Stage device, imaging device and lens barrel

Abstract

To appropriately control a plurality of actuators with different driving directions.SOLUTION: A stationary part 40b supports a movable part 40a in a relatively displaceable manner. Ultrasonic motors 30a, 30b use vibration to generate driving forces in directions not in parallel to each other. A shake correction control unit 15b generates Act. 30a, 30b drive commands on the basis of an Act. 30a, 30b control amount. An actuator driving unit 17b drives the ultrasonic motors 30a, 30b by outputting Act. 30a, 30b driving signals according to the Act. 30a, 30b drive commands. On the basis of a first control amount (Act. 30a control amount) corresponding to a certain ultrasonic motor 30a being one motor (certain actuator) and a second control amount (Act. 30b control amount) corresponding to a certain ultrasonic motor 30b being the other motor, the shake correction control unit 15b generates an Act. 30a drive command corresponding to the one motor.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a stage device, an imaging device, and a lens barrel that generate a driving force by vibration and frictional force. [Background technology]

[0002] Conventionally, stage devices that are applied to imaging devices and the like are known. Friction drive actuators, such as ultrasonic motors, are used as actuators for driving the stage devices. A friction drive actuator is a motor that transmits driving force by repeatedly rubbing the driven body in a certain direction by bringing a friction element into pressure contact with the driven body and vibrating it using a piezoelectric element or the like. Friction drive actuators are generally adopted for stage devices because they have characteristics such as small size, large stroke, high torque, and non-magnetic properties.

[0003] As an example of a friction drive actuator, Patent Document 1 discloses a resonance type ultrasonic motor. This ultrasonic motor generates a driving force by applying a two-phase alternating voltage to a piezoelectric element integrated with a vibrator having a friction element. Drive control is performed using the frequency, amplitude, and phase difference of the two-phase alternating voltage as parameters. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-225503 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, friction drive actuators such as those described above generally generate a driving force in only one direction (so-called linear actuators), and many of them exhibit large resistance in other directions because the friction element is in pressure contact with the driven body. Here, in stage devices that drive in two or more directions (so-called two-dimensional stage devices, etc.), there are some that have a configuration in which multiple friction drive actuators are connected to a single combination of a fixed part (support) and a movable part (driven body). In a stage device with such a configuration, when attempting to drive the movable part in two or more directions, the resistance in the other directions described above can become a problem.

[0006] An object of the present invention is to appropriately control a plurality of actuators with different drive directions. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a driving device comprising: a driven body; a support supporting the driven body so as to be displaceable relative to the driven body; a plurality of actuators each having a friction element, the friction element being fixed to either the driven body or the support, the friction element being in pressure contact with the other of the driven body or the support, and applying driving forces to the driven body in directions that are not parallel to each other using vibration; control means for generating drive commands corresponding to each of the actuators based on control amounts corresponding to each of the plurality of actuators; and drive means for driving each of the actuators by outputting a drive signal corresponding to the drive command generated by the control means, the drive signal is a signal for passing a two-phase alternating current through a piezoelectric element of each of the actuators, and the control amount includes, for each of the actuators, a drive force control amount indicating a drive force and a displacement amount control amount indicating an amount by which the driven body is to be displaced; The control means generates the drive command corresponding to a certain actuator based on a first control amount corresponding to a certain actuator among the plurality of actuators and a second control amount corresponding to another actuator other than the certain actuator among the plurality of actuators. At that time, a command related to a phase difference of the alternating current among the drive commands corresponding to the certain actuator is determined based on the drive force control amount in the first control amount, and a command related to an amplitude of the alternating current among the drive commands corresponding to the certain actuator is determined based on the drive force control amount in the first control amount and the drive force control amount or the displacement amount control amount in the second control amount. The present invention is characterized by the above. Effect of the Invention

[0008] According to the present invention, it is possible to appropriately control a plurality of actuators having different driving directions. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a system configuration of an imaging apparatus to which a stage device is applied. [Diagram 2] FIG. 2 is a cross-sectional view of the image stabilization mechanism taken along line AA as seen from the +Z side. [Diagram 3] 1A is a front view, a bottom view, and a cross-sectional view taken along line BB of an ultrasonic motor. [Figure 4] 2A and 2B are schematic diagrams showing resonance modes of an ultrasonic motor. [Diagram 5] 1 is a schematic diagram illustrating the principle of driving force transmission of an ultrasonic motor. [Figure 6] 1 is a diagram showing changes in the characteristics of an ultrasonic motor according to the phase difference of a two-phase alternating current; [Figure 7] 1A and 1B are a control block diagram for implementing drive control based on phase difference control, and a diagram showing characteristics of an ultrasonic motor in drive control based on phase difference control; [Figure 8] FIG. 4 is a diagram showing changes in the characteristics of an ultrasonic motor according to the amplitude of a two-phase alternating current. [Figure 9] 11A and 11B are diagrams illustrating the characteristics of an ultrasonic motor under power saving drive control. [Figure 10] FIG. 2 is a control block diagram relating to a shake correction mechanism. [Figure 11] FIG. 2 is a block diagram of an actuator controller. [Figure 12] 11A and 11B are diagrams illustrating a frequency LUT, an amplitude LUT, and a phase difference LUT. [Figure 13] 5A and 5B are diagrams illustrating the effect of drive control and drive characteristics. [Figure 14] FIG. 2 is a schematic diagram showing an actuator driving unit and its peripheral configuration. [Figure 15] 1A and 1B are diagrams showing the signals output by a logic IC and the potential of an electrode and the current flowing through a polarization region. [Figure 16] FIG. 2 is a schematic diagram showing a configuration of a shake correction mechanism. [Figure 17] FIG. 2 is a block diagram showing an output transducer, an actuator controller, and an evaluator. [Figure 18] FIG. 1 is a diagram showing a non-resonant ultrasonic motor. [Figure 19] 3A and 3B are a plan view and a front view of the spherical stage device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] (First embodiment) 1 is a block diagram showing the system configuration of an imaging device to which a stage device according to a first embodiment of the present invention is applied. As an example, this imaging device 10 is configured as an interchangeable lens digital camera 10 (hereinafter, camera 10). An interchangeable lens 10b (lens barrel) is detachably attached to a camera body 10a.

[0012] Camera body 10a has camera control unit 14a, imaging element 11, signal processing unit 19 (based on an integrated circuit and its program), shake correction mechanism 20, and camera shake detection unit 16a. Camera body 10a has shake correction control unit 15a (based on an integrated circuit and its program) and actuator driving unit 17a (based on an electronic circuit). Imaging element 11 has an imaging surface 11a.

[0013] Interchangeable lens 10b has a lens control unit 14b, a lens group 12, a blur correction mechanism 40, and a lens blur detection unit 16b. Lens group 12 constitutes an imaging optical system. Lens group 12 includes a blur correction lens 12b. Interchangeable lens 10b has a blur correction control unit 15b (based on an integrated circuit and its program) and an actuator drive unit 17b (based on an electronic circuit).

[0014] In the camera 10, the camera control unit 14a and the lens control unit 14b communicate with each other through a mount member 13 equipped with a communication path, and control the operation of each unit of the camera body 10a and the interchangeable lens 10b, respectively, and perform program processing. In the camera 10, light from a subject is refracted by the lens group 12, and an image of the subject is formed on the imaging surface 11a of the imaging element 11. The imaging element 11 photoelectrically converts this subject image to generate an image signal. A signal processing unit 19 performs various signal processing on this image signal and converts it into image data, allowing shooting to be performed.

[0015] The shake correction mechanisms 20 and 40 correspond to the stage device of the present invention in the camera body 10a and the interchangeable lens 10b, respectively. The detailed configuration of the shake correction mechanisms 20 and 40 will be described later, but the shake correction mechanisms 20 and 40 are configured as stage devices having a movable part and a fixed part that are relatively movable, and equipped with a friction drive actuator that moves the movable part relative to the fixed part. The image sensor 11 and the shake correction lens 12b are held in each movable part of the shake correction mechanisms 20 and 40. The fixed parts and the movable parts are arranged so that the movement direction of each movable part relative to each fixed part is approximately perpendicular to the optical axis 12a of the lens group 12 (hereinafter referred to as the optical axis perpendicular direction). Specifically, the image sensor 11 and the shake correction lens 12b can be moved and controlled in the optical axis perpendicular direction. This allows the camera 10 to perform optical shake correction.

