JP2009210784A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for reducing the effect on focusing accuracy of movement of an imaging device by a camera shake correction unit. <P>SOLUTION: The imaging apparatus 1A includes: an imaging device 101 which acquires a photographic image related to a subject image; a movement control means which moves the imaging device 101 within a plane vertical to an optical axis of a photographic optical system; a movement history generation part 622 which generates movement history information for movement of the imaging device 101; a focus adjustment information acquisition part 623 which acquires focus adjustment information according to a focus adjustment state; a focus adjustment information correction part 624 which corrects focus adjustment information according to the movement history information; and a focus adjustment means which performs focus adjustment based on corrected focus adjustment information corrected by the correction part 624. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having an automatic focus detection function.

  Some image pickup apparatuses configured as digital cameras include a shake correction unit that shifts the position of the image sensor in order to correct camera shake during shooting (for example, Patent Document 1).

  In a blur correction unit having an image sensor shift mechanism, a driving force is generally generated by a piezoelectric actuator disposed on a side of the image sensor, and the image sensor is moved in a plane perpendicular to the optical axis of the imaging optical system.

  Specifically, the blur correction unit holds a piezoelectric element that expands and contracts according to an applied voltage, a piezoelectric actuator having a drive shaft extending from the piezoelectric element, a fixing member including the piezoelectric actuator, and an imaging element. A driven body (also referred to as a “slider”) that is movable with respect to the fixed member. The blur correction unit includes a mechanism in which a bearing portion provided on the slider is frictionally coupled to a drive shaft of a piezoelectric actuator in a fixed member. In the shake correction unit having such a mechanism, when the drive shaft is displaced relatively slowly, the slider moves in synchronization with the frictional coupling force, and when the drive shaft is displaced relatively abruptly, friction is generated. The slider is driven by utilizing the principle that the slider does not move due to slippage in the coupling portion.

  In the shake correction unit having such a mechanism, the friction coupling portion (specifically, the drive shaft and / or the bearing portion) may be worn by the movement of the slider.

  When wear occurs in the friction coupling portion, the position of the friction coupling portion changes, and the position of the slider in the optical axis direction relatively changes.

JP 2006-259114 A

  Since the image sensor is held by the slider as described above, the image sensor is displaced in the optical axis direction when the position of the slider in the optical axis direction changes due to wear of the frictional coupling portion.

  Such displacement of the image sensor in the optical axis direction affects the focal point of the lens, and lowers the focusing accuracy by the automatic focusing (AF) operation.

  Accordingly, an object of the present invention is to provide a technique capable of reducing the influence of movement of an image sensor by a shake correction unit on focusing accuracy.

  A first aspect of the present invention is an imaging apparatus, an imaging element that acquires a captured image related to a subject image, a movement control unit that moves the imaging element in a plane perpendicular to the optical axis of the imaging optical system, Generating means for generating movement history information relating to movement of the image sensor; acquisition means for acquiring focus adjustment information according to a focus adjustment state; correction means for correcting the focus adjustment information according to the movement history information; Focus adjustment means for performing focus adjustment based on the corrected focus adjustment information corrected by the correction means.

  According to the present invention, movement history information relating to the movement of the image sensor is generated, and the focus adjustment information is corrected according to the movement history information, so that the influence of movement of the image sensor on the focusing accuracy can be reduced. Is possible.

  Embodiments of the present invention will be described below with reference to the drawings.

<1. First Embodiment>
<External Configuration of Imaging Device 1A>
1 and 2 are diagrams showing an external configuration of an imaging apparatus 1A according to the first embodiment of the present invention. Here, FIGS. 1 and 2 show a front view and a rear view, respectively.

  The imaging apparatus 1 </ b> A is configured as, for example, a single-lens reflex digital still camera, and includes a camera body 10 and a photographing lens unit 2 as an interchangeable lens that is detachable from the camera body 10.

  Specifically, as shown in FIG. 1, on the front side of the camera body 10, a mount portion 301 on which the photographing lens unit 2 is mounted at the front center and a lens disposed on the right side of the mount portion 301. An exchange button 302, a grip portion 303 for enabling gripping, a mode setting dial 305 disposed at the upper left portion of the front surface, a control value setting dial 306 disposed at the upper right portion of the front surface, and an upper surface of the grip portion 303 A shutter button (release button) 307 is provided.

  The photographing lens unit 2 functions as a lens window that takes in light that forms a subject image (subject light), and as a photographing optical system for guiding the subject light to the image sensor 101 disposed inside the camera body 10. Function.

  More specifically, the photographing lens unit 2 includes a lens group 21 including a plurality of lenses arranged in series along the optical axis LT (see FIG. 5). The lens group 21 includes a focus lens (also referred to as “focus adjustment lens” or “focusing lens”) 211 (FIG. 5) for adjusting the focus, and a zoom lens 212 (FIG. 5) for performing zooming. 5) is included, and each lens is driven in the direction of the optical axis LT to perform focus adjustment or zooming. The photographing lens unit 2 is provided with an operation ring that can rotate along the outer peripheral surface of the lens barrel at a suitable position on the outer periphery of the lens barrel. The zoom lens 212 can be operated manually or automatically. It moves in the direction of the optical axis LT according to the rotation direction and rotation amount of the operation ring, and is set to a zoom magnification (imaging magnification) according to the position of the movement destination.

  The mount 301 is provided with a connector Ec (see FIG. 5) for electrical connection with the mounted photographic lens unit 2 and a coupler 75 (FIG. 5) for mechanical connection.

  The lens exchange button 302 is a button that is pressed when the photographing lens unit 2 attached to the mount unit 301 is removed.

