JP2011061881A - Piezoelectric actuator and optical scanning apparatus employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator that is stably driven at a low speed, and to provide an optical scanning apparatus employing the piezoelectric actuator. <P>SOLUTION: The piezoelectric actuator 110, 111 or 112 for driving and tilting an object 30 or 31 to be driven around an axis X includes: a movable frame 70 which has an annular structure which surrounds in a planar manner the object 30 or 31 to be driven by weight sections 71 disposed on both sides of the axis X and by connections 72 extending so as to intersect the axis X and connecting the weight sections 71 to each other, is connected with the object 30 or 31 to be driven and connects and supports the object 30 or 31 to be driven; and drive beams 90 which are configured by forming piezoelectric thin films 22 on elastic bodies 15, disposed on the outer sides of the movable frame 70, and connected so as to apply a tilting force about the axis X to the connections 72 of the movable frame 70. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator and an optical scanning device using the same, and more particularly to a piezoelectric actuator that tilts and drives a driven object around an axis and an optical scanning device using the piezoelectric actuator.

  Conventionally, a piezoelectric unimorph diaphragm, a support body having a hollow portion for fixing and supporting one end of the piezoelectric unimorph diaphragm, an elastic body connected to the piezoelectric unimorph diaphragm, an elastic body connected to the elastic body, and an elastic body There is known an optical polarizer that includes a reflector that rotates and vibrates in a hollow portion by driving a unimorph diaphragm via the, and integrally forms them all (see, for example, Patent Document 1).

JP 2005-128147 A

  However, in the configuration described in Patent Document 1 described above, only the case where the reflection plate is driven at a high speed of 15 kHz or 20 kHz using resonance vibration is considered. For example, the reflection plate is driven at a low speed of about 60 Hz. When there is a demand to drive, there is a problem that low-speed driving cannot be performed when resonating, and sufficient rotational displacement of the reflector cannot be obtained when non-resonating.

  Therefore, an object of the present invention is to provide a piezoelectric actuator that can be driven stably at a low speed and an optical scanning device using the piezoelectric actuator.

In order to achieve the above object, the piezoelectric actuator (110, 111, 112) according to the first invention is a piezoelectric actuator (110, 111, 112) that drives the drive target (30, 31) to tilt around the axis (X). ) And
The drive target is composed of a weight portion (71) disposed on both sides of the shaft (X) and a connecting portion (72) extending across the shaft (X) and connecting the weight portion (71). A movable frame (70) having an annular structure surrounding the object (30, 31) in a plan view, the drive object (30, 31) being connected to support the drive object (30, 31);
It has a structure in which a piezoelectric thin film (22) is formed on an elastic body (15), is disposed outside the movable frame (70), and is connected to the connecting portion (72) of the movable frame (70) with the shaft ( X) a drive beam (90) connected to impart tilting power around.

  Thus, by applying tilting power to the movable frame having the weight portion, the resonance frequency of the driving force can be sufficiently slowed down by the weight portion, and the movable frame has an annular structure surrounding the drive object. The driving force around the axis can be reliably transmitted to the driving object without causing interference with the vibration generated inside the annular structure.

According to a second invention, in the piezoelectric actuator (110, 111, 112) according to the first invention,
The drive beam (90) is disposed to extend in a direction perpendicular to the axis (X) so as to sandwich the movable frame (70) from both sides in the axis (X) direction. The drive beams (90) that are paired on both sides are applied with voltages that are displaced in opposite directions.

  Thereby, tilting power can be reliably given to a movable frame using the drive beam of a simple structure.

A third invention is the piezoelectric actuator (110, 111, 112) according to the first or second invention,
The drive beam (90) and the connecting portion (72) are connected by a meandering spring (80) in which adjacent beams (15) meander with a gap.

  Thereby, the resonance frequency can be lowered, and the drive object can be tilted and driven at a desired low speed frequency.

A fourth invention is the piezoelectric actuator (110, 111, 112) according to the third invention,
The adjacent intervals (H, I, J) of the meandering spring (80) are determined according to the stress distribution applied to the meandering spring (80), and the intervals (H, I, J) where the stress is greatly applied are determined. Further, it is characterized by unequal intervals wider than the intervals between portions where stress is applied.

  Thereby, it is possible to set the adjacent interval between the serpentine springs in consideration of the stress, and even when an impact due to the maximum amplitude or external force is applied, it is possible to prevent damage due to contact between adjacent serpentine springs. In addition, it is possible to save space in a portion where the stress is small.

A fifth invention is the piezoelectric actuator (110, 111, 112) according to the fourth invention,
Adjacent spaces (H, I, J) of the meandering spring (80) are located at a location connected to the movable frame (70) of the meandering spring (80) and a location connected to the drive beam (90). The nearest meandering portion (H) is narrower than the meandering portion (I, J) at the central side of the meandering spring.

  As a result, one side is connected to a fixed object, and the vicinity of the connection part that is less affected by stress is configured with a narrow interval, and the central part that is greatly affected by stress is configured with a wider interval, thereby reducing both stress countermeasures and space saving. It can correspond to.

A sixth invention is the piezoelectric actuator (110, 111, 112) according to any one of the first to fifth inventions,
The drive beam (90) is resonantly driven.

  As a result, sufficient tilting power can be obtained with a small driving beam, and the drive target can be tilted and driven at a frequency at which the resonance frequency is sufficiently lowered with a configuration for reducing the speed.

A seventh invention is the piezoelectric actuator (110, 111, 112) according to any one of the first to sixth inventions,
A fixed frame (100) surrounding the movable frame (70) and the drive beam (90) in a plane;
The movable frame (70) is formed with the same thickness as the fixed frame (100),
The drive beam (90) is formed thinner than the fixed frame (100).

  Thereby, sufficient weight can be given to a movable frame, the function as a weight can fully be performed, and a movable frame and a drive beam can fully be protected by a fixed frame.

An eighth invention is the piezoelectric actuator (110, 111, 112) according to the seventh invention, wherein
The fixed frame (100) is provided with protrusions (101, 102) for restricting a movable range in the horizontal direction of the movable frame (70).

  Thereby, even when an impact is applied by dropping or the like, damage can be prevented.

A ninth invention is the piezoelectric actuator (110, 111, 112) according to any one of the first to eighth inventions,
The driving object (30, 31) is a second driving beam (structure) in which a piezoelectric thin film (22) is formed on an elastic body (15) on the connecting portion (72) of the movable frame (70). 50),
The second drive beam (50) tilts the drive object (30, 31) about a second axis (Y) different from the axis (X).

  Accordingly, the driving object can be tilted and driven by two axes, and the tilting power around the second axis that directly applies the tilting power to the driving object and the tilting power via the movable frame can be obtained. Mutual interference of the tilting power around the axis to be applied can be prevented, and both tilting motions can be appropriately performed.

A tenth aspect of the invention is the piezoelectric actuator (110, 111, 112) according to the ninth aspect of the invention.
The drive object (30, 31) and the second drive beam (50) are connected by an elastic connecting member (40) including an elastic body (15) having a beam structure.

  As a result, the tilting motion around the second axis can also be driven in a stable state with reduced stress.

An eleventh invention is the piezoelectric actuator (110, 111, 112) according to any one of the first to tenth inventions,
It is further provided with a vertical direction regulating component (120, 121, 130, 133, 136, 139) for regulating a movable range in the vertical direction of the movable frame (70).

  Thereby, the damage by impacts, such as a fall, can be prevented also with respect to the motion of an up-down direction.

A twelfth invention is the piezoelectric actuator (110, 111, 112) according to any one of the first to eleventh inventions.
The drive object (30, 31) is a mirror (31).

  Thereby, a piezoelectric actuator can be used for a projector, a scanner, or the like.

An optical scanning device according to a thirteenth invention includes a piezoelectric actuator according to the twelfth invention,
A light source that emits light;
A light guide means for guiding the light emitted from the light source to the piezoelectric actuator,
The light reflected by the mirror is scanned by tilting the mirror of the piezoelectric actuator.

  Accordingly, it is possible to provide an optical scanning device that performs stable operation with power saving.

A fourteenth invention is the optical scanning device according to the thirteenth invention, wherein
The light is scanned on a screen to form an image on the screen.

  Accordingly, it is possible to provide an optical scanning device such as a projector that performs stable operation with power saving.

  Note that the reference numerals in the parentheses are given for easy understanding, are merely examples, and are not limited to the illustrated modes.

  According to the present invention, it is possible to stably drive the driven object at a low speed.