[0016] The blur correction control units 15a and 15b respectively control the operation of each unit and perform program processing in the above-mentioned optical blur correction in the camera body 10a and the interchangeable lens 10b. The actuator driving units 17a and 17b respectively drive the friction drive actuators of the blur correction mechanisms 20 and 40 based on the driving commands of the blur correction control units 15a and 15b in the above-mentioned optical blur correction in the camera body 10a and the interchangeable lens 10b. From this perspective, the blur correction control units 15a and 15b function as the control means in the present invention, and the actuator driving units 17a and 17b function as the driving means in the present invention.

[0017] During shooting using the camera 10, the relative positional relationship between the camera 10 and the subject changes due to shaking of the hand holding the camera 10 or the subject moving, and as a result, the subject image on the imaging surface 11a moves and blurs the captured image. In response to this, the amount of movement of the subject image is detected (predicted), and the blur correction mechanism 20 controls the movement of the imaging element 11 in the direction perpendicular to the optical axis so as to correspond to this, thereby fixing the subject image on the imaging surface 11a and performing blur correction. Furthermore, when the blur correction lens 12b moves in the direction perpendicular to the optical axis, it refracts the optical axis 12a and causes the subject image on the imaging surface 11a to move. Therefore, the blur correction mechanism 40 controls the movement of the blur correction lens 12b in the direction perpendicular to the optical axis so as to correspond to (cancel) the amount of movement of the subject image described above, thereby performing blur correction.

[0018] Camera shake detection unit 16a and lens shake detection unit 16b detect shake of camera 10 in camera body 10a and interchangeable lens 10b, respectively. For example, a gyro sensor is used for these. The gyro sensor detects the angular velocity of shake in each direction of camera 10, and the amount of movement of the subject image can be calculated using the amount of angle obtained by integrating this and shooting information such as the focal length of lens group 12 as parameters. Therefore, shake correction can be performed by calculating the corresponding movements of image sensor 11 and shake correction lens 12b, setting target positions, and controlling the drive of shake correction mechanisms 20 and 40.

[0019] Also, it is possible to obtain a time-series preview image before shooting, and detect (predict) the amount of movement of the subject image due to the movement of the subject by detecting the motion vector of the subject with the signal processing unit 19, and then the camera body 10a can perform blur correction accordingly. Various techniques have been disclosed for detecting the amount of movement of the subject image for these blur corrections and for calculating the drive target, but as these are not essential to the present invention, detailed explanations will be omitted.

[0020] Here, the directions in the camera 10 are defined. As shown in FIG. 1, the direction parallel to the optical axis 12a in the camera 10 is defined as the Z direction, and in particular the direction toward the subject is defined as the +Z direction. Also, the direction perpendicular to the optical axis that is perpendicular to the Z direction and that faces vertically upward in the standard posture assumed by the camera 10 is defined as the +Y direction. Therefore, the up and down direction is the Y direction. Also, the direction perpendicular to the Y and Z directions (i.e. the left-right direction) is defined as the X direction, and in particular the left direction when the subject is viewed forward is defined as the +X direction.

[0021] Next, a detailed description will be given of the configuration of the image stabilization mechanisms 20 and 40 and the drive control method thereof. Note that since the image stabilization mechanisms 20 and 40 have similar roles and configurations, the image stabilization mechanism 40 on the interchangeable lens 10b side will be mainly described in detail as a representative.

[0022] Fig. 2(a) is a view of the image stabilization mechanism 40 as seen from the +Z side. Fig. 2(b) is a cross-sectional view taken along line AA in Fig. 2(a). The image stabilization mechanism 40 includes a movable part 40a and a fixed part 40b, and further includes ultrasonic motors 30a, 30b which are a plurality of friction drive actuators. The movable part 40a is the driven body, and the fixed part 40b is a support that supports the movable part 40a so that it can be displaced relatively.

[0023] The ultrasonic motors 30a and 30b are connected to the movable part 40a by thin plate-shaped connecting members 35a and 35b. The compression spring members 36a and 36b are elastic members for pressurizing the ultrasonic motors 30a and 30b to the fixed part 40a. The movable part 40a is supported by three ball members 47 and three tension spring members 48 on the fixed part 40b extending in a substantially planar shape so as to be capable of rolling. The blur correction mechanism 40 is disposed so that the moving plane of the movable part 40a is substantially perpendicular to the optical axis 12a. Therefore, the movable part 40a can move in the XY plane relative to the fixed part 40a. The blur correction lens 12b is held by the movable part 40a with the optical axis of the blur correction lens 12b aligned with the optical axis 12a. Thus, the blur correction mechanism 40 is a stage device that moves the blur correction lens 12b in the direction perpendicular to the optical axis (within the XY plane).

[0024] The ultrasonic motors 30a, 30b are pressed into contact with the fixed part 40b by the compression spring members 36a, 36b. The connection members 35a, 35b are designed to exhibit relatively high rigidity in the moving direction of the movable part 40a, while exhibiting relatively low rigidity in the other directions, that is, the optical axis 12a direction (Z direction) and the torsional directions (around the X-axis and the Y-axis). This allows the ultrasonic motors 30a, 30b to be pressed into contact with the fixed part 40b without any contradiction, following the biased support state of the movable part 40a on the fixed part 40b.

[0025] The ultrasonic motors 30a and 30b generate driving forces in the X and Y directions, respectively. The directions of these driving forces are not parallel to each other in the XY plane, which corresponds to the moving surface of the movable part 40a. That is, the ultrasonic motors 30a and 30b can transmit driving forces in the X and Y directions, respectively. Therefore, the movable part 40a can be moved to any position within a certain range in the XY plane. In addition, at that time, the rotation restriction part 49, which is a guide mechanism, restricts the rotational movement without interfering with the translational movement of the movable part 40a in the XY plane. This allows the movable part 40a to move while maintaining its posture in the XY plane.

[0026] In the image stabilization mechanism 40, multiple ultrasonic motors 30a, 30b are connected to a single combination of a movable part 40a and a fixed part 40b. This makes the image stabilization mechanism 40 thinner than a typical configuration with two or more stages (for example, a configuration in which a Y-direction moving stage is placed on an X-direction moving stage).

[0027] Next, the detailed configuration of the ultrasonic motors 30a, 30b will be described. Note that since the ultrasonic motors 30a, 30b have the same configuration, they will be generalized and described as the ultrasonic motor 30 here.

[0028] Fig. 3(a) is a front view, a bottom view, and a cross-sectional view along line BB of ultrasonic motor 30. Ultrasonic motor 30 has a metallic vibrator 31 equipped with a friction element, and a piezoelectric element 32 that excites vibrator 31. Vibrator 31 and piezoelectric element 32 are firmly fixed and integrated with adhesive or the like. Fig. 3(b) is a rear view of ultrasonic motor 30. Fig. 3(c) is a front view of piezoelectric element 32. Ultrasonic motor 30 is a resonance type ultrasonic motor.

[0029] Here, the directions used for the ultrasonic motor 30 are defined. The direction in which the ultrasonic motor 30 is brought into pressure contact with the driven body is the pressure direction, which is defined as the vertical direction for convenience. The transducer 31 and the piezoelectric element 32 are in a substantially flat plate shape extending in a plane perpendicular to the pressure direction, and a longitudinal direction and a lateral direction are defined for the substantially flat plate shape. Since the ultrasonic motor 30 transmits driving force in the longitudinal direction, this longitudinal direction is the driving direction, which is defined as the horizontal direction for convenience. The driven body is located on the front side of the ultrasonic motor 30. The back surface of the transducer 31 and the front surface of the piezoelectric element 32 are bonded.

[0030] According to this definition of directions, in the case where the ultrasonic motor 30 is the ultrasonic motor 30a in Fig. 3(a), the short side direction, the long side direction, and the pressure direction correspond to the Y direction, the X direction, and the Z direction, respectively. The front view and the right side view are views seen from the -Z side and the +X side, respectively.

[0031] 4(a) and (b) are schematic diagrams showing the resonance mode of the ultrasonic motor 30. FIG. 5 is a schematic diagram showing the driving force transmission principle of the ultrasonic motor 30. As shown in FIG. 5, the ultrasonic motor 30 is fixed to the movable part 40a (FIG. 2) and is configured to apply a driving force to the fixed part 40b. In this case, the fixed part 40b can be considered as the driven body. However, since the driving force is relative, the ultrasonic motor 30 may be configured to be fixed to the fixed part 40b and to apply a relative driving force to the movable part 40a. In other words, the ultrasonic motor 30 may be configured to be fixed to either the driven body or the support body, and to have a friction element in pressure contact with the other of the driven body or the support body.