  The grip portion 303 is a portion where the photographer (user) holds the imaging device 1A during photographing, and the surface of the grip portion 303 is provided with unevenness according to the shape of the finger in order to improve fitting properties. Note that a battery storage chamber and a card storage chamber (not shown) are provided inside the grip portion 303. A battery 69B (see FIG. 5) is housed in the battery compartment as a power source for the image pickup apparatus 1A, and a memory card 67 (FIG. 5) for recording image data of a photographed image is detachable in the card compartment. It is designed to be stored. The grip unit 303 may be provided with a grip sensor for detecting whether or not the user has gripped the grip unit 303.

  The mode setting dial 305 and the control value setting dial 306 are made of a substantially disk-shaped member that can rotate in a plane substantially parallel to the upper surface of the camera body 10. The mode setting dial 305 is used for various modes (such as various shooting modes (portrait shooting mode, landscape shooting mode, full-auto shooting mode, etc.), a playback mode for playing back a shot image, and an external device. This is for selecting a communication mode for performing data communication. On the other hand, the control value setting dial 306 is for setting control values for various functions installed in the imaging apparatus 1A.

  The shutter button 307 is a push switch that can detect a “half-pressed state” that is pressed halfway and a “full-pressed state” that is further pressed. When the shutter button 307 is half-pressed (S1) in the shooting mode, a preparatory operation (shooting preparatory operation such as exposure value setting and focus detection) for shooting a still image of the subject is executed, and the shutter button 307 is fully pressed. When pressed (S2), a shooting operation (a series of operations for exposing the image sensor 101 (see FIG. 4), performing predetermined image processing on the image signal obtained by the exposure, and recording the image signal in the memory card 67 or the like) Is executed.

  As shown in FIG. 2, an LCD (Liquid Crystal Display) 311 that functions as a display unit, a finder window 316 disposed above the LCD 311, and a finder window 316 are provided on the back side of the camera body 10. The surrounding eyecup 321, the main switch 317 disposed on the left side of the finder window 316, the exposure correction button 323 and the AE lock button 324 disposed on the right side of the finder window 316, and the finder window 316 A flash unit 318 and a connection terminal unit 319 disposed above are provided. On the back side of the camera body 10, a setting button group 312 disposed on the left side of the LCD 311, a direction selection key 314 disposed on the right side of the LCD 311, and a push disposed on the center of the direction selection key 314. A button 315 and a display changeover switch 85 arranged at the lower right of the direction selection key 314 are provided.

  The LCD 311 includes a color liquid crystal panel capable of displaying an image, and displays an image captured by the image sensor 101 (see FIG. 3) or reproduces and displays a recorded image, and is mounted on the image capturing apparatus 1A. Function or mode setting screen. Note that an organic EL display device or a plasma display device may be used instead of the LCD 311.

  The viewfinder window (eyepiece window) 316 constitutes an optical viewfinder (OVF), and light (subject light) that forms a subject image that has passed through the photographing lens unit 2 is guided to the viewfinder window 316. The user can view the subject image actually captured by the image sensor 101 by looking through the finder window 316.

  The main switch 317 is a two-contact slide switch that slides to the left and right. When the switch is set to the left, the power of the imaging device 1A is turned on, and when the switch is set to the right, the power of the imaging device 1A is turned off.

  The flash unit 318 is configured as a pop-up built-in flash. The external flash is attached to the camera body 10 using the connection terminal portion 319.

  The eye cup 321 functions as a light shielding member that suppresses the entry of external light into the finder window 316.

  The exposure correction button 323 is a button for manually adjusting the exposure value (aperture value and shutter speed), and the AE lock button 324 is a button for fixing the exposure.

  The setting button group 312 is a button for performing operations on various functions installed in the imaging apparatus 1A. The setting button group 312 includes, for example, a menu button for displaying a menu screen on the LCD 311 and a menu switching button for switching the contents of the menu screen.

  The direction selection key 314 has an annular member having a plurality of pressing portions (triangle marks in the drawing) arranged at regular intervals in the circumferential direction, and is not shown provided corresponding to each pressing portion. The pressing operation of the pressing portion is detected by the contact (switch). The push button 315 is disposed at the center of the direction selection key 314. The direction selection key 314 and the push button 315 are used to change the shooting magnification (movement of the zoom lens 212 (see FIG. 5) in the wide direction or the tele direction), frame advance of a recorded image to be reproduced on the LCD 311 and the like, and shooting conditions (aperture). Value, shutter speed, presence / absence of flash emission, etc.).

  The display changeover switch 85 is composed of two slide switches. When the contact point is set at the upper “optical” position, the optical finder mode (also referred to as “OVF mode”) is selected, and the subject image is displayed in the optical finder field of view. The Accordingly, the user can visually recognize a subject image displayed in the optical viewfinder field through the viewfinder window 316 and perform a composition determination operation (framing).

  On the other hand, when the contact of the display changeover switch 85 is set to the lower “monitor” position, the electronic finder mode (also referred to as “EVF mode” or “live view mode”) is selected, and the live view image related to the subject image is displayed on the LCD 311 as a moving image. Displayed in a specific manner. Thereby, the user can perform framing by visually recognizing the live view image displayed on the LCD 311.

  As described above, the user can switch the finder mode by operating the display changeover switch 85, and the imaging apparatus 1A determines the composition of the subject using the electronic finder or the optical finder on which the live view display is performed. Is possible.

<Internal Configuration of Imaging Device 1A>
Next, the internal configuration of the imaging apparatus 1A will be described. 3 and 4 are longitudinal sectional views of the imaging apparatus 1A.

  As shown in FIG. 3, an image sensor 101, a finder unit (also referred to as “finder optical system”) 102, a mirror mechanism 8, and a phase difference AF module (also simply referred to as “AF module”) 107 are provided inside the camera body 10. Etc. are provided.

