JP2008145894A - Imaging device, moving device, and piezoelectric bimorph actuator - Google Patents

Abstract

An imaging apparatus capable of moving a lens while minimizing power consumption is provided.
A camera shake correction mechanism includes a first piezoelectric bimorph actuator for moving a lens in an X direction and a first for moving a lens in a Y direction. 2 piezoelectric bimorph actuators 220. The camera shake correction mechanism 200 detects the camera shake by an angular velocity sensor using a vibrator or the like that detects Coriolis force and moves the lens 112 in the X direction and the Y direction so as to cancel the camera shake.
[Selection] Figure 1

Description

  The present invention relates to an imaging device such as a digital camera or a video camera, a moving device that can be used in such an imaging device, and a piezoelectric bimorph actuator.

In a camera shake correction mechanism used in a digital camera or the like, it is necessary to detect a camera shake and move the lens so as to cancel it. Conventionally, in order to move such a lens, for example, a voice coil motor is used (see, for example, Patent Document 1).
JP, 2006-171694, A (for example, Claim 1)

  Since a current corresponding to the movement amount of the lens flows through the voice coil motor, power consumption increases. Although an ultrasonic motor may be used instead of the voice coil motor, there are problems similar to those of the voice coil motor. In this type of battery-powered device, there is a strong demand for power saving, and therefore development of a new technology is required.

  In view of the circumstances as described above, an object of the present invention is to provide an imaging apparatus that can move a lens while suppressing power consumption as much as possible, and can be used in such an imaging apparatus. An object of the present invention is to provide a moving device and a piezoelectric bimorph actuator that can move.

  An image pickup apparatus according to the present invention includes an image pickup element, a lens for forming an image on the image pickup element, and a first piezoelectric bimorph actuator for moving the lens. The first piezoelectric bimorph actuator may move the lens in a first direction orthogonal to the optical axis of the lens for camera shake correction, and move the lens in the direction of the optical axis of the lens for autofocusing. You may let them.

  According to the knowledge of the present inventors, for example, the frequency of camera shake is about 1 Hz to 2 Hz, that is, extremely low frequency, and is almost close to a DC component. Since the piezoelectric bimorph actuator is a voltage drive type, resistance between elements is large and power consumption is small with respect to DC. Therefore, by using the piezoelectric bimorph actuator for the movement of the lens, it is possible to perform the camera shake correction while suppressing the power consumption as much as possible. Further, although the stroke by the piezoelectric bimorph actuator is very small as will be described later, the amount of camera shake correction is good enough to match this, so that the practicality is extremely high. The same applies to autofocus.

  In the present invention, the first piezoelectric bimorph actuator is attached to the lens side and has an optical axis and a first axis having an axial direction in a second direction orthogonal to the first direction. The first piezoelectric bimorph element of the cantilever type that can be displaced with respect to the first piezoelectric bimorph element is attached to the front end of the first piezoelectric bimorph element, the first axis engages, and the direction of the optical axis has a long hole with a long diameter. You may comprise so that it may have the 1st shaft connection member which has.

  Since the first shaft coupling member, which is engaged with the first shaft and has a long hole having a long diameter in the direction of the optical axis, is attached to the tip of the first piezoelectric bimorph element, the structure is very simple. The rotational motion of the cantilever type piezoelectric bimorph element can be smoothly converted into linear motion.

  In the present invention, a first shaft coupling member that is movably engaged in a first direction with respect to a first shaft that has an axial direction in a first direction provided in a part where the imaging device is mounted; A first holding member having a second shaft having an axial direction in the second direction, a lens holding portion for holding the lens, and a second engaging with the second shaft movably in the second direction And a second holding member having a third shaft having an axial direction in the first direction. The first piezoelectric bimorph actuator includes a first piezoelectric bimorph element of a cantilever type that can be displaced with respect to the first direction, and a third shaft that engages with the second shaft so as to be movable in the second direction. A shaft connecting member. The second piezoelectric bimorph actuator includes a second cantilever-type piezoelectric bimorph element that is displaceable with respect to the second direction, and a fourth shaft that engages with the third shaft so as to be movable in the first direction. A shaft connecting member.

  With such a configuration, it is possible to smoothly move the lens in, for example, the X direction and the Y direction using two piezoelectric bimorph actuators.

  Here, the third shaft connecting member has a first long hole having a long diameter in the direction of the optical axis that engages with the second shaft so as to be movable in the second direction, and the fourth shaft connecting member is The direction of the optical axis that engages with the third axis so as to be movable in the first direction may be configured to have a second long hole with a long diameter.

  Thereby, the rotational motion of the cantilever type piezoelectric bimorph element can be converted into a linear motion smoothly with a very simple structure.

  In the present invention, a first shaft coupling member that is movably engaged in a first direction with respect to a first shaft that has an axial direction in a first direction provided in a part where the imaging device is mounted; A first holding member having a second shaft having an axial direction in the second direction, a lens holding portion for holding the lens, and a second engaging with the second shaft movably in the second direction And a second holding member having a third shaft having an axial direction in the first direction. The first piezoelectric bimorph actuator is connected to a first cantilever type piezoelectric bimorph element that can be displaced with respect to the first direction, and a first holding member that can substantially extend and contract in the direction of the optical axis. And a telescopic connecting member. The second piezoelectric bimorph actuator includes a second piezoelectric bimorph element of a cantilever type that can be displaced in the second direction and a third shaft that is movable in the first direction and engages with the third shaft. 3 shaft coupling members.

  With such a configuration, it is possible to smoothly move the lens in, for example, the X direction and the Y direction using two piezoelectric bimorph actuators.