[0032] When an alternating current in the ultrasonic range is passed through the piezoelectric element 32 to vibrate it and excite the transducer 31, the ultrasonic motor 30 resonates in two resonance modes shown in Fig. 4(a) and (b) due to the combination of the transducer 31 and the piezoelectric element 32. The shapes of the transducer 31 and the piezoelectric element 32 are designed in advance so that the two resonances occur in frequency ranges close to each other. The transducer 31 has two protrusions 31a and 31b formed as parts corresponding to friction elements. The protrusions 31a and 31b vibrate to trace elliptical loci in phase with each other as shown in Fig. 5, and repeatedly frictionally drive the fixed part 40b in a single direction relative to each other.

[0033] 3, three electrodes 32a, 32b, and 32c are formed on the piezoelectric element 32, and thus two polarization regions 32ac and 32bc are formed on the piezoelectric element 32. The first electrode 32a and the second electrode 32b are present in approximately half of the longitudinal area of ​​the rear surface of the piezoelectric element 32. The third electrode 32c is present on almost the entire front surface of the piezoelectric element 32 and between the electrodes 32a and 32b on the rear surface. The front side and rear side portions of the third electrode 32c are electrically connected via the periphery.

[0034] The first polarization region 32ac and the second polarization region 32bc are a region located between the first electrode 32a and the third electrode 32c, and a region located between the second electrode 32b and the third electrode 32c in the pressure direction (vertical direction), respectively. When an alternating current is applied to the piezoelectric element 32, the polarization regions 32ac and 32bc vibrate by stretching due to the piezoelectric effect. Since the electrodes 32a and 32b can be independently energized, the polarization regions 32ac and 32bc can be semi-independently stretched and contracted. Therefore, the phase difference between the stretching vibrations of the polarization regions 32ac and 32bc can be controlled.

[0035] The protrusions 31a and 31b of the vibrator 31 are arranged in parallel in the longitudinal direction approximately on the center line of the vibrator 31 in the short side direction. These protrusions 31a and 31b are formed, for example, by drawing a metal plate, have rounded tips, and come into approximate point contact with the driven body.

[0036] Such an ultrasonic motor 30 shows two prominent modes of resonance in a frequency range close to each other as shown in FIG. 4 according to the alternating current flowing through the piezoelectric element 32. The first resonance mode is a primary resonance in the short direction as shown in FIG. 4(b). This is an excitation state that occurs when the first polarization region 32ac and the second polarization region 32bc of the piezoelectric element 32 are stretched and vibrated in the same phase (phase difference 0°). In order to properly realize this, it is preferable to set the third electrode 32c to a reference potential of 0 (GND) and to allow an alternating current to flow in the same phase to the electrodes 32a and 32b. That is, it is preferable to allow a two-phase alternating current (hereinafter simply referred to as "two-phase AC") with a phase difference of 0° to flow through the ultrasonic motor 30. At this time, both of the protrusions 31a and 31b are arranged at the antinodes of the resonance, and the protrusions 31a and 31b vibrate in the vertical direction as shown by the arrow 431ab.

[0037] The second resonance mode is a secondary resonance in the longitudinal direction as shown in FIG. 4(a). This is an excitation state that occurs when the first polarization region 32ac and the second polarization region 32bc of the piezoelectric element 32 are stretched and vibrated in opposite phases. In order to properly realize this, the third electrode 32c should be set to a reference potential 0 (GND) and an alternating current should be made to flow in opposite phases to the electrodes 32a and 32b. That is, a two-phase alternating current with a phase difference of 180° should be made to flow through the ultrasonic motor 30. In this case, both of the protrusions 31a and 31b are disposed near the nodes at every other node in the longitudinal direction and protrude in the vertical direction from the nodes. As a result, the tips of the protrusions 31a and 31b vibrate in the same phase approximately in the horizontal direction as shown by the arrows 431a and 431b.

[0038] These two resonant modes are designed to appear in frequency ranges close to each other, so that the two modes can be excited simultaneously by passing a current including both the above-mentioned two-phase AC component with a phase difference of 0° and the above-mentioned two-phase AC component with a phase difference of 180°. As such a current, for example, AC 501a with a phase difference of 0° and AC 501b with a phase difference of 90° may be passed as shown in Fig. 5. In this case, as shown in Fig. 5, the protrusions 31a and 31b exhibit a vibration in which the horizontal vibration indicated by the arrows 431a and 431b in Fig. 4(a) and the vertical vibration indicated by the arrow 431ab in Fig. 4(b) are superimposed.

[0039] That is, the protrusions 31a and 31b vibrate to describe elliptical loci as indicated by arrows 502a and 502b, respectively. As a result, the protrusions 31a and 31b exert frictional forces 503a and 503b on the driven body (fixed part 40b in this case) by repeatedly coming into contact with and separating from the driven body in the vertical direction and repeatedly vibrating in one horizontal direction. Therefore, the resultant force is transmitted to the driven body as the driving force of the ultrasonic motor 30.

[0040] Fig. 6 is a diagram showing changes in the characteristics of the ultrasonic motor 30 according to the phase difference of the two-phase AC flowing through the ultrasonic motor 30. Fig. 6 shows the vibration strength (horizontal, vertical), vibration locus, and driving force (horizontal friction force) transmitted by friction of the two protrusions 31a and 31b of the vibrator 31 according to the phase difference of the two-phase AC. Since the characteristics of the two protrusions 31a and 31b are similar to each other, Figs. 6 to 9 will be used to explain the characteristics of the ultrasonic motor 30, focusing on the protrusion 31a as a representative example. In the example shown in Fig. 6, the frequency and amplitude of the two-phase AC are constant.

[0041] As shown in Fig. 6, when the phase difference of the two-phase AC flowing through the ultrasonic motor 30 is 0°, the vibration of the protrusion 31a shows a large amplitude mainly in the vertical direction, as shown in Fig. 4(b). In contrast, when the phase difference of the two-phase AC increases to 90°, the component with a phase difference of 0° decreases, and the component with a phase difference of 180° increases. Therefore, the vibration of the protrusion 31a increases in the horizontal direction and decreases in the vertical direction, as shown in Fig. 4(a).

[0042] As a result, the vibration locus of the tip of the protrusion 31a is an ellipse with a large eccentricity (about 1) when the phase difference of the two-phase AC is 0°, but as the phase difference increases from there to 90°, the ellipse becomes a shape with a smaller eccentricity. As a result, the driving force transmitted by the lateral friction of the protrusion 31a is small and almost 0 when the phase difference of the two-phase AC is 0°, but increases as the phase difference increases to 90°. Therefore, the ultrasonic motor 30 can be used as an actuator capable of drive control (drive control by phase difference control) in which a two-phase AC is passed and the output is controlled using the phase difference as a parameter. Drive control by phase difference control will be described with reference to FIG. 7.

[0043] Fig. 7(a) is a control block diagram for realizing drive control by phase difference control, and Fig. 7(b) is a diagram showing the characteristics of the ultrasonic motor 30 in drive control by phase difference control.

[0044] In order to drive the ultrasonic motor 30, it is sufficient to allow a two-phase alternating current to flow, and as a drive signal for this purpose, for example, a two-phase alternating voltage may be applied as shown in Fig. 7(a). The piezoelectric element 32 is electrically equivalent to a capacitor. Therefore, when a two-phase alternating voltage is applied, a two-phase alternating current with equal frequency and phase difference and an amplitude determined by the reactance component of the circuit flows through the piezoelectric element 32.

[0045] Therefore, for example, the actuator driver 17 is configured with, for example, a sine wave generator. Then, when the actuator driver 17 receives the respective values ​​of the frequency command, the amplitude command, and the phase difference command as drive commands, it generates a two-phase alternating voltage, which is a drive signal corresponding to the respective values, and applies the voltage to the ultrasonic motor 30. The drive command at this time is determined by the blur correction control unit 15b and output to the actuator driver 17, as will be described in detail later.

[0046] The characteristics of the ultrasonic motor 30 when driven and controlled by the above-mentioned phase difference control are as shown in FIG. 7(b). As the phase difference command increases from 0° to 90°, the driving force tends to increase almost monotonically. This allows the ultrasonic motor 30 to be driven and controlled. However, there is a problem that the power consumption is large regardless of the phase difference command. That is, in the ultrasonic motor 30, unlike a general DC motor, the power consumption does not decrease much even at low output. This is because, as explained in FIG. 4(b) and FIG. 6, the ultrasonic motor 30 vibrates significantly in the vertical direction even at low output. Such vertical vibration hardly contributes to the output. Therefore, from the viewpoint of reducing power consumption, it is preferable to control the ultrasonic motor 30 to reduce the input to the ultrasonic motor 30 at low output.