FIG. 3 is a diagram illustrating an example of a cross-sectional configuration of the piezoelectric actuator according to the first embodiment. FIG. 3 is an explanatory diagram of a method for driving the piezoelectric actuator according to the first embodiment. FIG. 2A is an example of a side view showing portions of the beam 15 and the piezoelectric element 21. FIG. 2B is a diagram illustrating an example of a state in which the piezoelectric element 21 is contracted and deformed. FIG. 2C is a diagram illustrating an example of a state in which the piezoelectric element 21 is expanded and deformed. 1 is a perspective view showing an example of the overall configuration of a piezoelectric actuator according to Example 1. FIG. FIG. 3A is a top perspective view of the piezoelectric actuator according to the first embodiment. FIG. 3B is a bottom perspective view of the piezoelectric actuator according to the first embodiment. 1 is a diagram illustrating a detailed configuration of a piezoelectric actuator according to Example 1. FIG. FIG. 4A is a diagram showing a detailed configuration between the driving object 30 and the driving beam 90. FIG. 4B is an enlarged view around the meandering spring. FIG. 3 is a diagram illustrating an example of a configuration of a packaged piezoelectric actuator according to the first embodiment. FIG. 5A is a perspective view showing an example of the overall configuration of the piezoelectric actuator 200. FIG. 5B is an example of a central sectional perspective view of the piezoelectric actuator 200. FIG. 5C is an example of a central sectional view of the piezoelectric actuator 200. 1 is an example of an exploded view of a packaged piezoelectric actuator 200 according to Embodiment 1. FIG. FIG. 6A is an example of an overall exploded view of the piezoelectric actuator 200. FIG. 6B is an enlarged perspective view of the upper regulating member 120. FIG. 6C is an enlarged perspective view of the lower regulating member 130. 3 is a functional explanatory diagram of a meandering spring 80 of the piezoelectric actuator 110 according to Embodiment 1. FIG. FIG. 7A is a perspective view illustrating an example of the overall configuration of the piezoelectric actuator 110 according to the first embodiment. FIG. 7B is a diagram illustrating an overall configuration example of the piezoelectric actuator 110 according to the comparative reference example. FIG. 7C is a characteristic comparison diagram of the piezoelectric actuator 110 according to the first embodiment and the piezoelectric actuator according to the comparative reference example. FIG. 3 is a diagram illustrating a state when the piezoelectric actuator 110 according to the first embodiment is tilted around two axes. FIG. 8A is a diagram illustrating an example of a state in which the piezoelectric actuator 110 is driven to tilt around the X axis. FIG. 8B is a diagram illustrating an example of a state in which the piezoelectric actuator 110 is driven to tilt around the Y axis. It is the figure which showed an example of the maximum stress and inclination angle sensitivity in each resonance drive frequency. FIG. 9A is a diagram showing an example of maximum stress and tilt sensitivity in 60 Hz resonance driving. FIG. 9B is a diagram showing an example of maximum stress and tilt sensitivity in 30 kHz resonance driving. It is a figure for demonstrating the reason that interference does not generate | occur | produce by the biaxial tilt drive. As a comparative reference example, it is a diagram illustrating an example of an operation state of a piezoelectric actuator in which a connecting portion 80 is removed from a movable frame 70. FIG. FIG. 11A is a diagram showing an operation state at the time of 60 Hz resonance driving. FIG. 11B is a diagram showing an operation state at the time of 30 kHz resonance driving. It is a figure showing an example of a method of performing the optimal design of high-speed drive part. FIG. 12A is a diagram illustrating an example of a planar configuration of the high-speed drive unit 55. FIG. 12B is a diagram showing a change characteristic of the maximum stress under the condition of FIG. It is a figure for demonstrating the reason the length B of the spring connection part 43 has a minimum value. FIG. 13A shows the stress distribution of the actuator when B = 0.1 mm. FIG. 13B is a diagram showing the stress distribution of the actuator when B = 0.3 mm. FIG. 13C is a diagram showing the stress distribution of the actuator when B = 0.2 mm. It is the figure which showed the characteristic of the inclination sensitivity at the time of using the distance A between the 1st springs 41 and the length B of the spring connection part 43 as a parameter. 6 is an explanatory diagram of a configuration in which the wiring length of the piezoelectric actuator 110 according to the first embodiment is shortened. FIG. 3 is an enlarged view illustrating a planar configuration example of the piezoelectric actuator 110 according to the first embodiment. It is explanatory drawing of the arrangement configuration of the weight part protrusions 73 and 74 and the protrusions 101 and 102. FIG. FIG. 3 is a diagram illustrating an example of a cross-sectional configuration of the piezoelectric actuator 110 according to the first embodiment. 3 is an example of an enlarged view including the periphery of a meandering spring 80. FIG. It is the figure which showed an example of the shape and stress distribution of the meandering spring 80 at the time of a collision. FIG. 20A is an overall modification diagram of the piezoelectric actuator 110. FIG. 20B is an enlarged view of the left meandering spring 80. FIG. 20C is an enlarged view of the right meandering spring 80. It is the figure which showed an example of the shape of the meandering spring 80 at the time of a collision, and stress distribution. FIG. 21A is an overall modification diagram of the piezoelectric actuator 110. FIG. 21B is an enlarged view of the left meandering spring 80. FIG. 21C is an enlarged view of the elastic connecting portion 40. FIG. 21D is an enlarged view of the right meandering spring 80. As a comparative reference example, it is a diagram showing an example of a stress distribution when a linear spring 180 is provided instead of the meandering spring 80. FIG. FIG. 22A is an overall modification diagram. FIG. 22B is an enlarged view of the left linear spring 180. FIG. 22C is an enlarged view of the right linear spring 180. 6 is a diagram illustrating an example of an overall configuration of a piezoelectric actuator 111 according to Embodiment 2. FIG. FIG. 6 is an example of a diagram illustrating a driving deformation state of a piezoelectric actuator 111 according to a second embodiment. FIG. 24A is a modified view showing a low-speed driving state of the piezoelectric actuator 111. FIG. 24B is a modified view showing a high-speed driving state of the piezoelectric actuator 111. FIG. 10 is a diagram illustrating a changed portion of a piezoelectric actuator 112 according to a third embodiment. FIG. 25A is an example of a plan configuration diagram of the high-speed drive unit 55 of the piezoelectric actuator 112. FIG. 25B is a diagram showing a change characteristic of the tilt sensitivity [deg / V]. FIG. 25C is a diagram showing a change characteristic of the maximum principal stress. 6 is a perspective view illustrating an example of a configuration of a piezoelectric actuator 201 according to Embodiment 4. FIG. FIG. 26A is an example of an overall perspective view of the piezoelectric actuator 201. FIG. 26B is an example of an exploded perspective view of the piezoelectric actuator 201. FIG. 26C is an example of a cross-sectional perspective view of the piezoelectric actuator 201. FIG. 10 is a perspective view illustrating an example of a configuration of a piezoelectric actuator 202 according to a fifth embodiment. FIG. 27A is a perspective view showing an example of the overall configuration of the piezoelectric actuator 202. FIG. 27B is an example of an exploded perspective view of the piezoelectric actuator 202. FIG. 27C is an example of a cross-sectional configuration perspective view of the piezoelectric actuator 202. FIG. 10 is a perspective view illustrating an example of a configuration of a piezoelectric actuator 203 according to a sixth embodiment. FIG. 28A is a perspective view showing an example of the entire configuration of the piezoelectric actuator 203. FIG. 28B is an example of an exploded perspective view of the piezoelectric actuator 203. FIG. 28C is an example of a cross-sectional configuration perspective view of the piezoelectric actuator 203. It is the figure which showed an example of the structure of the projector 300 which concerns on Example 7 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of a cross-sectional configuration of the piezoelectric actuator according to the first embodiment of the present invention. In FIG. 1, the piezoelectric actuator according to the first embodiment includes a semiconductor wafer 10 and a drive source 20. The piezoelectric actuator according to the first embodiment can be manufactured by processing the semiconductor wafer 10 using, for example, MEMS (Micro Electro Mechanical Systems) technology. In FIG. 1, an example in which a piezoelectric actuator is configured using such a semiconductor wafer 10 will be described.

The semiconductor wafer 10 includes a silicon substrate 11, SiO ₂ 12 and 14, and a Si active layer 13. For example, an SOI (Silicon On Insulator) substrate may be used as the semiconductor wafer 10. SOI substrate, between the silicon substrate 11 is a substrate which SiO 2 ₁₂ is formed of an insulating film, in the case of cutting the silicon substrate 11 by deep reactive ion etching or the like, it is SiO ₂ on the bottom surface of the cutting end point Since it is formed, deep etching can be easily performed.

The beam 15 is formed by the SiO ₂ 12, the Si active layer 13 and the SiO ₂ 14. In the portion of the beam 15, an operation of supporting the driving object or transmitting the driving force is performed. The portion of the silicon substrate 11 is used as an outer fixed frame, for example.

For example, the semiconductor wafer 10 having a thickness of 300 to 500 [μm] as a whole may be used. For example, when the semiconductor wafer 10 is 350 [μm], the Si active layer 13 is about 30 [μm], the SiO ₂ 12 and 14 are about 0.5 [μm], and the beams 15 are about 31 [μm] in total. The thickness may be about 1/10 of that of the semiconductor wafer 10.

  The driving source 20 is a power source that generates a driving force in the piezoelectric actuator according to the present embodiment. In the piezoelectric actuator according to the present embodiment, various means can be used as the drive source 20, but in the first embodiment, a case where the piezoelectric element 21 is used as the drive source 20 will be described as an example. The piezoelectric element 21 is a passive element that converts a voltage applied to the piezoelectric body 22 into a force. In the piezoelectric actuator according to the present embodiment, the piezoelectric element 21 drives the mounted beam 15 by expanding and contracting its length when a voltage is applied. Various piezoelectric bodies 22 may be applied as the piezoelectric body 22, but for example, a PZT thin film (lead zirconate titanate) may be used. For example, when the beam 15 is about 30 [μm], the piezoelectric element 21 may be formed with a thickness of about 2 [μm].

  The piezoelectric element 21 includes an upper electrode 23 and a lower electrode 24. The upper electrode 23 and the lower electrode 24 are electrodes for applying a voltage to the piezoelectric body 22, and when the voltage is applied to the upper electrode 23 and the lower electrode 24, the piezoelectric body 22 expands and contracts to drive the beam 15. Let

  FIG. 2 is a diagram for explaining a method in which the piezoelectric element 21 drives the piezoelectric actuator according to the first embodiment by generating a bending vibration in the beam 15. FIG. 2A is an example of a side view schematically showing the beam 15 and the piezoelectric element 21 made of silicon. As shown in FIG. 2A, a piezoelectric element 21 is mounted in a thin film on a beam 15 composed of a Si active layer 13 or the like.

  FIG. 2B is a diagram illustrating an example of a state in which the piezoelectric element 21 is contracted and deformed. As shown in FIG. 2B, when the piezoelectric element 21 contracts, the beam 15 has a shape that warps upward and downward.

  FIG. 2C is a diagram illustrating an example of a state in which the piezoelectric element 21 is expanded and deformed. As shown in FIG. 2C, when the piezoelectric element 21 extends, the beam 15 has a shape that warps upward and downward.

  As shown in FIGS. 2B and 2C, the piezoelectric element 21 warps upward or follows downward depending on the polarity or phase of the applied voltage. In the piezoelectric actuator according to the present embodiment, for example, the driving target is driven using the piezoelectric element 21 as the driving source 20 by utilizing such a property of the piezoelectric element 21.

  As described in FIGS. 2B and 2C, the structure in which the piezoelectric thin film 22 is formed on the beam 15 and the piezoelectric element 21 is provided as shown in FIG. Since it is possible to generate a vibration force by contracting or extending and to impart tilting power to the driven object, it is referred to as a driving beam.

  FIG. 3 is a perspective view illustrating an example of the overall configuration of the piezoelectric actuator according to the first embodiment. FIG. 3A is a top perspective view of the piezoelectric actuator according to the first embodiment, and FIG. 3B is a bottom perspective view of the piezoelectric actuator according to the first embodiment.

  3A, the piezoelectric actuator according to the first embodiment includes a driving object 30, an elastic connecting member 40, a second driving beam 50, a movable frame 70, a meandering spring 80, and a driving beam 90. And a fixed frame 100. In the first embodiment, the drive beam 90 and the second drive beam 50 are provided, and the piezoelectric actuator is described as a biaxial drive type. However, the piezoelectric actuator is a single axis low speed drive type. In the case of the configuration, only the drive beam 90 may be provided. Therefore, the second drive beam 50 may be provided as necessary.

The upper surface of the piezoelectric actuator is all except that the driving object 30 is disposed on the surface of the central portion, and the surfaces of the driving beam 90 and the second driving beam 50 are covered with the driving source 20 including the piezoelectric element 21. It is composed of a Si active layer 13 covered with SiO ₂ 14.

  Various objects that are tilt-driven may be applied to the driving object 30, but the mirror may be the driving object 30, for example. The mirror tilt drive can be used for projectors, printer scanners, and the like.

  The X axis and the Y axis are set through the center of the driving object 30. The X-axis is a tilting axis when the piezoelectric actuator according to the present embodiment is used as a low-speed driving single-axis actuator. The Y axis is a tilt axis on the high speed drive side when the piezoelectric actuator according to the present embodiment is used as a biaxial piezoelectric actuator that drives at low speed around the X axis and drives at high speed around the Y axis. Further, when the driven object 30 is only driven at high speed around the Y axis, it can be configured as a high speed driven single axis type piezoelectric actuator.