  The moving device according to the present invention is a moving device that moves an object in the X direction and the Y direction, the first piezoelectric bimorph actuator for moving the object in the X direction, and the object in the Y direction. A second voltage bimorph actuator, a first shaft coupling member engaged with a first shaft having an axial direction in the X direction provided at a predetermined portion so as to be movable in the X direction, and Y A first holding member having a second shaft having an axial direction in the direction, a holding portion for holding the object, and a second shaft coupling member engaged with the second shaft so as to be movable in the Y direction And a second holding member having a third shaft having an axial direction in the X direction. The first piezoelectric bimorph actuator includes a cantilever type first piezoelectric bimorph element that can be displaced in the X direction, and a third shaft coupling member that engages with the second shaft to be movable in the Y direction. Have The second piezoelectric bimorph actuator includes a second piezoelectric bimorph element of a cantilever type that is movable in the Y direction, and a fourth shaft coupling member that engages with a third shaft so as to be movable in the X direction. Have

  With such a configuration, an object can be smoothly moved in the X direction and the Y direction using two piezoelectric bimorph actuators.

  Here, the third shaft connecting member has a first long hole having a long diameter in the Z direction engaged with the second shaft so as to be movable in the Y direction, and the fourth shaft connecting member is arranged in the X direction. You may comprise so that the Z direction which engages with a 3rd axis | shaft so that a movement is possible may have a 2nd long hole with a long diameter.

  Accordingly, the rotational motion of the cantilever type piezoelectric bimorph element can be converted into a linear motion in the Z direction smoothly with a very simple structure.

  A moving device according to another aspect of the present invention is a moving device that moves an object in the X direction and the Y direction, the first piezoelectric bimorph actuator for moving the object in the X direction, and an object. A second voltage bimorph actuator for moving in the Y direction, and a first shaft coupling engaged with a first shaft having an axial direction in the X direction provided at a predetermined portion so as to be movable in the X direction A first holding member having a member and a second shaft having an axial direction in the Y direction; a holding portion for holding the object; and a second engaging with the second shaft so as to be movable in the Y direction. A second holding member having a shaft connecting member and a third shaft having an axial direction in the X direction; The first piezoelectric bimorph actuator includes a cantilever type first piezoelectric bimorph element that can be displaced in the X direction, and a telescopic coupling member that is coupled to the first holding member so as to substantially expand and contract in the Z direction. And have. The second piezoelectric bimorph actuator includes a second cantilever-type piezoelectric bimorph element that is movable in the Y direction, and a first Z axis that has a major axis in the Z direction that engages with the second shaft to be movable in the Y direction. And a third shaft connecting member having a long hole.

  Accordingly, the rotational motion of the cantilever type piezoelectric bimorph element can be converted into a linear motion in the Z direction smoothly with a very simple structure.

  A piezoelectric bimorph actuator according to the present invention is a piezoelectric bimorph actuator that moves an object via an axis provided on the object, and cantilevered in a first direction orthogonal to the axial direction of the axis. A beam-type piezoelectric bimorph element, and a shaft coupling member that is attached to the tip of the piezoelectric bimorph element, engages with a shaft, and has a long hole with a long diameter in the second direction perpendicular to the axial direction and the first direction. It has.

  Thereby, the rotational motion of the cantilever type piezoelectric bimorph element can be converted into a linear motion smoothly with a very simple structure.

  As described above, according to the present invention, it is possible to move an object (for example, a lens) while suppressing power consumption as much as possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Imaging device]
FIG. 1 is a diagram showing a schematic configuration of a digital camera according to an embodiment of the present invention.
As shown in FIG. 1, the digital camera 100 includes an optical unit 110 including a prism 111 and a lens 112, an image sensor 120 such as a CCD, and a camera shake correction mechanism 200 for correcting camera shake of the lens 112. Have
The camera shake correction mechanism 200 has a first piezoelectric bimorph actuator 210 for moving the lens 112 in the X direction and a second piezoelectric bimorph for moving the lens 112 in the Y direction, with the optical axis of the optical system as the Z axis. And an actuator 220. The camera shake correction mechanism 200 detects the camera shake by an angular velocity sensor using a vibrator or the like that detects Coriolis force and moves the lens 112 in the X direction and the Y direction so as to cancel the camera shake. The angular velocity sensor is described in detail in, for example, JP-A-2005-227110.

As already described, for example, the frequency of camera shake is about 1 Hz to 2 Hz, that is, extremely low frequency, and is almost close to a DC component. Since the piezoelectric bimorph actuators 210 and 220 are of a voltage drive type, resistance between elements is large with respect to DC and power consumption is small. Therefore, by using the piezoelectric bimorph actuators 210 and 220 to move the lens 112 for camera shake correction, it is possible to execute the camera shake correction while suppressing power consumption as much as possible. In addition, the stroke by the piezoelectric bimorph actuators 210 and 220 is as small as about 500 μm, as will be described later, but the amount of camera shake correction is good enough to match this, so the practicality is extremely high. Furthermore, it is possible to take a larger stroke by adopting a multilayer structure of piezoelectric elements described later.
[Piezoelectric bimorph actuator]
FIG. 2 is a diagram showing a schematic configuration of the first piezoelectric bimorph actuator 210 and the second piezoelectric bimorph actuator 220.

  As shown in FIG. 2, a cantilever-type piezoelectric bimorph element 211 that can be shifted in the vertical direction in the figure, and a tip (212, for example, a round pin) 213 are attached to a tip portion 212 of the piezoelectric bimorph element 211, And a shaft coupling member 215 having a long hole 214 having a long diameter L in the horizontal direction in the figure. The shaft 213 is attached to an object 216 to be moved.

