Light deflector

Abstract

To provide an optical deflector which makes it possible to reduce a device size while maintaining intact a deflection angle per drive voltage.SOLUTION: The optical deflector comprises: a mirror part 2 that includes a reflection plane 2a; a frame part 3 that encloses the periphery of the mirror part 2; a pair of torsion bar parts 4 that connect the mirror part 2 and the frame part 3; and a pair of actuator parts 5 for oscillating the mirror part 2 around the axis of the torsion bar parts 4 while being connected to the torsion bar parts 4. The actuator parts 5 include a pair of cantilever parts 7A, 7B that are resonantly driven by a plurality of piezoelectric elements 6a-6d which are located at both ends across the torsion bar parts 4. The cantilever parts 7A, 7B have such a structure that the plurality of piezoelectric elements 6a-6d are arranged side by side in the axial direction of the torsion bar parts 4 and the one ends and the other ends of the mutually adjacent piezoelectric elements 6a-6d are connected by being folded back via folding parts 8a, 8b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical deflector. [Background technology]

[0002] Conventionally, galvanometer mirrors and polygon mirrors are commonly used as examples of optical deflectors that deflect and scan light beams such as laser light. Of these, the galvanometer mirror is an optical deflector in which a plane mirror for polarization is attached to a rotating shaft, and the rotation angle of the mirror is made variable by driving an electromagnetic motor in response to an electric signal. This galvanometer mirror is a non-resonant optical deflector, so it can be driven by sawtooth or random electric signals. On the other hand, the polygon mirror is an optical deflector in which a multi-faceted mirror for polarization is attached to a rotating shaft, and it can scan faster than the galvanometer mirror.

[0003] However, since galvanometer mirrors and polygon mirrors use electromagnetic motors as their driving sources, it is difficult to reduce their size and weight, and it is difficult to use them in applications that require space saving.

[0004] In response to this, optical deflectors (also called micromirrors) have been proposed in which mechanical components such as mirrors and elastic bodies are integrally formed on a semiconductor substrate using micromachining technology (so-called MEMS technology), which applies semiconductor manufacturing technology to finely process silicon or glass (see, for example, Patent Documents 1 to 3 below).

[0005] Specifically, this optical deflector uses a piezoelectric actuator in which multiple piezoelectric elements with electrodes on the top and bottom of the piezoelectric body are arranged on a support plate and an elastic body is connected to the top of the piezoelectric elements. The piezoelectric actuator generates a linear reciprocating vibration up and down in the piezoelectric body by applying an AC voltage between the top and bottom electrodes, and this vibration is transmitted to the reflector plate via the elastic body, deflecting the reflector plate left and right around the rotating support.

[0006] Such optical deflectors are MEMS devices composed entirely of tiny mechanical structures, making them easy to miniaturize and reduce weight. Furthermore, multiple devices can be fabricated simultaneously from a single wafer, just like in semiconductor processes, making mass production easy and reducing costs.

[0007] Furthermore, in such optical deflectors, in order to obtain a large amount of displacement and deflection angle with the minute force generated by driving the piezoelectric actuator, a resonant type piezoelectric actuator is configured and the mirror portion is driven at a specific resonant frequency, making it possible to increase the deflection angle per drive voltage through this resonant drive. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5493735 [Patent Document 2] JP 2011-013621 A [Patent Document 3] JP 2009-244602 A Summary of the Invention [Problem to be solved by the invention]

[0009] In the above-mentioned optical deflector, in order to increase the deflection angle of the mirror section, it is necessary to extend the length of the piezoelectric actuator. However, extending the length of the piezoelectric actuator will result in an increase in the size of the device. Furthermore, as the device becomes larger, the number of chips that can be simultaneously manufactured from a single wafer decreases, and the cost per chip increases. Therefore, since the chip size affects the cost, there is a demand to design the device itself as small as possible.

