and is not provided thereafter.

  A first positive phase drive wiring Wy1 is provided on a part of the interlayer insulating film M1 provided on one first piezoelectric cantilever 31A as shown in FIG. Further, as shown in FIG. 3, a first reverse-phase drive wiring Wy2 is provided on a part of the interlayer insulating film M1 provided on the other first piezoelectric cantilever 32A. At this time, the two first drive wirings Wy1 and Wy2 are electrically connected to the upper electrode L3 of the first piezoelectric cantilevers 31A and 32A by the conductive material disposed in the electrode via provided in the interlayer insulating film M1. ing. Further, the two first drive wires Wy1 and Wy2 provided in the first piezoelectric cantilevers 31A and 32A are provided up to the electrode vias corresponding to each, and are not provided thereafter.

  Further, the passivation film M2 is formed on the upper electrode wiring W so as to surround the upper electrode wiring W by using a semiconductor planar process. Further, the reflecting surface support 2b, the torsion bars 21, 22, the support B, the first support 4 and the second support 6 are made of a semiconductor substrate (silicon substrate) composed of a plurality of layers. It is integrally formed by shape processing. As a technique for processing the shape of the semiconductor substrate, a semiconductor planar process and a MEMS process using a photolithography technique, a dry etching technique, or the like are used.

  As described above, the optical deflector 1 of the present embodiment is configured. Such an optical deflector 1 is mounted on a projector, a copy machine, or the like. Such an external device such as a projector or a copier corresponds to “outside of the optical deflector” in the present invention.

  Next, the operation of the optical deflector 1 of this embodiment will be described. First, the case where the mirror part 2 is swung around the first axis Y with respect to the first support part 4 by the first piezoelectric actuators 31 and 32 will be described.

  In this case, the optical deflector 1 applies a driving voltage as shown in FIG. 4A to the first piezoelectric actuators 31 and 32 (in FIG. 4, all graphs have time [s ], And the vertical axis represents the voltage value [V]). Specifically, the first voltage Vy1 (solid line) is applied between the positive phase first upper electrode pads 61b and 62b and the lower electrode pads 61a and 62a, whereby the first voltage is applied to one of the first piezoelectric actuators 31. Vy1 is applied to drive one first piezoelectric cantilever 31A. Further, the second voltage Vy2 is applied to the other first piezoelectric actuator 32 by applying the second voltage Vy2 (broken line) between the negative phase first upper electrode pads 61c, 62c and the lower electrode pads 61a, 62a. Then, the other first piezoelectric cantilever 32A is driven. Here, the first voltage Vy1 and the second voltage Vy2 are alternating voltages having opposite phases (for example, a sine wave).

  At this time, the voltage component for oscillation of the first voltage Vy1 and the second voltage Vy2 is one in the vertical direction of the first piezoelectric actuators 31 and 32 (the upward direction U in FIG. 1 and the downward direction which is the opposite direction). This voltage component is such that the angular displacement between the first piezoelectric cantilever 31A and the other first piezoelectric cantilever 32A occurs in the opposite direction.

  For example, when the tip of one of the first piezoelectric actuators 31 is displaced upward when swinging about the first axis Y, one of the first piezoelectric cantilevers 31A is displaced upward (bending deformation). Let In order to displace the tip portion of one first piezoelectric actuator 31 downward, one first piezoelectric cantilever 31A is displaced downward (bending deformation).

  Similarly to the first piezoelectric actuator 31, the other first piezoelectric actuator 32 can be moved by moving the other first piezoelectric cantilever 32 </ b> A when the tip of the other first piezoelectric actuator 32 is displaced upward. Displace upward (bend deformation). In order to displace the tip of the other first piezoelectric actuator 32 downward, the other first piezoelectric cantilever 32A is displaced downward (bending deformation).

  Thus, the bending deformation of one of the first piezoelectric cantilevers 31 </ b> A causes torsional displacement in one of the torsion bars 21, and rotational torque about the one torsion bar 21 acts on the mirror portion 2. Similarly, bending deformation of the other first piezoelectric cantilever 32A causes torsional displacement in the same direction in the other torsion bar 22, and rotational torque about the other torsion bar 22 acts on the mirror portion 2. As described above, the rotational torque about the torsion bars 21 and 22 acts on the mirror portion 2 by driving the first piezoelectric actuators 31 and 32. As a result, the mirror unit 2 rotates around the first axis Y with the torsion bars 21 and 22 as the central axes.