  In the shaft connecting member 215, since the shaft connecting member 215 has the long hole 214 having the long diameter DL, the curved motion of the tip portion 212 of the piezoelectric bimorph element 211 can be converted into a linear motion. That is, the first piezoelectric bimorph actuator 210 and the second piezoelectric bimorph actuator 220 can move the object 216 linearly.

  The piezoelectric bimorph element 211 includes a fixed portion 218 that is fixed to the pedestal 217 and does not deform, and a deformable portion 219 that deforms so as to perform the above-described curved motion. An example of the structure of the piezoelectric bimorph element 211 and a manufacturing method thereof will be described in detail later.

  The shaft connecting member 215 is manufactured as a resin molded part by, for example, molding. The shaft connecting member 215 may be made of a commonly used material such as PC (polycarbonate), ABS (acrylonitrile / butadiene / styrene). Of course, a metal material may be used.

  3 and 4 are diagrams showing a connection structure between the piezoelectric bimorph element 211 and the shaft coupling member 215. FIG.

  As shown in FIGS. 3 and 4, the shaft coupling member 215 has a coupling portion 215 b that covers the front surface and both side surfaces of the piezoelectric bimorph element 211 excluding the back surface. The connecting portion 215b and the tip end portion 212 of the piezoelectric bimorph element 211 may be bonded with, for example, an instantaneous adhesive.

  5 and 6 are diagrams showing another example of a connection structure between the piezoelectric bimorph element 211 and the shaft coupling member 215. FIG.

  As shown in FIGS. 5 and 6, the shaft coupling member 215 has a coupling portion 215 c that covers both the front and back surfaces and the other side surface of the piezoelectric bimorph element 211 except for one side surface. Similarly to the above, the connecting portion 215c and the tip portion 212 of the piezoelectric bimorph element 211 may be bonded by, for example, an instantaneous adhesive.

  FIG. 7 is a diagram schematically showing the relationship between the shaft 213 of the object 216 and the long hole 214 of the shaft coupling member 215.

  As shown in FIG. 7, if the axis 213 is a circle of φD having an arbitrary tolerance, φD = D in the linear movement direction Y direction of the displacement object 216. In the case of a general metal pin constituting the shaft 213, the outer diameter tolerance is about several μm. The φD shaft 213 and the long hole 214 of the shaft coupling member 215 need to be larger than D, and this is Da. In order to provide a degree of freedom of rotation between the first piezoelectric bimorph actuator 210 or the second piezoelectric bimorph actuator 220 and the object 216, the minimum diameter Da of the shaft 213 with respect to the maximum diameter D (max) of the shaft 213. (Min) needs to be Da (min) = D (max) + m. This m is the minimum clearance. For example, if the tolerance width of the shaft 213 is 5 μm and the hole tolerance is 10 μm, the clearance between the shaft 213 and the long hole 214 is m + 5 + 10 = m + 15 μm, and if m = 5 μm, the clearance is 5 μm to 20 μm.

  Increasing the clearance reduces the frictional resistance in the shaft rotation, while increasing the “backlash”. On the other hand, it is desirable to make the clearance as small as possible in consideration of the shaft rotation friction. What is necessary is just to be about 10 micrometers. On the other hand, the outer diameter of the shaft 213 is D in the same direction as the Y-axis direction with respect to the X-axis direction that is the longitudinal direction of the piezoelectric bimorph element 211 in the direction orthogonal to the moving direction of the displacement object 216, whereas The long hole 214 becomes DL. When the clearance in the X-axis direction is mL, DL = D + mL. As shown in FIG. 8, this mL needs to be mL> mX with respect to the protrusion difference mX in the X-axis direction of the tip end portion 212 of the piezoelectric bimorph element 211. In consideration of tolerances and variations, DL = It is sufficient if D (max) + mX (max). In addition, it is possible to increase the DL in consideration of variations in the mounting accuracy of the actual first piezoelectric bimorph actuator 210 and the second piezoelectric bimorph actuator 220. In principle, there is no displacement performance degradation caused by increasing DL.

It is effective to reduce the amount of friction by applying generally used silicon grease or the like to the shaft coupling portion between the shaft 213 of the object 216 and the long hole 214 of the shaft coupling member 215. .
9 and 10 are views showing a structure in which grease is easily filled in the shaft coupling portion.
As shown in FIGS. 9 and 10, this structure is provided with a grease filling hole 221 that penetrates the long hole 214 from one side surface parallel to the long hole 214 of the shaft connecting member 215. The grease filling hole 221 is filled with grease 222. The grease 222 is supplied to a shaft coupling portion between the shaft 213 and the long hole 214 of the shaft coupling member 215 so that the lubricity between them is enhanced.

By using the first piezoelectric bimorph actuator 210 and the second piezoelectric bimorph actuator 220 configured as described above, the rotational motion of the cantilever-type piezoelectric bimorph element 211 can be smoothly linearized with a very simple structure. Can be converted into motion.
[Camera shake correction mechanism (moving device)]
11 is a perspective view showing the configuration of the camera shake correction mechanism 200, and FIG. 12 is a side view of the camera shake correction mechanism 200 shown in FIG.

  As shown in FIGS. 11 and 12, a shaft holding member 102 for holding both ends of a shaft 101 having an axial direction in the X direction is provided at a predetermined portion where the camera shake correction mechanism 200 in the digital camera 100 is disposed. 103, similarly, shaft holding members 105 and 106 for holding both ends of the shaft 104 having the axial direction in the X direction are arranged. A camera shake correction mechanism 200 is disposed between the shaft 101 and the shaft 104.

  The camera shake correction mechanism 200 includes a first holding member 230 and a second holding member 250.