[0010] The present invention has been proposed in view of the above-mentioned conventional circumstances, and has an object to provide an optical deflector that can be made smaller while maintaining the deflection angle per drive voltage. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides the following means. [1] A mirror portion including a reflective surface; A frame portion surrounding the periphery of the mirror portion; a pair of torsion bar portions connecting the mirror portion and the frame portion; a pair of actuator units connected to the torsion bar unit to swing the mirror unit around an axis of the torsion bar unit, the actuator section has a pair of cantilever sections that are resonantly driven by a plurality of piezoelectric elements located on both sides of the torsion bar section, The cantilever portion is an optical deflector characterized in that the plurality of piezoelectric elements are arranged in a line in the axial direction of the torsion bar portion, and one end and the other end of adjacent ones of the plurality of piezoelectric elements are folded back and connected via a folded back portion. [2] The optical deflector according to [1], wherein the pair of cantilever portions are arranged symmetrically on both sides of the torsion bar portion. [3] The optical deflector described in [1] or [2], wherein the actuator section is driven by applying opposite-phase driving voltages between adjacent ones of the plurality of piezoelectric elements. [4] The optical deflector described in any one of [1] to [3], characterized in that the actuator section drives the piezoelectric elements by applying driving voltages of opposite phases between those piezoelectric elements facing each other across the torsion bar section. [5] The optical deflector described in any one of [1] to [4], wherein the actuator portion has a structure in which the frame portion and the cantilever portion are connected via a connecting portion. [6] The optical deflector described in any one of [1] to [4], wherein the pair of actuator members have a structure in which a cantilever member on one side connected to one of the pair of torsion bar members and a cantilever member on the other side connected to the other torsion bar member are connected via a connecting member. Effect of the Invention

[0012] As described above, according to the present invention, it is possible to provide an optical deflector that can be made smaller while maintaining the deflection angle per drive voltage. [Brief description of the drawings]

[0013] [Figure 1] 1 is a plan view showing a configuration of an optical deflector according to a first embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of the actuator portion taken along line AA shown in FIG. [Diagram 3] 2 is a cross-sectional view of the actuator portion taken along line BB shown in FIG. [Figure 4] 4 shows drive voltages applied to a plurality of piezoelectric elements of an actuator section, where (A) is a graph showing the waveform of one drive voltage, and (B) is a graph showing the waveform of the other drive voltage. [Diagram 5] FIG. 11 is a plan view showing a configuration of an optical deflector according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a plan view showing a configuration of an optical deflector according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a plan view showing a configuration of an optical deflector according to a fourth embodiment of the present invention. [Figure 8] 1A is a plan view of an optical deflector according to a first embodiment, FIG. 1B is a plan view of an optical deflector according to a first comparative example, and FIG. 1C is a plan view of an optical deflector according to a second comparative example. [Figure 9] 1 is a graph showing the simulation results of measuring the deflection angle versus drive voltage in Example 1 and Comparative Examples 1 and 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make each component easier to see, the dimensions of the components may be shown at different scales, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0015] (First embodiment) First, as a first embodiment of the present invention, an optical deflector 1 shown in, for example, FIGS. 1 to 4 will be described.

[0016] Fig. 1 is a plan view showing the configuration of the optical deflector 1. Fig. 2 is a cross-sectional view of the actuator section 5 taken along line segment AA shown in Fig. 1. Fig. 3 is a cross-sectional view of the actuator section 5 taken along line segment BB shown in Fig. 1. Fig. 4 shows drive voltages applied to multiple piezoelectric elements in the actuator section 5, with (A) being a graph showing the waveform of one drive voltage and (B) being a graph showing the waveform of the other drive voltage.

[0017] In addition, in the drawings shown below, an XYZ Cartesian coordinate system is set, and the X-axis direction is shown as a first direction (horizontal direction) within the plane of the optical deflector 1, the Y-axis direction is shown as a second direction (vertical direction) perpendicular to the first direction within the plane of the optical deflector 1, and the Z-axis direction is shown as a third direction (thickness direction) perpendicular to the plane of the optical deflector 1.

[0018] As shown in Figures 1 to 3, the optical deflector 1 of this embodiment includes a mirror portion 2 including a reflective surface 2a, a frame portion 3 surrounding the periphery of the mirror portion 2, a pair of torsion bar portions 4 connecting the mirror portion 2 and the frame portion 3, and a pair of actuator portions 5 that oscillate the mirror portion 2 around the axis of the torsion bar portions 4 while connected to the torsion bar portions 4.