[0047] Fig. 8 is a diagram showing changes in the characteristics of the ultrasonic motor 30 according to the amplitude of the two-phase AC current flowing through the ultrasonic motor 30. Fig. 8 shows the power consumption, the vibration locus of the protrusion 31a, the driving force, and the holding force (lateral static friction force) according to the amplitude of the two-phase AC current. In the example shown in Fig. 8, the frequency of the two-phase AC current is constant.

[0048] As shown in Fig. 8, when the amplitude of the two-phase AC is reduced, the power consumption is also reduced. In this case, since the power consumption is proportional to the square of the current, the effect of reducing the power consumption by reducing the amplitude is large. On the other hand, when the amplitude of the two-phase AC is reduced, the long side of the ellipse of the vibration locus of the protrusion 31a of the vibrator 31 is reduced, but at the same time, the short side is also reduced, and the eccentricity of the ellipse does not change much. Therefore, even if the amplitude of the two-phase AC is reduced, the driving force does not change drastically, and the originally small driving force only becomes smaller.

[0049] 9 is a diagram showing the characteristics of the ultrasonic motor 30 in power-saving drive control. In addition to drive control using phase difference control, "power-saving drive control" is a control that reduces the amplitude command so that the amplitude of the two-phase AC current flowing is reduced during low output. In other words, drive control using phase difference control reduces the phase difference as the required drive force becomes lower, while power-saving drive control additionally reduces not only the phase difference but also the amplitude as the required drive force becomes lower.

[0050] Since the current and voltage flowing through the piezoelectric element 32 are approximately proportional to each other, the amplitude command in the power saving drive control can be set to reduce the voltage at the same rate as the rate at which the current is reduced (coefficient α indicating this rate). This rate is taken as coefficient α. Coefficient α is a coefficient greater than 0 and less than 1.

[0051] As shown in Fig. 9, by performing power-saving drive control, it is possible to greatly reduce power consumption at low output compared to drive control by simple phase difference control shown in Fig. 7(b). On the other hand, the drive force still tends to increase monotonically with respect to the phase difference command, so there is no problem in drive control of the ultrasonic motor 30.

[0052] Such power-saving drive control can generally be applied as is to a stage device (so-called linear stage) that is driven in only one direction. However, the image stabilization mechanism 40 in this embodiment is a stage device (so-called two-dimensional stage, etc.) in which multiple ultrasonic motors 30 are connected to a combination of a movable part 40a and a fixed part 40b, and which is driven within the XY plane. Therefore, simply applying the power-saving drive control may result in a new problem. This problem will be explained.

[0053] 8, when the amplitude of the two-phase AC current flowing through the ultrasonic motor 30 decreases, the vertical component of the vibration of the protrusion 31a of the vibrator 31 decreases, so the proportion of time in contact with the driven body increases in the repeated contact and separation. This increases the holding force (static friction force) exerted on the driven body, and therefore increases the resistance force exerted in a direction different from the driving direction.

[0054] 2, for example, when power-saving drive control is applied to the ultrasonic motor 30a for driving in the X direction, resistance to driving in the Y direction (driving the ultrasonic motor 30b) increases. This may result in a problem that the drive controllability of the blur correction mechanism 40 decreases.

[0055] For example, in the case where the camera 10 does not shake much in the X direction but shakes a lot in the Y direction, the image stabilization mechanism 40 does not move much in the X direction but tries to move with a large driving force in the Y direction. In this case, the ultrasonic motor 30a for driving in the X direction is controlled to have a low output, but because a large resistance force is exhibited in the Y direction due to the power saving drive control, the motor does not move with a large driving force in the Y direction even if it tries to do so. For example, the movement may be delayed and the correction may not be completed in time.

[0056] Also, for example, when the camera 10 performs pixel shift photography using shake correction, the shake correction mechanism 40 may not move in the Y direction, but may move very small amounts precisely in the X direction. In other words, this is the case when the position deviation to the target position in the X direction is very small. In this case, if the ultrasonic motor 30b for driving in the Y direction exhibits a large resistance in the X direction due to the application of power saving drive control, the motor may not move very small amounts precisely in the X direction, and the feedback control may eventually overshoot.

[0057] For these reasons, in the drive control of a two-dimensional stage device such as the image stabilization mechanism 40, when applying power-saving drive control to each ultrasonic motor, it is advisable to take into consideration the effect on drive control in directions other than the drive direction of the ultrasonic motor itself. To this end, in the power-saving drive control of the ultrasonic motor to be controlled, it is advisable to refer to the control amounts of multiple ultrasonic motors, including the other ultrasonic motors.

[0058] Such a control amount can be, for example, a control amount that is an operation amount for controlling the output of an ultrasonic motor, or a control amount that is a displacement amount to a target position in feedback control. Hereinafter, a control amount that indicates a required driving force is referred to as a "driving force control amount." A control amount that indicates a required displacement amount (amount to displace a driven body), i.e., a position deviation from a current position to a target position, may be referred to as a "displacement amount control amount."

[0059] For example, when the driving force control amount required in the other ultrasonic motor is large, it can be determined that the driven body is to be moved with a large driving force, so in such a case, it is advisable to refrain from the power-saving driving control. Also, when the displacement control amount in the feedback control of the other ultrasonic motor is small, it can be determined that the driven body is to be moved precisely by the extremely small amount described above, so it is advisable to refrain from the power-saving driving control in the same way. Here, "refraining from the power-saving driving control" means that the lower the driving force required in the other ultrasonic motor, the more relaxed the degree to which the amplitude of the two-phase AC in the ultrasonic motor itself (the controlled object) is reduced (the degree to which the amplitude is reduced is reduced). Therefore, by refraining from the power-saving driving control, the effect of power saving is slightly reduced, but it is possible to avoid the correction not being able to be made in time or the feedback control overshooting. In this embodiment, an "improved power-saving driving control" is adopted, which combines the simple power-saving driving control with control that relaxes the degree to which the amplitude of the two-phase AC is reduced.

[0060] In other words, when determining the amplitude command for each ultrasonic motor, it is advisable to determine the amplitude command based on not only the control amount of the ultrasonic motor to which the command is to be given, but also the control amounts of a plurality of ultrasonic motors including the other ultrasonic motors. The details of this content will be explained using the drive control of the image stabilization mechanism 40 as an example.

[0061] Fig. 10 is a control block diagram relating to the vibration reduction mechanism 40. As described above, the vibration reduction mechanisms 20 and 40 have similar roles and configurations, and therefore the control configuration of the vibration reduction mechanism 40 will be described in detail as a representative example. In Fig. 10, actual signals in the drive control are indicated by solid lines, and the action of virtual forces is indicated by dashed lines. Furthermore, since the processing in the X direction and the processing in the Y direction are the same in content although the parameters are different, the blocks and signals are shown together. In this case, combinations of multiple signals are indicated by thick lines.

[0062] First, the operation (role and input / output) of each main part in controlling the blur correction mechanism 40 will be described. Although not shown in FIG. 2, the blur correction mechanism 40 is equipped with a position sensor 1011. The position sensor 1011 detects the relative position of the movable part 40a with respect to the fixed part 40b, and outputs this to the lens control unit 14b as position information (X, Y) relating to the position of the blur correction lens 12b. The position information (X, Y) includes information in the X and Y directions. The blur information is input to the lens control unit 14b from the lens blur detection unit 16b.

[0063] The lens control unit 14b serves to calculate a target position and a position detection amount so that the blur correction control unit 15b can perform feedback control regarding the position of the blur correction lens 12b. First, the lens control unit 14b calculates a target position (X, Y) based on the blur information, and calculates a position detection amount (X, Y) indicating the current state based on the position information (X, Y). The lens control unit 14b then outputs the target position (X, Y) and the position detection amount (X, Y) to the blur correction control unit 15b. Note that this process may be performed directly by the blur correction control unit 15b.

[0064] The motion compensation control unit 15b performs feedback control regarding the position of the motion compensation lens 12b. The motion compensation control unit 15b receives the target position (X, Y) and position detection amount (X, Y) of the motion compensation lens 12b from the lens control unit 14b. The feedback controller 1000 calculates control amounts (X, Y) corresponding to the amounts at which the ultrasonic motors 30a and 30b are driven in order to eliminate the position deviation between the position target amount and the position detection amount for each of the X and Y directions. The feedback controller 1000 outputs the calculated control amounts (X, Y) to the output converter 1001.

[0065] The output converter 1001 converts the control amount (X, Y) received from the feedback controller 1000 into an Act.30a control amount (first control amount) and an Act.30b control amount (second control amount) which are the control amounts of the ultrasonic motors 30a and 30b. In the shake correction mechanism 40, the driving directions of the ultrasonic motors 30a and 30b are aligned with the X direction and the Y direction, respectively, so that the control amounts for the X direction and the Y direction can be directly assigned as the control amounts of the ultrasonic motors 30a and 30b. On the other hand, if the driving direction of each actuator does not match the direction of the control amount output by the feedback controller 1000, the output converter 1001 performs a conversion calculation to match them. In addition, each of the Act.30a and 30b control amounts includes a driving force control amount, a displacement control amount, and a frequency control amount for controlling the frequency.