  The first holding member 230 has two shaft coupling members 231 and 232 that engage with the shaft 101 so as to be movable in the X direction, and can move in the X direction with respect to the shaft 104. And two shaft coupling members 233 and 234 that engage with each other on the other side in the Y direction. The first holding member 230 has a shaft 235 having an axial direction in the Y direction on one side in the X direction, a shaft 236 having an axial direction in the Y direction on the other side in the X direction, and both ends of the shaft 235. Shaft holding members 237 and 238 for holding the shaft 236 on one side in the X direction, and shaft holding members 239 and 240 for holding both ends of the shaft 236 on the other side in the X direction.

  The second holding member 250 has a lens holding portion 251 that holds the lens 112. The second holding member 250 has two shaft coupling members 252 and 253 that engage with the shaft 235 so as to be movable in the Y direction, and can move in the Y direction with respect to the shaft 236. And two shaft coupling members 254 and 255 that engage with each other on the other side in the X direction. The second holding member 250 has a shaft 256 having an axial direction in the X direction on one side in the Y direction, and has shaft holding members 257 and 258 for holding both ends of the shaft 256 on one side in the Y direction. .

  The long hole 214 of the shaft coupling member 215 of the first piezoelectric bimorph actuator 210 is engaged with the shaft 235 so as to be movable in the Y direction. The long hole 214 of the shaft coupling member 215 of the second piezoelectric bimorph actuator 220 engages with the shaft 256 so as to be movable in the X direction.

  For example, the width of the piezoelectric bimorph element 211 of the first piezoelectric bimorph actuator 210 and the second piezoelectric bimorph actuator 220 is 2.4 mm, and the length (free length) of the deformable portion 219 is 20 mm. The length of the piezoelectric bimorph element 211 including the extended portion is 28 mm. Here, a 0.8 mm × 1.5 mm long hole 214 (R0.4 mm) is provided in the shaft connecting member 215, and a φ0.8 mm shaft 213 is engaged with the long hole 214.

  FIG. 13 is a graph showing the relationship between the driving frequency of the first and second piezoelectric bimorph actuators 210 and 220 and the amount of lens displacement, and FIG. 14 is a graph showing the relationship between the driving voltage and the amount of lens displacement. .

  The displacement of the tip of the first and second piezoelectric bimorph actuators 210 and 220 alone is about 550 μm around 1 Hz, which is the actual operating frequency of camera shake correction. However, only the linear motion has a degree of freedom. In this case, a linear displacement of about 500 μm can be secured, and the displacement reduction is only about 10%. In the graph of FIG. 13, the horizontal axis represents the displacement frequency, and the displacement amount decreases as the frequency increases. This is due to the inertia weight (about 0.5 g) of the object to be displaced. Further, as shown in FIG. 14, the driving voltage and the displacement amount of the lens have a substantially linear relationship, and here, the linear displacement of about 500 μm can be secured at 18V.

(Other examples of camera shake correction mechanism (moving device))
FIG. 15 is a perspective view showing the configuration of the camera shake correction mechanism 300.
As shown in FIG. 15, the camera shake correction mechanism 300 is disposed between the shaft 101 and the shaft 104 of a predetermined part in the digital camera 100.

  The camera shake correction mechanism 300 includes a first holding member 330 and a second holding member 350.

  The first holding member 330 has two shaft coupling members 331 and 332 that engage with the shaft 101 so as to be movable in the X direction, and is movable in the X direction with respect to the shaft 104. Two shaft coupling members 333 and 334 that engage with each other are provided on the other side in the Y direction. The first holding member 330 has a shaft 335 having an axial direction in the Y direction on one side in the X direction, a shaft 336 having an axial direction in the Y direction on the other side in the X direction, and both ends of the shaft 335. Shaft holding members 337 and 338 are provided on one side in the X direction, and shaft holding members 339 and 340 are provided on the other side in the X direction for holding both ends of the shaft 336.

  The second holding member 350 has a lens holding portion 351 that holds the lens 112. The second holding member 350 has two shaft coupling members 352 and 353 that are movably engaged with the shaft 335 in the Y direction, and can move in the Y direction with respect to the shaft 336. And two shaft coupling members 354 and 355 that engage with each other on the other side in the X direction. The second holding member 350 has a shaft 356 having an axial direction in the X direction on one side in the Y direction, and has shaft holding members 357 and 358 for holding both ends of the shaft 356 on one side in the Y direction. .

  The first piezoelectric bimorph actuator 310 differs from the first piezoelectric bimorph actuator 210 and the second piezoelectric bimorph actuator 220 in the configuration of the connecting member. The first piezoelectric bimorph actuator 310 is connected to the other side of the first holding member 330 in the X-axis direction.

  FIG. 16 is a view showing the first piezoelectric bimorph actuator 310, the first holding member 330, and the connecting portion.

  As shown in FIG. 16, a cross-sectional structure (U-shaped) such that an expansion / contraction connection member 311 attached to the tip of the first piezoelectric bimorph actuator 310 can substantially expand and contract in the Z direction (vertical direction). The open part of the character faces the X direction. Thereby, the rotational motion of the first piezoelectric bimorph actuator 310 is converted into a linear motion in the X direction.

  The second piezoelectric bimorph actuator 320 has the same configuration as the second piezoelectric bimorph actuator 220 already described. That is, the long hole 214 of the shaft coupling member 215 of the second piezoelectric bimorph actuator 320 is engaged with the shaft 356 so as to be movable in the X direction.

  Needless to say, the expansion / contraction connecting member attached to the tip of the first piezoelectric bimorph actuator 310 may have another configuration.

