JP2006345630A - Driving device, lens unit, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To guarantee the accuracy of drive control by correcting the influence of an external force on a movable part caused by movement of the device or change of posture in a lens driving device or an imaging device using a driving element utilizing deformation.
In a driving apparatus 1 for an object 3, a driving element 2 (piezoelectric element) using an inverse piezoelectric effect is used. The amount of distortion of the drive element 2 is detected, and the drive control unit 6 calculates the drive amount based on the detection result to control the drive unit 4. Detecting means for detecting the influence of the force “F” acting on the device (gravity or inertial force according to acceleration of external force acting on the device) is provided, and gravity or inertia in the driving direction of the object 3 according to the detection result The control accuracy is improved by correcting the drive amount according to the force component.
[Selection] Figure 1

Description

  The present invention relates to a device that drives a movable member using a driving element (a so-called “piezoelectric element”) that uses an inverse piezoelectric effect, and a component of gravity corresponding to a change in the posture of the device or an inertial force due to an external force acting on the device. The present invention relates to a technique for accurately performing drive control of a movable member that is affected by the above components.

  In a camera device or the like, a linear motor is used as a driving source of a lens driving device. For example, lens driving for zooming or focus control, lens driving for a camera shake correction optical system, or the like is performed.

  A linear motor is an actuator that uses a field means (or magnetic field means) using a magnetic circuit including a permanent magnet and a yoke, and a coil disposed in the magnetic field, and generates thrust according to the coil current. In order to precisely control the driving amount, a position detecting means using a Hall element, a magnetoresistive element, an optical sensor, or the like is required (which contributes to a complicated structure). In addition, since thrust is obtained by energizing the coil, energization is always necessary to maintain the position of the movable lens or the like even in a stationary state, and power consumption is a problem.

  Therefore, a configuration using, for example, a bimorph type or unimorph type piezoelectric element instead of the linear motor is known. These piezoelectric elements are elements that are deformed by the accumulation of electric charges, and can hold displacement by intermittent energization, and thus have a feature that power consumption is small in comparison with a linear motor.

  For example, a configuration in which a piezoelectric element is used as a driving unit of a camera shake correction optical system (for example, see Patent Document 1), a piezoelectric element is used as a driving unit of a focus lens, and a driving amount is detected by a strain gauge. Such a configuration is known (for example, see Patent Document 2).

JP 2000-194026 A JP 2000-316120 A

  By the way, in a conventional lens driving device using a piezoelectric element, the influence on the movable lens due to the inertial force when the device is not stationary, and the influence of the gravity component on the movable lens due to the change in the posture of the device This is not considered, and there is a problem that the lens drive cannot be accurately controlled.

  Piezoelectric elements have the property of deforming with a uniform curvature according to their energization. Therefore, when the influence of external force is not taken into account, such as when the apparatus is stationary or the apparatus posture is kept horizontal, the element If the strain amount of a part or the entire device is detected by a strain gauge or the like, the drive amount of the device can be easily calculated based on the detection result.

  However, for example, when the apparatus is not stationary and the usage state is accompanied by a change in the apparatus posture, an inertial force acts on the driven part including the movable lens, or in a direction corresponding to the change in the attitude. Gravity (component force component) is applied in the driving direction. Since the piezoelectric element used for the driving means also has a leaf spring property, elastic deformation occurs when a load change due to an external force is applied to the element. This deformation causes a disturbance of the “uniform curvature according to the energization” of the piezoelectric element, and thus an error factor when the drive amount is calculated based on the detected value of the strain gauge. That is, if the detected value of the strain gauge attached to the piezoelectric element is trusted as it is without considering the influence on the driven part due to inertial force or gravity, the element is driven as it is. There is a risk of performance degradation in the application of the above (the driving amount of the element cannot be calculated correctly, and the expected accuracy cannot be guaranteed).

  Therefore, an object of the present invention is to guarantee the accuracy of drive control by performing correction on the influence of an external force on a movable part associated with movement of the device or change in posture in a lens driving device, an imaging device, or the like.