  The imaging element 101 is disposed perpendicular to the optical axis LT on the optical axis LT of the photographing lens unit 2 when the photographing lens unit 2 is attached to the camera body 10. As the image sensor 101, for example, a CMOS color area sensor (CMOS type image sensor) in which a plurality of pixels configured with photodiodes are two-dimensionally arranged in a matrix is used. The image sensor 101 generates analog electrical signals (image signals) of R (red), G (green), and B (blue) color components related to the subject image formed through the photographing lens unit 2, and R, Output as image signals of G and B colors.

  The image sensor 101 is held by the blur correction unit 100 so as to be movable in a two-dimensional manner on a plane orthogonal to the optical axis LT.

  The shake correction unit 100 moves the image sensor 101 in the vertical (Y-axis) direction and the left and right (X-axis) according to the shake information detected by a shake detection unit (for example, a gyro sensor) 99 (see FIG. 5) in the image pickup apparatus 1A. Slide it in the (axis) direction.

  A shutter unit 40 is disposed on the imaging surface side of the imaging element 101. The shutter unit 40 includes a curtain body that moves in the vertical direction, and is configured as a mechanical focal plane shutter that performs an optical path opening operation and an optical path blocking operation of subject light guided to the image sensor 101 along the optical axis LT. The shutter unit 40 can be omitted when the image sensor 101 is an image sensor capable of complete electronic shutter.

  As shown in FIG. 3, a mirror mechanism 8 is provided on the optical path (also referred to as “imaging optical path”) from the imaging lens unit 2 to the image sensor 101.

  The mirror mechanism 8 has a main mirror 81 (main reflection surface) that reflects light from the photographing optical system upward. For example, a part or all of the main mirror 81 is configured as a half mirror, and transmits a part of light from the photographing optical system. The mirror mechanism 8 also includes a sub mirror 82 (sub reflective surface) that reflects light transmitted through the main mirror 81 downward.

  Further, the mirror mechanism 8 is configured as a so-called quick return mirror, and the posture can be switched between a mirror-down state and a mirror-up state.

  Specifically, until the shutter button 307 is fully pressed S2 in the shooting mode, in other words, when determining the composition, the mirror mechanism 8 is arranged to be in the mirror down state (see FIG. 3). . In the mirror-down state, the subject light from the photographic lens unit 2 is reflected upward by the main mirror 81, enters the finder optical system 102 as an observation light beam, and is guided to the finder window 316.

  The finder optical system 102 includes a pentaprism 105, an eyepiece lens 106, a photometric element 109, and a finder window 316.

  The pentaprism 105 has a pentagonal cross section, and is a prism for changing the top and right sides of the optical image into an upright image by reflection inside the subject image incident from the lower surface thereof.

  The eyepiece 106 has a function of guiding the subject image that has been made upright by the pentaprism 105 to the outside of the finder window 316.

  The photometric element 109 is disposed above the pentaprism 105 and measures the brightness of the subject (subject brightness). The subject brightness is used for setting an exposure value.

  The finder optical system 102 having the above-described members functions as an optical finder for confirming the object field at the time of shooting standby before actual shooting.

  A part of the subject light is transmitted through the main mirror 81, reflected downward by the sub mirror 82, and guided to the AF module 107.

  The AF module 107 is configured by a line sensor or the like that detects focus information of a subject, and functions as a so-called AF sensor. The AF module 107 is disposed at the bottom of the mirror mechanism 8 and has a phase difference detection function for generating a phase difference detection signal corresponding to the degree of focus of the subject image. That is, in the mirror-down state at the time of shooting standby, the phase difference detection signal is output from the AF module 107 based on the subject light guided to the AF module 107.

  On the other hand, when the shutter button 307 is fully pressed S2, the mirror mechanism 8 is driven so as to be in the mirror up state (see FIG. 4), and the exposure operation is started.

  Specifically, as shown in FIG. 4, at the time of exposure, the mirror mechanism 8 jumps upward with the rotating shaft 83 as a fulcrum and retracts from the photographing optical path. Specifically, the main mirror 81 and the sub mirror 82 are retracted upward so as not to block the light from the photographing optical system, and the light from the photographing lens unit 2 reaches the image sensor 101 in accordance with the opening timing of the shutter unit 40. To do. The image sensor 101 generates an image signal related to the subject image based on the received light flux by photoelectric conversion. As described above, the light from the subject is guided to the image sensor 101 via the photographing lens unit 2, so that a photographed image (photographed image data) relating to the subject is obtained.

<Electrical Configuration of Imaging Device 1A>
FIG. 5 is a block diagram illustrating an electrical configuration of the imaging apparatus 1A. In FIG. 5, the same members as those shown in FIGS. 1 to 4 are denoted by the same reference numerals. For convenience of explanation, the electrical configuration of the photographic lens unit 2 will be described first.

  The photographic lens unit 2 includes a lens driving mechanism 24, a lens position detection unit 25, a lens control unit 26, and an aperture driving mechanism 27 in addition to the lens group 21 constituting the above-described photographic optical system.

  In the lens group 21, a focus lens 211 and a zoom lens 212, and a diaphragm 23 for adjusting the amount of light incident on the image sensor 101 are held in the optical axis LT direction in the lens barrel. The captured subject light is imaged on the image sensor 101. In the automatic focusing control (AF control), the focus lens 211 is driven in the direction of the optical axis LT by the AF actuator 71M in the photographing lens unit 2 to perform focus adjustment.

  The focus drive control unit 71A generates a drive control signal necessary for moving the focus lens 211 to the in-focus position based on the AF control signal given from the overall control unit 62 via the lens control unit 26, and the drive The AF actuator 71M is controlled using the control signal. The AF actuator 71M is composed of a stepping motor or the like, and applies a lens driving force to the lens driving mechanism 24.