[0066] The output converter 1001 outputs the Act.30a control amount to the actuator controllers 1002a and 1002b, and also outputs the Act.30b control amount to the actuator controllers 1002a and 1002b. The actuator controller 1002a generates an Act.30a drive command as a drive command for the ultrasonic motor 30a based on both the Act.30a control amount and the Act.30b control amount. The actuator controller 1002b generates an Act.30b drive command as a drive command for the ultrasonic motor 30b based on both the Act.30a control amount and the Act.30b control amount.

[0067] Here, the Act.30a drive command includes an Act.30a phase difference command, an Act.30a amplitude command, and an Act.30a frequency command. Similarly, the Act.30b drive command includes an Act.30b phase difference command, an Act.30b amplitude command, and an Act.30b frequency command. The actuator controllers 1002a and 1002b output the generated Act.30a drive command and Act.30b drive command to the drive units 1003a and 1003b of the actuator drive unit 17b, respectively. In this way, the actuator controllers 1002a and 1002b receive not only the control amount for the corresponding ultrasonic motor but also the control amount for other ultrasonic motors, and determine the drive command based on them.

[0068] The driving units 1003a and 1003b generate two-phase AC Act.30a driving signals and Act.30b driving signals as driving signals for the ultrasonic motors 30a and 30b based on the Act.30a driving command and the Act.30b driving command, respectively. The driving units 1003a and 1003b then apply the Act.30a driving signals and the Act.30b driving signals to the ultrasonic motors 30a and 30b in the image stabilization mechanism 40 to drive them.

[0069] The motion compensation mechanism 40 serves to move the motion compensation lens 12b to a target position. The ultrasonic motors 30a and 30b are driven by Act. 30a and Act. 30b drive commands to apply a relative driving force to the movable part 40a, thereby moving the motion compensation lens 12b.

[0070] FIG. 11 is a block diagram of the actuator controllers 1002a and 1002b. The actuator controllers 1002a and 1002b have the same configuration, so only the actuator controller 1002a will be described. The actuator controller 1002a has a look-up table (LUT) for determining each of the Act.30a phase difference command, the Act.30a amplitude command, and the Act.30a frequency command. Each LUT is information for generating a command value corresponding to an input control amount. Note that the internal configuration of the actuator controller 1002a is not limited to such an LUT, and may be a configuration capable of determining each command value for an input control amount by more basic gain multiplication and offset calculation, and processing by case classification.

[0071] The amplitude LUT for calculating the amplitude command is two-dimensional (2D) and receives not only the control amount of the ultrasonic motor to be controlled but also the control amount of other ultrasonic motors. In the amplitude LUT, a table according to the control amount of the other ultrasonic motor is selected, and an amplitude command according to the control amount of the ultrasonic motor to be controlled is output using this table. For example, the amplitude LUT in the actuator controller 1002a receives not only the Act.30a control amount but also the Act.30b control amount, and outputs the Act.30a amplitude command according to the Act.30a control amount using a table according to the Act.30b control amount.

[0072] 12(a), (b), and (c) are diagrams showing the frequency LUT, the amplitude LUT, and the phase difference LUT in the actuator controller 1002a, respectively. As shown in FIG. 12(b), the amplitude LUT is two-dimensional. Depending on the input of the control amount of the other ultrasonic motor, one of the multiple amplitude LUTs is selected as the amplitude LUT to be used.

[0073] For example, when the driving force control amount of the other ultrasonic motor is small, table 1201 is selected, when the driving force control amount of the other ultrasonic motor is medium, table 1202 is selected, and when the driving force control amount of the other ultrasonic motor is large, table 1203 is selected. The degree to which the amplitude is reduced is more lenient in table 1202 than in table 1201. Furthermore, the degree to which the amplitude is reduced is more lenient in table 1203 than in table 1202. As a result, the degree to which the amplitude is reduced is more lenient the lower the driving force required for the other ultrasonic motor.

[0074] Note that the amplitude LUT to be used may be selected based on the displacement control amount of the other ultrasonic motor, rather than the driving force control amount of the other ultrasonic motor. For example, if the displacement control amount of the other ultrasonic motor is large, table 1201 is selected, if the displacement control amount of the other ultrasonic motor is medium, table 1202 is selected, and if the displacement control amount of the other ultrasonic motor is small, table 1203 is selected.

[0075] The number of amplitude LUTs is not limited to three, and may be four or more. When selecting an amplitude LUT to be used, the selection may be based on both the driving force control amount of the other ultrasonic motor and the displacement amount control amount of the other ultrasonic motor. In this case, weighting may be provided in advance for the driving force control amount and the displacement amount control amount. If the amplitude LUT selected based on the driving force control amount does not match the amplitude LUT selected based on the displacement amount control amount, one of the amplitude LUTs or an intermediate amplitude LUT may be selected according to the weighting.

[0076] In the phase difference LUT (FIG. 12(c)), the phase difference command generally increases or decreases monotonically according to the positive and negative control amounts. As for the frequency command, the closer the frequency (resonance peak frequency) of the ultrasonic motor 30 shown in FIGS. 4(a) and 4(b) is, the larger the vibration in both the vertical and horizontal directions is, and the greater the output of the ultrasonic motor 30 becomes. However, this may cause problems such as a decrease in the response characteristics on the low output side and the ultrasonic motor 30 becoming more susceptible to damage. For this reason, the frequency LUT (FIG. 12(a)) is designed to drive at an initial frequency that is far from the resonance peak frequency during normal low to medium output. In addition, the frequency LUT is designed to drive at the initial frequency, and then to raise the phase difference from 0° to 90° to increase the output, and when a higher output is required, to issue a frequency command so that the frequency gradually approaches the resonance peak frequency.

[0077] Figures 13(a) to (c) are diagrams showing the effects and drive characteristics of drive control according to the drive force control amount in two ultrasonic motors. Figure 13(a) shows improved power-saving drive control in this embodiment, Figure 13(b) shows simple power-saving drive control, and Figure 13(c) shows conventional drive control that is not power-saving drive control. In each figure, the power consumption and drive characteristics qualitatively show the characteristics of the image stabilization mechanism 40. The control amount shown in each figure is the drive force control amount.

[0078] As an example, the ultrasonic motor 30a will be described as an object to be controlled (herein referred to as the own motor), and the ultrasonic motor 30b will be described as another ultrasonic motor (herein referred to as the other motor).

[0079] As shown in Fig. 13(c), in conventional drive control, when the drive force control amount of the own motor is reduced, only the phase difference of the own motor is reduced and the amplitude is kept constant, regardless of the magnitude of the drive force control amount of the other motor. In this case, even if the output of each ultrasonic motor is small, the power consumption does not decrease much as shown in Fig. 7(b). Therefore, the power consumption of the image stabilization mechanism 40 is always large.

[0080] In the simple power-saving drive control shown in Fig. 13(b), when the drive force control amount of the own motor is reduced, not only the phase difference but also the amplitude of the own motor is reduced, regardless of the magnitude of the drive force control amount of the other motor. In this case, when the output of each ultrasonic motor is small, the power consumption is reduced as shown in Fig. 9, which has the effect of reducing the power consumption of the vibration reduction mechanism 40. However, the resistance force exerted on the other motors increases, which degrades the drive characteristics of the vibration reduction mechanism 40.

[0081] In the improved power-saving drive control shown in FIG. 13(a), when the driving force control amount of the own motor is reduced, not only the phase difference of the own motor but also the amplitude of the own motor is reduced, as in the simple power-saving drive control (FIG. 13(b)), thereby reducing power consumption. Furthermore, at that time, the own motor changes the degree to which the amplitude is reduced depending on the magnitude of the driving force control amount of the other motor. In other words, when the driving force control amount of the other motor is large (the bottom two lines of FIG. 13(a)), the degree to which the amplitude is reduced is mitigated compared to when the driving force control amount of the other motor is small (the top two lines of FIG. 13(a)). As a result, although the effect of reducing power consumption is reduced compared to the simple power-saving drive control, a significant deterioration in drive characteristics is avoided. Therefore, a well-balanced drive control of the shake reduction mechanism 40 can be performed.

[0082] When improved power-saving drive control is implemented in accordance with the displacement control amount of the other motor, the vertical axis of each graph in FIG. 13 represents the displacement control amount of the other motor, and the magnitude relationship is reversed from that shown in the figure.