  In order to solve the above-mentioned problems, the present invention is provided with detection means for detecting an inertial force corresponding to the gravity acting on the device or the acceleration of the external force acting on the device, and the driving direction of the object according to the detection result The drive control means performs a correction calculation for correcting the drive amount with respect to a change in the distortion amount of the drive element in accordance with the gravity or inertial force component.

  Therefore, in the present invention, the calculation accuracy of the driving amount can be improved by correcting the driving amount in consideration of the influence of gravity or inertial force in the driving direction of the object.

  According to the present invention, in a configuration in which an object is moved using a driving element using the inverse piezoelectric effect, the influence of gravity or inertial force in the driving direction of the object does not cause a significant error in the calculation of the driving amount. In addition, performance can be improved by assuring highly accurate drive control.

  For the drive amount correction calculation, the drive amount is calculated based on the distortion amount detection result according to the relational expression established between the distortion amount and the drive amount when gravity or inertia force does not act in the drive direction of the object. Furthermore, it is preferable to correct the driving amount in accordance with the magnitude of gravity or inertial force component in the driving direction of the object. That is, the drive amount can be corrected according to the difference (deviation amount) from the basic relational expression between the distortion amount and the drive amount, which is effective for error removal.

  In addition, a data table indicating the relationship between the detection amount obtained by the detection unit related to gravity or inertia force and the correction amount with respect to the drive amount calculated based on the change in the distortion amount according to the detection amount is stored in the storage unit. According to the configuration in which the data table is stored in advance and the data table is referred to at the time of the correction calculation, the correction amount that has been found in advance can be read and correction processing can be easily performed. In addition, since the data for each device can be written at the time of manufacture for inherent error factors such as manufacturing variations for each device and variations in characteristics of the detecting means, it is effective for improving accuracy. For intermediate values not included in the discrete data stored in the data table, the data can be supplemented by processing such as interpolation calculation.

  Data of a calculation formula indicating the relationship between the detection amount obtained by the detection unit relating to gravity or inertia force and the correction amount with respect to the driving amount, which is calculated based on a change in the distortion amount according to the detection amount, is stored in the storage unit. According to the configuration in which the calculation formula based on the data is stored in advance and the correction calculation is performed, it is only necessary to use a relatively small number of constant value data necessary for the calculation, and thus it is necessary to store a large amount of data in the storage unit. The advantage that there is no is obtained.

  When a strain gauge attached to the surface of the driving element is used as the strain amount detection means, the amount of deflection of the element can be calculated by detecting the amount of expansion and contraction on the surface of the element. As a means, when a sensor for detecting the amount of charge accumulated in the driving element is used, the amount of distortion at the time of element deformation can be detected from the amount of charge.

  To prevent performance degradation due to errors due to the influence of gravity and inertial force in the driving direction of the movable part in application to a lens driving device, lens unit or imaging device whose driving object is a movable part including a lens or an optical element This is effective for improving image quality.

  The present invention relates to an actuator using a driving element such as a piezoelectric element, and a configuration for performing drive control by calculating a driving amount of the actuator based on a detection result after detecting a distortion amount of the driving element. The purpose is to improve control accuracy in consideration of the influence of gravity and inertial force acting on the device.

  For example, the force acting on the movable part due to the influence of gravity or inertial force acts as a bending moment on the piezoelectric element, and as a result, the amount of strain changes due to the elastic deformation of the element (from a deformed state with a constant curvature). Deviation occurs.) This becomes an error factor in detecting the distortion amount. Therefore, in order to eliminate the occurrence of such detection errors, accurate drive control can be ensured by calculating the correction amount according to the detection result relating to gravity and inertial force and correcting the drive amount. .

  The present invention relates to a driving device used for a portable device, for example, a driving device for moving a movable part including a lens and an optical element along a predetermined direction, or a lens barrel and a lens unit including the driving device, The present invention can be widely applied to a still camera, a video camera, and various imaging devices capable of shooting still images and moving images.