[0019] Moreover, the optical deflector 1 of this embodiment is composed of a micromirror in which a mirror portion 2, a frame portion 3, a pair of torsion bar portions 4, and a pair of actuator portions 5 are integrally formed on a semiconductor substrate serving as a support using MEMS technology.

[0020] An optical deflector 1 of this embodiment has a space K between a mirror portion 2 having a substantially circular shape in a plan view and a frame portion 3 having a substantially rectangular frame shape surrounding the mirror portion 2.

[0021] The pair of torsion bar portions 4 are each formed linearly while extending in the second direction in a plan view, and connect the mirror portion 2 and the frame portion 3 while supporting the mirror portion 2 so that it can swing freely around a central axis in the second direction relative to the frame portion 3.

[0022] A pair of actuator portions 5 are provided corresponding to each of the pair of torsion bar portions 4. Each actuator portion 5 has a pair of cantilever portions 7A, 7B that are resonantly driven by a plurality of (four in this embodiment) piezoelectric elements 6a-6d located on both sides of each torsion bar portion 4 in the first direction.

[0023] The pair of cantilever portions 7A, 7B are arranged symmetrically on both sides in the first direction across the torsion bar portion 4. The pair of torsion bar portions 4 are arranged symmetrically on both sides in the second direction across the mirror portion 2. In addition, of the pair of torsion bar portions 4, the pair of cantilever portions 7A, 7B connected to the torsion bar portion 4 on one side and the pair of cantilever portions 7A, 7B connected to the torsion bar portion 4 on the other side are arranged symmetrically on both sides in the second direction across the mirror portion 2.

[0024] The plurality of piezoelectric elements 6a to 6d are configured by laminating a lower electrode 12, a piezoelectric body 13, and an upper electrode 14 in this order on a vibration plate 11 connected to the torsion bar portion 4.

[0025] Each cantilever portion 7A (7B) has a plurality (two in this embodiment) of piezoelectric elements 6a, 6b (6c, 6d) arranged side by side in the axial direction (second direction) of the torsion bar portion 4, and has a structure in which one end and the other end of adjacent ones of the plurality of piezoelectric elements 6a, 6b (6c, 6d) are folded back and connected via a fold back portion 8a (8b) (hereinafter referred to as a "folded back structure").

[0026] Specifically, of the multiple piezoelectric elements 6a to 6d, the first piezoelectric element 6a and the second piezoelectric element 6b that constitute the cantilever portion 7A on one side are connected via a folded portion 8a, and the third piezoelectric element 6c and the fourth piezoelectric element 6d that constitute the cantilever portion 7B on the other side are connected via a folded portion 8b.

[0027] The first piezoelectric element 6a and the third piezoelectric element 6c are located on the frame section 3 side of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4. On the other hand, the second piezoelectric element 6b and the fourth piezoelectric element 6d are located on the mirror section 2 side of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4.

[0028] In the cantilever portion 7A on one side, one end of a first piezoelectric element 6a extending in a first direction is connected to the torsion bar portion 4, the other end of this first piezoelectric element 6a is connected to one end of a folded portion 8a extending in a second direction, one end of a second piezoelectric element 6b extending in the first direction is connected to the other end of the folded portion 8a, and the other end of the second piezoelectric element 6b is not connected and is a free end.

[0029] In the cantilever portion 7B on the other side, one end of the third piezoelectric element 6c extending in the first direction is connected to the torsion bar portion 4, the other end of this third piezoelectric element 6c is connected to one end of the folded portion 8b extending in the second direction, one end of the fourth piezoelectric element 6d extending in the first direction is connected to the other end of the folded portion 8b extending in the second direction, and the other end of this fourth piezoelectric element 6d is not connected and is a free end.

[0030] In the actuator section 5, a driving voltage (e.g., an AC voltage such as a sine wave or a square wave) is applied to the multiple piezoelectric elements 6a to 6d to bend the pair of cantilever sections 7A, 7B, thereby making it possible to oscillate the mirror section 2 around the axis of the torsion bar section 4.

[0031] Specifically, in the actuator section 5, adjacent piezoelectric elements 6a-6d are driven by applying drive voltages of opposite phases to each other. Also, in the actuator section 5, adjacent piezoelectric elements 6a-6d are driven by applying drive voltages of opposite phases to each other across the torsion bar section 4.