  When the piezoelectric actuator according to the present embodiment is used as a piezoelectric actuator for driving the driving object 30 about one axis around the X axis, the driving object 30, the elastic connecting member 40, and the second driving beam are used. 50 is integrally driven around the X axis. In this case, the driving object 30, the elastic connecting member 40, and the second driving beam 50 may be considered as the driving object 60 as a unit.

  The movable frame 70 is a member for connecting the driving objects 30 and 60 to connect and support the driving objects 30 and 60 and transmitting the tilting power from the driving beam 90 to the driving objects 30 and 60. .

  As shown in FIG. 3B, the movable frame 70 is configured to be thick with the Si support layer 11 described in FIG. Therefore, the movable frame 70 is configured to be heavier than the portion configured as the beam 15. In addition, the movable frame 70 is formed as a weight (weight) portion 71 with a large area on both sides of the X axis, and both sides of the Y axis are formed as connection portions 72 that connect the weight portions 71. Thereby, with respect to the tilting motion around the axis of the X axis, the applied tilting power can be reduced by the weight of the weight portion 71. That is, even when the tilting power applied by the driving beam 90 is larger than the desired tilting power, the driving force can be reduced and the desired low-speed driving can be performed.

  Returning to FIG. In FIG. 3A, the connecting portion 72 of the movable frame 70 is hidden, but as described in FIG. 3B, the second drive beam 50 is connected to the connecting portion 72 of the movable frame 70. It becomes the composition.

  The meandering spring 80 is a member for transmitting the tilting power generated by the drive beam 90 to the movable frame 70. Since the meandering spring 80 has the structure of the beam 15, it has elasticity and can absorb and reduce the tilting power transmitted from the driving beam 90. In addition, the meandering spring 80 has a meandering shape with a gap and has a shape that further increases the elasticity, so that the elasticity can be greatly increased as compared with a simple linear beam 15. The meandering spring 80 also transmits to the connecting portion 72 of the movable frame 70 while reducing the tilting force generated in the drive beam 90.

  As described with reference to FIG. 2, the driving beam 90 is a driving force generating unit that includes the piezoelectric element 21 as the driving source 20 and generates tilting power that tilts and vibrates by alternately repeating upward or downward deformation. is there. The drive beam 90 is disposed so as to sandwich the movable frame 70 from both sides in the extending direction of the X axis and extends in a direction perpendicular to the X axis. That is, it is arranged so that the letter H is drawn by the X axis and the drive beam 90. Separately, the drive beam 90 is disposed on both sides of the X axis so that the drive beam 90 is divided along the X axis. A voltage that is displaced in the same direction is applied to the drive beam 90 on the same side with respect to the X axis, and an electrode that is applied with a voltage that is displaced in the opposite direction to the drive beam 90 on the opposite side with respect to the X axis. And a wiring configuration. Thereby, with the X axis as a boundary, one side warps upward and the other side warps downward, so that a driving force that tilts the meandering spring 80 can be generated.

  The vibration of the drive beam 90 is resonant vibration. Resonance vibration has large vibration energy and can generate a large tilt angle sensitivity. However, since the vibration frequency is high, it is generally difficult to use it directly for low-speed driving. However, in the piezoelectric actuator according to the present embodiment, the tilting power is transmitted to the driven objects 30 and 60 through the meandering spring 80 having great elasticity and the movable frame 70 having the weight portion 71, so that the frequency is sufficiently high. It can be lowered and driven at a low speed.

  In addition, the actuator according to the present embodiment generates tilting power by resonance vibration for the second drive beam 50 when the drive target 30 is driven in two axes. The second drive beam 50 only needs to drive the driven object 30 at high speed around the Y axis. Therefore, the second drive beam 50 generates high speed vibration by resonance and vibrates while reducing the stress via the elastic connecting member 40. The configuration is such that the tilting power is directly imparted to the driven object 30 by transmitting.

  Hereinafter, when the pressure actuator according to the present embodiment is configured as a two-axis drive type, the actuator is tilted around the X axis at 60 Hz with an inclination of ± 9 deg, and around the Y axis at ± 12 deg at 30 kHz. An example in the case where a pressure actuator that tilts at an inclination angle is configured will be described.

  Next, the detailed structure of the piezoelectric actuator according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating a detailed configuration of the piezoelectric actuator according to the first embodiment. FIG. 4A is a diagram illustrating a detailed configuration between the driving object 30 and the driving beam 90 of the piezoelectric actuator according to the first embodiment.

  In FIG. 4A, a mirror 31 is used as the driving object 30, and the details of the configuration of the elastic connecting member 40 that connects the mirror 31 and the second driving beam 50 and the weight portion 71 of the movable frame 70 are fixed. Details between the frame 100 and details of the connection relationship between the drive beam 90 and the connecting portion 72 of the movable frame 70 are shown.

  In FIG. 4A, the periphery of the mirror 31 shows the structure of the high-speed drive unit 55 that performs resonance drive at 30 kHz. The high speed drive unit 55 includes the second drive beam 50 and the elastic connecting member 40. The elastic coupling member 40 that couples the mirror 31 and the second drive beam 50 has a structure of two springs in which a portion coupled to the mirror 31 is separated into two. As described with reference to FIG. 1, the elastic connecting member 40 is formed as an elastic body because it is formed as a thin beam 15 and is also formed as a thin linear beam 15 in terms of shape.

  Projections 101 and 102 are formed on the fixed frame 100 side between the weight portion 71 and the fixed frame 100. Further, weight projections 73 and 74 are formed on the weight portion 71 so as to face each of the projections 101 and 102. Accordingly, the movable range of the weight portion 71 in the horizontal direction can be restricted. The protrusion 101 restricts the movable range of the weight portion 71 in the vertical direction (Y-axis direction), and the protrusion 102 restricts the movable range of the weight portion 71 in the horizontal direction (X-axis direction). In other words, if the protrusion 101 is not present, the weight portion 71 can move by the size of the gap between the weight portion 71 and the fixed frame 100, so that a large force is applied to the serpentine spring 80 and the like due to external impact, which may cause damage. However, by providing the protrusion 101, the risk of breakage can be reduced. Similarly, if the protrusion 102 does not exist, the weight portion 71 may collide with the drive source 90 due to an impact of an external force and cause damage. However, the provision of the protrusion 102 can prevent the damage.

  In FIG. 4A, a high-speed driving portion wiring terminal 103 and an electrode wiring 104 are provided on the surface of the fixed frame 100. The high-speed driving unit wiring terminal 103 is a wiring terminal for supplying electric power to the electrodes 23 and 24 of the second driving beam 50 of the high-speed driving unit 55, and the electrode wiring 104 has the same purpose. Since the second drive beam 50 is in the central region near the drive target 30, in order to supply power to the second drive beam 50, the fixed frame 100, the drive beam 90, and the meandering spring 80 on the outside are provided. However, in the piezoelectric actuator according to this embodiment, since the driving beam 90 has a simple shape, the wiring of the electrode wiring 104 can be reduced and the power consumption can be reduced. . Details of this point will be described later.

  FIG. 4B is an enlarged view around the meandering spring. As shown in FIG. 4B, the drive source 90 has a gap 91 along the X axis, and can perform different deformations on both sides of the X axis. The meandering spring 80 is connected to both of the two drive sources 90 on both sides of the X axis so as to straddle the gap 91. As a result, the drive source 90 can impart a tilting force that alternately vibrates to the meandering spring 80 by performing warping deformation opposite to each other in the vertical vertical direction on the near side and the far side with the X axis as a boundary. The drive target parts 30 and 60 can be tilted. In FIG. 4B, only the left end portion of the entire piezoelectric actuator is shown, but the right end portion is also driven by the drive source 90 in the same tilting direction so that both the left and right sides (on the X axis) The drive objects 30, 60 can be tilted by applying tilting power from both the positive and negative sides).

  Further, the spring structure of the meandering spring 80 has a spring structure with unequal intervals in which the distances between adjacent spring portions are not uniform at all. Details of this point will be described later.

  The electrode wiring 104 is installed along the meandering spring 80. Since the number of turns of the meandering spring 80 is small and the total length is short, the electrode wiring 104 can be configured with a low resistance, and the power consumption can be improved. Details of this point will be described later.

  FIG. 5 is a diagram illustrating an example of the configuration of the packaged piezoelectric actuator according to the first embodiment. FIG. 5A is a perspective view illustrating an example of the overall configuration of the packaged piezoelectric actuator 200 according to the first embodiment. FIG. 5B is a packaged piezoelectric actuator 200 according to the first embodiment. 5C is an example of a central sectional view of the packaged piezoelectric actuator 200 according to the first embodiment.

As shown in FIG. 5A, the packaged piezoelectric actuator 200 according to the present embodiment is configured such that the piezoelectric actuator 110 is accommodated in a package 140 and the upper surface is sealed with a sealing glass 150. The piezoelectric actuator 110 according to the present embodiment is gas-sealed using the sealing glass 150 by, for example, vacuum sealing or Ar or N ₂ . When the driving object 30 is a mirror 31, light is irradiated to the mirror 31 through the sealing glass 150, and the irradiated light is reflected and scanned by tilting, thereby being packaged for a projector or a scanner. The piezoelectric actuator 200 can be configured.

  In FIG. 5B, the packaged piezoelectric actuator 200 includes a package 140 in which a lower regulating member 130 is accommodated, a piezoelectric actuator 110 is accommodated thereon, and an upper regulating member 120 is disposed above the piezoelectric actuator 110. It is provided and sealed with sealing glass 150 thereon. The lower regulating member 130 has an adhesive reservoir 131 at the center, and is configured to be able to adhere and fix to the package 140 by accumulating the adhesive.

  5C, a lower restricting member 130 is provided below the piezoelectric actuator 110, and an upper restricting member 120 is provided above, and the entire package 140 is accommodated from below, and a sealing glass 150 is provided on the upper surface. A cross-sectional configuration is shown. Further, an adhesive reservoir 131 is provided at the center of the lower regulating member 130.

  The movable range of the piezoelectric actuator 110 is restricted by the upper restricting member 120 on the upper side and restricted by the lower restricting member 130 on the lower side. Thereby, even when the packaged piezoelectric actuator 200 receives a large impact due to dropping or the like, it is possible to restrict rapid movement of the piezoelectric actuator 110 and prevent damage.

  FIG. 6 is an example of an exploded view of the packaged piezoelectric actuator 200 according to the first embodiment. FIG. 6A is an example of an entire exploded view of the packaged piezoelectric actuator 200. 6A, an upper restricting member 120 is provided above the piezoelectric actuator 110, and a lower restricting member 130 is provided below the piezoelectric actuator 110. The package 140 accommodates the whole from below, and the sealing glass 150 covers the upper surface. It has become.