  In the optical deflector 1 of the present embodiment, an AC voltage having a frequency near the mechanical resonance frequency of the mirror unit 2 including the first piezoelectric actuators 31 and 32 is applied to the first piezoelectric actuators 31 and 32 for resonance driving. ing. In the present embodiment, the mirror unit 2 can be swung around the first axis Y, and optical scanning with a predetermined first deflection angle can be performed at a predetermined first frequency Fy.

  Next, a case where the first support portion 4 is swung around the second axis X with respect to the second support portion 6 by the second piezoelectric actuators 51 and 52 will be described.

  In this case, the optical deflector 1 applies a driving voltage as shown in FIG. 4B to the second piezoelectric actuators 51 and 52. Specifically, a third voltage Vx1 (solid line) is applied between one odd-numbered second upper electrode pad 61d and one lower electrode pad 61a, whereby a third voltage is applied to one second piezoelectric actuator 51. Vx1 is applied to drive one of the odd-numbered second piezoelectric cantilevers 51A and 51C. At the same time, by applying a fourth voltage Vx2 (broken line) between one even-numbered second upper electrode pad 61e and one lower electrode pad 61a, the fourth voltage Vx2 is applied to one second piezoelectric actuator 51. Is applied to drive one of the even-numbered second piezoelectric cantilevers 51B and 51D.

  Furthermore, the third voltage Vx1 is applied to the other second piezoelectric actuator 52 by applying the third voltage Vx1 between the other odd-numbered second upper electrode pad 62d and the other lower electrode pad 62a. The odd-numbered second piezoelectric cantilevers 52A and 52C are driven. At the same time, by applying the fourth voltage Vx2 between the other even-numbered second upper electrode pad 62e and the other lower electrode pad 62a, the fourth voltage Vx2 is applied to the other second piezoelectric actuator 52, The other even-numbered second piezoelectric cantilevers 52B and 52D are driven.

  Here, the third voltage Vx1 and the fourth voltage Vx2 are alternating voltages (for example, a sine wave, a sawtooth wave, etc.) that have opposite phases or shifted phases. At this time, the voltage components for oscillation of the third voltage Vx1 and the fourth voltage Vx2 are odd numbers in the vertical direction of the second piezoelectric actuators 51 and 52 (upward direction U in FIG. 1 and the downward direction which is the opposite direction). The angular displacements of the second piezoelectric cantilevers 51A, 51C, 52A, 52C and the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, 52D are set to occur in opposite directions.

  For example, when the tip of the second piezoelectric actuators 51 and 52 is displaced upward (direction U shown in FIG. 1) when swinging around the second axis X, the odd-numbered second piezoelectric cantilevers 51A, 51C, 52A, and 52C are displaced upward, and the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, and 52D are displaced downward. In order to displace the tips of the second piezoelectric actuators 51 and 52 in the downward direction, the odd-numbered second piezoelectric cantilevers 51A, 51C, 52A and 52C are displaced in the downward direction, and the even-numbered second piezoelectric cantilevers 51B and 51D. , 52B, 52D are displaced upward.

  As a result, the odd-numbered second piezoelectric cantilevers 51A, 51C, 52A, 52C and the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, 52D are bent and deformed in opposite directions.

  FIG. 5 is a diagram illustrating the operation of one second piezoelectric actuator 51 of the optical deflector 1. FIG. 5A shows a state where one second piezoelectric actuator 51 is not operating, and FIG. 5B shows a state where one second piezoelectric actuator 51 is operating.

  As shown in FIG. 5B, the fourth one second piezoelectric cantilever 51 </ b> D generates a downward angular displacement at its distal end with the base end connected to the second support 6 as a fulcrum. ing. In the third one second piezoelectric cantilever 51C, an upward angular displacement is generated at the distal end of the base end connected to the distal end of the fourth one second piezoelectric cantilever 51D.

  The second one second piezoelectric cantilever 51B has an angular displacement in the downward direction at the distal end with the base end connected to the distal end of the third one second piezoelectric cantilever 51C as a fulcrum. The first one second piezoelectric cantilever 51A has a base end connected to the tip of the second one second piezoelectric cantilever 51B as a fulcrum (connected to the first support 4). An upward angular displacement has occurred. Thereby, in one of the second piezoelectric actuators 51, an angular displacement having a magnitude obtained by adding the magnitude of the bending deformation of each of the second piezoelectric cantilevers 51A to 51D occurs.