[0032] That is, among the plurality of piezoelectric elements 6a to 6d, a driving voltage having a waveform shown in Fig. 4(A) is applied to the first and fourth piezoelectric elements 6a, 6d, while a driving voltage having a waveform shown in Fig. 4(B), which is in opposite phase to the driving voltage shown in Fig. 4(A), is applied to the second and third piezoelectric elements 6b, 6c.

[0033] Furthermore, a drive voltage near the resonance frequency is applied to the piezoelectric elements 6a to 6d in the actuator section 5. This makes it possible to drive the pair of cantilever sections 7A and 7B in a resonant state (hereinafter referred to as "resonant drive") and to oscillate the mirror section 2 at a larger deflection angle.

[0034] The optical deflector 1 of this embodiment having the above-mentioned configuration has a folded structure in which the first piezoelectric element 6a and the second piezoelectric element 6b constituting the cantilever portion 7A on one side described above are connected via a folded portion 8a, and the third piezoelectric element 6c and the fourth piezoelectric element 6d constituting the cantilever portion 7B on the other side are connected via a folded portion 8b.

[0035] As a result, in optical deflector 1 of this embodiment, the pair of cantilever portions 7A, 7B can be efficiently arranged in space K while ensuring the length of the pair of cantilever portions 7A, 7B.

[0036] As described above, in the optical deflector 1 of this embodiment, the device can be made smaller while maintaining the deflection angle per drive voltage. In addition, by increasing the number of chips that can be simultaneously manufactured from one wafer, it is possible to reduce the cost per chip.

[0037] Second embodiment Next, as a second embodiment of the present invention, an optical deflector 1A shown in FIG. 5 will be described.

[0038] 5 is a plan view showing the configuration of the optical deflector 1 A. In the following explanation, the explanation of the same parts as those in the optical deflector 1 will be omitted and the same reference numerals will be used in the drawings.

[0039] An optical deflector 1A of this embodiment basically has the same configuration as the optical deflector 1 described above, except that it includes a pair of actuator units 5A as shown in FIG.

[0040] Specifically, each actuator section 5A has a pair of cantilever sections 7C, 7D that are resonantly driven by multiple (six in this embodiment) piezoelectric elements 16a to 16f located on both sides of each torsion bar section 4 in the first direction.

[0041] Each cantilever portion 7C (7D) has multiple (three in this embodiment) piezoelectric elements 16a, 16b, 16c (16d, 16e, 16f) arranged side by side in the axial direction (second direction) of the torsion bar portion 4, and has a folded structure in which one end and the other end of adjacent ones of the multiple piezoelectric elements 16a, 16b, 16c (16d, 16e, 16f) are folded back and connected via folded portions 18a, 18b (18c, 18d).

[0042] Specifically, of the multiple piezoelectric elements 16a to 16f, the first piezoelectric element 16a, the second piezoelectric element 16b, and the third piezoelectric element 16c that constitute the cantilever portion 7C on one side are connected via folded portions 18a and 18b, and the fourth piezoelectric element 16d, the fifth piezoelectric element 16e, and the sixth piezoelectric element 16f that constitute the cantilever portion 7D on the other side are connected via folded portions 18c and 18d.

[0043] The first piezoelectric element 16a and the fourth piezoelectric element 16d are located on the frame section 3 side of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4. On the other hand, the second piezoelectric element 16b and the fifth piezoelectric element 16e are located in the middle of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4. On the other hand, the third piezoelectric element 16c and the sixth piezoelectric element 16f are located on the mirror section 2 side of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4.

[0044] The second and fifth piezoelectric elements 16b, 16e are shorter than the first and fourth piezoelectric elements 16a, 16d, and the third and sixth piezoelectric elements 16c, 16f are narrower than the second and fifth piezoelectric elements 16b, 16e. That is, the lengths and widths of the multiple piezoelectric elements 16a to 16f can be changed as appropriate.

[0045] In the cantilever portion 7C on one side, one end of a first piezoelectric element 16a extending in a first direction is connected to the torsion bar portion 4, the other end of this first piezoelectric element 16a is connected to one end of a folded portion 18a extending in a second direction, one end of a second piezoelectric element 16b extending in the first direction is connected to the other end of the folded portion 18a, the other end of this second piezoelectric element 16b is connected to one end of the folded portion 18b extending in the second direction, and one end of a third piezoelectric element 16c extending in the first direction is connected to the other end of the folded portion 18b.