  For example, as shown in FIG. 17, the extensible connecting member 340 has a thin plate portion 341 having a thin plate structure in the X direction and the first piezoelectric bimorph actuator 310 is connected to the first end of the first piezoelectric bimorph actuator 310 via the thin plate portion 341. The holding member 330 may be connected to be substantially extendable and contractible in the Z direction (up and down direction).

Further, as shown in FIG. 18, the extensible connecting member 350 has a thin plate portion 351 having a thin plate structure in the Z direction, and the first piezoelectric bimorph actuator 310 is connected to the first end via the thin plate portion 351. The holding member 330 may be connected to be substantially extendable and contractible in the Z direction (up and down direction).
[Structure of piezoelectric bimorph element]
19 is a perspective view showing the configuration of the piezoelectric bimorph element 211 according to this embodiment, FIG. 20 is a plan view of the piezoelectric bimorph element 221 shown in FIG. 19, and FIG. 21 is a left side view of the piezoelectric bimorph element 221 shown in FIG. FIG. 22 is a right side view of the piezoelectric bimorph element 221 shown in FIG. FIG. 23 is a conceptual diagram in which the piezoelectric bimorph element 221 shown in FIG. 19 is disassembled for each layer.

  As shown in these drawings, this piezoelectric bimorph element 211 has a structure in which a total of four layers of piezoelectric elements 501 to 508 including four layers of piezoelectric elements 501 to 504 and four layers of piezoelectric elements 505 to 508 are stacked on the upper side. It has become.

  As shown in FIG. 23, an external electrode 509 is formed on the surface of the uppermost piezoelectric element 501, and an external electrode 510 is formed on the back surface of the lowermost piezoelectric element 508. A first internal electrode 511 is formed between the piezoelectric element 501 and the piezoelectric element 502. A second internal electrode 512 is formed between the piezoelectric element 502 and the piezoelectric element 503. A first internal electrode 513 is formed between the piezoelectric element 503 and the piezoelectric element 504. A second internal electrode 514 is formed between the piezoelectric element 504 and the piezoelectric element 505. A third internal electrode 515 is formed between the piezoelectric element 505 and the piezoelectric element 506. A second internal electrode 516 is formed between the piezoelectric element 506 and the piezoelectric element 507. A third internal electrode 517 is formed between the piezoelectric element 507 and the piezoelectric element 508.

  As shown in FIGS. 19 and 20, an extraction electrode 518 having a width smaller than that of the external electrode 509 is formed on the surface of the piezoelectric element 501 in a region on one side of one end of the surface of the piezoelectric element 501. One end of the extraction electrode 518 is connected to the external electrode 509 and extends toward the end of the piezoelectric element 501, and the other end of the extraction electrode 518 is led out to the side surface side by bending in an L shape. Similarly, a lead electrode 518 connected to the external electrode 510 is formed on the back surface of the lowermost piezoelectric element 508.

  As shown in FIG. 24, lead electrodes (exposed terminals) 519 and 520 extending toward the other side surface and leading to the other side surface are connected to the first inner electrodes 511 and 513. As shown in FIG. 25, lead electrodes (exposed terminals) 521, 522, and 523 that extend toward one side surface and lead out to one side surface are connected to the second inner electrodes 512, 514, and 516, respectively. Yes. As shown in FIG. 26, extraction electrodes (exposed terminals) 524 and 525 extending toward the other side surface and leading to the other side surface are connected to the third inner electrodes 515 and 517, respectively. The extraction electrode 519 and the extraction electrode 520 are led out to a position where they overlap in a plane, and the extraction electrode 524 and the extraction electrode 525 are similarly led out to a position where they overlap in a plane. The extraction electrode 519 and the extraction electrode 520 and the extraction electrode 524 and the extraction electrode 525 are spaced apart by, for example, about 0.4 mm so as not to overlap in plan view.

  As shown in FIG. 21, the lead electrodes 519 and 520 led out to the other side surface (left side surface) are connected to the side surface of the piezoelectric bimorph element 211 by an external electrode 526 formed in a band shape. Similarly, lead electrodes (exposed terminals) 524 and 525 are also connected by an external electrode 527. As shown in FIG. 22, the extraction electrodes 521, 522, and 523 are also connected by the external electrode 528. As shown in FIGS. 19 and 20, the external electrodes 526, 527, and 528 are formed so as to extend to the surface of the uppermost piezoelectric element 501 and the back surface of the lowermost piezoelectric element 508. 27 to 29 show the piezoelectric bimorph element 211 before the external electrodes 526, 527, and 528 are formed.

Here, if the width of each extraction electrode 519 to 525 and the distance between the extraction electrodes 519 to 525 are each 0.4 mm, and the distance from the end of the piezoelectric bimorph element 211 is also 0.4 mm, three extraction electrodes 519 are used. The dimensions necessary to form ˜525 are 0.4 × 3 (number of electrodes) + 0.4 × 2 (distance between electrodes) + 0.4 × 2 (number of element terminals) = 2.8 mm
It becomes.

Therefore, as shown in FIG. 30, in order to form the three extraction electrodes 519 to 525 in the width direction of the piezoelectric bimorph element 211, the width of the piezoelectric bimorph element 211 needs to be 2.8 mm or more. On the other hand, when the electrode arrangement as shown in FIG. 20 is adopted, the lead electrode piezoelectric bimorph elements 211 are not arranged in the width direction of the piezoelectric bimorph element 211, and the required dimensions on the two electrodes 519, 520, 524, and 525 side are 2 mm. There is no need to be restricted by the width of the element 211. From FIG. 20, when the fixed part length of the element is 2 mm, the effective displacement length of the piezoelectric bimorph element 211 is 20 mm.
[Method of manufacturing piezoelectric bimorph element]
FIG. 31 is a process flow showing a general manufacturing method of a piezoelectric bimorph element.
A predetermined calcining process is performed on the piezoelectric powder mixed with the material (step 401) (step 402), and then pulverized into fine particles (step 403).