  The package 140 has a recess 141 at the center, and the fixed frame 100 of the piezoelectric actuator 110 is placed on the flat portion 142 outside the recess 141. Further, on the X axis of the flat portion 142, a placement portion 143 for placing the lower regulating member 130 is provided. As described with reference to FIG. 4, the packaged piezoelectric actuator 200 according to the present embodiment includes the protrusions 101 and 102 that restrict the horizontal movable range of the piezoelectric actuator 110 itself. In the vertical direction, an upper restricting member 120 attached to the fixed frame 100 of the piezoelectric actuator 110 and a lower restricting member 130 attached to the package 140 are provided. Therefore, the packaged piezoelectric actuator 200 according to the present embodiment has a configuration that restricts the movable range of the movable frame 70 in each of the two horizontal directions and the two vertical directions, and is configured to be resistant to impacts such as dropping. Yes.

  FIG. 6B is an enlarged perspective view of the upper regulating member 120, and FIG. 6C is an enlarged perspective view of the lower regulating member 130. The upper restricting member 120 is configured to be placed on the fixed frame 100 of the piezoelectric actuator 110, and the lower restricting member 130 is placed and suspended on the placing portions 143 on both sides of the center of the package 140. , And has a suspended portion 132. Moreover, the point which has the adhesive sump 131 in the center part of the downward control member 130 is as having demonstrated in FIG.

  As described above, the upper restricting member 120 and the lower restricting member 130 can be easily provided by being placed on the piezoelectric actuator 110 or the package 140, and the piezoelectric actuator 110 that is resistant to an impact in the vertical direction can be realized. It has become.

  Next, the functions achieved by the respective configurations of the piezoelectric actuator 110 according to the first embodiment described with reference to FIGS. 3 and 4 will be described in detail.

  First, the function of the meandering spring 80 will be described with reference to FIG. FIG. 7 is a diagram for explaining the function of the meandering spring 80 of the piezoelectric actuator 110 according to the first embodiment. FIG. 7A is a perspective view illustrating an example of the overall configuration of the piezoelectric actuator 110 according to the first embodiment, and FIG. 7B illustrates a meandering of the piezoelectric actuator 110 according to the first embodiment as a comparative reference example. It is the figure which showed an example of the whole structure at the time of making the spring 80 into the connection member 180 by the linear beam 15. FIG. 7C shows the piezoelectric actuator 110 according to the first embodiment having the meandering spring 80 shown in FIG. 7A and the connecting member 180 without the meandering spring 80 shown in FIG. It is the figure which showed the characteristic comparison with the piezoelectric actuator which has these.

  In FIG. 7C, the upper stage shows the characteristics of the piezoelectric actuator 110 according to Example 1 having the meandering spring of FIG. 7A, and the lower stage is a comparative reference example that does not have the meandering spring 80 of FIG. The characteristic of the piezoelectric actuator which concerns is shown. When both are compared, the tilt sensitivity is the same at 2.21 deg / V, but the resonance frequency is 60 Hz for the piezoelectric actuator 110 according to the first embodiment, whereas the piezoelectric actuator according to the comparative reference example is 200 Hz. It has become. That is, it is considered that the meandering spring 80 has an effect of reducing the resonance frequency.

  7C, when comparing the maximum stress, the piezoelectric actuator 110 according to Example 1 is 0.08 GPa, whereas the piezoelectric actuator according to the comparative reference example is 0.35 GPa. 1 is higher than the piezoelectric actuator 110 according to 1. From this, it is considered that the meandering spring 80 has an effect of reducing the maximum stress and preventing stress concentration.

  In summary, the meandering spring 80 of the piezoelectric actuator 110 according to the first embodiment has no effect on the tilt sensitivity, but has an effect of reducing the resonance frequency and preventing stress concentration. Thus, by installing the meandering spring 80 between the drive source 90 and the movable frame 70, the resonance frequency can be lowered and the maximum stress can be reduced.

  Next, the weight portion 71 of the movable frame 70 described in FIG. 3 will be described. As shown in FIG. 3B, the movable frame 70 has weight portions 71 so as to sandwich the X axis on both sides of the X axis, and the weight portion 71 is connected by a connecting portion 72 that sandwiches the Y axis. Has a shape. The movable frame 70 including the weight portion 71 is formed of the Si support layer 11 described with reference to FIG. The weight portion 71 has a function of reducing the vibration frequency of the tilting power generated by the drive source 90, like the meandering spring 80 described in FIG. If the area of the weight part 71 is made larger and the thickness of the Si support layer 11 is made thicker, the mass of the weight part 71 is increased, and the resonance frequency can be greatly reduced.

  On the other hand, the piezoelectric actuator 110 is usually demanded to be small and space-saving. Therefore, the shape of the movable frame 70 including the weight portion 71 is determined based on the shape of the meandering spring 80. Adjustments may be made to obtain the desired low frequency. For example, when the driven object 30 is driven at a low speed of 60 Hz in the X-axis direction, the meandering spring 80 and the weight portion are reduced so that the frequency of the resonance vibration generated by the drive source 90 is reduced to obtain a frequency of 60 Hz. 71 may be adjusted and configured.

  Thus, by having two resonance frequency lowering means, the meandering spring and the weight portion 71, even if the drive source 90 is caused to resonate and vibrate, a desired low frequency vibration can be reliably obtained.

  Next, another function of the movable frame 70 will be described with reference to FIGS. FIG. 8 is a diagram illustrating a state in which the piezoelectric actuator 110 according to the first embodiment is configured with two axes and is tilted around each axis. FIG. 8A is a diagram illustrating an example of a state in which the piezoelectric actuator 110 according to the first embodiment is driven to tilt around the X axis, and FIG. 8B illustrates the piezoelectric actuator according to the first embodiment. FIG. 10 is a diagram illustrating an example of a state in which 110 is tilted and driven around the Y axis.

  In FIG. 8A, the driven object 30 is driven to tilt around the X-axis axis, but the elastic connecting member 40 is not deformed at all and does not transmit any vibration to the Y-axis. It has become. Similarly, in FIG. 8B, the drive object 30 is driven to tilt around the axis of the Y axis, but the meandering spring 80 is not deformed at all and does not transmit any vibration to the X axis. It has become.

  Thus, when the piezoelectric actuator 110 according to the first embodiment is configured as a two-axis type, the low-speed driving around the X axis and the high-speed driving around the Y axis are independent vibration systems that do not give vibration to each other's driving system. It has become. In the first embodiment, the tilt around the X axis is driven at 60 Hz and the tilt around the Y axis is driven at 30 kHz. However, the setting of the drive frequency is variously changed according to the application. Can also be configured as a similar independent vibration system.

  FIG. 9 is a diagram showing an example of the maximum stress and the tilt sensitivity at the adjacent resonance frequency of each resonance drive frequency. FIG. 9A is a diagram showing an example of the maximum stress and tilt sensitivity at the adjacent resonance frequency of the resonance vibration frequency in the 60 Hz drive around the X axis. Usually, when driving the drive target 30 at a certain resonance frequency, it is known that interference does not occur in vibration unless a high frequency component is present at a value that is a multiple of the resonance frequency within a range of 5 times the resonance frequency. ing. Therefore, when the driven object 30 is driven at a resonance frequency of 60 Hz, high-frequency components do not have to appear at frequencies of 120 Hz, 180 Hz, 240 Hz, and 300 Hz that are multiples of 60 Hz. In FIG. 9A, there is no peak in the tilt sensitivity characteristic with the above-mentioned frequency value in the range of 60 Hz to 300 Hz. In addition, as described above, the maximum stress is 0.5 GPa or less as a problem-free value. However, in FIG. 9A, the maximum stress does not exceed 0.2 Gpa, and there is no problem. ing. Therefore, from FIG. 9A, the tilt drive around the X axis of the piezoelectric actuator 110 according to the first embodiment does not cause interference with the tilt of the Y axis, and there is no problem in strength. I understand that.

  FIG. 9B is a diagram showing an example of the maximum stress and the tilt sensitivity at the adjacent resonance frequency of the resonance vibration frequency in the 30 kHz drive around the Y axis. In FIG. 9B, the tilt sensitivity has a peak around 30 kHz, and the maximum stress also has a peak. In the tilt sensitivity characteristic, no peak occurs in a region other than 30 kHz, and the maximum stress is 0.49 GPa, which is a peak value smaller than 0.5 GPa. Therefore, it can be seen from FIG. 9B that the tilt drive around the Y-axis axis does not cause interference with the X-axis tilt drive and there is no problem in strength.

  As described above, the piezoelectric actuator 110 according to the present embodiment is an independent vibration system that does not cause interference in the tilting of the X axis and the Y axis, and has a configuration with no problem in strength.

  FIG. 10 is a diagram for explaining the reason why no interference occurs between the tilt drive around the X axis and the tilt drive around the Y axis. In FIG. 10, a perspective view of an example of the overall configuration of the lower surface side of the piezoelectric actuator 110 according to the first embodiment is shown, but focusing on the shape of the movable frame 70, the movable frame 70 moves the driving object 30. It has an annular structure that surrounds it in plan view. The tilting motion around the Y axis is completed within the frame of the movable frame 70, and the tilting motion around the X axis is completed by applying tilting power to the connecting portion 72 of the movable frame 70. It has become. In addition, the movable frame 70 is formed of the Si support layer 11 and is made of a rigid member.

  That is, in the piezoelectric actuator 110 according to the first embodiment, the second drive source 50 that is the 30 kHz resonance drive unit, the elastic coupling member 40, and the movable frame 70 that includes the drive target 30 have an annular structure. The structure is strong, and there is an effect that vibrations at 30 kHz resonance are not transmitted to the meandering spring 80 and the drive source 90. Conversely, vibration propagation from the drive source 90, which is a 60 Hz resonance drive unit, to the second drive source 50 and the elastic connecting member 40 is also hindered. Therefore, the piezoelectric actuator 110 according to the first embodiment has a structure in which the drive sources 50 and 90 are vibrationally independent and the occurrence of interference is suppressed.

  FIG. 11 shows, as a comparative reference example, an example of an operation state of a piezoelectric actuator in which the connecting portion 80 is eliminated from the movable frame 70, the movable frame 70 is not an annular structure, and only the weight portions 71 exist on both sides of the X axis. FIG. FIG. 11A shows an operation state at the time of 60 Hz resonance drive, and FIG. 11B shows an operation state at the time of 30 kHz resonance drive.

  In FIG. 11 (A), it is not clearly shown whether or not the elastic connecting portion 40 perpendicular to the drive shaft is resonating, but in FIG. 11 (B), the meandering spring 80 which is not the drive shaft is distorted. It is shown that resonance occurs in the meandering spring 80 perpendicular to the Y axis that is the drive shaft. As described above, when the movable frame 70 is not of an annular structure and the connecting portion 72 of the Si support layer 11 does not exist between the meandering spring 80 and the second driving beam 50 of the high-speed driving portion 55, the meandering spring is driven during 30 kHz driving. It can be seen that 80 resonates and interference occurs between the X-axis tilt drive and the Y-axis tilt drive.

  Next, a low power consumption structure of the piezoelectric actuator 110 according to the first embodiment will be described with reference to FIGS. The piezoelectric actuator 110 according to the present embodiment has a low power consumption structure by improving the tilt angle sensitivity, shortening the wiring length, reducing the resistance, reducing the electrode area, and the like.

  First, a configuration for improving the tilt sensitivity of the high-speed drive unit 55 around the Y axis and reducing the maximum stress will be described with reference to FIGS.