[0083] According to this embodiment, the image stabilization control unit 15b generates Act.30a, 30b drive commands corresponding to the ultrasonic motors 30a, 30b based on the Act.30a, 30b control amounts corresponding to the ultrasonic motors 30a, 30b. At this time, the image stabilization control unit 15b generates the Act.30a drive command corresponding to the own motor based on the first control amount (Act.30a control amount) corresponding to the own motor to be controlled and the second control amount (Act.30b control amount) corresponding to the other motor. The actuator drive unit 17b drives the ultrasonic motors 30a, 30b by outputting Act.30a, 30b drive signals according to the Act.30a, 30b drive commands.

[0084] For example, the image stabilization control unit 15b determines a command related to the phase difference of the alternating current among the drive commands corresponding to the own motor (a certain actuator) based on the control amount in the first control amount (Act.30a control amount). At the same time, the image stabilization control unit 15b determines an amplitude command among the drive commands corresponding to the own motor based on the first control amount (Act.30a control amount) and the second control amount (Act.30b control amount) (driving force control amount or displacement amount control amount).

[0085] This reduces the resistance that the motor (actuator) exerts on the other motors (actuators), making it possible to appropriately control a plurality of actuators with different drive directions.

[0086] That is, first, by the simple power-saving drive control (Fig. 13(b)), the smaller the drive force control amount of the own motor, the smaller the amplitude is, so that the amount of power consumption can be suppressed. Furthermore, by the improved power-saving drive control (Fig. 13(a)), the larger the drive force control amount of the other motor, the less the degree to which the amplitude is reduced, so that it is possible to avoid a significant deterioration in the drive characteristics while maintaining the effect of suppressing power consumption to a certain extent. Furthermore, by the improved power-saving drive control (Fig. 13(a)), the smaller the displacement amount control amount of the other motor, the less the degree to which the amplitude is reduced, so that it is possible to avoid a significant deterioration in the drive characteristics while maintaining the effect of suppressing power consumption to a certain extent. The above effects can also be obtained in the shake correction control unit 15a.

[0087] In addition, in each LUT, it is not necessary to have a configuration in which the parameters are increased or decreased uniformly in all regions, and the parameters may be constant in some regions. In consideration of this point of view, it may be expressed as follows. Take the case where the blur correction control unit 15b serves as the control means as an example.

[0088] 9 etc., in order to save power, when determining the amplitude command of the alternating current corresponding to the own motor, the following is done: The blur correction control unit 15b makes the amplitude smaller when the driving force control amount in the first control amount (Act.30a control amount) is a second amount smaller than the first amount than when it is the first amount.

[0089] As shown in Fig. 13(a), in the improved power-saving drive control, when determining the amplitude command of the alternating current corresponding to the motor itself and reducing the amplitude, the following is done: The blur correction control unit 15b reduces the degree of amplitude reduction to a lower extent when the driving force control amount in the second control amount (Act.30b control amount) is a fourth amount larger than the third amount (the bottom two lines in Fig. 13(a)) than when it is the third amount (the top two lines in Fig. 13(a)). Alternatively, the blur correction control unit 15b reduces the degree of amplitude reduction to a lower extent when the displacement amount control amount in the second control amount (Act.30b control amount) is a sixth amount smaller than the fifth amount than when it is the fifth amount.

[0090] (Second embodiment) In the first embodiment, a sine wave generator is exemplified as the actuator drivers 17a and 17b. Generally, a sine wave generator has a large electronic circuit scale and a large logical configuration scale, which makes it disadvantageous for mounting in a small precision device. Therefore, in the second embodiment of the present invention, a smaller configuration is adopted for the actuator drivers 17a and 17b.

[0091] FIG. 14 is a schematic diagram showing the actuator driving unit and its peripheral configuration. In this embodiment, the actuator driving units 17a and 17b correspond to the actuator driving unit 17-2. A logic IC 1400 is connected to the actuator driving unit 17-2. The actuator driving unit 17-2 includes a motor driver IC 1401 and inductors 1402a and 1402b and transformers 1403a and 1403b as a driving circuit including an inductance component and a transformer component. The logic IC 1400 is configured separately from the actuator driving unit 17-2, but may be configured as a part of the actuator driving unit 17-2. Conversely, the logic IC 1400 may be configured to include a part or the whole of the actuator driving unit 17-2.

[0092] Fig. 15(a) is a diagram showing each signal output by the logic IC 1400. Fig. 15(b) is a diagram showing the potentials of the electrodes 32a and 32b of the piezoelectric element 32 (when the electrode 32c has a reference potential of 0) and the currents flowing through the polarization regions 32ac and 32bc.

[0093] When the logic IC 1400 receives a drive command as shown in Fig. 7(a), i.e., a command related to the frequency, amplitude, and phase difference of the two-phase AC, it outputs four types of signals A, NA, B, and NB shown in Fig. 15(a) in response. Here, A indicates the A-phase signal, and B indicates the B-phase signal. NA and NB are signals whose phases are shifted by 180° from the A-phase and B-phase signals, respectively. In addition, because the combination of the A phase and the NA phase, and the combination of the B phase and the NB phase function as differential inputs, their differential signals A-NA and B-NB are also shown.

[0094] The A-phase and B-phase signals are each a periodic pulse signal. The frequency command and phase difference command of the two-phase AC are applied directly to the frequency f and phase difference Δθ of these signals. Furthermore, these signals are output with a predetermined duty ratio D, which is determined based on the amplitude command. Specifically, while the amplitude command changes from 0 to a predetermined maximum value, the duty ratio D changes from 0% to 50%, and is determined by D=τ / (1 / f). τ is the period during which the signal is not zero.

[0095] The motor driver IC 1401 functions as a buffer, receiving the four types of signals described above and outputting the same signals. The reason why such a buffer is necessary is that a large current flows when the ultrasonic motor 30 is driven, but the logic IC 1400 generally cannot pass a large current, so the motor driver IC 1401 is provided as a separate dedicated IC.

[0096] A drive signal is applied between electrodes 32a and 32c of the piezoelectric element 32 via a circuit formed by an inductor 1402a and a transformer 1403a due to the differential combination of an A-phase signal and an NA-phase signal output from the motor driver IC 1401. Also, a drive signal is applied between electrodes 32b and 32c of the piezoelectric element 32 via a circuit formed by an inductor 1402b and a transformer 1403b due to the differential combination of a B-phase signal and an NB-phase signal.

[0097] Here, the electrode 32c is connected to the reference potential (GND), so the potential is constant (0). In contrast, the potentials of the electrodes 32a and 32b change while periodically inverting between positive and negative. In this configuration, the voltages applied between the electrodes 32a and 32c, and between the electrodes 32b and 32c, are equal to those of the electrodes 32a and 32b, respectively. Therefore, hereinafter, these voltages are referred to as the A-phase voltage and the B-phase voltage for convenience. In addition, the currents flowing through the polarization regions 32ac and 32bc of the piezoelectric element 32 as a result thereof are referred to as the A-phase current and the B-phase current, respectively.

[0098] The A-phase voltage and the B-phase voltage become substantially sinusoidal with high-frequency components attenuated from the differential signals A-NA and B-NB due to the inductance components of the inductor 1402 and the transformer 1403, and the capacitance component of the piezoelectric element 32. As a result, even in the configuration of the actuator driving unit 17-2, a driving signal close to the two-phase alternating voltage shown in Fig. 7(a) can be applied to the ultrasonic motor 30, and the ultrasonic motor 30 can be driven.

[0099] At this time, the frequency and phase difference of the main components of the A-phase voltage and B-phase voltage correspond to those of the A-phase and B-phase signals output by the logic IC 1400, that is, correspond to the frequency command and phase difference command. Also, the amplitude of the main components of the A-phase voltage and B-phase voltage is amplified from the amplitude (Hi level) of the A-phase and B-phase signals output by the motor driver IC 1401 due to the effect of the transformer 1403 and the electrical resonance of the so-called LC circuit. At this time, the amplitude increases monotonically according to the duty ratio of the A-phase and B-phase signals. As a result, the amplitude increases monotonically indirectly according to the amplitude command as well.

[0100] According to this embodiment, the command regarding the amplitude of the alternating current is controlled by the duty ratio D of the pulse AC. Therefore, even in the configuration of this embodiment, the ultrasonic motor 30 can be driven and controlled by a frequency command, a phase difference command, and an amplitude command. This allows the actuator drive unit to be made smaller, thereby expanding the range of applicable targets. Note that the above-mentioned duty ratio D may be directly specified instead of the amplitude command.