[0046] In addition, in the cantilever portion 7C on one side, the other end of the third piezoelectric element 16c is connected to the frame portion 3 via a connecting portion 9a extending in the first direction.

[0047] In the cantilever portion 7D on the other side, one end of a fourth piezoelectric element 16d extending in the first direction is connected to the torsion bar portion 4, the other end of this fourth piezoelectric element 16d is connected to one end of the folded portion 18c extending in the second direction, one end of a fifth piezoelectric element 16e extending in the first direction is connected to the other end of the folded portion 18c, the other end of this fifth piezoelectric element 16e is connected to one end of the folded portion 18d extending in the second direction, and one end of a sixth piezoelectric element 16f extending in the first direction is connected to the other end of the folded portion 18d.

[0048] In the cantilever portion 7D on the other side, the other end of the sixth piezoelectric element 16f is connected to the frame portion 3 via a connecting portion 9b extending in the first direction.

[0049] In the actuator section 5A, a driving voltage (e.g., an AC voltage such as a sine wave or a square wave) is applied to multiple piezoelectric elements 16a to 16f to bend a pair of cantilever sections 7C, 7D, thereby making it possible to oscillate the mirror section 2 around the axis of the torsion bar section 4.

[0050] Specifically, in the actuator section 5A, among the plurality of piezoelectric elements 16a-16d, adjacent ones are driven by applying drive voltages of opposite phases. Also, in the actuator section 5A, among the plurality of piezoelectric elements 16a-16f, opposite ones facing each other across the torsion bar section 4 are driven by applying drive voltages of opposite phases.

[0051] That is, among the plurality of piezoelectric elements 16a to 16f, the first, third and fifth piezoelectric elements 16a, 16c and 16e are applied with a driving voltage having a waveform shown in Fig. 4(A). On the other hand, the second, fourth and sixth piezoelectric elements 16b, 16d and 16f are applied with a driving voltage having a waveform shown in Fig. 4(B), which is in opposite phase to the driving voltage shown in Fig. 4(A).

[0052] In addition, in the actuator section 5A, a drive voltage close to the resonant frequency is applied to the piezoelectric elements 16a to 16f, which makes it possible to resonate and drive the pair of cantilever sections 7C and 7D and to oscillate the mirror section 2 at a larger deflection angle.

[0053] In the optical deflector 1A of this embodiment having the above-mentioned configuration, the first, second and third piezoelectric elements 16a, 16b, 16c constituting the cantilever portion 7C on one side described above are connected via folded portions 18a, 18b, and the fourth, fifth and sixth piezoelectric elements 16d, 16e, 16f constituting the cantilever portion 7D on the other side have a folded structure connected via folded portions 18c, 18d.

[0054] As a result, in optical deflector 1A of this embodiment, the pair of cantilever portions 7C, 7D can be efficiently disposed in space K while ensuring the length of the pair of cantilever portions 7C, 7D.

[0055] In addition, the optical deflector 1A of this embodiment has a structure in which the frame portion 3 and the pair of cantilever portions 7C and 7D are connected via connecting portions 9a and 9b. In this configuration, the deflection angle is lower than that of the optical deflector 1, but it is possible to improve vibration resistance.

[0056] As described above, in the optical deflector 1A of this embodiment, the device can be made smaller while maintaining the deflection angle per driving voltage. In addition, by increasing the number of chips that can be simultaneously manufactured from one wafer, it is possible to reduce the cost per chip.

[0057] (Third embodiment) Next, as a third embodiment of the present invention, an optical deflector 1B shown in FIG. 6 will be described.

[0058] 6 is a plan view showing the configuration of the optical deflector 1B. In the following description, the description of the same parts as those in the optical deflector 1 will be omitted and the same reference numerals will be used in the drawings.

[0059] An optical deflector 1B of this embodiment basically has the same configuration as the optical deflector 1 described above, except that it includes a pair of actuator units 5B as shown in FIG.

[0060] Specifically, each actuator portion 5B has a pair of cantilever portions 7E, 7F that are resonantly driven by multiple (six in this embodiment) piezoelectric elements 26a to 26f located on both sides of each torsion bar portion 4 in the first direction.