  FIG. 1 is a schematic diagram showing an example of a basic configuration of a drive device according to the present invention.

  The driving device 1 includes driving means 4 for moving the object 3 by using a driving element 2 utilizing a reverse piezoelectric effect (distortion occurs when an electric field is applied). For example, one end 2 a of the driving element 2 is fixed, and the other end 2 b (see the black circle in the figure) is engaged with a part 5 of the object 3.

  An example of the driving element 2 is a piezoelectric bimorph, which has a structure in which a metal plate is sandwiched between piezoelectric ceramic plates from both sides thereof, and the device is deformed when an electric charge is applied. In that case, since the displacement amount at the time of deformation can be maintained even when the power to the element is cut off, the power consumption is small, and there are no problems such as heat generation and electromagnetic noise.

  In this example, there is provided a drive control means 6 for calculating a drive amount related to the drive means 4 using the drive element 2 and performing control according to the drive amount, and using the drive element 2 under the control. The object 3 to be driven is moved in a predetermined direction defined by the guide mechanism 7 (see the x-axis in the figure). The guide mechanism 7 includes a guide shaft 7 a and a guided portion 7 b, and a part 8 of the guided portion 7 b is coupled to the object 3.

  The point “G” shown in the figure indicates the center of gravity of the object 3 (movable part), and the arrow indicated by “F” indicates the inertial force corresponding to the gravity component acting on the device or the acceleration of the external force acting on the device. Ingredients are shown. “L” indicates a distance from the center of gravity G at an arbitrary position in the driving element 2, and “M” indicates a bending moment at the distance “L”.

  In this configuration, by causing the element to be deformed (bent) by driving control of the driving element 2, for example, the object 3 can be moved in a desired direction as shown by a two-dot chain line in the figure. However, when a component of gravity or inertial force in the direction indicated by the arrow “F” is applied to the object 3, a bending moment “M” acts on the driving element 2. Since the size is proportional to the distance “L” from the center of gravity “G”, the size varies depending on the position on the element. As a result, regarding the deformation of the element, a deviation from a curved state with a uniform curvature is a problem. Become.

  Therefore, in the present invention, an inertial force corresponding to the gravity acting on the device or the acceleration of the external force acting on the device is detected, and the driving force corresponding to the gravity or inertial force component in the driving direction of the object 3 is detected according to the detection result. The calculation accuracy is improved by correcting the driving amount with respect to the change in the distortion amount of the element 2.

  In the drive control, it is necessary to grasp the deformation state of the driving element 2. For this purpose, examples of the distortion amount detecting means for detecting the distortion amount of the driving element 2 include the following forms. .

(I) A configuration using a strain gauge attached to the surface of the driving element. (II) A configuration using a sensor for detecting the amount of charge accumulated in the driving element.

  In (I) above, the amount of deflection of the element can be calculated by detecting the amount of expansion / contraction on the surface of the element, the amount of deflection is compared with the control target value, and drive control is performed so that the difference between the two becomes zero. Feedback control is performed by means 6.

  In the above (II), the amount of distortion at the time of device deformation can be detected by detecting the amount of charge accumulated in the device. Therefore, the amount of deflection of the element according to the amount of strain is calculated, the amount of deflection is compared with the control target value, and feedback control is performed by the drive control means 6 so that the difference between the two becomes zero.

  In any form, the driving control of the object 3 is performed by calculating the driving amount related to the driving unit 4 using the driving element 2 based on the detection result by the distortion amount detecting unit and controlling the driving unit. Done.

  Examples of the case where the drive device according to the present invention is applied to a lens unit or an imaging device include the following forms.

A configuration in which a movable lens for focus adjustment is moved along the optical axis direction. A configuration in which a movable lens for zooming and other zooming operations is moved. A movable lens that constitutes an image stabilization optical system is moved with respect to the optical axis. Configuration form for moving along an orthogonal direction-Configuration form for moving an optical member such as a filter or a light shielding member.

  In the following, the configuration of the apparatus will be described with a lens element driving mechanism as an example.