  The lens driving mechanism 24 includes, for example, a helicoid and a gear (not shown) that rotates the helicoid, and receives the driving force from the AF actuator 71M to drive the focus lens 211 and the like in the optical axis direction. Note that the movement direction and movement amount of the focus lens 211 (also referred to as “lens movement amount”) follow the rotation direction and rotation speed of the AF actuator 71M, respectively.

  The lens position detection unit 25 moves integrally with the lens while being in sliding contact with the encode plate in which a plurality of code patterns are formed at a predetermined pitch in the optical axis LT direction within the movement range of the lens group 21. An encoder brush, and detects the amount of movement of the lens group 21 during focus adjustment. The lens position detected by the lens position detection unit 25 is output as the number of pulses, for example.

  The lens control unit 26 is composed of, for example, a microcomputer having a built-in memory such as a ROM that stores a control program or a flash memory that stores data relating to status information.

  The lens control unit 26 has a communication function for communicating with the overall control unit 62 of the camera body 10 via the connector Ec. Thereby, for example, the state information data such as the focal length, the aperture value, the focusing distance or the peripheral light amount state of the lens group 21 and the position information of the focus lens 211 detected by the lens position detection unit 25 are transmitted to the overall control unit 62. In addition, for example, data of the lens movement amount (lens driving amount) of the focus lens 211 can be received from the overall control unit 62.

  The aperture drive mechanism 27 receives the driving force from the aperture drive actuator 76M via the coupler 75 and changes the aperture diameter of the aperture 23.

  Next, the electrical configuration of the camera body 10 will be described. The camera body 10 includes an AFE (analog front end) 5, an image processing unit 61, an image memory 614, an overall control unit 62, a flash circuit 63, an operation unit 64, and a VRAM 65 in addition to the above-described imaging device 101 and shutter unit 40. Card I / F 66, memory card 67, communication I / F 68, power supply circuit 69, battery 69B, mirror drive control unit 72A, shutter drive control unit 73A, and aperture drive control unit 76A.

  The image sensor 101 is composed of a CMOS color area sensor as described above, and the timing control circuit 51 described below starts (and ends) the exposure operation of the image sensor 101, selects the output of each pixel included in the image sensor 101, In addition, an imaging operation such as readout of pixel signals is controlled.

  The AFE 5 gives a timing pulse for causing the image sensor 101 to perform a predetermined operation, performs predetermined signal processing on the image signal output from the image sensor 101, converts the image signal to a digital signal, and outputs the digital signal to the image processing unit 61. It has a function to do. The AFE 5 includes a timing control circuit 51, a signal processing unit 52, an A / D conversion unit 53, and the like.

  The timing control circuit 51 generates a predetermined timing pulse (a pulse for generating a vertical scanning pulse φVn, a horizontal scanning pulse φVm, a reset signal φVr, and the like) based on the reference clock output from the overall control unit 62, and the imaging device 101. And the imaging operation of the image sensor 101 is controlled. In addition, the operation of the signal processing unit 52 and the A / D conversion unit 53 is controlled by outputting predetermined timing pulses to the signal processing unit 52 and the A / D conversion unit 53, respectively.

  The signal processing unit 52 performs predetermined analog signal processing on the analog image signal output from the image sensor 101. The signal processing unit 52 includes a CDS (correlated double sampling) circuit, an AGC (auto gain control) circuit, a clamp circuit, and the like. The A / D conversion unit 53 converts the analog R, G, B image signals output from the signal processing unit 52 into a plurality of bits (for example, 12 bits) based on the timing pulse output from the timing control circuit 51. Is converted into a digital image signal.

  The image processing unit 61 performs predetermined signal processing on the image data output from the AFE 5 to create an image file, and includes a black level correction circuit 611, a white balance control circuit 612, a gamma correction circuit 613, and the like. Has been. The image data captured by the image processing unit 61 is temporarily written in the image memory 614 in synchronization with the reading of the image sensor 101. Thereafter, the image data written in the image memory 614 is accessed to access the image processing unit. Processing is performed in each of the 61 blocks.

  The black level correction circuit 611 corrects the black level of each of the R, G, and B digital image signals A / D converted by the A / D conversion unit 53 to a reference black level.

  The white balance control circuit 612 performs level conversion (white balance (WB) adjustment) of digital signals of R (red), G (green), and B (blue) color components based on the white reference corresponding to the light source. . Specifically, the white balance control circuit 612 identifies a portion that is originally estimated to be white in the photographic subject from the luminance or saturation data based on the WB adjustment data provided from the overall control unit 62, and the portion. The R, G, and B color components are averaged, and the G / R ratio and G / B ratio are obtained, and the levels are corrected as R and B correction gains.

  The gamma correction circuit 613 corrects the gradation characteristics of the image data subjected to WB adjustment. Specifically, the gamma correction circuit 613 performs non-linear conversion of the image data level for each color component and offset adjustment using a preset gamma correction table.

  The image memory 614 temporarily stores the image data output from the image processing unit 61 in the shooting mode and is used as a work area for performing predetermined processing on the image data by the overall control unit 62. It is. In the playback mode, the image data read from the memory card 67 is temporarily stored.

  The overall control unit 62 includes a microcomputer. Specifically, the overall control unit 62 includes a CPU 62A that performs various arithmetic processes, a RAM 62B that is a work area for performing arithmetic, and a ROM 62C that stores a control program and the like, and the imaging apparatus 1A as described above. Centrally controls the operation of each processing unit. As the ROM 62C, for example, an EEPROM capable of additionally writing data is adopted. Thereby, the ROM 62C can additionally write data, and retains the contents of the data even when the power is turned off.