  Accordingly, the first support portion 4 can be swung around the second axis X, and optical scanning with a predetermined second deflection angle can be performed at a predetermined second frequency Fx. At this time, an alternating voltage having a frequency near the mechanical resonance frequency of the first support portion 4 including the second piezoelectric actuators 51 and 52 is applied as a driving voltage to the second piezoelectric actuators 51 and 52 to drive resonance. By doing so, optical scanning can be performed with a larger deflection angle.

  Further, when the first support portion 4 is swung around the second axis X, it is not necessary to apply an AC voltage as described above, and a DC voltage may be applied. In this case, the magnitude of the bending deformation generated in the second piezoelectric cantilevers 51A to 51D and 52A to 52D changes linearly according to the magnitude of the DC voltage. Therefore, for example, unlike the case where the piezoelectric cantilever is resonantly driven by applying an AC voltage, an arbitrary output can be obtained from the second piezoelectric actuators 51 and 52 by controlling the magnitude of the DC voltage.

  As described above, in the optical deflector 1, when swinging around the second axis X, the deflection angle can be controlled linearly according to the magnitude of the DC voltage applied as the drive voltage. An arbitrary deflection angle can be obtained at a speed of.

  The second piezoelectric actuators 51 and 52 are each formed in a meander shape. As a result, the bending deformation of each piezoelectric cantilever is accumulated. For this reason, the second piezoelectric actuators 51 and 52 can easily obtain a larger deflection angle than the first piezoelectric actuators 31 and 32.

  Therefore, in the present embodiment, when the first piezoelectric actuators 31 and 32 are swung, the upward or downward displacement of the first piezoelectric actuators 31 and 32 is changed in order to obtain as large a deflection angle as possible. The frequency, that is, the first frequency Fy is set to be a resonance frequency determined by the structure and material of the optical deflector 1 (particularly, a piezoelectric cantilever or the like).

  In addition, the second piezoelectric actuators 51 and 52 are formed in a meander shape and are more likely to swing than the first piezoelectric actuators 31 and 32. For this reason, the second frequency Fx is set sufficiently lower than the first frequency Fy. In the present embodiment, for example, the first frequency Fy is set to 30 kHz, and the second frequency Fx is set to 60 Hz. In FIG. 4, each voltage waveform is conceptually showing the difference between the high frequency and the low frequency, and shows each waveform when the first frequency Fy is 30 kHz and the second frequency Fx is 160 Hz. is not.

  As described above, the optical deflector 1 of the present embodiment swings the mirror portion 2 around the first axis Y and swings the first support portion 4 around the second axis X, thereby causing the mirror portion 2 to swing. Can be driven at various angles, and light incident on the reflecting surface 2a can be emitted at various angles.

  Thus, the second frequency Fx is set sufficiently lower than the first frequency Fy, and the first piezoelectric actuators 31 and 32 and the second piezoelectric actuators 51 and 52 are driven at these frequencies. This means that in the present invention, “the second piezoelectric actuator swings the first support portion around the second axis at a second frequency, and the first piezoelectric actuator moves the mirror portion to the second frequency. This is equivalent to swinging around the first axis at a higher first frequency.

  In addition, the first voltage Vy1 and the second voltage Vy2 having the first frequency Fy sufficiently higher than the second frequency Fx are applied to the first piezoelectric actuators 31 and 32 via the two first drive wirings Wy1 and Wy2. The third voltage Vx1 and the fourth voltage Vx2 having the second frequency Fx are applied to the second piezoelectric actuators 51 and 52 via the two second drive wirings Wo and We. In the present invention, this means that "a voltage having a first frequency is applied to the first drive wiring, and a voltage having a second frequency different from the first frequency is applied to the second drive wiring." It corresponds to that.

  In the present embodiment, since the first frequency Fy is set higher than the second frequency Fx, the two first drive wirings Wy1 and Wy2 correspond to “the first drive wiring and the second frequency in the present invention”. This corresponds to a “drive wiring to which a high frequency voltage is applied among the drive wirings”. In addition, the first voltage Vy1 and the second voltage Vy2 having the first frequency Fy having opposite phases are applied to each of the two first drive wirings Wy1 and Wy2. Such two first drive wirings Wy1 and Wy2 correspond to “two drive wirings to which voltages having phases opposite to each other are applied” in the present invention.