  FIG. 2 shows a configuration example 9 of the imaging apparatus, which includes an imaging unit (or imaging unit) 10, a signal processing unit 11, and a control unit 12.

  The imaging unit 10 is provided with an optical system 13 (only the movable lens 13a is shown in the figure) and an imaging element 14 disposed on the optical axis of the optical system 13, and the imaging signal is A / After being converted from an analog signal to a digital signal by the D conversion circuit 15, it is sent to a camera DSP (Digital Signal Processor) unit 22 of the signal processing unit 11.

  For example, a solid-state imaging device (area image sensor) such as a CCD (Charge Coupled Device) type or a CMOS (Complementary Metal-Oxide Semiconductor) type is used as the imaging device 14, and is supplied from the drive circuit 16 or the timing signal generation circuit 17. Drive control and imaging control are performed in response to the signal.

  For example, a bimorph type or unimorph type piezoelectric element 19 is used as the driving means 18 for moving the movable lens 13a, and is controlled according to a signal from the driving circuit 20. In focus adjustment, etc., a configuration for moving the movable lens along the optical axis direction using the piezoelectric element 19 is adopted. However, in the camera shake prevention optical system, the movable lens is moved in a direction perpendicular to the optical axis. The structure for making it adopt is adopted.

  The strain amount detection means 21 is provided to detect the strain amount of the piezoelectric element 19. For example, the strain amount detection means 21 includes a strain gauge and a bridge circuit including the strain gauge on one side, or a sensor for detecting charges accumulated in the piezoelectric element 19. A detection circuit is used. Then, a signal indicating the detection result is sent to the control unit 12 (CPU 24).

  The camera DSP unit 22 constituting the signal processing unit 11 includes a circuit unit 22a that compresses image data or decompresses and restores compressed data, automatic focus adjustment (AF), automatic exposure (AE), and auto white balance ( A circuit unit 22b that performs processing such as (AWB) and the like, and a memory controller 22c of a memory 23 (such as SDRAM) used for data processing are included.

  The control unit 12 includes a CPU (Central Processing Unit) 24, a main memory (RAM) 25, a read-only memory (ROM) 26, and a clock circuit 27, which send and receive data via the system bus 28. . The system bus 28 is connected to the interface unit of the camera DSP unit 22 and the recording / playback processing unit 29.

  A control signal from the CPU 24 is sent to the A / D conversion circuit 15, the drive circuit 20, and the timing signal generation circuit 17, and the optical system 13 and the image sensor 14 are controlled.

  The detecting means 30 is provided for detecting the influence of inertial force corresponding to the gravity acting on the device or the acceleration of the external force acting on the device (it is not necessary to determine the difference between the gravity component and the inertial force component). The detection signal is sent to the CPU 24. As the detection means 30, for example, an angular velocity sensor for detecting a change in the posture of the apparatus, an acceleration sensor, or the like is used, and a gyro sensor or the like used for camera shake correction can be used.

  In this example, the CPU 24, the memories 25 and 26, the drive circuit 20 and the like constitute drive control means for controlling the drive means 18, and according to the detection result by the detection means 30, gravity in the driving direction of the movable lens 13a or A correction calculation is performed to correct the driving amount with respect to a change in the distortion amount of the piezoelectric element 19 in accordance with the inertial force component. The deformation state of the piezoelectric element 19 is grasped by the CPU 24 by receiving a detection signal from the strain amount detection means 21, and the influence of gravity and inertial force acting on the device is known from the detection signal from the detection means 30. be able to. Therefore, it is possible to perform correction related to the driving amount based on these detection signals. For example, the following processing is performed according to the signal from the detection unit 30.

(A) When the gravity or inertia force component does not act in the driving direction of the movable lens, the driving amount is calculated according to the relational expression established between the distortion amount of the piezoelectric element and the driving amount of the element. (B) When a gravity or inertial force component acts in the driving direction of the movable lens, the driving amount is calculated according to the above relational expression, and then the driving is performed based on a change in the distortion amount according to the magnitude of the component. Correct the amount.