  FIG. 12 is a diagram illustrating an example of a method for optimally designing the shape of the high-speed drive unit 55 of the pressure actuator 110 according to the first embodiment. FIG. 12A is a diagram illustrating an example of a planar configuration of the high-speed drive unit 55 of the piezoelectric actuator according to the first embodiment. As described in FIG. 1, the piezoelectric actuator 110 may be configured by the semiconductor wafer 10 or the like, but the dynamic breaking stress due to the twist mode of Si is about 2 GPa. Considering a work-affected layer by D-RIE (Deep Reactive Ion Etching), the breaking stress is about 1.5 GPa. Furthermore, considering the application of repeated stress, it is necessary to design the maximum stress to 0.5 GPa or less. Further, the tilt sensitivity is set to 1.2 deg / V or more as a target value.

  In FIG. 12A, the high-speed drive unit 55 of the piezoelectric actuator 110 includes an elastic connecting member 40 and a second drive beam 50. The elastic connecting member 40 includes a first spring 41, a second spring 42, and a spring connecting portion 43. The driving object 30 is connected to the second driving beam 50 via the first spring 41, the spring connecting portion 43, and the second spring 42.

  In FIG. 12, it is assumed that each parameter is determined as follows. The widths of the first spring 41 and the second spring are both 0.06 mm. By changing the spring width, the resonance frequency can be greatly changed. Further, the distance between the first springs 41 is A, the distance between the first and second springs (the length of the spring connecting portion 43) is B, and the first spring 41 and the second spring 42 from the outermost side in the X-axis direction to the Y axis If the distance to C is C, the resonance frequency can be adjusted to a constant 30 kHz by making C variable. Further, if the R radius of the connecting portion 45 between the first spring 41 and the driven object 30 is R1, R1 = A / 2 is set. Similarly, if the R radius inside the spring connecting portion 43 is R2, R2 = B / 2 is set. Under such conditions, parameters A and B that maximize the tilt angle sensitivity are calculated. The driving object 30 calculates the parameters A and B under the condition that the driving object 30 is tilted by ± 12 deg around the Y axis.

  FIG. 12B shows the distance A between the two first springs 41 and the length B of the spring connecting portion 43 when the driven object 30 is tilted by ± 12 deg under the conditions of FIG. FIG. 6 is a diagram showing a change characteristic of maximum stress when and are used as parameters. In FIG. 12B, the horizontal axis indicates the length B [mm] of the spring connecting portion 43, and the vertical axis indicates the maximum stress [GPa].

  FIG. 12B shows that the smaller the value of A, the smaller the maximum stress. Further, when the length B of the spring connecting portion 43 at which the stress σ is minimized is Bmin, the relationship of the expression (1) is satisfied.

（１）式は、各特性曲線の極小値を結んで得られた関係式である。

Expression (1) is a relational expression obtained by connecting the minimum values of the characteristic curves.

  FIG. 13 is a diagram for explaining the reason why the length B of the spring connecting portion 43 has a minimum value. From equation (1), the minimum value in the curve of A = 0.3 mm is Bmin = (− 0.2) * 0.3 + 0.28 = 0.22≈0.2. FIG. 13 shows a stress distribution diagram in which the value of B is changed when A = 0.3 mm.

  FIG. 13A shows the stress distribution of the actuator when B = 0.1 mm. FIG. 13A shows the stress distribution when B <Bmin = 0.2 mm. In this case, the stress is concentrated on the second spring 42.

  FIG. 13B is a diagram showing the stress distribution of the actuator when B = 0.3 mm. FIG. 13B shows the stress distribution when B> Bmin = 0.2 mm. In this case, the stress is concentrated on the first spring 41.

  FIG. 13C is a diagram showing the stress distribution of the actuator when B = 0.2 mm. FIG. 13C shows the stress distribution when B = Bmin = 0.2 mm. In this case, the stress is concentrated at the position of the spring connecting portion 43 near the middle between the first spring 41 and the second spring 42. To do.

  In the configuration shown in FIG. 12A, the widths of the first spring 41 and the second spring 42 are 0.06 mm, which is narrower than the spring connecting portion 43 connecting them, and includes a twisted portion. . Therefore, when the length of the spring connecting portion 43 is shortened, stress concentrates on the twisted portion of the second spring 42, and when the length of the spring connecting portion 43 is increased, stress concentrates on the twisted portion of the first spring 41. The stress concentration portion can be moved to the spring connecting portion 43 by setting the length of the spring connecting portion 43 to an intermediate length. By moving the stress concentration portion to the spring connection portion 43 that is wide and does not include a large twist portion, the stress when the drive target 30 is tilted by ± 12 deg can be reduced and a minimum value can be obtained.

  Returning to FIG. In the change characteristics shown in FIG. 12B, the stress has a limit value of 5 GPa or less within a range of a part of the curves of A = 0.1 mm, A = 0.03 mm, and A = 0.005 mm. That is, in the characteristic curve shown in FIG. 12B, A <0.2 mm, and B is a region within a predetermined range. On the other hand, in the characteristic curve of A ≧ 0.2 mm, the maximum stress is 0.5 GPa regardless of the value of B.

  Here, in the characteristic curve of A <0.2 mm, the relational expression with the smaller value of B where the stress crosses the limit value of 0.5 GPa is as shown in Expression (2).

また、各特性曲線が、応力が０．５ＧＰａで交わるＢの値が大きい方の関係式は、（３）式のようになる。

Further, the relational expression in which the characteristic curve has a larger value of B at which the stress intersects at 0.5 GPa is as shown in Expression (3).

よって、応力が限界値の０．５ＧＰａ以下を示すのは、（１）式を満たすＢｍｉｎだけでなく、（４）式の範囲となる。

Therefore, the stress having a limit value of 0.5 GPa or less is not only Bmin that satisfies the formula (1) but also the range of the formula (4).

図１２（Ｃ）は、上述の（１）〜（４）の関係式が満たす領域を示した図である。図１２（Ｃ）において、横軸は第１ばね４１間の距離Ａ〔ｍｍ〕、縦軸はばね連結部４３の長さＢ〔ｍｍ〕を示している。図１２（Ｃ）において、（４）式を満たす範囲が斜線で示されており、領域の境界線である（２）式と（３）式の間に、（１）式が示されている。応力の低減の観点から見れば、（１）式を満たすＡ、Ｂの組み合わせが最適であるが、（４）式の範囲内に入っていれば、設計上問題無いと言える。よって、（４）式を満たす斜線の範囲内で第１ばね４１間の距離Ａ及びばね連結部４３の長さＢを定めればよいことが分かる。

FIG. 12C is a diagram illustrating a region that is satisfied by the relational expressions (1) to (4) described above. In FIG. 12C, the horizontal axis indicates the distance A [mm] between the first springs 41, and the vertical axis indicates the length B [mm] of the spring connecting portion 43. In FIG. 12C, the range satisfying the equation (4) is indicated by oblique lines, and the equation (1) is indicated between the regions (2) and (3) which are the boundary lines of the region. . From the viewpoint of reducing the stress, the combination of A and B satisfying the expression (1) is optimal, but if it falls within the range of the expression (4), it can be said that there is no problem in design. Therefore, it can be seen that the distance A between the first springs 41 and the length B of the spring coupling portion 43 may be determined within the range of the oblique line that satisfies the equation (4).

  FIG. 14 is a diagram showing the characteristics of the tilt sensitivity when the distance A between the first springs 41 and the length B of the spring connecting portion 43 are used as parameters. In FIG. 14, the horizontal axis indicates the length B [mm] of the spring connecting portion 43, and the vertical axis indicates the tilt sensitivity [deg / V].

  FIG. 14 shows that the tilt angle sensitivity increases as the values of A and B both increase. Therefore, the values of A and B that maximize the tilt sensitivity within the range of the maximum stress of 0.5 GPa or less calculated in FIG. 12C are the optimum parameter settings.

  In this range, A = 0.03 mm and B = 0.35 mm are optimum values. At this time, the width of each of the first spring 41 and the second spring 42 is 0.06 mm, C = 1.2 mm, R1 = 0.015 mm, and R2 = 0.175 mm. In this case, the tilt sensitivity is 3.58 deg / V, the voltage for tilting at a tilt angle of ± 12 deg is 0 to 6.5 V, and the maximum stress is 0.49 GPa.

  Conventionally, since the tilt angle was 1.2 deg / V, the voltage for tilting at a tilt angle of ± 12 deg was 0-20V. According to the piezoelectric actuator 110 according to the present embodiment, the power consumption of the high-speed drive unit 55 is reduced to 1 / 9.5 due to the improvement in sensitivity.

  FIG. 15 is a diagram for explaining a configuration for shortening the wiring length of the piezoelectric actuator 110 according to the first embodiment. In general, in the case of a biaxial piezoelectric actuator, the drive source 20 that performs high-speed driving is provided in the vicinity of the object to be driven 30, and the drive source that performs low-speed driving is located outside the drive source 20 that performs high-speed driving. Often provided. In this case, the wiring for supplying power to the electrodes 23 and 24 of the driving source 20 that performs high-speed driving is often installed along the driving beam 90 that performs outer low-speed driving.

  The piezoelectric actuator 110 according to the present embodiment does not use a method in which tilting is stacked by non-resonant driving of a driving beam that is folded back many times, but performs resonance driving, and the frequency is lowered by the meandering spring 80 and the weight portion 71. And adopting a low-speed drive method. Therefore, the driving beam 90 that performs low-speed driving does not have a complicated folding structure, and there are only two (4 pieces) near the fixed frame 100. Therefore, in order to supply power to the 30 kHz drive units 40 and 50 existing in the central portion, it is not necessary to lay out complicated wiring along the folded structure, and power can be supplied with short wiring.

  As shown in FIG. 15, the fixed frame 100 is provided with four high-speed drive wiring terminals 103. As described with reference to FIG. 4, when wiring is performed along the driving beam 90 that exists in only two rows on the outside as a whole, the second driving beam 50 of the 30 kHz resonance unit can be reached with extremely short wiring, and the wiring can be shortened. A power supply wiring for a 30 kHz resonance unit can be arranged. As a result, the wiring length is reduced to 1/10 as compared with the prior art, and the power consumption can be reduced due to the reduction of the wiring resistance.

  Also, the driving beam 90 that performs low-speed driving is not a folded structure as described above, but has a structure in which only two driving beams 90 are arranged on the outside, so that the area of the driving source 20 is greatly reduced. It has a configuration. Due to the reduction in the area of the drive source 20 and the improvement in the tilt angle sensitivity (conventional 0.8 deg / V → the present embodiment 2.2 deg / V), the power consumption of the drive beam 90 that drives at low speed is about 1/15. Can be reduced.

  In addition, since the area of the drive source 20 of the second drive beam 50 that performs high-speed driving is the same as the area of the conventional drive source 20 that performs high-speed driving, a synergistic effect of improving tilt sensitivity and reducing wiring resistance is also achieved. Thus, the power consumption of the second drive beam 50 can be reduced to about 1/20.