  Further, the first frequency Fy is a frequency near the mechanical resonance frequency of the mirror unit 2 including the first piezoelectric actuators 31 and 32. The first frequency Fy is set higher than the second frequency Fx. This corresponds to “the first frequency is a resonance frequency of the first piezoelectric actuator and the mirror unit and is higher than the second frequency” in the present invention. Further, the detection wiring Wm is arranged between the two first drive wirings Wy1 and Wy2 in the second piezoelectric actuators 51 and 52. This corresponds to “the detection wiring is disposed between the two drive wirings” in the present invention.

  As described above, in the optical deflector 1 of the present embodiment, the mirror unit 2 and the first support unit 4 are connected to the first axis Y and the first piezoelectric actuators 31 and 32 by the piezoelectric drive of the second piezoelectric actuators 51 and 52. It swings around the second axis X. At this time, since the first piezoelectric actuators 31 and 32 and the second piezoelectric actuators 51 and 52 are connected to the first support portion 4, vibration due to these swings is transmitted. Specifically, the first support 4 is transmitted to the first vibration transmitted when the mirror 2 is swung about the first axis Y, and when the first support 4 is swung about the second axis X. The second vibration to be transmitted is transmitted.

  The first support portion 4 is bent and deformed by the transmitted vibration. Accordingly, the piezoelectric body L2 of the detection units 71 and 72 provided on the first support unit 4 is bent and deformed. The piezoelectric body L2 of the detectors 71 and 72 generates a voltage corresponding to the amount of deformation. As a result, the voltage generated from the piezoelectric body L2 of the one detection unit 71 due to the first vibration and the second vibration transmitted to the first support unit 4 is detected as shown in FIG. The voltage generated from the piezoelectric body L2 of the other detection unit 72 is output as a potential difference between the electrode pad 61f for use and the one lower electrode pad 61a, and the voltage generated from the piezoelectric body L2 of the other detection unit 72 is Is output as a potential difference between. Hereinafter, these outputs (output signals) are referred to as “detected output voltage Sy + Sx”.

  The bending deformation of the first support portion 4 occurs according to the vibrations (first vibration and second vibration) transmitted to the first support portion 4. Here, the voltage signal generated from the detectors 71 and 72 in response to the first vibration is referred to as a first signal Sy. A voltage signal generated from the detection units 71 and 72 in response to the second vibration is referred to as a second signal Sx.

  For this reason, changes in the voltage values of the first signal Sy and the second signal Sx are caused by the first voltage Vy1 and the second voltage applied to drive the first piezoelectric actuators 31 and 32 and the second piezoelectric actuators 51 and 52 in a piezoelectric manner. The voltage corresponds to the voltage Vy2, the third voltage Vx1, and the fourth voltage Vx2. The frequency of the first signal Sy is equivalent to the frequencies of the first voltage Vy1 and the second voltage Vy2, and the frequency of the second signal Sx is equivalent to the frequencies of the third voltage Vx1 and the fourth voltage Vx2.

  The voltage generated from the piezoelectric body L2 of the detectors 71 and 72 includes the first signal Sy and the second signal Sx. This is because both the first vibration and the second vibration are transmitted to the first support portion 4, so that the bending deformation of the first support portion 4 is also affected by the two vibrations of the first vibration and the second vibration. This is because it bends and deforms.

  As described above, the second frequency Fx is set sufficiently lower than the first frequency Fy. That is, the second signal Sx has a sufficiently lower frequency than the first signal Sy. Therefore, each signal can be extracted from the detected output voltage Sy + Sx by separating the first signal Sy and the second signal Sx by a frequency filter. Specifically, only the first signal Sy as shown in FIG. 4D can be extracted by passing the detection output voltage Sy + Sx through the high-pass filter FH that passes the high frequency band. By passing the detected output voltage Sy + Sx through the low-pass filter FL that passes the low frequency band, only the second signal Sx as shown in FIG. 4E can be extracted.

  The first signal Sy thus extracted is the amount by which the first piezoelectric actuators 31 and 32 are actually displaced by applying the first voltage Vy1 and the second voltage Vy2 (deformation of the first piezoelectric cantilevers 31A and 32A). Equivalent to the quantity). Similarly, the second signal Sx extracted in this way is an amount (second piezoelectric cantilevers 51A to 51A to 51A) that are actually displaced by applying the third voltage Vx1 and the fourth voltage Vx2. 51D and 52A to 52D is equivalent to the accumulated amount of deformation).

  Note that the cutoff frequencies of the high-pass filter FH and the low-pass filter FL are set to frequencies that can sufficiently separate the first signal Sy and the second signal Sx.