  In the overall control unit 62, various functions are realized by the CPU 62A performing arithmetic processing in accordance with a control program stored in the ROM 62C in advance. In FIG. 5, some of the functions realized by the overall control unit 62 (specifically, a shake correction control unit 621, a movement history generation unit (also simply referred to as “history generation unit”) 622, a focus adjustment information acquisition unit 623, And a focus adjustment information correction unit 624) are schematically shown.

  The blur correction control unit 621 has a function of moving the image sensor 101 in accordance with an output signal (blur signal) from the blur detection unit 99 and correcting the blur of the imaging device 1A caused by camera shake or the like.

  The movement history generation unit 622 calculates the position of the image sensor 101 based on an output signal from the image sensor position sensor 98 (FIG. 5) provided in the shake correction unit 100, and records history information regarding movement of the image sensor 101 ( (Also referred to as “movement history information”). In the present embodiment, the number of movements CU of the image sensor 101 is used as the movement history information. Details will be described later.

  The focus adjustment information acquisition unit 623 acquires information on focus adjustment according to the focus adjustment state (also referred to as “focus adjustment information”).

  Specifically, the focus adjustment information acquisition unit 623 has a function of detecting a defocus amount that represents a shift amount from the focus (also referred to as a “focus detection function”). More specifically, the focus adjustment information acquisition unit 623 calculates the defocus amount based on the output signal from the phase difference detection signal acquired by the AF module 107, and the photographing lens at the time of focusing (more specifically, A focus lens position specifying operation (also simply referred to as “focus detection operation”) for specifying the position (focus lens position) of the focus lens) is performed.

  Further, the focus adjustment information acquisition unit 623 has a function (also referred to as “lens drive amount calculation function”) that converts the defocus amount into a drive amount (lens drive amount) of the photographing lens up to the focus lens position. .

  The focus adjustment information correction unit 624 has a function of correcting the focus adjustment information according to the movement history information. Details will be described later.

  The flash circuit 63 controls the light emission amount of the external flash connected to the flash unit 318 or the connection terminal unit 319 to the light emission amount set by the overall control unit 62 in the flash photographing mode.

  The operation unit 64 includes the mode setting dial 305, the control value setting dial 306, the shutter button 307, the setting button group 312, the direction selection key 314, the push button 315, the main switch 317, and the like. 62 for input.

  The VRAM 65 has an image signal storage capacity corresponding to the number of pixels of the LCD 311 and is a buffer memory between the overall control unit 62 and the LCD 311. The card I / F 66 is an interface for enabling transmission / reception of signals between the memory card 67 and the overall control unit 62. The memory card 67 is a recording medium that stores image data generated by the overall control unit 62. The communication I / F 68 is an interface for enabling transmission of image data and the like to a personal computer or other external device.

  The power supply circuit 69 includes, for example, a constant voltage circuit, and generates a voltage for driving the entire imaging apparatus 1A (for example, the overall control unit 62, the imaging element 101, etc.). Note that energization control to the image sensor 101 is performed by a control signal supplied from the overall control unit 62 to the power supply circuit 69. The battery 69B includes a primary battery such as an alkaline battery or a secondary battery such as a nickel metal hydride battery, and is a power source that supplies power to the entire imaging apparatus 1A.

  The mirror drive control unit 72A generates a drive signal for driving the mirror drive actuator 72M in accordance with the switching of the finder mode or the timing of the photographing operation. The mirror drive actuator 72M is an actuator that rotates the mirror mechanism 8 to a horizontal posture or an inclined posture.

  The shutter drive control unit 73A generates a drive control signal for the shutter drive actuator 73M based on a control signal given from the overall control unit 62. The shutter drive actuator 73M is an actuator that opens and closes the shutter unit 40.

  The aperture drive control unit 76A generates a drive control signal for the aperture drive actuator 76M based on the control signal given from the overall control unit 62. The aperture driving actuator 76M applies a driving force to the aperture driving mechanism 27 via the coupler 75.

<About the image stabilization unit 100>
Next, the blur correction unit 100 will be described. FIG. 6 is an exploded perspective view of the blur correction unit 100. FIG. 7 is a diagram showing the piezoelectric actuators 901 and 921.

  As shown in FIG. 6, the shake correction unit 100 includes a fixed substrate 90, a first slider 91 that moves in the X-axis direction (yaw direction) with respect to the fixed substrate 90, and a Y-axis with respect to the first slider 91. And a second slider (also referred to as “image sensor folder”) 92 that moves in the direction (pitch direction).

  The fixed substrate 90 is a base material for mounting the shake correction unit 100 inside the imaging apparatus 1A, and includes a piezoelectric actuator (also referred to as “yaw direction actuator”) 901.

  As shown in FIG. 7, the yaw direction actuator 901 includes a stacked piezoelectric element AK2 in which ceramics are stacked in a rod shape, a rectangular stationary member AK1 connected to one end side in the stacking direction of the piezoelectric element AK2, And a carbon drive rod (also referred to as “drive shaft”) AK3 connected to the other end side in the stacking direction. The piezoelectric element AK2 has a property of expanding and contracting in the stacking direction according to the applied voltage, and the drive shaft AK3 moves in the stacking direction (the direction indicated by the double arrow YW in FIG. 7) as the piezoelectric element AK2 expands and contracts. It is like that.

  The second slider 92 is formed so as to be able to hold the image sensor 101 on one main surface side HM, and has a pitch direction actuator 921 on a side portion.

  The pitch direction actuator 921 has the same configuration as the yaw direction actuator 901 (see FIG. 7), and the drive shaft AK3 moves in the stacking direction as the piezoelectric element AK2 expands and contracts.