  Furthermore, if the system that performs non-resonant driving and accumulates the displacement of tilting as a driving source for low-speed driving, a folded structure that includes multiple layers is included, so that there are many line / space portions with narrow intervals. . Such a folded structure is difficult to manufacture, and the manufacturing yield tends to decrease. On the other hand, in the piezoelectric actuator 110 according to the present embodiment, since the driving beam 90 that performs low-speed driving does not include a complicated folding structure, there is an advantage that manufacturing is easy and manufacturing yield is improved. For example, when the folded structure has a manufacturing yield of 50%, the piezoelectric actuator according to the present embodiment can achieve a yield of 95% or more.

  Next, a structure resistant to the drop impact of the piezoelectric actuator 110 according to the first embodiment will be described with reference to FIGS. First, referring to FIGS. 16 to 18, a configuration serving as a countermeasure against impact of the movable frame 70 and the fixed frame 100 will be described.

  FIG. 16 is an enlarged view of the left back side illustrating an example of a planar configuration of the piezoelectric actuator 110 according to the first embodiment. In FIG. 16, when paying attention to the weight part 71 of the fixed frame 100 and the movable frame 70, the weight part 71 is provided with weight part protrusions 73 and 74, and the fixed frame 100 is provided with protrusions 101 and 102. The projection 73 and the projection 101, and the weight projection 74 and the projection 102 are opposed to each other. The weight projections 73 and 74 and the projections 101 and 102 of the fixed frame 100 regulate the movable range of the movable frame 70 in the X-axis direction and the Y-axis direction when an impact is applied to the piezoelectric actuator 110 due to dropping or the like. This serves to prevent the piezoelectric actuator 110 from being damaged. In the piezoelectric actuator 110 according to the present embodiment, since the interval between the weight projections 73 and 74 and the projections 101 and 102 is set to an appropriate interval, this point will be described.

  In FIG. 16, when the weight portion 71 is tilted by ± 9 deg about the X axis, the weight portions 71 on both sides of the X axis approach the fixed frame 100 of about 0.05 mm in the Y axis direction. Here, a margin of 0.02 mm was provided, and the distance D between the weight projection 73 and the projection 101 was set to D = 0.07 mm. Further, the distance E between the weight projection 74 and the projection 102 in the X-axis direction is set to the minimum width necessary for etching the Si support layer 11 with a thickness of about 500 μm, and E = 0.035 mm. By performing such setting, in normal tilt drive, the weight projection 72 and the projection 101 operate normally without contact even when tilted around the X axis, and there is no impact force due to dropping or the like. When added, the rapid movement of the movable frame 70 can be reliably stopped with the minimum distances D and E, and the piezoelectric actuator 110 can be prevented from being damaged.

  FIG. 17 is a diagram for explaining an arrangement configuration of the weight protrusions 73 and 74 and the protrusions 101 and 102. FIG. 17 is a perspective view of the lower surface of the piezoelectric actuator 110 according to the first embodiment. In FIG. 17, paying attention to the arrangement of the connecting portion 72 and the weight portion protrusion 73 of the movable frame 70, the weight portion protrusion 73 is provided on the extension line of the connecting portion 72 extending in the Y-axis direction. A protrusion 101 is provided on the opposite outer side. Therefore, regarding the movement in the Y-axis direction, a force is received at a portion resistant to the impact on the extension line of the connecting portion 72, and the movable frame 70 is highly resistant to the impact. Similarly, in the X-axis direction, the weight portion protrusion 74 and the protrusion 102 are provided not on the portion of the weight portion 71 having a hollow shape near the driven object 30 but on the outer portion where the weight portion 72 extends in the X direction. In the X-axis direction, the structure is strong against impact.

  FIG. 18 is a diagram illustrating an example of a cross-sectional configuration taken along the X axis of the packaged piezoelectric actuator 110 according to the first embodiment. In FIG. 18, when the piezoelectric actuator 110 is tilted by ± 9 deg about the X axis, the weight portion 71 approaches the upper restricting part 120 and the lower isomeric part 130 by about 0.15 mm. Therefore, a margin of 0.05 mm is provided on both the upper and lower sides, and both the upper gap F and the lower gap G are set to F = G = 0.2 mm. Thereby, the piezoelectric actuator 110 can be reliably protected from impacts such as dropping without affecting the normal tilting operation.

  Next, a configuration serving as a countermeasure against impact of the meandering spring 80 will be described with reference to FIGS. 19 to 22. FIG. 19 is an example of an enlarged view including the periphery of the meandering spring 80.

  In FIG. 19, a meandering spring 80 is shown, and two electrode wirings 104 pass through the meandering spring 80 in order to supply power to the drive source 20 of the second drive beam 50 on the high speed side. Therefore, when the width of the electrode wiring 104 is 0.02 mm, the spring width of the meandering spring 80 is set to 0.07 mm (line 0.02 mm × 2 + space 0.01 mm).

  In FIG. 19, the interval between adjacent springs of the meandering spring 80 is expressed as H, I, J from the outside to the inside, and the length of the meandering spring 80 in the X-axis direction is K. In FIG. 19, adjacent spring intervals H, I, and J have a relationship of H <J <I, and are not equal intervals. Hereinafter, an example of a method for setting the adjacent spring intervals H, I, and J will be described.

  20 and 21 are diagrams illustrating an example of a stress distribution when impact acceleration is applied to the piezoelectric actuator 110 according to the first embodiment in the X, Y, and Z directions by an implicit method.

  FIG. 20 shows an example of the shape and stress distribution of the meandering spring 80 when X = + 0.07 mm, Y = + 0.035 mm, and Z = + 0.02 mm, when colliding with the respective restricting portions 101, 102, 120, and 130. FIG. 20A is an overall deformation view of the piezoelectric actuator 110, FIG. 20B is an enlarged view of the left meandering spring 80, and FIG. 20C is an enlarged view of the right meandering spring 80. FIG. It is.

  Here, the breaking stress is 1.5 GPa, and the stress is not repeatedly applied in the drop impact. Therefore, if the design is made so that the maximum stress is 1.0 GPa or less by multiplying the safety factor, it is sufficient for the drop impact. Designed to withstand. In the piezoelectric actuator 110, the interval D described in FIGS. 16 and 18 is symmetric with respect to the X axis, the interval E is symmetric with respect to the Y axis, and the meandering spring 80 is also symmetrical with respect to the Y axis. Shall.

  FIG. 20A shows that a large stress is applied in the + Y direction. 20B, it can be seen that the left meandering spring 80 has the adjacent spring interval H narrowed, the adjacent spring interval I opened, and the spring shape is deformed. It is also shown in FIG. 20B that the maximum stress of the meandering spring 80 is applied to the connecting portion of the adjacent spring interval I. 20C shows that the spring shape of the right meandering spring 80 is deformed so that the adjacent spring intervals H and J are narrowed and the adjacent spring interval I is opened. Here, the maximum stress value was 0.66 GPa.

  FIG. 21 shows the shape and stress distribution of the meandering spring 80 when it is made to collide with the respective restricting portions 101, 102, 120, and 130 at X = −0.07 mm, Y = −0.035 mm, and Z = + 0.2 mm. It is the figure which showed an example. FIG. 21A is an overall deformation view of the piezoelectric actuator 110, and FIG. 21B is an enlarged view of the left meandering spring 80. FIG. 21C is an enlarged view of the elastic connecting portion 40, and FIG. 21D is an enlarged view of the right meandering spring 80.

  From FIG. 21 (B), it can be seen that the left meander spring 80 has wider adjacent spring intervals H, I, and J. In FIG. 21B, it can be seen that among the adjacent spring intervals H, I, and J, the adjacent spring interval I is deformed most widely.

  From FIG. 21 (C), it can be seen that maximum stress is generated in the connecting portion between the second spring 42 and the weight portion 71 of the movable frame 70 in the elastic connecting portion 40. The maximum stress generated is 0.76 GPa. Since it is a value of 1.0 GPa or less, it is a numerical value with no problem.

  From FIG. 21 (D), it can be seen that the right meandering spring 80 has narrower adjacent spring intervals H and I.

  20 and 21, the stress distribution when the acceleration is applied to the piezoelectric actuator 110 according to Example 1 is shown. In this case, the generated stress is 0.1 GPa or less. That is, the piezoelectric actuator 110 according to the first embodiment generates stress even when the driving object 30, the high-speed driving unit 55, and the movable frame 70 are displaced maximum in the X, Y, and Z directions by applying the drop impact acceleration. 1.0 GPa or less.

  At that time, the adjacent spring intervals H, I, and J at the time of deformation can be secured to 0.05 mm or more so that the adjacent springs of the meandering spring 80 do not contact each other. As a result, as shown in FIG. 19, the interval between adjacent springs of the meandering spring 80 became unequal. In other words, when the adjacent spring intervals H and J are equal to the adjacent spring interval I having the widest interval, the total length K of the meandering spring 80 increases and the overall size of the piezoelectric actuator 110 increases. Therefore, by forming the meandering spring 80 by narrowing the portion where the interval between adjacent springs can be narrowed, the interval between adjacent springs of the meandering spring 80 becomes unequal.

  Next, as a comparative reference example, a description will be given of deformation and stress distribution when the meandering spring 80 is a simple elastic beam having no spring shape.

  FIG. 22 is a diagram showing an example of a stress distribution when the driving beam 90 and the movable frame 70 are connected by a linear spring 180 of an elastic beam without providing the meandering spring 80 as a comparative reference example. . FIG. 22A is an overall modified view, FIG. 22B is an enlarged view of the left linear spring 180, and FIG. 22C is an enlarged view of the right linear spring 180. It is. In addition, the displacement of X = + 0.07 mm, Y = + 0.035 mm, and Z = + 0.2 mm is added to the piezoelectric actuator which concerns on a comparative reference example.

  In FIG. 22 (B), almost the entire linear spring 180 exceeds 1 GPa. Further, in the linear spring 180 on the right side of FIG. 22C, the maximum stress is generated at the connection portion outside the drive beam 90. At this time, the maximum stress is 4.13 GPa, which greatly exceeds 1.0 GPa. Therefore, in the piezoelectric actuator according to the comparative reference example, when the movable frame 70 and the high-speed driving unit 55 and the driving object 30 connected thereto are displaced in the X, Y, and Z directions by the application of the drop impact acceleration, It can be seen that the generated stress exceeds 1.0 GPa and breaks.

  As described above, the meandering spring 80 has the effect of preventing stress concentration by reducing the resonance frequency described in FIG. 7 and dispersing stress generated by the drop impact and preventing the piezoelectric actuator 110 from being damaged. I understand.