  The present applicant conducted an experiment of the operation of the optical deflector 1 configured as described above. In this experiment (hereinafter referred to as “first experiment”), the first piezoelectric actuators 31 and 32 are AC voltages composed of sine waves having a peak value of 5 V and a frequency of 30 kHz, and are set in opposite phases to each other. A first voltage Vy1 and a second voltage Vy2 were applied. Further, the third voltage Vx1 and the fourth voltage Vx2, which are alternating voltages composed of sine waves having a peak value of 15 V and a frequency of 60 Hz, are set to opposite phases to the second piezoelectric actuators 51 and 52, respectively. .

  Accordingly, the first voltage Vy1 is applied to the first positive phase drive wiring Wy1, the second voltage Vy2 is applied to the first negative phase drive wiring Wy2, and the third voltage Vx1 is applied to the second odd drive wiring Wo. The fourth voltage Vx2 is applied to the second even drive wiring We. Accordingly, the mirror unit 2 swings around the first axis Y at a frequency of 30 kHz and swings around the second axis X at a frequency of 60 Hz.

  When the mirror unit 2 is swung, the first signal Sy via the high-pass filter FH is applied to one detection electrode pad 61f, and the first signal Sy is provided via the low-pass filter FL to the other detection electrode pad 62f. Two signals Sx were measured with a measuring instrument such as an oscilloscope. As a result, the first signal Sy is observed as a waveform close to a sine wave having a peak value of 776 mV and a frequency of 30 kHz, and the second signal Sx has a waveform close to a sine wave having a peak value of 440 mV and a frequency of 60 Hz. Observed.

  Thus, the frequency of the first signal Sy is equivalent to the frequencies of the first voltage Vy1 and the second voltage Vy2, and the frequency of the second signal Sx is equivalent to the frequencies of the third voltage Vx1 and the fourth voltage Vx2. Therefore, it can be seen that the detection units 71 and 72 can correctly detect the swing of the mirror unit 2 around the two axes.

  Further, in order to confirm the influence of interference, an experiment different from the first experiment (hereinafter referred to as “second experiment”) was performed. In the second experiment, the optical deflector is used so that only one of the two first drive wirings Wy1 and Wy2 is provided among the upper electrode wirings W arranged in the second piezoelectric cantilevers 51A to 51D and 52A to 52D. Configured. Specifically, from the configuration of the upper electrode wirings W of the present embodiment, the first piezoelectric cantilevers 51A to 51D of the first embodiment exclude the first negative phase driving wiring Wy2 and the first piezoelectric cantilevers 52A to 52D of the other one. The positive phase drive wiring Wy1 was excluded. As a result, the detection wiring Wm is not disposed between the two first drive wirings Wy1 and Wy2. In the second experiment, conditions other than the arrangement of the upper electrode wiring W are the same as in the above experiment. In this case, the first signal Sy was observed as a waveform having a peak value of 5V.

  As another experiment (hereinafter referred to as “third experiment”), the experiment was performed by changing the frequency of the first voltage Vy1 and the second voltage Vy2 to 40 kHz in the structure of the second experiment. In the third experiment, the other conditions are the same as those in the second experiment. In this case, the first signal Sy was observed as a waveform having a peak value of 5V.

  As described above, unlike the second piezoelectric actuators 51 and 52, the first piezoelectric actuators 31 and 32 are not formed in a meander shape that accumulates bending deformation of the piezoelectric cantilever. For this reason, in order to obtain a sufficient deflection angle for swinging the mirror unit 2, an alternating voltage having a frequency near the mechanical resonance frequency of the mirror unit 2 including the first piezoelectric actuators 31 and 32 is applied to the first piezoelectric actuator. Resonance drive is performed by applying to 31 and 32, and a sufficient deflection angle is obtained. For this reason, by applying a voltage having a frequency different from the resonance frequency, the oscillation of the mirror portion 2 around the first axis Y is almost eliminated.

  In the third experiment, the first signal Sy does not appear in spite of the fact that the mirror unit 2 does not swing around the first axis Y (or swings small enough to be handled as not swinging). A waveform having a peak value of 5V, that is, the same waveform as the peak values of the first voltage Vy1 and the second voltage Vy2 was observed. From this, in the structure of the second experiment and the third experiment, it was confirmed that the signal passing through the detection wiring Wm generated interference from the first drive wiring (Wy1 or Wy2).