[0061] Each cantilever portion 7E (7F) has multiple (three in this embodiment) piezoelectric elements 26a, 26b, 26c (26d, 26e, 26f) arranged side by side in the axial direction (second direction) of the torsion bar portion 4, and has a folded structure in which one end and the other end of adjacent ones of the multiple piezoelectric elements 26a, 26b, 26c (26d, 26e, 26f) are folded back and connected via folded portions 28a, 28b (28c, 28d).

[0062] Specifically, of the multiple piezoelectric elements 26a to 26f, the first piezoelectric element 26a, the second piezoelectric element 26b, and the third piezoelectric element 26c that constitute the cantilever portion 7E on one side are connected via folded portions 28a, 28b, and the fourth piezoelectric element 26d, the fifth piezoelectric element 26e, and the sixth piezoelectric element 26f that constitute the cantilever portion 7F on the other side are connected via folded portions 28c, 28d.

[0063] The first piezoelectric element 26a and the fourth piezoelectric element 26d are located on the mirror section 2 side of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4. On the other hand, the second piezoelectric element 26b and the fifth piezoelectric element 26e are located in the middle of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4. On the other hand, the third piezoelectric element 26c and the sixth piezoelectric element 26f are located on the frame section 3 side of the torsion bar section 4 and are arranged symmetrically on both sides in the first direction across the torsion bar section 4.

[0064] The second and fifth piezoelectric elements 26b, 26e are shorter than the first and fourth piezoelectric elements 26a, 26d, and the third and sixth piezoelectric elements 26c, 26f are narrower than the second and fifth piezoelectric elements 26b, 26e. That is, the lengths and widths of the multiple piezoelectric elements 26a to 26f can be changed as appropriate.

[0065] In the cantilever portion 7E on one side, one end of a first piezoelectric element 26a extending in a first direction is connected to the torsion bar portion 4, the other end of the first piezoelectric element 26a is connected to one end of a folded portion 28a extending in a second direction, one end of a second piezoelectric element 26b extending in the first direction is connected to the other end of the folded portion 28a, the other end of the second piezoelectric element 26b is connected to one end of the folded portion 28b extending in the second direction, and one end of a third piezoelectric element 26c extending in the first direction is connected to the other end of the folded portion 28b.

[0066] In addition, in the cantilever portion 7E on one side, the other end of the third piezoelectric element 16c is connected to the frame portion 3 via a connecting portion 9c extending in the second direction.

[0067] In the cantilever portion 7F on the other side, one end of a fourth piezoelectric element 26d extending in a first direction is connected to the torsion bar portion 4, the other end of this fourth piezoelectric element 26d is connected to one end of the folded portion 28c extending in the second direction, one end of a fifth piezoelectric element 26e extending in the first direction is connected to the other end of the folded portion 28c, the other end of this fifth piezoelectric element 26e is connected to one end of the folded portion 28d extending in the second direction, and one end of a sixth piezoelectric element 26f extending in the first direction is connected to the other end of the folded portion 28d.

[0068] In the cantilever portion 7F on the other side, the other end of the sixth piezoelectric element 26f is connected to the frame portion 3 via a connecting portion 9d extending in the second direction.

[0069] In the actuator section 5B, a driving voltage (e.g., an AC voltage such as a sine wave or a square wave) is applied to the multiple piezoelectric elements 26a to 26f to bend the pair of cantilever sections 7E, 7F, thereby making it possible to oscillate the mirror section 2 around the axis of the torsion bar section 4.

[0070] Specifically, in the actuator section 5B, among the plurality of piezoelectric elements 26a-26d, adjacent ones are driven by applying drive voltages of opposite phases. Also, in the actuator section 5B, among the plurality of piezoelectric elements 26a-26f, opposite ones facing each other across the torsion bar section 4 are driven by applying drive voltages of opposite phases.

[0071] That is, among the plurality of piezoelectric elements 26a to 26f, a driving voltage having a waveform shown in Fig. 4(A) is applied to the first, third and fifth piezoelectric elements 26a, 26c and 26e, while a driving voltage having a waveform shown in Fig. 4(B) that is in the opposite phase to the driving voltage shown in Fig. 4(A) is applied to the second, fourth and sixth piezoelectric elements 26b, 26d and 26f.