  Thus, according to the piezoelectric actuator 110 according to the first embodiment, the driving beam 90 for low-speed driving has a simple configuration of two outside (four pieces), and the driving beam 90 is driven to resonate, and the meandering spring 80 and The frequency is lowered to the low-speed driving frequency by the weight portion 71 of the movable frame 70, and the second driving beam 50 is provided inside the movable beam 70, so that the independent vibration type piezoelectric actuator 110 that does not cause interference in two axes is provided. Can be configured. In addition, power consumption can be reduced by reducing the length of the wiring 104 and the area of the driving source 20. Furthermore, the protrusions 101 and 102 are provided on the fixed frame 100 and the weight protrusions 73 and 74 are provided on the weight 71 of the movable frame 70 to restrict the movable range in the X and Y directions, and the upper restriction member 120 and the lower restriction member 130 are provided. The vertical movable range is also provided, and even if an impact caused by dropping occurs, the structure is not easily damaged. In addition, the meandering spring 80 has a function of reducing stress due to a drop impact, so that the drop resistance can be further increased.

  FIG. 23 is a perspective view illustrating an example of the overall configuration of the piezoelectric actuator 111 according to the second embodiment of the present invention. The piezoelectric actuator 111 according to the second embodiment includes the driving object 30, the elastic coupling portion 40, the second driving beam 50, the movable frame 70, the meandering spring 80, the driving beam 92, and the fixed frame 100. The points provided are the same as those of the piezoelectric actuator 100 according to the first embodiment. The piezoelectric actuator 111 according to the second embodiment differs from the piezoelectric actuator 110 according to the first embodiment only in that the driving beam 92 that performs low-speed driving has a folded structure. Since other components are the same as those of the piezoelectric actuator 110 according to the first embodiment, the same reference numerals are given and description thereof is omitted.

  In the piezoelectric actuator 111 according to the second embodiment, the driving beam 92 having a folded structure is used as the driving beam 92 that is driven at a low speed. Similar to the piezoelectric actuator 110, resonance driving is performed. In FIG. 23, the inner driving beam 92 close to the driving object 30 is connected to the fixed frame 100 and the ends of the adjacent driving beams 92 are sequentially connected to each other. The displacement is accumulated as the tilting power is transmitted to the drive beam 92, and a larger tilt angle than that of the single drive beam 92 can be obtained. In FIG. 23, one drive beam group 93 is composed of three drive beams 92.

  As described above, the driving beam 92 for low-speed driving has a folded structure, and the driving beam group 93 is configured by a plurality of driving beams 92, whereby the tilt angle sensitivity can be improved. Specifically, the tilt sensitivity of the piezoelectric actuator 111 according to Example 2 was 4.4 deg / V, and the tilt angle sensitivity about twice that of the piezoelectric actuator 111 according to Example 1 was obtained. . Further, the maximum stress was about 3 MPa, and there was no problem.

  FIG. 24 is an example of a diagram illustrating a deformed state when the piezoelectric actuator 111 according to the second embodiment is driven. FIG. 24A is a modified view showing a state in which the piezoelectric actuator 111 according to the second embodiment is driven at a low speed around the X axis, and FIG. 24B is a diagram illustrating the piezoelectric actuator 111 according to the second embodiment. It is the deformation | transformation figure which showed the state driven to high-speed around the axis | shaft of the Y-axis.

  In FIG. 24A, the movable frame 70 and the driving object 30 are tilted around the X axis, but the first spring of the elastic coupling portion 40 in the movable frame 70 is not resonated, and the X axis It shows that the tilting drive around does not interfere with the tilting drive around the Y axis.

  In FIG. 24B, the driven object 30 is tilted around the Y axis, but the drive beam 92 is not resonating, and the tilt drive around the Y axis interferes with the tilt drive around the X axis. It shows that it does not occur.

  As described above, even when the piezoelectric actuator 111 according to the second embodiment is configured as the two-axis piezoelectric actuator 111, the tilting drive around the axis of the drive shaft interferes with the tilting drive around the other axis. It has no configuration.

  Further, in the piezoelectric actuator 111 according to the second embodiment, since the driving beam 92 has a folded structure, the manufacturing process is slightly more complicated than the piezoelectric actuator 110 according to the first embodiment, but the number of steps of the folded structure is small. It is unlikely that the power consumption will increase significantly or the manufacturing yield will not deteriorate significantly. In this respect, the piezoelectric actuator 111 according to the second embodiment has advantages in terms of power consumption and manufacturing yield as compared with a piezoelectric actuator using a non-resonant driving beam for low-speed driving.

  Therefore, the piezoelectric actuator 111 according to the second embodiment is employed when the tilt angle sensitivity is important, and the piezoelectric actuator 110 according to the first embodiment is employed when the reduction of power consumption and the improvement of the manufacturing yield are important. As described above, the piezoelectric actuator 110 according to the first embodiment and the piezoelectric actuator 111 according to the second embodiment can be selectively used depending on the application.

  According to the piezoelectric actuator 111 according to the second embodiment, the tilt sensitivity can be further improved.

  FIG. 25 is a diagram for explaining a changed portion of the piezoelectric actuator 112 according to the third embodiment of the present invention. The piezoelectric actuator 112 according to the third embodiment has a configuration that improves the tilt angle sensitivity and reduces the maximum stress in the high-speed drive unit 55.

  FIG. 25A is an example of a diagram illustrating a planar configuration of the high-speed drive unit 55 of the piezoelectric actuator 112 according to the third embodiment. In the piezoelectric actuator 112 according to the third embodiment, the elastic coupling portion 40 of the high-speed drive portion 55 is configured by two first springs 41 in that the first spring 44 is one. 1 is different from the piezoelectric actuator 110 according to FIG. Since other components are the same as those of the piezoelectric actuator 110 according to the first embodiment, illustration and description thereof are omitted. In addition, the same components as those of the piezoelectric actuator 110 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the piezoelectric actuator 112 according to the third embodiment, parameters are set in the high-speed drive unit 55 so as to improve the tilt sensitivity and reduce the maximum stress.

  In FIG. 25A, the width of the first spring 44 is set to A, and the width of the second spring 42 is set to A / 2 that is ½ of the width A of the first spring 44. The length of the spring connecting portion 43 is B, and the distance from the outer ends of the first spring 44 and the second spring 42 to the X axis is C. And the resonance frequency is set to fixed 30 kHz by making the distance C to the X-axis of the 1st spring 44 and the spring connection part 43 variable. In addition, although the spring connection part 43 exists in four places as a whole, all are set to a common value. Further, the R radius of the connection portion 46 between the drive object 30 and the first spring 44 is set to R1 = 0.15 mm, and the R radius inside the spring connection portion 43 is set to R2 = B / 2. And the width A of the 1st spring 44 and the length B of the spring connection part 43 were changed as a parameter, and the optimal value of inclination sensitivity and the maximum stress was examined.

  FIG. 25 (B) shows a change in tilt sensitivity [deg / V] with respect to changes in the width A of the first spring 44 and the length B of the spring coupling portion 43 when the drive target 30 is tilted at an inclination angle of ± 12 deg. It is the figure which showed the characteristic. In FIG. 25B, the inclination angle sensitivity is highest when A = 0.12 mm, and the inclination angle sensitivity is maximum at a value in the vicinity of B = 0.5 mm where 0.4 mm <B <0.6 mm. It is shown.

  FIG. 25C is a diagram showing a change characteristic of the maximum principal stress with respect to a change in the width A of the first spring 44 and the length B of the support beam side connecting portion 54. If the maximum stress is 0.5 GPa or less, it is a numerical value having no problem as the durability of the actuator. In FIG. 25C, when A> 0.1 mm, the maximum stress is 0.5 GPa or less. In addition, a characteristic in which the maximum principal stress is minimum in the vicinity of B = 0.5 mm where A = 0.14 mm or A = 0.12 mm and 0.4 mm <B <0.6 mm is shown. Yes.

  Accordingly, as a shape having a high inclination sensitivity, a small maximum stress, and a relatively small size, for example, A = 0.12 mm, B = 0.5 mm, C = 1.4 mm, R1 = 0.15 mm, R2 = 0. A 25 mm shape may be employed. In this case, the tilt sensitivity is 4.50 deg / V, the voltage for tilting at a tilt angle of ± 12 deg is 0-3.5 V, the maximum stress can be 0.38 GPa, the maximum stress is small, and the tilt sensitivity is high. Good characteristics can be obtained.

  Thus, according to the piezoelectric actuator 112 according to the third embodiment, it is possible to improve the tilt angle sensitivity of the high-speed drive unit 55 and reduce the maximum stress.

  FIG. 26 is a perspective view showing an example of the configuration of the packaged piezoelectric actuator 201 according to the fourth embodiment of the present invention. FIG. 26A is an example of an overall perspective view of the packaged piezoelectric actuator 201 according to the fourth embodiment, and FIG. 26B is an exploded perspective view of the packaged piezoelectric actuator 201 according to the fourth embodiment. FIG. 26C is an example of a cross-sectional perspective view of the packaged piezoelectric actuator 201 according to the fourth embodiment.

  In FIG. 26A, the piezoelectric actuator 110 is housed in the package 140 and the upper surface is covered with the sealing glass 150, which is the same as the packaged piezoelectric actuator 200 according to the first embodiment.

  In the packaged piezoelectric actuator 201 according to the fourth embodiment, the upper restricting member 120 is such that the member that restricts the movable range in the vertical direction is the vertical restricting member 133 in which the upper restricting member and the lower restricting member are integrated. And the lower restricting member 130 are different from the packaged piezoelectric actuator 200 according to the first embodiment. Since the other components are the same as those in the first embodiment, the same reference numerals as those in the first embodiment are attached and the description thereof is omitted.

  In FIG. 26B, a perspective view of the up / down direction regulating member 133 is shown, but the up / down walking regulating member 133 has an upper regulating portion 134 and a lower regulating portion 135. The lower restricting portion 135 is placed and accommodated on the package 140, and the upper restricting portion 134 extends upward so as to sandwich the meandering spring 80, and restricts the upward movement of the piezoelectric actuator 110.

  FIG. 26C illustrates a cross-sectional configuration of the packaged piezoelectric actuator 201 according to the fourth embodiment. The lower restricting portion 135 floats at the center and restricts the movable range below the piezoelectric actuator 110. Further, the upper restricting portion 134 extends from the gap on both sides of the meandering spring 80 of the piezoelectric actuator 110 so as to penetrate the piezoelectric actuator 110, and the movable range above the piezoelectric actuator 110 is restricted by a key-shaped portion. is doing.

  As described above, according to the packaged piezoelectric actuator 201 according to the fourth embodiment, both the upper and lower piezoelectric actuators 201 are used by using the one vertical regulating member 133 having both the upper restriction function and the lower restriction function. The movable range can be regulated. Thereby, it is possible to prevent damage due to impact such as dropping with a simple configuration that is easy to assemble.

  FIG. 27 is a perspective view showing an example of the configuration of the packaged piezoelectric actuator 202 according to the fifth embodiment of the present invention. FIG. 27A is a perspective view illustrating an example of the overall configuration of the packaged piezoelectric actuator 202 according to the fifth embodiment, and FIG. 27B is a packaged piezoelectric actuator 202 according to the fifth embodiment. FIG. 27C is an example of a cross-sectional configuration perspective view of the packaged piezoelectric actuator 202 according to the fifth embodiment.