  In comparison with this, in the first experiment, it was found that neither the first signal Sy nor the second signal Sx was interfering because a peak value of less than 5 V was observed. In the optical deflector used in the first experiment, that is, the optical deflector 1 of the present embodiment, the detection wiring Wm is located between the two first driving wirings Wy1 and Wy2 (that is, the “first positive phase driving wiring Wy1”. And “first antiphase drive wiring Wy2”). As a result, the influence of the high frequency voltage applied to the two first drive wirings Wy1 and Wy2 on the signal passing through the detection wiring Wm can be reduced to a negligible level.

  In addition, as described above, in the present embodiment, in order to obtain a large deflection angle, the first piezoelectric actuators 31 and 32 include voltages at the mechanical resonance frequency of the mirror unit 2 including the first piezoelectric actuators 31 and 32. Is applied. On the other hand, since the second piezoelectric actuators 51 and 52 are formed in a so-called meander shape (a shape in which the bending deformation of each cantilever can be accumulated), even when a DC voltage is applied, the first piezoelectric actuators 31 and 32 are formed. Large bending deformation can be obtained compared to For this reason, the second frequency Fx is set smaller than the first frequency Fy.

  A plurality of wirings arranged in parallel and close to each other are more likely to affect signals passing through other wirings as the frequency of the signal passing through the one wiring increases. In addition, the longer the distance between these wirings arranged in parallel, the easier it is to influence each other's signals from one wiring to the other.

  As described above, in the present embodiment, the wiring for applying a high-frequency voltage to the first piezoelectric actuators 31 and 32 is configured by the two first driving wirings Wy1 and Wy2, and these have phases opposite to each other. An alternating voltage is applied. The detection wiring Wm is arranged between the two first drive wirings Wy1 and Wy2. Since the AC voltage passing through the two first drive wirings Wy1 and Wy2 has an opposite phase, the voltages leaking from the two wirings Wy1 and Wy2 cancel each other.

  Since the detection wiring Wm is arranged between the two first drive wirings Wy1 and Wy2, the influence of the voltage leaking from the two wirings Wy1 and Wy2 on the detection wiring Wm is reduced to a negligible level. The At this time, it is preferable to arrange the detection wiring Wm so that the distance from each of the two first drive wirings Wy1 and Wy2 is equal. Thereby, the influence of the leaked voltage can be reduced more effectively. Note that “the distances are equal” does not need to be exactly the same, and may be slightly different as long as the influence of the leaked voltage is reduced to a negligible level.

  Further, in the optical deflector 1 of the present embodiment, the first support 4 to which the first piezoelectric actuators 31 and 32 and the second piezoelectric actuators 51 and 52 are connected is detected to detect the first vibration and the second vibration. Portions 71 and 72 are provided. As a result, the amount of actual displacement of the first piezoelectric actuators 31 and 32 and the second piezoelectric actuators 51 and 52 can be detected, so that the first piezoelectric cantilevers 31A and 32A and the second piezoelectric cantilevers 51A to 51D and 52A to 52D can detect them. There is no need to provide a piezoelectric element.

  Therefore, as compared with the piezoelectric cantilever of the piezoelectric actuator as in Patent Document 1, the driving piezoelectric element (on the piezoelectric cantilever occupying on the piezoelectric cantilever is compared with the sensor element, which is provided with the detection unit corresponding to the detection units 71 and 72 of the present embodiment). The area of the first piezoelectric cantilevers 31A and 32A and the second piezoelectric cantilevers 51A to 51D, 52A to 52D) does not decrease, and the amount of bending deformation of the piezoelectric cantilevers does not decrease.

  As described above, the optical deflector 1 of the present embodiment can accurately detect the swing of the reflecting surface 2a around the two axes without reducing the rotation angle when the reflecting surface 2a is swung around the two axes.

  Moreover, like the optical deflector 1 of this embodiment, a MEMS device is small. For this reason, when the number of wirings arranged on the piezoelectric cantilever is large, the distance between the wirings is shortened. As a result, the influence of the leaked voltage on the signal passing through the other wiring tends to increase. Further, when the distance between the wirings is shortened, it is necessary to manufacture with high accuracy, and the yield is lowered. Therefore, by providing the detection units 71 and 72 on the first support unit 4 and reducing the number of detection wirings arranged on the piezoelectric cantilever to one, a leaked voltage is given to signals passing through other wirings. The influence can be suppressed and the decrease in yield can be suppressed.