  A slurry is prepared by mixing the fine particles with a predetermined organic solvent or water-soluble solvent and a binder (step 404). A sheet (green sheet) having a predetermined thickness is prepared from the slurry using a sheet molding apparatus (step 405). An internal electrode paste is printed on the green sheet by screen printing or the like (step 406). The internal electrode material of the laminated piezoelectric element is, for example, silver, an alloy of silver and palladium, platinum or the like.

  The sheets on which the internal electrodes are printed are stacked with a predetermined positional accuracy (steps 407 and 408), and a laminated sheet is formed by hot pressing (step 409). The laminated sheet is divided into a predetermined size to form a substrate (step 410), and the organic component contained in the laminated body is pyrolyzed in a high-temperature furnace (degreasing: step 411). The substrate having no organic content is sintered in a high-temperature furnace adjusted in a predetermined atmosphere, and the laminate is made into a sintered body (step 412).

  The sintered device is appropriately processed (step 413), and external electrodes are formed on the surface of the device (step 414). In general, a silver electrode is formed by heat treatment after a silver paste is applied to an appropriate place by screen printing. Thereafter, polarization processing is performed by applying a predetermined voltage (step 415).

  In this embodiment, in steps 407, 408, and 409, three types of internal electrodes 511 to 517 are stacked as shown in FIGS. The electrodes in the stacking direction at this time are as shown in FIG.

  When the three types of internal electrodes 511 to 517 are laminated in this way, as shown in FIGS. 27 to 29 after the width processing after firing (after steps 412 and 413), each of the three extraction electrodes 519 to 525 is obtained. Is exposed on the side surface of the piezoelectric bimorph element 211. As shown in FIG. 28, lead electrodes 519, 520, 524, and 525 are exposed on the left side surface of the piezoelectric bimorph element 211 in a state offset in the longitudinal direction of the piezoelectric bimorph element 211, and as shown in FIG. 29, the piezoelectric bimorph element 211 is exposed. Lead electrodes 521, 522, and 523 are exposed on the right side surface of 211. When external electrodes 526, 527, and 528 are formed on the piezoelectric bimorph element 211 (step 414), the structure shown in FIGS. 19 to 22 is obtained.

  32, the lead electrodes 521, 522, and 523 have a potential difference of + V than the lead electrodes 524 and 525, and the lead electrodes 519 and 520 have a potential difference of + V than the lead electrodes 521, 522, and 523. When voltage is applied and polarization is performed (step 415), the piezoelectric bimorph element 211 is polarized as shown in FIG. As shown in FIG. 34, a voltage is applied between the extraction electrodes 521, 522, and 523 and the extraction electrodes 524 and 525 and the extraction electrodes 519 and 520 with respect to the piezoelectric bimorph element 211 polarized as shown in FIG. By applying V, the expansion and contraction of the upper part of the piezoelectric bimorph element 211 and the lower part of the piezoelectric bimorph element 211 is reversed and acts as a piezoelectric bimorph.

  As can be seen from the above description, an electrode lead-out surface is provided in the width direction of the piezoelectric bimorph element 211. In the step 413, the width direction of the piezoelectric bimorph element 211 is set to an appropriate dimensional accuracy and surface shape using a diamond grindstone or the like. It is necessary to expose the internal electrodes 511 to 517 by external processing and to electrically connect them to the external electrodes 526, 527, and 528, but in the longitudinal direction of the piezoelectric bimorph element 211, the electrodes are Since there is no need to expose, the longitudinal direction does not have to be processed unless there is a restriction on dimensional accuracy.

  Although the voltage application method is different between polarization and driving, as shown in FIGS. 35 and 36, the voltage application method differs depending on whether the number of piezoelectric elements is even or odd. Become. In FIG. 36, when the number of piezoelectric elements is an even number, the left side of the element shows wiring at the time of polarization, and the right side shows wiring at the time of driving. In FIG. 37, when the number of piezoelectric elements is an odd number, the left side of the element shows wiring at the time of polarization, and the right side shows wiring at the time of driving. 35 and 36, A represents an electrode, and B represents a piezoelectric element.

  In addition, in order to increase the efficiency of the process, it is desired that the piezoelectric bimorph elements 211 are not fired individually but are arranged in an appropriate quantity as a substrate as shown in step 410 and fired. . In this case, the dimensions between the piezoelectric bimorph elements 211 need to be designed in consideration of the firing shrinkage ratio, the grindstone width during external processing, and the like. For this dimension calculation, it is necessary to consider the shrinkage rate at the time of firing, for example, as shown in FIG. 37, the fired substrate (laminated structure) 600 is processed with a predetermined accuracy, and each time The extraction electrodes 519 to 525 need to be exposed. However, for example, if the internal electrodes 511 to 517 are at a position as shown in FIG. 38 due to printing misalignment or other factors, the extraction electrodes 519 to 525 are not exposed due to the width processing, that is, the electrodes cannot be extracted. For this reason, the lead electrodes 519 to 525 need to be dimensioned so as to be surely exposed by grinding wheel processing. On the other hand, in order to increase the number of piezoelectric bimorph elements 211 to be taken out with respect to the size of the substrate (laminated structure) 600, it is desirable to process with a grindstone having a cutting width R as small as possible, and the cutting width R is 0.5 mm or less. Can be done. In order to reliably expose the extraction electrodes 519 to 525 by the width processing, the extraction electrodes 519 to 525 are overlapped with the adjacent piezoelectric bimorph elements 211 as shown in FIG. FIG. 39 is a cross-sectional view in which a drawer portion is particularly extracted. As shown in FIG. 39, if the extraction electrodes 519 to 525 overlap with adjacent piezoelectric bimorph elements 211, the overlap electrode 601 is also exposed as shown in FIG. Originally, it is necessary to electrically extract the thick-line lead electrodes 519 to 525. However, as shown in FIG. 41, the overlap electrode 601 which is overlapped and exposed has the adhesion strength of the external electrodes 526, 527 and 528. The effect of increasing can be expected. This is because the adhesion strength of the external electrodes 526, 527, and 528 to the electrode material is higher than that of the ceramic surface.