  27A and 27B, in the packaged piezoelectric actuator 202 according to the fifth embodiment, the piezoelectric actuator 110 is accommodated in the package 140, and the sealing glass 150 covers the upper surface. These are the same as the packaged piezoelectric actuator 200 according to the first and fourth embodiments. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  As shown in FIGS. 27A to 27C, in the packaged piezoelectric actuator 202 according to the fifth embodiment, the vertical regulating member 136 is attached to the movable frame 70 instead of the package 140. This is different from the packaged piezoelectric actuator 201 according to the fourth embodiment. For example, if the vertical restricting member 136 is provided at a position between the movable frame 70 and the meandering spring 80, only the vertical movable range can be restricted without hindering normal tilting drive. As shown in FIG. 27B, the up-down direction regulating member 136 is the same as the packaged piezoelectric actuator 201 according to the fourth embodiment in that it has an upper regulating portion 137 and a lower regulating portion 138.

  As shown in FIGS. 27B and 27C, according to the packaged piezoelectric actuator 202 according to the fifth embodiment, the piezoelectric actuator 110 can be prevented from falling by using a small vertical regulating member 136. In addition, the drop impact can be appropriately performed while making the whole small.

  FIG. 28 is a perspective view showing an example of the configuration of the packaged piezoelectric actuator 203 according to the sixth embodiment of the present invention. FIG. 28A is a perspective view illustrating an example of the overall configuration of the packaged piezoelectric actuator 203 according to the sixth embodiment, and FIG. 28B is a packaged piezoelectric actuator 203 according to the sixth embodiment. FIG. 28C is an example of a cross-sectional configuration perspective view of the packaged piezoelectric actuator 203 according to the sixth embodiment.

  As shown in FIGS. 28A and 28B, in the packaged piezoelectric actuator 203 according to the sixth embodiment, the piezoelectric actuator 110 is accommodated in the package 140, and the sealing glass 150 covers the upper surface. Is the same as the packaged piezoelectric actuator 200 according to the first, fourth, and fifth embodiments. Therefore, the same components as those in the first, fourth, and fifth embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 28B, the packaged piezoelectric actuator 203 according to the sixth embodiment includes an upper restriction member 121 attached to the sealing glass 150 and a lower restriction member 139 attached to the package 140. Different from the packaged piezoelectric actuator 203 according to the first, fourth and fifth embodiments. As described above, the upper regulating member 121 may be configured to be attached to the sealing glass 150.

  Further, as shown in FIGS. 28B and 28C, both the upper restricting member 121 and the lower restricting member 139 are linear members having a thickness and have a simple configuration, and are restricted. The processing of the members 121 and 139 is extremely easy.

  As described above, according to the packaged piezoelectric actuator 203 according to the sixth embodiment, by using the upper restricting member 121 and the lower restricting member 139 which are easy to process with a simple configuration, it is possible to reliably perform the fall prevention measures. it can.

  FIG. 29 is a diagram illustrating an example of a configuration of an optical scanning device according to the seventh embodiment of the present invention, for example, a projector 300. In the seventh embodiment, an example in which the piezoelectric actuators 110 to 112 and 200 to 203 described in the first to sixth embodiments are applied to the projector 300 will be described.

  In FIG. 29, the projector 300 according to the seventh embodiment includes a piezoelectric mirror 205, a laser diode 210, a collimator lens 220, a polarization beam splitter 230, a quarter wavelength plate 240, and a CPU (Central Processing Unit). Device) 250, laser diode driver IC (Integrated Circuit) 260, and piezoelectric mirror driver IC 270. In FIG. 29, a screen 310 is shown as a related component.

  The projector 300 is a device that projects and projects an image on a screen 310. The piezoelectric actuators 110 to 112 and 200 to 203 according to the present embodiment are configured as a biaxially driven piezoelectric mirror 205 and can be applied to the projector 300.

  The laser diode 210 is a light source that emits laser light. The laser light emitted from the laser diode 210 may be diverging light.

  The collimator lens 220 is means for converting divergent light into parallel light. Even if divergent light is incident from the laser diode 210, the collimator lens 220 can make the components of the laser light uniform.

  The polarizing beam splitter 230 is a beam separating unit on which a polarizing film that reflects P-polarized light (or S-polarized light) and transmits S-polarized light (or P-polarized light) is formed. Here, P-polarized light is a component of light that oscillates within the light incident surface, and S-polarized light is a component of light that oscillates perpendicularly to the light incident surface. That is, the polarization beam splitter 230 reflects one of P-polarized light and S-polarized light and transmits the other.

  Accordingly, the parallel light (P-polarized light) from the collimator lens 220 is totally reflected by the polarization beam splitter 230 toward the biaxial piezoelectric mirror 205 side. The polarization beam splitter 230 functions as a light guiding unit that guides light in the direction of the piezoelectric mirror 205.

  The quarter wavelength plate 240 is a phase difference generating unit that generates a phase difference of π / 2 (90 degrees) in the light. The quarter wavelength plate 240 converts linearly polarized light into circularly polarized light and converts circularly polarized light into linearly polarized light. The quarter wavelength plate 240 may be configured integrally with the polarization beam splitter 230.

  The laser beam reflected by the polarization beam splitter 230 passes through the quarter wavelength plate 240 integrally formed with the polarization beam splitter 230 and travels toward the piezoelectric mirror 205.

  The piezoelectric mirror 205 reflects the laser light from the quarter-wave plate 240 by driving the mirror 31 biaxially. The laser beam reflected by the piezoelectric mirror 205 is transmitted through the quarter-wave plate 240 again to be converted to S-polarized light, transmitted through the polarization beam splitter 230, and irradiated onto the screen 310.

  The CPU 250 is means for controlling the laser diode driver IC 260 and the piezoelectric mirror driver IC 270. The laser diode driver IC 260 is means for driving the laser diode 210. The piezoelectric mirror driver IC 270 is means for driving the piezoelectric mirror 205.

  The CPU 250 controls the laser driver IC 260 and drives the laser diode 210. The CPU 250 also controls the piezoelectric mirror driver 270 to control the tilting movement of the piezoelectric mirror 205 around the X axis and the Y axis. When the piezoelectric mirror 205 tilts, the light reflected by the mirror 31 of the piezoelectric mirror 205 is scanned on the screen 310, and an image is formed on the screen 310.

  As described above, the piezoelectric actuators 110 to 112 and 200 to 204 according to the present embodiment can be suitably applied as the piezoelectric mirror 205 for the projector 300, and can stably drive the mirror 31 in two axes with low power consumption. Can display images.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  In particular, the biaxial piezoelectric actuators 110, 111, 112, 200, 201, 202, 203, and 205 have been described in the first to seventh embodiments. However, as described in the first embodiment, the low-speed driving or the high-speed driving is performed. The present invention can also be applied to a uniaxial piezoelectric actuator that performs only the above. Even in the case of a biaxial piezoelectric actuator, the configuration and functions of the piezoelectric actuators 110 to 112, 200 to 203, and 205 according to the present embodiment are applied to only one axis that is driven at high speed or low speed. Also good.

  INDUSTRIAL APPLICABILITY The present invention can be used for a small actuator that scans a light beam or the like by tilting and driving an object to be driven such as a mirror, and a projector and a scanner using the actuator.

10 Semiconductor wafer 11 Si support layer 12, 14 SiO ₂
13 Si active layer 15 Beam 20 Drive source 21 Piezoelectric element 22 Piezoelectric thin film 23, 24 Electrode 30, 60 Drive target 31 Mirror 40 Elastic connecting member 41, 44 First spring 42 Second spring 43 Spring connecting portion 45, 46 Connection location 50 Second drive source 55 High-speed drive unit 70 Movable frame 71 Weight unit 72 Connection unit 73, 74 Weight unit projection 80 Meander spring 90, 92 Drive beam 91 Gap 93 Drive beam group 100 Fixed frame 110, 111, 112 Piezoelectric actuator 120 , 121, upper regulating member 130, 139 lower regulating member 131 adhesive reservoir 132 hanging portion 133, 136 vertical regulating member 134, 137 upper regulating portion 135, 138 lower regulating portion 140 package 150 sealing glass 200-203, 205 package Piezoelectric Actuator 210 CPU
220, 230 Driver IC
240 Laser diode 250 Collimator lens 260 Deflection beam splitter 270 1/4 wavelength plate 300 Projector 310 Screen

Claims (14)

A piezoelectric actuator that tilts and drives a driven object around an axis,
An annular structure that planarly surrounds the object to be driven by weight portions disposed on both sides of the shaft and a connecting portion that extends across the shaft and connects the weight portions; A movable frame that is connected to support the driven object by connecting an object;
A drive beam having a structure in which a piezoelectric thin film is formed on an elastic body, disposed outside the movable frame, and coupled to impart tilting power about the axis to the coupling portion of the movable frame; A piezoelectric actuator comprising:   The drive beams are arranged so as to extend in a direction perpendicular to the axis so as to sandwich the movable frame from both sides in the axial direction, and the paired drive beams are displaced in opposite directions to each other on both sides of the shaft. The piezoelectric actuator according to claim 1, wherein a voltage is applied.   3. The piezoelectric actuator according to claim 1, wherein the drive beam and the connecting portion are connected by a meandering spring in which adjacent beams meander with a gap.   The adjacent interval between the serpentine springs is determined according to the deformation amount of the serpentine spring or the stress distribution applied to the serpentine spring, and the interval between the portions where the deformation amount is large or the stress is greatly applied is small. The piezoelectric actuator according to claim 3, wherein the unequal intervals are wider than the intervals between the small portions.   The adjacent spacing of the meandering spring is such that the meandering portion closest to the location connected to the movable frame and the location connected to the drive beam of the meandering spring is more than the meandering portion of the location on the center side of the meandering spring. The piezoelectric actuator according to claim 4, wherein the piezoelectric actuator is narrow.   The piezoelectric actuator according to claim 1, wherein the driving beam is resonantly driven. A fixed frame surrounding the movable frame and the drive beam in a plane;
The movable frame is formed with the same thickness as the fixed frame,
The piezoelectric actuator according to claim 1, wherein the drive beam is formed thinner than the fixed frame.   The piezoelectric actuator according to claim 7, wherein the fixed frame is provided with a protrusion that regulates a movable range in a horizontal direction of the movable frame. The driving object is connected to the connecting portion of the movable frame via a second driving beam having a structure in which a piezoelectric thin film is formed on an elastic body,
The piezoelectric actuator according to any one of claims 1 to 8, wherein the second driving beam tilts the driving object around a second axis different from the axis.   The piezoelectric actuator according to claim 9, wherein the driving object and the second driving beam are connected by an elastic connecting member including an elastic body having a beam structure.   11. The piezoelectric actuator according to claim 1, further comprising a vertical direction regulating part that regulates a movable range of the movable frame in a vertical direction.   The piezoelectric actuator according to claim 1, wherein the object to be driven is a mirror. A piezoelectric actuator according to claim 12,
A light source that emits light;
A light guide means for guiding the light emitted from the light source to the piezoelectric actuator,
An optical scanning device characterized in that the light reflected by the mirror is scanned by tilting the mirror of the piezoelectric actuator.   The optical scanning device according to claim 13, wherein the light is scanned on a screen to form an image on the screen.

Images