  In the optical deflector 1 of the present embodiment, the detection units 71 and 72 are arranged along a side parallel to the second axis X of the first support unit 4. Not exclusively. As long as the first vibration and the second vibration transmitted to the first support portion 4 can be sufficiently detected, they may be disposed anywhere.

  Further, in the present embodiment, the first axis Y and the second axis X are orthogonal to each other, but it is not necessary to be exactly orthogonal, and the reflecting surface 2a intersects at an angle capable of swinging around two axes. If you do.

  In the optical deflector 1 of the present embodiment, the second piezoelectric actuators 51 and 52 are each composed of four piezoelectric cantilevers, but the number of piezoelectric cantilevers is not limited to this. Similarly, the number of piezoelectric cantilevers constituting the first piezoelectric actuators 31 and 32 is not limited to one as in this embodiment.

  Further, in the optical deflector 1 of the present embodiment, the first piezoelectric actuators 31 and 32 are disposed so as to face each other with the mirror part 2 interposed therebetween, and the first support part 4 is disposed on the mirror part 2 and the first piezoelectric actuators 31 and 32. The second piezoelectric cantilevers 51A to 51D and 52A to 52D are formed in a meander shape by arranging the second piezoelectric actuators 51 and 52 so as to face each other with the first support portion 4 interposed therebetween, The support portion 6 is formed so as to surround the first support portion 4 and the second piezoelectric actuators 51 and 52, but is not limited thereto.

  For example, the first piezoelectric actuator and the second piezoelectric actuator may be formed in a so-called meander shape like the second piezoelectric actuators 51 and 52 of the optical deflector 1 of the present embodiment. In this case, since the first piezoelectric actuator is configured to accumulate the bending deformation of each piezoelectric cantilever, the frequency of the voltage applied to the first piezoelectric actuator is the mechanical frequency of the mirror unit including the first piezoelectric actuator. It need not be at a resonant frequency. In such a case, the frequency of the voltage applied to the first piezoelectric actuator may be lower than the frequency of the voltage applied to the second piezoelectric actuator. At this time, the first frequency Fy and the second frequency Fx are set to a difference that can detect the first signal Sy or the second signal Sx by passing the detection output voltage through the high-pass filter FH or the low-pass filter FL. That's fine.

  In the present embodiment, the first frequency Fy is set to 30 kHz, whereas the second frequency Fx is set to 60 Hz and about 1/500. Therefore, the influence of the signal passing through the second odd-numbered drive wiring Wo and the second even-numbered drive wiring We, which are the second drive wiring, on the signal passing through the detection wiring Wm is so small that it can be ignored. If the influence is so great that it cannot be ignored, the upper electrode wirings W of the second piezoelectric actuators 51 and 52 may be arranged as will be described below.

  Specifically, on the interlayer insulating film M1 provided on the even-numbered second piezoelectric cantilevers 51B, 51D, 52B, and 52D, the upper electrode wiring W is provided from the first support portion 4 side toward the opposite side. The second even drive wiring We → the first reverse phase drive wiring Wy2 → the detection wiring Wm → the first positive phase drive wiring Wy1 → the second odd drive wiring Wo are provided separately in a plane. Further, on the interlayer insulating film M1 provided on the third second piezoelectric cantilevers 51C and 52C, the upper electrode wiring W is connected to the “second odd-numbered driving wiring Wo from the first support portion 4 side toward the opposite side. → First positive phase drive wiring Wy1 → detection wiring Wm → first reverse phase drive wiring Wy2 → second even drive wiring We ”are provided separately from each other in a plane. Further, on the interlayer insulating film M1 provided on the first second piezoelectric cantilevers 51A and 52A, the upper electrode wiring W is connected to the “second odd-numbered driving wiring Wo from the first support portion 4 side toward the opposite side. → the first positive phase drive wiring Wy1 → the detection wiring Wm → the first reverse phase drive wiring Wy2 → ”are provided separately in a plane. At this time, the interval between adjacent wirings among the upper electrode wirings W is set to be equal.

  Thereby, the detection wiring Wm is disposed between the two second drive wirings Wo and We. A third voltage Vx1 and a fourth voltage Vx2 having opposite phases are applied to the two second drive wirings Wo and We. Therefore, even when the voltage leaks from the two second drive wirings Wo and We, the influence on the signal passing through the detection wiring Wm can be reduced. Moreover, since the distance between the detection wiring Wm and each of the two second drive wirings Wo and We is equal, the influence can be reduced more effectively. In addition, since the detection wiring Wm is arranged between the two first drive wirings Wy1 and Wy2 in the same manner as in the present embodiment, the voltage is leaked from the two first drive wirings Wy1 and Wy2. However, the effect that the influence on the signal passing through the detection wiring Wm can be reduced is the same.