[0072] In addition, in the actuator section 5B, a drive voltage close to the resonant frequency is applied to the piezoelectric elements 26a to 26f, which makes it possible to oscillate the mirror section 2 at a larger deflection angle while resonatingly driving the pair of cantilever sections 7E and 7F.

[0073] The optical deflector 1B of this embodiment having the above-mentioned configuration has a folded structure in which the first, second, and third piezoelectric elements 26a, 26b, and 26c constituting the cantilever portion 7E on one side described above are connected via folded portions 28a and 28b, and the fourth, fifth, and sixth piezoelectric elements 26d, 26e, and 26f constituting the cantilever portion 7F on the other side are connected via folded portions 28c and 28d.

[0074] As a result, in the optical deflector 1B of this embodiment, the pair of cantilever portions 7E, 7F can be efficiently disposed in the space K while ensuring the length of the pair of cantilever portions 7E, 7F.

[0075] In addition, the optical deflector 1B of this embodiment has a structure in which the frame portion 3 and the pair of cantilever portions 7E and 7F are connected via connecting portions 9c and 9d. In this configuration, the deflection angle is lower than that of the optical deflector 1, but it is possible to improve the vibration resistance.

[0076] As described above, in the optical deflector 1B of this embodiment, the device can be made smaller while maintaining the deflection angle per driving voltage. In addition, by increasing the number of chips that can be simultaneously manufactured from one wafer, it is possible to reduce the cost per chip.

[0077] (Fourth embodiment) Next, as a fourth embodiment of the present invention, an optical deflector 1C shown in FIG. 7 will be described.

[0078] 7 is a plan view showing the configuration of the optical deflector 1C. In the following description, the description of the same parts as those of the optical deflectors 1 and 1A will be omitted and the same reference numerals will be used in the drawings.

[0079] An optical deflector 1C of this embodiment basically has the same configuration as the optical deflector 1 described above, except that it includes a pair of actuator units 5C as shown in FIG.

[0080] Specifically, each actuator section 5C has a structure in which, instead of the connecting sections 9a, 9b provided in the actuator section 5A, one cantilever section 7C, 7D connected to one of a pair of torsion bar sections 4 and the other cantilever section 7C, 7D connected to the other torsion bar section 4 are connected via connecting sections 9e, 9f.

[0081] In the optical deflector 1C of this embodiment having the above-mentioned configuration, the first, second and third piezoelectric elements 16a, 16b, 16c constituting the cantilever portion 7C on one side described above are connected via folded portions 18a, 18b, and the fourth, fifth and sixth piezoelectric elements 16d, 16e, 16f constituting the cantilever portion 7D on the other side have a folded structure connected via folded portions 18c, 18d.

[0082] As a result, in the optical deflector 1C of this embodiment, the pair of cantilever portions 7C, 7D can be efficiently arranged in the space K while ensuring the length of the pair of cantilever portions 7C, 7D.

[0083] Moreover, the optical deflector 1C of this embodiment has a structure in which the cantilever portions 7C, 7D on one side connected to one of the above-mentioned torsion bar portions 4 and the cantilever portions 7C, 7D on the other side connected to the other torsion bar portion 4 are connected via connecting portions 9e, 9f. With this configuration, it is possible to improve vibration resistance while maintaining the deflection angle, as compared with the optical deflector 1 described above.

[0084] As described above, in the optical deflector 1C of this embodiment, the device can be made smaller while maintaining the deflection angle per driving voltage. In addition, by increasing the number of chips that can be simultaneously manufactured from one wafer, it is possible to reduce the cost per chip.

[0085] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the optical deflector 1A (1B), the frame portion 3 and a pair of cantilever portions 7C, 7D (7E, 7F) are connected via connecting portions 9a, 9b (9c, 9d), but it is also possible to extend the third and sixth piezoelectric elements 16c, 16f (26c, 26f) and connect them to the frame portion 3. EXAMPLES

[0086] The effects of the present invention will be more clearly understood by the following examples. Note that the present invention is not limited to the following examples, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[0087] In this embodiment, the deflection angle with respect to the driving voltage was measured by simulation using an optical deflector 1 serving as Example 1 shown in FIG. 8(A), an optical deflector 100A serving as Comparative Example 1 shown in FIG. 8(B), and an optical deflector 100B serving as Comparative Example 2 shown in FIG. 8(C).