  Then, a control signal is sent from the CPU 24 to the drive circuit 20 in accordance with the drive amount calculated according to the relational expression or the corrected drive amount, and drive control is performed.

  The drive amount correction calculation includes, for example, the following forms. A program that is interpreted and executed by the CPU 24 is stored in the ROM 26, and the program is read and stored in the main memory 25.

(1) Form referring to data table (2) Form using calculation formula.

  First, in the above (1), the correction amount for the driving amount, which is calculated based on the detection amount obtained by the detection means 30 relating to gravity or inertial force and the distortion amount of the piezoelectric element 19 corresponding to the detection amount. Is stored in advance in a non-volatile storage means (for example, the ROM 26). Then, in the correction of (B) above, the driving amount is calculated by performing a correction calculation with reference to the data table.

  The correction amount that has been known in advance can be stored in the apparatus as data in a table format, and the correction process can be easily performed by reading the data as necessary. Further, since the data for each apparatus can be written to the storage means at the time of manufacture for inherent error factors such as manufacturing variations for each apparatus and variations in characteristics of the detection means, it is effective in improving control accuracy.

  Since discrete digital data is used for the data table, it is desirable to complement the quantitative processing by interpolation calculation when calculating the correction amount from the distortion amount detection data. That is, when the detected data does not match the data stored in advance and indicates an intermediate value between adjacent data, the corresponding correction data may be calculated by interpolation processing.

  In the above (2), the correction amount for the driving amount, which is calculated based on the detection amount obtained by the detection means 30 relating to gravity or inertial force and the distortion amount of the piezoelectric element 19 corresponding to the detection amount. The calculation formula showing the relationship is used. That is, the data for the calculation formula is stored in advance in a nonvolatile storage means (for example, the ROM 26), and the correction calculation is performed according to the calculation formula based on the data. In comparison with the above (1), it is not necessary to store a large amount of data in the storage means, and the constant value used in the calculation formula or the like for the manufacturing variation of each apparatus or the characteristic variation of the detection means This can be dealt with by adjusting parameter values or changing settings.

  The image information captured under the drive control related to the optical system 13 is recorded on the recording medium 31 by the recording / reproducing processor 29. That is, for example, a detachable recording medium using a semiconductor storage element or a magnetic or optical recording medium is used for the recording / reproducing processing unit 29, and recording or reproducing of shooting data or the like on the recording medium is performed. For this purpose, a medium interface (I / F) unit 32 connected to the system bus 28 is provided.

  The operation unit 33 includes various operation buttons and switches provided on the main body of the imaging device 9. A signal based on an operation input or setting by the user is sent to the input unit of the CPU 24.

  The display unit 34 includes a display panel 35 using a liquid crystal display device (LCD) and the like and a display control unit 36 thereof, and the display control unit 36 is connected to the system bus 28.

  The external interface (I / F) unit 37 is used for data transmission / reception to / from the external device or the external device 38 using wired, infrared, or wireless communication with the imaging device 9.

  FIG. 3 shows a main part of an example of an embodiment related to an imaging unit to which the present invention is applied, and shows a configuration example 39 of a camera lens unit.

  The optical system 40 has a four-group configuration, a non-movable first group 41, a second group 42 that is driven and controlled for zoom magnification operation, a non-movable third group 43, and for focus adjustment. A fourth group 44 to be driven is arranged on the optical axis. An imaging element 45 is disposed at the rear end of the lens unit 39 (hereinafter, the subject side is defined as the front), and receives an optical image formed by the optical system 40 and converts it into an electrical signal. The image signal is output after conversion.

  The constituent lenses of the first group 41 are fixed to the front lens barrel member 46. The constituent lenses of the second group 42 are attached to the movable frame 47, and the constituent lenses of the fourth group 44 are attached to the movable frame 48.

  The movable frames 47, 48 are supported in a slidable manner along guide shafts 50, 50 extending in a direction parallel to the optical axis across the front lens barrel member 46 and the rear lens barrel member 49.