[0101] (Third embodiment) In the third embodiment of the present invention, a stage device having three ultrasonic motors will be described. As an example of a stage device having three ultrasonic motors, a blur correction mechanism 20 on the camera body 10a side will be taken.

[0102] In the image stabilization mechanism 20, the object to be driven is the image sensor 11 serving as the image capturing section. Compared to the image stabilization mechanism 40 on the interchangeable lens 10b side, the image stabilization mechanism 20 controls the drive in the θ direction as well in order to correct not only the shake in the X direction and the Y direction but also the shake in the rotational direction (hereinafter referred to as the θ direction) in the XY plane. For this reason, the image stabilization mechanism 20 is equipped with at least three ultrasonic motors.

[0103] Fig. 16 is a schematic diagram showing the configuration of the blur correction mechanism 20. The blur correction mechanism 20 includes a movable part 20a and a fixed part 20b, and further includes ultrasonic motors 30a, 30b, and 30c which are a plurality of friction drive actuators. The movable part 20a is the driven body, and the fixed part 20b is a support that supports the movable part 20a so that it can be displaced relatively. The arrows shown in Fig. 16 indicate the driving direction (the direction of the driving force transmitted) by each ultrasonic motor. Other parts are not shown in the figure.

[0104] In the image stabilization mechanism 20, the combination of ultrasonic motors 30a, 30b is arranged to transmit driving forces in mutually orthogonal X and Y directions, similar to the case of the image stabilization mechanism 40. In addition, the third ultrasonic motor 30c is arranged at a position away from the second ultrasonic motor 30b and to transmit driving forces in the same direction (Y direction). Furthermore, similar to the case of the image stabilization mechanism 40, a plurality of ultrasonic motors 30a, 30b, 30c are connected to a single combination of a movable part 20a and a fixed part 20b. Therefore, while it is thin, it has a problem of degradation of driving characteristics due to the resistance forces exerted on each other, similar to that described in the first embodiment.

[0105] By driving the second ultrasonic motor 30b and the third ultrasonic motor 30c in opposite phases, a rotational moment can be applied to the movable part 20a, so that it can be driven in the θ direction. Also, by driving these in the same phase, it can be driven in the Y direction as well.

[0106] The drive control in the vibration reduction mechanism 20 is basically the same as the drive control in the vibration reduction mechanism 40 (FIG. 10), and corresponds to an increase in the number of position signals for which position feedback is performed from two, X and Y, to three, X, Y and θ. However, since the configurations of the output converter 1001 and the actuator controller in the vibration reduction control section 15a change accordingly, these will be explained.

[0107] 17(a) and (b) are block diagrams showing the output converter and the actuator controller in the shake correction control unit 15a, respectively. FIG. 17(b) shows an actuator controller 1702a corresponding to the ultrasonic motor 30a as a representative. The output converter 1701 (FIG. 17(a)) corresponds to the output converter 1001 in the first embodiment. The actuator controller 1702a includes an evaluator 1703a. The configurations of the actuator controllers 1702a in the ultrasonic motors 30a, 30b, and 30c are basically the same as each other except for the configuration of the included evaluator. FIG. 17(c) shows an evaluator 1703b in the ultrasonic motor 30b. The configuration of the evaluator (not shown) in the ultrasonic motor 30c is the same as the evaluator 1703b.

[0108] As shown in FIG. 17(a), in the output converter 1701, the input X-direction control amount (X) can be directly used as the Act. 30a control amount of the first ultrasonic motor 30a. At this time, in order to perform conversion according to the output direction of the ultrasonic motor 30a, a positive or negative directional unit gain is multiplied depending on the configuration. On the other hand, the input Y-direction control amount (Y) is allocated to the ultrasonic motors 30b and 30c as an in-phase component with the same sign and equal magnitude. At this time, in order to match the output level with the first ultrasonic motor 30a, the directional unit gain is set to half the size. Furthermore, the input θ-direction control amount (θ) is allocated to either the ultrasonic motors 30b and 30c as a positive component and to either one as a negative component with equal magnitude.

[0109] As shown in FIG. 17(b), the actuator controller 1702a determines the drive command for each ultrasonic motor, and at this time, there are two control amounts of other ultrasonic motors that the actuator controller 1702a refers to. For example, the ultrasonic motor 30a is the control target (herein referred to as the own motor), and the ultrasonic motors 30b and 30c are the other ultrasonic motors (herein referred to as the other motors). When determining the Act. 30a drive command for the own motor, the Act. 30b and 30c control amounts of the other motors are also referenced. In particular, as shown in FIG. 17(b), the Act. 30a amplitude command for the own motor is determined taking into account not only the Act. 30a control amount of the own motor, but also the Act. 30b and 30c control amounts of the other motors. Moreover, the evaluator 1703a weights the Act. 30b and 30c control amounts, and reflects them in the calculation of the Act. 30a amplitude command. In the example shown in FIG. 17(b), the weighting of the control amounts of Act. 30b and Act. 30c is 0.5 each, and thus the weighting is equal.

[0110] The weighting by the evaluator 1703a is determined in advance, taking into consideration the magnitude of the resistance applied to the other motors. As shown in Fig. 17(b), the evaluator 1703a in the actuator controller 1702a for the ultrasonic motor 30a refers to the outputs of the other ultrasonic motors 30b and 30c by the same amount, adds them, and outputs them as a second control amount 1704b. This is because the ultrasonic motors 30b and 30c are both driven in directions substantially perpendicular to the ultrasonic motor 30a, and therefore the magnitude of the resistance applied to each of them is substantially equal.

[0111] Incidentally, evaluator 1703a is configured to function as a parameter converter and a dimension reducer, and the second control amount is output as one-dimensional information, thereby realizing processing related to amplitude commands similar to that shown in Fig. 11 and Fig. 12. However, without being limited to this, the amplitude LUT may be configured as a three- or higher-dimensional table, and the amplitude LUT may be configured to perform processing that also serves as evaluator 1703a.

[0112] On the other hand, when the ultrasonic motor 30b is the own motor, the ultrasonic motors 30a and 30c are the other motors. In this case, as shown in FIG. 17(c), the evaluator 1703b in the ultrasonic motor 30b determines the Act.30b amplitude command of the own motor by taking into account not only the Act.30b control amount of the own motor but also the Act.30a and 30c control amount of the other motors. In the example shown in FIG. 17(c), the weighting of the Act.30a and 30c control amounts is 0.8 to 0.2, and the weighting of the Act.30a control amount is greater than the Act.30c control amount. This is because the driving direction of the ultrasonic motor 30c is approximately parallel to the ultrasonic motor 30b, while the driving direction of the ultrasonic motor 30a is approximately perpendicular to the ultrasonic motor 30b, so the resistance given to the ultrasonic motor 30a is greater than the resistance given to the ultrasonic motor 30c.

[0113] According to this embodiment, when determining the amplitude command corresponding to the motor itself, the weight of the second control amount corresponding to the motor having a larger driving resistance due to driving by the motor itself is set higher than that of the motor having a smaller driving resistance due to driving by the motor itself. In this way, by calculating the amplitude command while taking into account the degree of influence of the resistance each of the motors exerts on each other, it is possible to appropriately control three or more actuators having different driving directions.

[0114] In this embodiment, if the drive direction of the motor itself and the drive direction of the other motors are neither parallel nor perpendicular to each other, the following control may be performed: When determining the amplitude command corresponding to the motor itself, the second control amount corresponding to one of two or more other motors whose drive direction is closer to being parallel to the drive direction of the motor itself is weighted more heavily than the second control amount corresponding to the other motor whose drive direction is closer to being parallel to the drive direction of the motor itself.

[0115] (Fourth embodiment) In the first to third embodiments, a resonance type ultrasonic motor 30 is exemplified as a friction drive actuator, but the drive control of the present invention can be applied to other types of friction drive actuators. For example, the drive control of the present invention can be applied to a non-resonance type ultrasonic motor 1800 as shown in FIG.

[0116] In Fig. 18, ultrasonic motor 1800 includes main housings 1800a and 1800b, friction element 1801, piezoelectric elements 1802a and 1802b, and pressure member (compression spring) 1803. Movable part 1810a moves relatively to fixed part 1810b. In Fig. 18, the stretching vibration of piezoelectric elements 1802a and 1802b and the resulting vibration locus of the tip of friction element 1801 are indicated by arrow F1. Also, the driving force transmitted thereby is indicated by arrow F2.