[0088] Fig. 8(A) is a plan view of an optical deflector according to Example 1. Fig. 8(B) is a plan view of an optical deflector 100A according to Comparative Example 1. Fig. 8(C) is a plan view of an optical deflector 100B according to Comparative Example 2. In the following description, the same parts as those in the optical deflector 1 will not be described and will be denoted by the same reference numerals in the drawings.

[0089] 8(B) has a pair of cantilever portions 70A, 70B that are resonantly driven by a pair of piezoelectric elements 60a, 60b located on both sides in the first direction sandwiching the torsion bar portion 4. In the pair of cantilever portions 70A, 70B, one end of the pair of piezoelectric elements 60a, 60b is connected to the torsion bar portion 4, and the other end of the pair of piezoelectric elements 60a, 60b is not connected and is a free end.

[0090] 8(C) has a pair of cantilever portions 70C, 70D that are resonantly driven by a pair of piezoelectric elements 60a, 60b located on both sides in the first direction sandwiching the torsion bar portion 4. In the pair of cantilever portions 70C, 70D, one end of the pair of piezoelectric elements 60a, 60b is connected to the torsion bar portion 4, and the other end of the pair of piezoelectric elements 60a, 60b is connected to the frame portion 3 via connecting portions 80a, 80b extending in the first direction.

[0091] FIG. 9 shows the results of a simulation in which the deflection angle was measured with respect to the drive voltage for the optical deflectors 1, 100A, and 100B of Example 1 and Comparative Examples 1 and 2.

[0092] 9, the optical deflectors 1, 100A of the embodiment 1 and the comparative example 1 can have a larger deflection angle than the optical deflector 100B of the comparative example 2. Moreover, the optical deflector 1 of the embodiment 1 can be made smaller in size than the optical deflector 100A of the comparative example 1.

[0093] Therefore, in the optical deflector 1 of the first embodiment, it is possible to reduce the size of the device while maintaining the deflection angle per drive voltage. [Explanation of symbols]

[0094] 1, 1A to 1C... Optical deflector 2... Mirror section 2a... Reflecting surface 3... Frame section 4... Torsion bar section 5, 5A to 5C... Actuator section 6a to 6d... Piezoelectric element 7A to 7F... Cantilever section 8a, 8b... Turned section 9a to 9f... Connection section 16a to 6f... Piezoelectric element 18a to 18d... Turned section 26a to 26f... Piezoelectric element 28a to 28d... Turned section K... Space

Claims

1. A mirror portion including a reflective surface; A frame portion surrounding the periphery of the mirror portion; a pair of torsion bar portions connecting the mirror portion and the frame portion; a pair of actuator units connected to the torsion bar unit to swing the mirror unit around an axis of the torsion bar unit, the actuator section has a pair of cantilever sections that are driven in a resonant state by a plurality of piezoelectric elements located on both sides of the torsion bar section, The cantilever portion is an optical deflector characterized in that the plurality of piezoelectric elements are arranged in a line in the axial direction of the torsion bar portion, and one end and the other end of adjacent ones of the plurality of piezoelectric elements are folded back and connected via a folded back portion.

2. 2. The optical deflector according to claim 1, wherein the pair of cantilever portions are disposed symmetrically on both sides of the torsion bar portion.

3. 3. The optical deflector according to claim 1, wherein the actuator section drives adjacent ones of the plurality of piezoelectric elements while applying driving voltages of opposite phases between them.

4. The optical deflector according to any one of claims 1 to 3, characterized in that the actuator section drives the piezoelectric elements by applying driving voltages of opposite phases between those of the plurality of piezoelectric elements that face each other across the torsion bar section.

5. 5. The optical deflector according to claim 1, wherein the actuator portion has a structure in which the frame portion and the cantilever portion are connected via a connecting portion.

6. The optical deflector according to any one of claims 1 to 4, characterized in that the pair of actuator members have a structure in which a cantilever member on one side connected to one of the pair of torsion bar members and a cantilever member on the other side connected to the other torsion bar member are connected via a connecting member.

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