  Although not shown, an outer cylinder member is provided for connecting the front lens barrel member 46 and the rear lens barrel member 49 and holding the constituent lenses of the third group 43.

  In the movable frame 48 of the second group 42, a lens holding portion 48a and a guided portion 48b are integrally formed, and the guided portion 48b is supported by the guide shaft 50 in a slidable state. The guided portion 48b is formed with a U-shaped engaging recess 51.

  A support portion 52 protruding forward from the rear barrel member 49 is provided with a piezoelectric element (bimorph type) 53 having an elongated rectangular plate shape. For example, one end portion of the piezoelectric element 53 is fixed to the support portion 52, and the other end portion of the element 53 is provided with a columnar engagement portion 54, and the engagement portion 54 is engaged with the engagement portion 54. It is engaged with the recess 51.

  When a drive signal from a circuit unit (not shown) is supplied to the piezoelectric element 53 and electric charge is applied to the element, deformation occurs. That is, the element bends in the direction indicated by the arrow “K” in the drawing, and as a result, the movable frame 48 moves in the front-rear direction (direction indicated by the arrow “S” in the drawing). That is, when the piezoelectric element 53 is bent backward (or forward), the engaging portion 54 and the engaging recess 51 are moved backward (or forward) with the deformation.

  Strain gauges 55 and 55 are integrally joined to the front and back surfaces of the piezoelectric element 53, and the expansion and contraction amounts of the front and back surfaces of the piezoelectric element 53 are detected, and the detection signals are sent to the control unit (see FIG. 2). Is done. Based on the detection result, the drive amount calculation and correction calculation related to the piezoelectric element 53 are performed.

  FIG. 4 is a schematic diagram for explaining the amount of bending due to the deformation of the piezoelectric element 53.

  When the lens unit 39 is maintained in a horizontal posture and is in a stationary state, there is no influence of external force on the piezoelectric element 53. That is, the component in the moving direction of the movable frame 48 due to gravity is zero or negligible, and the component of the inertial force in the direction is also zero or negligible.

  When an electric charge is applied to the piezoelectric element 53 in such a state, deformation with uniform curvature is caused. That is, when the radius of curvature related to the element shape viewed from the side is denoted as “R”, the curvature “1 / R” is constant.

  At this time, if the amount of expansion / contraction of the front and back surfaces is detected using the strain gauges 55 and 55 attached to the piezoelectric element, the amount of contraction is detected by one strain gauge, and the amount of extension is detected by the other strain gauge. . Therefore, the amount of deflection of the piezoelectric element 53 (see “X” in the figure) can be calculated based on the detection results, and is there any error in the calculation of the driving amount of the movable frame accompanying the deformation of the piezoelectric element? Or hardly occurs.

  However, in the situation where the influence of gravity and inertial force cannot be ignored, the premise of “uniform curvature” is not satisfied, and this becomes an error factor related to the calculation of the driving amount. For example, when the entire lens unit is tilted back and forth, the gravity direction component of the gravity acting on the movable frame 48 of the fourth group 44 acts on the piezoelectric element 53 from the guided portion 48b. In addition, an optical component in the optical axis direction of the inertia force (a component opposite to the acceleration of the external force) acts on the piezoelectric element 53 in the same manner with respect to the acceleration of the external force when the entire lens unit is moved. With respect to these force components, a bending moment proportional to the distance from the center point of the engaging portion 54 is generated and applied to the piezoelectric element 53. The elastic deformation of the element at this time appears as a change in the amount of distortion from the above-mentioned “uniform curvature” state, which becomes an error factor in the calculation of the driving amount. That is, if the drive amount is calculated based only on the detection result by the strain amount detection means such as a strain gauge, if the calculation error is large, there will be a problem in control accuracy. Therefore, the detection means 30 (see FIG. 2) ) Is used to monitor the attitude and movement of the apparatus, and the drive amount is corrected based on the change in the amount of distortion in accordance with the magnitude of the gravity or inertial force component in the drive direction of the movable frame.