  In addition, this invention is not limited to said embodiment.

  For example, the piezoelectric bimorph actuator may be used for autofocusing of the imaging apparatus.

  In addition, the moving device can be used not only for moving the lens but also for various purposes.

It is a figure which shows schematic structure of the digital camera which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of a 1st piezoelectric bimorph actuator and a 2nd piezoelectric bimorph actuator. It is sectional drawing which showed the connection structure of a piezoelectric bimorph element and a shaft coupling member. It is a top view of the connection structure of the piezoelectric bimorph element and the shaft coupling member shown in FIG. It is sectional drawing which showed the other example of the connection structure of a piezoelectric bimorph element and a shaft coupling member. FIG. 6 is a plan view of a connection structure between the piezoelectric bimorph element and the shaft coupling member shown in FIG. 5. It is the figure which represented typically the relationship between the axis | shaft of a target object, and the long hole of a shaft connection member. It is the figure which showed the displacement amount of the front-end | tip part of a piezoelectric bimorph element. It is the top view which showed the structure where grease is easily filled in the part of a shaft connection. It is the side view which showed the structure where grease is easily filled in the part of a shaft connection. It is a perspective view which shows the structure of a camera-shake correction mechanism. It is a side view which shows the structure of the camera-shake correction mechanism shown in FIG. It is the graph which showed the relationship between the drive frequency of a 1st and 2nd piezoelectric bimorph actuator, and the displacement amount of a lens. It is the graph which showed the relationship between the drive voltage of a 1st and 2nd piezoelectric bimorph actuator, and the displacement amount of a lens. It is a perspective view which shows the structure of the other example of a camera shake correction mechanism. It is a figure which shows the 1st piezoelectric bimorph actuator shown in FIG. 15, a 1st holding member, and a connection part. It is a figure which shows the other example of a 1st piezoelectric bimorph actuator shown in FIG. 15, a 1st holding member, and a connection part. It is a figure which shows another example of the 1st piezoelectric bimorph actuator shown in FIG. 15, a 1st holding member, and a connection part. It is a perspective view which shows the structure of a piezoelectric bimorph element. FIG. 20 is a plan view of the piezoelectric bimorph element shown in FIG. 19. FIG. 20 is a left side view of the piezoelectric bimorph element shown in FIG. 19. FIG. 20 is a right side view of the piezoelectric bimorph element shown in FIG. 19. It is the conceptual diagram which decomposed | disassembled the piezoelectric bimorph element shown in FIG. 19 for every layer. It is a top view of the 1st internal electrode. It is a top view of the 2nd internal electrode. It is a top view of the 3rd internal electrode. It is a perspective view which shows the structure of the piezoelectric bimorph element before an external electrode is formed. It is a left view of the piezoelectric bimorph element shown in FIG. It is a right view of the piezoelectric bimorph element shown in FIG. It is a top view which shows the example which formed three extraction electrodes in the width direction of a piezoelectric bimorph element. It is a process flow which shows the general manufacturing method of a piezoelectric bimorph element. It is the figure which showed the wiring at the time of polarization of a piezoelectric bimorph element. It is the conceptual diagram which showed the polarization state of the piezoelectric bimorph element. It is the figure which showed the wiring at the time of the drive of a piezoelectric bimorph element. It is the figure which showed the wiring at the time of polarization and a drive when the lamination number of a piezoelectric element is an even number. It is the figure which showed the wiring at the time of polarization and a drive when the lamination number of a piezoelectric element is an odd number. It is a figure for demonstrating the processing method of the board | substrate (laminated structure) after baking. It is a figure for demonstrating the processing method (when there exists a malfunction) of the board | substrate (laminated structure) after baking. It is sectional drawing which extracted the extraction part in order to demonstrate making an extraction electrode overlap with an adjacent piezoelectric bimorph element. It is a perspective view of a piezoelectric bimorph element in the state where an overlap electrode is exposed. It is a perspective view of a piezoelectric bimorph element in a state where an external electrode is covered on an overlap electrode.

Explanation of symbols

100 Digital Camera 101, 104, 213, 235, 236, 256 Axis 112 Lens 120 Image Sensor 200 Camera Shake Correction Mechanism 210 First Piezoelectric Bimorph Actuator 211 Piezoelectric Bimorph Element 214 Slots 215, 231 to 234, 237 to 240, 252 255, 257, 258 Axis connecting member 216 Object 220 Second piezoelectric bimorph actuator 230 First holding member 250 Second holding member 251 Lens holding portions 501 to 508 Piezoelectric elements 509, 510, 526 to 528 External electrodes 511 517 Internal electrode 518-525 Lead electrode 601 Overlap electrode

Claims (12)