  The first slider 91 is a bearing portion (also referred to as “yaw direction bearing portion”) 911 of the drive shaft AK3 of the yaw direction actuator 901 and a bearing portion (also referred to as “pitch direction bearing portion”) of the drive shaft AK3 of the pitch direction actuator 921. 912). Each of the bearing portions 911 and 912 has a V-groove, and is configured so that the drive shaft AK3 of the piezoelectric actuators 901 and 921 can be slidably fitted.

  When the shake correction unit 100 is assembled, the yaw direction bearing portion 911 is slidably frictionally coupled to the drive shaft AK3 of the yaw direction actuator 901, and the pitch direction bearing portion 912 is driven to the drive shaft AK3 of the pitch direction actuator 921. Are slidably frictionally coupled to each other. In the assembled state (the assembled state), the yaw direction bearing portion 911 and the drive shaft AK3 of the yaw direction actuator 901 constitute a yaw direction friction coupling portion, and the pitch direction bearing portion 912 and the drive shaft of the pitch direction actuator 921 AK3 constitutes a pitch direction frictional coupling part.

  Further, in the assembled state, the blur correction unit 100 is urged against the fixed substrate 90 with the second slider 92 sandwiched between the fixed substrate 90 and the first slider 91. .

  In the shake correction unit 100 assembled in this way, the first slider 91 moves in the yaw direction (the direction indicated by the double arrow YD in FIG. 6 (X-axis direction) with respect to the fixed substrate 90 by driving the yaw direction actuator 901. ) Is moved to slide. Further, by driving the pitch direction actuator 921, the second slider 92 slides in the pitch direction (direction indicated by the double arrow PD in FIG. 6 (Y-axis direction)) with respect to the first slider 91 (and thus the fixed substrate 90). Is done.

  That is, the image sensor 101 held by the second slider 92 can move in the pitch direction and the yaw direction with respect to the fixed substrate 90, in other words, can move in a plane perpendicular to the optical axis LT.

  The four Hall elements 902 provided on the fixed substrate 90 and the magnets (permanent magnets) 922 provided on the second slider 92 constitute an image sensor position sensor 98 in the assembled state. From each Hall element 902 constituting the image sensor position sensor 98, a voltage corresponding to the position of the image sensor 101 is output to the overall control unit 62.

  In the shake correction unit 100 having the above-described configuration, wear may occur in the frictional coupling portion (specifically, the drive shaft AK3 and / or the bearing portions 911 and 912) when the accumulated drive time for moving the image sensor 101 becomes long. is there. Specifically, the shake correction unit 100 employs a configuration in which the bearing portions 911 and 912 and the drive shaft AK3 are in direct contact with each other, and therefore, when the integrated drive time becomes long, the drive shaft for moving the image sensor 101 is increased. The drive shaft AK3 and / or the bearing portions 911, 912 of the piezoelectric actuators 901, 921 are worn due to the sliding between the AK3 and the bearing portions 911, 912. When wear occurs in the frictional coupling portion in this way, the positions of the first slider 91 and the second slider 92 biased against the fixed substrate 90 change in the optical axis direction, and as a result, the imaging element in the optical axis direction. The position of 101 changes relatively.

  Such positional change (displacement) of the image sensor 101 in the optical axis direction changes the distance (also referred to as “flange back”) FB (see FIG. 4) from the lens mounting surface to the image sensor surface (image surface) of the image sensor. I will let you.

  The flange back FB is an important element that affects the focal point of the lens, and when the flange back FB changes with time, the focusing accuracy by the automatic focusing control is lowered.

  Specifically, the defocus amount detected by the focus adjustment information acquisition unit 623 is based on the assumption that the flange back FB at the time of shipment (in other words, the position of the image sensor 101 on the optical axis) does not change with time. Has been detected. For this reason, when the flange back FB changes with time, the defocus amount detected by the focus adjustment information acquisition unit 623 is different from the actual defocus amount, and as a result, the accuracy of specifying the focus lens position decreases. Will do.

<About AF Operation of Imaging Device 1A>
Next, an AF operation executed in the imaging apparatus 1A will be described in detail.

  As described above, the displacement of the image sensor 101 in the optical axis direction (also referred to as “optical axis direction displacement”) is a factor that reduces the focusing accuracy of the AF operation in the image capturing apparatus 1A. In 1A, an AF operation for reducing the influence of the displacement of the image sensor 101 in the optical axis direction is executed.

  Specifically, in the AF operation of the imaging apparatus 1A, movement history information of the image sensor 101 is generated, and focus adjustment information used for focus adjustment is corrected according to the movement history information. Then, focus adjustment is performed based on the corrected focus adjustment information (also referred to as “corrected focus adjustment information”).

  In the following, the movement history information generation processing (also referred to as “history information generation processing”) of the image sensor 101 will be described first, and then focus adjustment information correction processing according to the movement history information (“adjustment information correction processing”). Will also be described.

  First, history information generation processing will be described. FIG. 8 is a block diagram relating to the AF operation of the imaging apparatus 1A. 9 to 12 are arrangement diagrams of elements constituting the image sensor position sensor 98. FIG. For simplification of illustration, the pitch direction Hall element pair 902c and 902d are omitted in FIGS. 10 and 11, and the yaw direction Hall element pair 902a and 902b are omitted in FIG. Further, in FIG. 11, the locus of the center GP of the magnet 922 drawn by the movement of the magnet 922 is schematically represented by arrows KH1 and KH2.

  As illustrated in FIG. 8, the history information generation process is executed in the movement number accumulation unit 622 a in the movement history generation unit 622 based on the output value of the image sensor position sensor 98 provided in the shake correction unit 100.

  As shown in FIG. 9, the image sensor position sensor 98 includes a magnet 922 and four Hall elements 902 that detect magnetism from the magnet 922.