  Deviation from the above "uniform curvature" state occurs due to the influence of gravity and inertial force, but when the amount of change is relatively small, it is preferable to perform a difference correction based on the state, for example, As described above, a configuration mode by referring to the data table, a configuration mode in which a correction amount is obtained by a calculation formula, a combination of both modes, and the like can be given.

  FIG. 5 is a flowchart showing an example of drive control.

  First, in step S1, the initial reference position of the piezoelectric element 53 is detected. When a driving voltage is applied to the piezoelectric element, the piezoelectric element is deformed according to the amount of electric charge, and the movable part moves in a predetermined direction along with this. A restricting part for mechanically limiting the movable range is provided. When the movement of the movable portion is restricted by the restricting portion, the amount of strain generated in the piezoelectric element increases rapidly, and this is detected by a strain amount detecting means such as a strain gauge.

  FIG. 6 is a graph illustrating the relationship between the displacement amount relating to the drive means using the piezoelectric element on the horizontal axis (arbitrary unit) and the distortion amount detected by the strain amount detection means on the vertical axis (arbitrary unit). FIG. In addition, the graph shown by a solid line exemplifies a case where a strain gauge is used, and the graph shown by a broken line exemplifies a case where a sensor for detecting the amount of charge is used. Corresponds to position.

  When the movable part (movable frame 48 in the above example) is moved and driven so as to press against the respective restricting parts, the inflection points indicated by points P and P when the movable part comes into contact with the restricting parts are obtained. Appears in each. That is, the position of each restricting portion can be detected from the detection value of the strain amount detection means at the inflection point. Since the movable range of the movable part is determined as a section between the two positions by the positions of the two restricting parts, the center position of the range can be set as the reference position (or reset position). Thereafter, the driving amount is calculated based on the position. It should be noted that such detection of the initial reference position is preferably performed every time or periodically when the apparatus is used in consideration of changes with time, changes in ambient conditions (such as temperature and humidity), and the like.

  In the next step S2, after detecting the distortion amount of the piezoelectric element 53, the process proceeds to step S3, where the deflection amount of the element and the drive amount are calculated. For example, the drive amount is calculated according to a relational expression that is established between the amount of distortion and the drive amount when gravity or inertia force does not act in the moving direction of the movable part.

  In step S4, the detection means 30 detects the gravity and inertial force, and in the next step S5, it is determined whether or not there is an influence thereof. That is, if there is no influence of the gravity or inertial force component in the moving direction of the movable part or it can be ignored, the process proceeds to step S7, but if the influence of the gravity or inertial force component in the moving direction of the movable part cannot be ignored. Advances to step S6, and a drive amount correction calculation is performed.

  In step S6, the drive amount calculated in step S2 is corrected by difference correction or the like based on the detection result regarding gravity or inertial force. That is, the driving amount is calculated according to the correction amount corresponding to the magnitude of the gravity or inertial force component in the moving direction of the movable part.

  In step S7, a driving voltage is supplied to the piezoelectric element 53 according to the calculated driving amount, and the movable portion is driven by deformation of the element.

  In the above example, the configuration using the bimorph type element to move the movable frame 48 in the front-rear direction is shown. However, for example, when the movable frame is moved only in one of the front and the rear (one-way property). A unimorph element can be used for the drive control. In addition to the configuration in which the lens is moved in the optical axis direction for focus adjustment, a configuration in which lens drive control is performed for zooming magnification operation, and the lens is approximately relative to the optical axis for camera shake correction. The present invention can be applied to a configuration form that moves in an orthogonal direction.

  According to the configuration described above, for example, the following advantages can be obtained.

・ There is no need to energize constantly to hold the movable part as in the linear motor drive system, and the power consumption and heat generation are low. ・ The structure including the actuator and detection means is simplified and the parts It is advantageous in reducing the number of points and downsizing of the device. ・ Effect of gravity component in the driving direction of the movable part due to the change in the device attitude, or inertial force component in the driving direction of the moving part when the device is moved Control accuracy can be improved by calculating the drive amount in consideration of the influence (for example, focusing accuracy and camera shake correction accuracy in application to equipment that is used while being held by hand, such as a camera) Etc., and contributes to improvement of image quality.)