  DESCRIPTION OF SYMBOLS 1 ... Optical deflector, 2 ... Mirror part, 2a ... Reflecting surface, 21, 22 ... Torsion bar, 31, 32 ... 1st piezoelectric actuator, 4 ... 1st support part, 51, 52 ... 2nd piezoelectric actuator, 51A- 51D, 52A-52D ... 2nd piezoelectric cantilever (a plurality of piezoelectric cantilevers), 6 ... 2nd support part, 71, 72 ... detection part (piezoelectric element for detection), Y ... 1st axis, X ... 2nd axis, L2 ... Piezoelectric body, Wy1, Wy2 ... Two first drive lines (drive lines to which a high frequency voltage is applied), Wy1 ... First positive phase drive line (first drive line), Wy2 ... First reverse phase drive line (First drive wiring), Wo, We ... two second drive wirings (second drive wiring), Wm ... detection wiring, 61a, 62a ... lower electrode pad (connection part), 61b, 62b ... positive first upper portion Electrode pads (connection parts), 61c, 62c ... reversed phase 1 upper electrode pad (connection part), 61d, 62d ... second upper electrode pad (connection part) for odd number, 61e, 62e ... second upper electrode pad (connection part) for even number, 61f, 62f ... detection electrode pad ( Connection portion), Fy ... first frequency, Fx ... second frequency, Vy1 ... first voltage (voltage of the first frequency, voltage opposite in phase), Vy2 ... second voltage (voltage of the first frequency, opposite phase to each other) ), Vx1... Third voltage (second frequency voltage), Vx2... Fourth voltage (second frequency voltage), Sy... First signal, Sx... Second signal, FH... High pass filter (frequency filter) , FL: Low-pass filter (frequency filter).

Claims (4)

A mirror part having a reflective surface; a first support part for supporting the mirror part; one end connected to the mirror part; the other end connected to the first support part; A first piezoelectric actuator that swings about a first axis with respect to the first support; a second support that supports the first support; one end connected to the first support; and the other end connected to the first support A light including a second piezoelectric actuator coupled to the second support portion and configured to swing the first support portion around a second axis intersecting the first axis with respect to the second support portion by piezoelectric driving; A deflector,
The first support portion is provided with a detection piezoelectric element that detects the first vibration transmitted by the piezoelectric drive of the first piezoelectric actuator and the second vibration transmitted by the piezoelectric drive of the second piezoelectric actuator. And
The second support part is provided with a connection part for electrically connecting to the outside of the optical deflector,
The second piezoelectric actuator includes a first drive wiring that electrically connects the first piezoelectric actuator and the connection portion, and a second drive wiring that electrically connects the second piezoelectric actuator and the connection portion. And the detection wiring that electrically connects the detection piezoelectric element and the connection portion are arranged in parallel,
A voltage having a first frequency is applied to the first drive wiring, and a voltage having a second frequency different from the first frequency is applied to the second drive wiring.
Of the first drive wiring and the second drive wiring, the drive wiring to which a high frequency voltage is applied is composed of two drive wirings to which voltages having opposite phases are applied,
The optical deflector, wherein the detection wiring is disposed between the two drive wirings.   The optical deflector according to claim 1, further comprising a frequency filter that separates an output signal of the detection piezoelectric element into a first signal due to the first vibration and a second signal due to the second vibration. Light deflector. The optical deflector according to claim 1 or 2,
The second piezoelectric actuator is
A piezoelectric body that bends and deforms when a drive voltage is applied;
A plurality of piezoelectric cantilevers that support the piezoelectric body and bend and deform together when the piezoelectric body is bent and deformed;
The plurality of piezoelectric cantilevers are arranged side by side so that both ends of each piezoelectric cantilever are adjacent to each other, and the ends are mechanically connected so as to be folded back to the adjacent piezoelectric cantilevers so as to accumulate each bending deformation. Each piezoelectric cantilever is formed to bend and deform in a direction perpendicular to the direction in which the piezoelectric cantilevers are arranged.   4. The optical deflector according to claim 1, wherein the first frequency is a resonance frequency of the first piezoelectric actuator and the mirror unit, and is higher than the second frequency. Characteristic light deflector.