[0117] In this ultrasonic motor 1800, the friction element 1801 corresponds to one of the protrusions of the vibrator 31 in the ultrasonic motor 30a. The two piezoelectric elements 1802a and 1802b correspond to the two polarization regions 32ac and 32bc of the piezoelectric element 32 in the ultrasonic motor 30a, respectively. As in the ultrasonic motor 30a, by applying a drive signal to the two piezoelectric elements 1802a and 1802b so as to pass a two-phase alternating current, the tip of the friction element 1801 vibrates in an elliptical locus and rubs the movable part 1810a, so that a driving force can be transmitted to the movable part 1810a. In this ultrasonic motor 1800, the main housing 1800a and the friction element 1801 are separate bodies, and the main housing 1800a is a rigid body. Therefore, although the friction element 1801 does not resonate, the principle of driving force transmission is the same as that of the ultrasonic motor 30a, so that the present invention can be applied.

[0118] (Fifth embodiment) In the above embodiments, the image stabilization mechanisms 20 and 40 correspond to a planar stage in the XY directions, but the present invention can also be applied to other types of stage devices.

[0119] 19(a) and (b) are a plan view and a front view of a spherical stage device. This spherical stage device 1920 is used, for example, in a network camera or the like. A camera unit 1901 is provided on a movable part 1920a of the spherical stage device 1920. In order to selectively capture a wide range of the so-called northern hemisphere side (lower half), a plurality of ultrasonic motors 1930a, 1930b, and 1930c are connected to the southern hemisphere (upper half) of the spherical stage device 1920. By controlling these in cooperation with each other, the movable part 1920a moves relatively to the fixed part 1920b, and the camera unit 1901 is driven and controlled to face an arbitrary direction on the northern hemisphere side.

[0120] A plurality of ultrasonic motors 1930a to 1930c are connected to the movable section 1920a so that the camera section 1901 can face any direction in the northern hemisphere. The ultrasonic motors 1930a to 1930c are arranged so as not to be parallel to each other in a spherical coordinate system indicated by the rotation direction indicated by the arrow 1950a and the translation directions indicated by the arrows 1950b and 1950c.

[0121] Therefore, the problems caused by the resistance explained in each of the above embodiments occur. That is, if simple power-saving drive control is performed on each of the ultrasonic motors 1930a to 1930c, the resistance to the other ultrasonic motors increases, and the drive characteristics deteriorate. By applying the drive control of the present invention to such a spherical stage device 1920, drive control with a good balance between power saving and drive characteristics can be performed.

[0122] In each embodiment, the word "approximately" does not mean to completely exclude. For example, "approximately perpendicular," "approximately parallel," "approximately proportional," "approximately planar," "approximately plate-shaped," and "approximately on the center line" are intended to include the completely "orthogonal," "parallel," "proportional," "planar," "plate-shaped," and "on the center line," respectively.

[0123] Although the present invention has been described in detail based on the preferred embodiments, the present invention is not limited to these specific embodiments, and various forms within the scope of the gist of the present invention are also included in the present invention. Parts of the above-described embodiments may be combined as appropriate. [Explanation of symbols]

[0124] 15a, 15b Image stabilization control section 17a, 17b Actuator drive unit 30a, 30b, 30c Ultrasonic motor 31a, 31b protrusions 40b, 20b fixed part 40a, 20a moving parts

Claims

1. A driven body; A support body that supports the driven body so that the driven body can be displaced relatively; a plurality of actuators each having a friction element, the actuator being fixed to either the driven body or the support, the friction element being in pressure contact with the other of the driven body or the support, and applying driving forces to the driven body in directions that are not parallel to each other by using vibration; a control means for generating a drive command corresponding to each of the plurality of actuators based on a control amount corresponding to each of the plurality of actuators; a driving means for driving each of the actuators by outputting a driving signal corresponding to a driving command generated by the control means, the drive signal is a signal for passing a two-phase alternating current through a piezoelectric element of each of the actuators, the control amount includes, for each of the actuators, a driving force control amount indicating a driving force and a displacement amount control amount indicating an amount by which the driven body is displaced; the control means, when generating the drive command corresponding to a certain actuator among the plurality of actuators based on a first control amount corresponding to the certain actuator and a second control amount corresponding to another actuator among the plurality of actuators other than the certain actuator, determines a command related to a phase difference of the alternating current among the drive command corresponding to the certain actuator based on the drive force control amount in the first control amount, and determines a command related to an amplitude of the alternating current among the drive command corresponding to the certain actuator based on the drive force control amount in the first control amount and the drive force control amount or the displacement amount control amount in the second control amount.

2. 2. The stage apparatus according to claim 1, wherein, when determining a command related to the amplitude of the alternating current among the drive commands corresponding to the certain actuator, the control means makes the amplitude smaller when the drive force control amount in the first control amount is a second amount smaller than the first amount than when the drive force control amount in the first control amount is a first amount.

3. 3. The stage apparatus according to claim 2, wherein, when determining a command related to the amplitude of the alternating current among the drive commands corresponding to the certain actuator, the control means reduces the degree to which the amplitude is reduced when the drive force control amount in the first control amount is the second amount and the amplitude is reduced, in a case where the drive force control amount in the second control amount is a fourth amount larger than the third amount, compared to a case where the drive force control amount in the second control amount is a third amount.

4. 3. The stage apparatus according to claim 2, wherein, when determining a command related to the amplitude of the alternating current among the drive commands corresponding to the certain actuator, the control means reduces the degree to which the amplitude is reduced when the drive force control amount in the first control amount is the second amount and the amplitude is reduced, in a case where the displacement amount control amount in the second control amount is a sixth amount smaller than the fifth amount, compared to a case where the displacement amount control amount in the second control amount is a fifth amount.

5. A driven body; A support body that supports the driven body so that the driven body can be displaced relatively; a plurality of actuators each having a friction element, the actuator being fixed to either the driven body or the support, the friction element being in pressure contact with the other of the driven body or the support, and applying driving forces to the driven body in directions that are not parallel to each other by using vibration; a control means for generating a drive command corresponding to each of the plurality of actuators based on a control amount corresponding to each of the plurality of actuators; a driving means for driving each of the actuators by outputting a driving signal corresponding to a driving command generated by the control means, the drive signal is a signal for passing a two-phase alternating current through a piezoelectric element of each of the actuators, the control means generates the drive command corresponding to a certain actuator based on a first control amount corresponding to a certain actuator among the plurality of actuators and a second control amount corresponding to another actuator other than the certain actuator among the plurality of actuators; the other actuators include two or more other actuators; the control means, when determining a command related to the amplitude of the alternating current among the drive commands corresponding to the certain actuator, weights the second control amount corresponding to one of the two or more other actuators having a larger drive resistance provided by driving the certain actuator more heavily than the second control amount corresponding to one of the two or more other actuators having a smaller drive resistance provided by driving the certain actuator.

6. A driven body; A support body that supports the driven body so that the driven body can be displaced relatively; a plurality of actuators each having a friction element, the actuator being fixed to either the driven body or the support, the friction element being in pressure contact with the other of the driven body or the support, and applying driving forces to the driven body in directions that are not parallel to each other by using vibration; a control means for generating a drive command corresponding to each of the plurality of actuators based on a control amount corresponding to each of the plurality of actuators; a driving means for driving each of the actuators by outputting a driving signal corresponding to a driving command generated by the control means, the drive signal is a signal for passing a two-phase alternating current through a piezoelectric element of each of the actuators, the control means generates the drive command corresponding to a certain actuator based on a first control amount corresponding to a certain actuator among the plurality of actuators and a second control amount corresponding to another actuator other than the certain actuator among the plurality of actuators; the other actuators include two or more other actuators; the control means, when determining a command related to the amplitude of the alternating current among the drive commands corresponding to the certain actuator, weights the second control amount corresponding to one of the two or more other actuators whose drive direction is not nearly parallel to the drive direction of the certain actuator more heavily than weights the second control amount corresponding to one of the two or more other actuators whose drive direction is closer to parallel to the drive direction of the certain actuator.

7. Each of the actuators has a piezoelectric element, and two polarization regions are formed by three electrodes.

2. The stage device according to claim 1, wherein the drive signal is a signal for passing a two-phase alternating current through the two polarized regions.

8. the drive signal is a signal for passing a two-phase alternating current through a piezoelectric element of each of the actuators, The driving means includes a motor driver IC and a driving circuit including an inductance component and a transformer component, The driving means generates a pulse AC as the driving signal and applies the pulse AC to the piezoelectric element; 2. The stage device according to claim 1, wherein a command relating to the amplitude of the alternating current among the drive commands is controlled by a duty ratio of the pulse AC.

9. A stage device according to any one of claims 1 to 8, an imaging section driven by the stage device.

10. A stage device according to any one of claims 1 to 8, a lens driven by the stage device.

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