It is the schematic which shows the basic structural example of the drive device which concerns on this invention. It is a block diagram which shows the structural example of the imaging device which concerns on this invention. It is a perspective view of the principal part which shows the Example of the lens unit for cameras to which this invention is applied. It is the schematic for demonstrating the bending amount by a deformation | transformation of a piezoelectric element. It is a flowchart figure which shows an example of drive control. It is the graph which illustrated the relationship between the displacement amount and distortion amount which concern on a piezoelectric element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Drive device, 2 ... Drive element, 3 ... Object, 4 ... Drive means, 6 ... Drive control means, 9 ... Imaging device, 21 ... Distortion amount detection means, 30 ... Detection means, 39 ... Lens unit, 55 ... strain gauge

Claims (8)

Based on the detection result of the drive means for moving the object using the drive element using the reverse piezoelectric effect, the distortion amount detection means for detecting the distortion amount of the drive element, and the detection result by the distortion amount detection means In a drive apparatus comprising: a drive control unit that calculates a drive amount related to the drive unit and controls the drive unit according to the drive amount;
A detecting means for detecting an inertial force corresponding to the gravity acting on the device or the acceleration of the external force acting on the device is provided, and according to the detection result by the detecting means, depending on the gravity or inertial force component in the driving direction of the object. Further, the drive control means performs correction calculation for correcting the drive amount with respect to the change in the distortion amount. The drive device according to claim 1,
The drive amount is calculated based on the detection result by the strain amount detecting means according to the relational expression established between the strain amount and the drive amount when the gravity or inertia force does not act in the drive direction of the object. Furthermore, the driving amount is corrected according to the magnitude of the gravity or inertial force component in the driving direction of the object. The drive device according to claim 1,
A data table indicating a relationship between a detection amount obtained by the detection unit relating to the gravitational force or the inertial force and a correction amount with respect to the driving amount, which is calculated based on a change in the distortion amount according to the detection amount. Is stored in advance, and the correction calculation is performed with reference to the data table. The drive device according to claim 1,
Data of a calculation formula indicating the relationship between the detection amount obtained by the detection means related to the gravity or inertia force and the correction amount for the driving amount calculated based on the change in the distortion amount according to the detection amount is stored. A drive device characterized in that the correction calculation is performed in accordance with a calculation formula stored in advance in the means and based on the data. The drive device according to claim 1,
As the strain amount detecting means, a strain gauge attached to the surface of the driving element is used. The drive device according to claim 1,
A driving device characterized in that a sensor for detecting the amount of charge accumulated in the driving element is used as the strain amount detecting means. A driving means for moving the lens using a driving element utilizing the inverse piezoelectric effect, a distortion amount detecting means for detecting a distortion amount of the driving element, and the driving based on a detection result by the distortion amount detecting means In a lens unit comprising a drive control means for calculating a drive amount related to the means and controlling the drive means according to the drive amount,
Detecting means for detecting gravity acting on the movable part including the lens or inertial force corresponding to acceleration of external force acting on the movable part is provided, and gravity in the driving direction of the movable part is determined according to a detection result by the detecting means. Alternatively, the driving amount is calculated by performing a correction calculation for correcting the change in the distortion amount according to the component of the inertial force by the drive control unit. Based on a drive means for moving a lens or an optical element using a drive element using an inverse piezoelectric effect, a strain amount detection means for detecting a strain amount of the drive element, and a detection result by the strain amount detection means An imaging device comprising: a drive control unit that calculates a drive amount related to the drive unit and controls the drive unit according to the drive amount;
A detecting means for detecting an inertial force corresponding to the gravity acting on the device or the acceleration of the external force acting on the device is provided, and a component of gravity or inertial force in the driving direction of the lens or optical element according to the detection result by the detecting means An image pickup apparatus, wherein the drive amount is calculated by performing a correction calculation for correcting a change in the distortion amount according to the drive control means.

Images