  The four Hall elements 902 are provided on a fixed body (here, the fixed substrate 90), and the magnet 922 is provided on a moving body (here, the second slider 92) that moves relative to the fixed body.

  In addition, the four Hall elements 902 are arranged along the moving direction of the moving body for each set, with two as a set. Specifically, a pair of Hall elements (also referred to as “yaw direction Hall element pair”) 902a and 902b are arranged apart from each other along the X-axis direction in which the movable body can move, and the movable body moves. A pair of Hall elements (also referred to as “pitch direction Hall element pairs”) 902c and 902d are arranged apart from each other along the possible Y-axis direction.

  The yaw direction hall element pair 902a, 902b functions as a position detection element for detecting the position of the moving body in the X direction, and the pitch direction hall element pair 902c, 902d is a position detection element for detecting the position of the moving body in the Y direction. Function as.

  Further, when the magnet 922 is positioned in the middle of each Hall element pair that is spaced apart, the moving body is positioned at an initial position (also referred to as a “reference position”) when starting the shake correction operation. become.

  In the image sensor position sensor 98 having such a configuration, for example, a range in the X-axis direction (also referred to as “X-direction reference range”) including the magnet 922 when the moving body is positioned at the reference position (referred to as “X-direction reference range” in FIG. 10). The movement until a part of the magnet 922 protrudes from the range (range indicated by the double arrow RH1) until it falls within the X-direction reference range is regarded as one movement in the X-axis direction. Specifically, the movement in the + X direction side indicated by the arrow KH1 and the movement in the −X direction side indicated by the arrow KH2 in FIG. 11 are each determined as one movement of the image sensor 101, and the number of movements It is counted by the integrating unit 622a.

  Further, the moving body can also move in the Y-axis direction. For example, a range in the Y-axis direction including the magnet 922 when the moving body is positioned at the reference position (also referred to as “Y-direction reference range”) (in FIG. 12). From the range indicated by the double arrow RH2), the movement until a part of the magnet 922 protrudes and then falls within the Y-direction reference range is regarded as one movement in the Y-axis direction. One movement in the Y-axis direction is also counted as one movement of the image sensor 101 by the movement number accumulating unit 622a.

  When the number of movements of the image sensor 101 is confirmed, the movement number integrating unit 622a moves to the number of movements accumulated from the time of shipment of the imaging apparatus 1A (also referred to as “integrated movement number”) CU. Integration processing is performed.

  The accumulated number of movements CU of the image sensor 101 is stored in the ROM 62C at a predetermined timing such as when the image sensor 101 is turned off, and is read from the ROM 62C when the image sensor 101 is powered on.

  Further, in the above description, one entry / exit of the magnet 922 from the reference range defined by the magnet 922 at the reference position is counted as the number of movements CU. However, the range (“imaging” A single entry / exit of the image sensor 101 from the “element reference range”) may be counted as the number of movements CU. In this case, it is determined that the movement from the image pickup element reference range including the image pickup element 101 at the reference position until the image pickup element 101 protrudes again and falls within the reference range is the movement of the image pickup element 101 once.

  Thus, in the imaging apparatus 1A, the number of movements CU of the image sensor 101 is acquired as movement history information by the number-of-movements accumulation unit 622a.

  Next, adjustment information correction processing will be described. FIG. 13 is a diagram illustrating a relationship between the number of movements CU of the image sensor 101 and the change amount VM of the image sensor 101 in the optical axis direction.

  The adjustment information correction process is executed in the focus adjustment information correction unit 624 using the number of movements CU of the image sensor 101.

  Specifically, as illustrated in FIG. 8, the defocus amount obtained by the focus detection unit 623 a included in the focus adjustment information acquisition unit 623 is the lens drive amount calculation unit 623 b included in the focus adjustment information acquisition unit 623. Is converted into the lens driving amount of the photographing lens. The lens driving amount is corrected by the focus adjustment information correction unit 624 according to the number of movements CU of the image sensor 101 given from the number-of-movements integration unit 622a.

  The lens drive amount correction by the focus adjustment information correction unit 624 is, for example, the relationship between the number of movements CU of the image sensor 101 and the change amount (also simply referred to as “position change amount”) VM of the image sensor 101 in the optical axis direction. This is performed using a graph GC (see FIG. 13) representing

  Specifically, the focus adjustment information correction unit 624 acquires the position change amount VM from the graph GC according to the number of movements CU of the image sensor 101, and removes the error corresponding to the position change amount VM from the lens drive amount. . Then, the corrected lens drive amount (also referred to as “correction lens drive amount”) is transmitted to the lens control unit 26 constituting the focus adjustment unit via the connector Ec, and the focus adjustment unit determines the correction lens drive amount. The taking lens is moved.

  Note that the data of the graph GC shown in FIG. 13 is acquired in advance by a factory test or the like, and is stored in advance in the ROM 62C of the overall control unit 62 at the time of shipment.

  As described above, in the image pickup apparatus 1A, the number of movements CU of the image sensor 101 is integrated as movement history information, and the displacement in the optical axis direction of the image sensor 101 caused by the movement of the image sensor 101 according to the number of movements CU. Calculated. Then, the displacement error (also referred to as “displacement error”) is removed from the lens driving amount as the focus adjustment information.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described.

  In the imaging apparatus 1A according to the first embodiment, the lens driving amount is corrected according to the number of movements CU of the imaging element 101. However, in the imaging apparatus 1B according to the second embodiment, the defocus amount is that of the imaging element 101. It is corrected according to the number of movements CU. FIG. 14 is a block diagram relating to the AF operation of the imaging apparatus 1B.