An image sensor;
A lens for forming an image on the image sensor;
An imaging device comprising: a first piezoelectric bimorph actuator for moving the lens. The imaging apparatus according to claim 1,
The first piezoelectric bimorph actuator moves the lens in a first direction orthogonal to the optical axis of the lens for camera shake correction. The imaging apparatus according to claim 2,
A first axis attached to the lens side and having an axial direction in a second direction orthogonal to the optical axis and the first direction;
The first piezoelectric bimorph actuator is attached to the first piezoelectric bimorph element of the cantilever type that can be displaced in the first direction, and to the tip of the first piezoelectric bimorph element. An imaging device comprising: a first shaft coupling member having a long hole with a long diameter in the direction of the optical axis. The imaging apparatus according to claim 2,
An image pickup apparatus, further comprising: a second voltage bimorph actuator that moves the lens in a second direction orthogonal to the optical axis of the lens and the first direction for camera shake correction. The imaging apparatus according to claim 4,
A first shaft coupling member that is movably engaged in the first direction with respect to the first shaft that has an axial direction in the first direction provided in a site where the imaging device is mounted; A first holding member having a second shaft having an axial direction in the second direction;
A lens holding portion that holds the lens; a second shaft coupling member that engages with the second shaft so as to be movable in the second direction; and a third shaft that has an axial direction in the first direction. And a second holding member having
The first piezoelectric bimorph actuator engages with the second shaft movably in the second direction and a first cantilever-type piezoelectric bimorph element that can be displaced in the first direction. And a third shaft connecting member
The second piezoelectric bimorph actuator engages with the third shaft movably in the first direction, and a second piezoelectric bimorph element of a cantilever type that can be displaced with respect to the second direction. An imaging device comprising: a fourth shaft connecting member. The imaging apparatus according to claim 5,
The third shaft connecting member has a first long hole having a long diameter in the direction of the optical axis that engages with the second shaft so as to be movable in the second direction,
The image pickup apparatus, wherein the fourth shaft connecting member has a second long hole having a long diameter in the direction of the optical axis that engages with the third shaft so as to be movable in the first direction. The imaging apparatus according to claim 4,
A first shaft coupling member that is movably engaged in the first direction with respect to the first shaft that has an axial direction in the first direction provided in a site where the imaging device is mounted; A first holding member having a second shaft having an axial direction in the second direction;
A lens holding portion that holds the lens; a second shaft coupling member that engages with the second shaft so as to be movable in the second direction; and a third shaft that has an axial direction in the first direction. And a second holding member having
The first piezoelectric bimorph actuator includes a cantilever type first piezoelectric bimorph element that can be displaced with respect to the first direction, and the first holding unit that is substantially extendable and contractible in the direction of the optical axis. A telescopic connecting member connected to the member,
The second piezoelectric bimorph actuator engages with the third shaft movably in the first direction, and a second piezoelectric bimorph element of a cantilever type that can be displaced with respect to the second direction. An imaging apparatus comprising: a third shaft coupling member that performs the following. The imaging apparatus according to claim 1,
The first piezoelectric bimorph actuator moves the lens in the direction of the optical axis of the lens for autofocusing. A moving device for moving an object in the X and Y directions,
A first piezoelectric bimorph actuator for moving the object in the X direction;
A second voltage bimorph actuator for moving the object in the Y direction;
A first shaft coupling member that is movably engaged in the X direction with respect to a first shaft having an axial direction in the X direction provided in a predetermined portion; and a second shaft having an axial direction in the Y direction; A first holding member having
A second portion having a holding portion for holding the object, a second shaft coupling member that engages with the second shaft so as to be movable in the Y direction, and a third shaft having an axial direction in the X direction. A holding member,
The first piezoelectric bimorph actuator includes a first cantilever-type piezoelectric bimorph element that is movable in the X direction, and a third shaft coupling that engages with the second shaft to be movable in the Y direction. And having a member
The second piezoelectric bimorph actuator includes a second piezoelectric bimorph element of a cantilever type that is movable in the Y direction, and a fourth shaft coupling that engages with the third shaft to be movable in the X direction. A moving device comprising: a member. The mobile device according to claim 9,
The third shaft connecting member has a first long hole having a long diameter in the Z direction that engages with the second shaft so as to be movable in the Y direction.
The moving device, wherein the fourth shaft connecting member has a second long hole having a long diameter in the Z direction that engages with the third shaft so as to be movable in the X direction. A moving device for moving an object in the X and Y directions,
A first piezoelectric bimorph actuator for moving the object in the X direction;
A second voltage bimorph actuator for moving the object in the Y direction;
A first shaft coupling member that is movably engaged in the X direction with respect to a first shaft having an axial direction in the X direction provided in a predetermined portion; and a second shaft having an axial direction in the Y direction; A first holding member having
A second portion having a holding portion for holding the object, a second shaft coupling member that engages with the second shaft so as to be movable in the Y direction, and a third shaft having an axial direction in the X direction. A holding member,
The first piezoelectric bimorph actuator includes a first cantilever-type piezoelectric bimorph element that can be displaced in the X direction, and an expansion / contraction that is connected to the first holding member so as to be substantially expandable / contractible in the Z direction. A connecting member,
The second piezoelectric bimorph actuator has a cantilever type second piezoelectric bimorph element that is movable in the Y direction, and a long axis in the Z direction that engages with the second shaft so as to be movable in the Y direction. And a third shaft connecting member having a first elongated hole. A piezoelectric bimorph actuator that moves the object via an axis provided on the object,
A cantilever-type piezoelectric bimorph element capable of shifting with respect to a first direction orthogonal to the axial direction of the axis;
A shaft coupling member attached to the tip of the piezoelectric bimorph element, engaged with the shaft, and having a long hole with a long diameter in the axial direction and a second direction orthogonal to the first direction. Features a piezoelectric bimorph actuator.

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