  Note that the imaging apparatus 1B according to the second embodiment has substantially the same configuration and functions as those of the imaging apparatus 1A according to the first embodiment except that the defocus amount is corrected by the focus adjustment information correction unit 624 (FIG. 1). The common parts are denoted by the same reference numerals and the description thereof is omitted.

  As illustrated in FIG. 14, in the imaging apparatus 1B, the history information generation processing is performed based on the output value of the imaging element position sensor 98 provided in the shake correction unit 100, as in the imaging apparatus 1A. Executed by.

  In the imaging apparatus 1B, the focus adjustment information correction unit 624 performs a process of correcting the defocus amount as the focus adjustment information according to the number of movements CU of the image sensor 101 (also referred to as “defocus amount correction process”). .

  Specifically, the defocus amount obtained by the focus detection unit 623a is corrected by the focus adjustment information correction unit 624 according to the number of movements CU of the image sensor 101 given from the number-of-movements accumulation unit 622a.

  The defocus amount correction by the focus adjustment information correction unit 624 is performed using, for example, a graph GC (see FIG. 13) that represents the relationship between the number of movements CU of the image sensor 101 and the position change amount VM of the image sensor 101. Is called.

  Specifically, the focus adjustment information correction unit 624 acquires the position change amount VM from the graph GC according to the number of movements CU of the image sensor 101, and removes the error corresponding to the position change amount VM from the defocus amount. . Then, the corrected defocus amount (also referred to as “corrected defocus amount”) is converted into the lens drive amount of the photographing lens by the lens drive amount calculation unit 623b. The lens driving amount acquired in this way is transmitted to the lens control unit 26 constituting the focus adjusting means via the connector Ec, and the photographing lens is moved in accordance with the lens driving amount in the focus adjusting means. .

  As described above, in the imaging apparatus 1B, the focus adjustment information correction unit 624 corrects the defocus amount as the focus adjustment information according to the movement history information.

<3. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the contents described above.

  For example, in each of the above embodiments, the number of movements CU of the image sensor 101 is used as the movement history information, but the present invention is not limited to this.

  Specifically, in a movement distance accumulation unit (not shown) in the movement history generation unit 622, the total movement distance moved by the image sensor 101 may be accumulated and the total movement distance may be used as movement history information.

  In each of the above embodiments, the displacement in the optical axis direction of the image sensor 101 is temporarily calculated according to the movement history information, and the error corresponding to the displacement is removed from the focus adjustment information. However, the present invention is not limited to this.

  Specifically, data on the relationship between the movement history information and the displacement error included in the focus adjustment information is stored in the ROM 62C in advance, and the displacement error included in the focus adjustment information is directly determined according to the movement history information. It may be calculated.

1 is a diagram illustrating an external configuration of an imaging apparatus according to a first embodiment of the present invention. 1 is a diagram illustrating an external configuration of an imaging apparatus according to a first embodiment of the present invention. It is a longitudinal cross-sectional view of an imaging device. It is a longitudinal cross-sectional view of an imaging device. It is a block diagram which shows the electrical structure of an imaging device. It is a disassembled perspective view of a shake correction unit. It is a figure which shows a piezoelectric actuator. It is a block diagram regarding AF operation of an imaging device. It is an arrangement plan of elements constituting an image sensor position sensor. It is an arrangement plan of elements constituting an image sensor position sensor. It is an arrangement plan of elements constituting an image sensor position sensor. It is an arrangement plan of elements constituting an image sensor position sensor. It is a figure which shows the relationship between the frequency | count of a movement of an image pick-up element, and the variation | change_quantity of the optical axis direction of an image pick-up element. It is a block diagram regarding AF operation | movement of the imaging device which concerns on 2nd Embodiment.

Explanation of symbols

1A, 1B Imaging device 62 Overall control unit 62A CPU
621 Blur correction control unit 622 Movement history generation unit 622a Movement number accumulation unit 623 Focus adjustment information acquisition unit 623a Focus detection unit 623b Lens drive amount calculation unit 624 Focus adjustment information correction unit 98 Image sensor position sensor 99 Blur detection unit 100 Blur correction unit 101 Image sensor 107 AF module CU Number of movements VM Position change FB Flange back LT Optical axis

Claims (6)

An imaging device,
An image sensor for acquiring a captured image related to the subject image;
Movement control means for moving the image sensor in a plane perpendicular to the optical axis of the imaging optical system;
Generating means for generating movement history information relating to movement of the image sensor;
Acquisition means for acquiring focus adjustment information according to the focus adjustment state;
Correction means for correcting the focus adjustment information according to the movement history information;
Focus adjusting means for performing focus adjustment based on the corrected focus adjustment information corrected by the correcting means;
An imaging apparatus comprising: The imaging device according to claim 1,
The correction unit calculates a displacement in the optical axis direction of the image sensor caused by the movement of the image sensor according to the movement history information, and removes an error corresponding to the displacement from the focus adjustment information. An imaging device. The imaging device according to claim 2,
The image pickup apparatus characterized in that the movement history information includes the number of movements of the image pickup element. The imaging device according to claim 3.
The number of times of movement is obtained by integrating movements from a reference range including the image sensor at a reference position until the image sensor protrudes again and again within the reference range as one movement. An imaging device. The imaging device according to claim 1,
The acquisition means includes
Focus detection means for detecting a defocus amount representing the focus adjustment state;
Have
The image pickup apparatus, wherein the correction unit corrects the defocus amount according to the movement history information. The imaging device according to claim 1,
The acquisition means includes
Focus detection means for detecting a defocus amount representing the focus adjustment state;
Drive amount calculation means for converting the defocus amount into a lens drive amount of a focusing lens;
Have
The image pickup apparatus, wherein the correction unit corrects the lens driving amount in accordance with the movement history information.

Images