JP7066395B2 - Image pickup device and its control method - Google Patents

Description

The present invention relates to a technique for image stabilization processing of a captured image.

As the magnification of the image pickup device increases, the shaking applied to the image pickup device due to camera shake or the like becomes more noticeable in telephoto shooting, so it is required to improve the performance of the image stabilization mechanism. The image shake correction mechanism detects camera shake and the like, and moves the shake correction lens (hereinafter, also simply referred to as a correction lens) constituting the image pickup optical system in a direction substantially orthogonal to the optical axis. If the correction lens moves significantly to improve the image stabilization performance, the amount of deviation from the optical axis increases, so that the subject contrast at the center of the captured image decreases, and the optical performance may decrease.

In the contrast AF (autofocus) method, in the through image before the start of exposure, the position where the subject contrast becomes high in order to focus on a predetermined subject is calculated. The focus lens moves to the calculated position, and when the subject is in focus, the focus lens holds that position. If the image pickup device shakes while the subject is in focus, the correction lens moves according to the shake detection signal, and the shake is canceled.

For example, it is assumed that the correction lens is greatly deviated from the optical axis of the imaging optical system, so that the subject contrast in the center of the image is lowered and the through image becomes a blurred image. It is assumed that the exposure to the image sensor is started and the focus lens is held in a fixed position during the exposure. When the shake of the image pickup apparatus is detected during the exposure, the correction lens is driven, so that the captured image becomes an exposed image with the subject contrast lowered. To solve this problem, when the drive amount of the correction means is large, a method of returning the correction means to a predetermined drive range in which image deterioration due to aberration does not occur before exposure, or a method of returning the correction means to a predetermined drive range before exposure, or a drive amount of the correction means before exposure. There is a way to limit and even prohibit exposure. Patent Document 1 discloses an autofocus device having a correction limiting function of limiting camera shake correction to prevent overcorrection.

Japanese Unexamined Patent Publication No. 2009-145852

The device disclosed in Patent Document 1 makes it possible to reduce the influence of camera shake on the focusing accuracy, but limits the drive of the correction lens, so that the camera shake correction effect may be reduced.
An object of the present invention is to be able to acquire a captured image with good image quality by notifying a change in image quality while exhibiting an image blur correction effect.

The apparatus of one embodiment of the present invention calculates a correction amount for correcting image blur from a detection signal by the shake detecting means, and controls an image blur correction means for correcting image blur of an image captured by the imaging means. A control means, a focus adjustment control means for controlling the drive of a focus lens that adjusts the focus in conjunction with the drive of the correction means, and an image captured by the image pickup means before an imaging instruction accompanied by image storage is given. Notification that controls to notify the image range in which the image quality is lower than the standard image quality when the image quality of the image captured by the image pickup means is changed by the drive of the correction means while the display means is displaying the live view. It is provided with a control means.

According to the present invention, it is possible to acquire a captured image with good image quality by notifying the change in image quality while exhibiting the image stabilization effect.

It is sectional drawing of the lens barrel at the time of retracting of the image pickup apparatus which concerns on embodiment of this invention. It is sectional drawing of the lens barrel at the time of photographing of the image pickup apparatus which concerns on embodiment of this invention. It is an exploded perspective view of the lens barrel which concerns on embodiment of this invention. It is a detailed view of the zoom drive part of the image pickup apparatus which concerns on embodiment of this invention. It is a front view and the sectional view of the correction lens which concerns on embodiment of this invention. It is a figure which shows the focus drive mechanism part which concerns on embodiment of this invention. It is a block diagram which shows the structural example of the image pickup apparatus. It is a figure explaining the decrease of the subject contrast by driving a correction lens. It is a figure which shows the correction amount of a focus lens corresponding to the movement amount of a correction lens. It is a figure which shows the relationship between the movement of a correction lens, and the judgment of the image quality deterioration. It is explanatory drawing of the notification of the image quality deterioration range and the image cutout range. It is a figure explaining the image quality determination method. It is a flowchart explaining the process of the image pickup apparatus which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process which follows FIG. It is a flowchart explaining the process of the image pickup apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process following FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, with respect to the configuration of the device common to each embodiment, the overall configuration of the zoom lens barrel is shown in FIGS. 1 to 3. FIG. 1 shows a zoom lens barrel in a retracted state (hereinafter, simply referred to as a lens barrel), and FIG. 2 shows a lens barrel in a extended state. FIG. 3 is an exploded perspective view of the lens barrel. In the following, the positional relationship of each part will be described by defining the subject side as the front side and the side away from the optical axis of the imaging optical system as the outer peripheral side.

In this embodiment, a lens barrel having a three-group lens configuration is illustrated. The group 1 unit comprises a group 1 lens holding frame 11 that holds the first lens group 1 and a group 1 base plate 12 that holds the group 1 lens holding frame 11 and includes a lens barrier member that protects the lens. The second group unit includes an aperture unit 21 including a light amount adjusting member at the time of shooting, a second group lens holding frame 31 for holding the second lens group 2, and a second group base plate 32 including a shutter member (not shown). The 1st group unit, the aperture unit 21, and the 2nd group unit form a variable magnification optical system. The 2nd group unit is equipped with an image stabilization mechanism, and the 2nd lens group 2 and the 2nd group lens holding frame 31 move in a direction substantially orthogonal to the optical axis during shooting to cause image blurring due to camera shake during shooting. to correct. The third lens group 3 is a focus lens group for focusing on the subject, and is held by the third group lens holding frame 41.

In the shooting standby state of FIG. 1, each lens group is in the retracted state, and in the shooting state of FIG. 2, each lens group is extended in the optical axis direction. A third lens group 3 and an image pickup device 5 are attached to a sensor holder unit located near the rear end in the optical axis direction. The image pickup device 5 is supported on the sensor holder 501 via the sensor plate 505. The optical filter 4 at the front of the image pickup element 5 is arranged in a state of being sandwiched between the sensor holder 501 and a sensor rubber (not shown). As shown in the perspective view of FIG. 3, the lens barrel includes a fixed cam cylinder 504 that constitutes a zoom mechanism unit. The fixed cam cylinder 504 is fastened to the sensor holder unit with screws.

FIG. 3 shows a group 1 base plate 12, an aperture unit 21, a group 2 lens holding frame 31, a fixed cam cylinder 504, a moving cam ring 503, a straight guide cylinder 502, and a sensor holder 501. FIG. 4 shows the moving cam ring 503 and its drive mechanism. A zoom motor 601 and gear trains 603 to 606 are arranged on the sensor holder 501. The gear 602 attached to the drive shaft of the zoom motor 601 is rotated by the drive force of the zoom motor 601. The rotational force is transmitted to the moving cam ring 503 via the gear trains 603 to 606, and the lens barrel is the optical axis. Driven in the direction. The gear trains 603 to 606 are stepped gears having a large diameter gear and a small diameter gear coaxially having different numbers of teeth. The final gear 606 that meshes with the gear portion 503e of the moving cam ring 503 is composed of a large-diameter gear portion and a small-diameter gear portion that is long in the optical axis direction.

Next, a tubular member and a zoom drive mechanism for moving each lens group in the optical axis direction will be described. As shown in FIGS. 1 and 2, a moving cam ring 503 is arranged on the outer peripheral side of each lens group. Cam grooves 503a, 503b, and 503c (FIG. 3) having different trajectories of three types are formed on the inner peripheral surface portion of the moving cam ring 503. The follower pins 12a, 21a, 32a formed on the outer periphery of the first group ground plate 12, the throttle unit 21, and the second group ground plate 32 are engaged with each cam groove to follow each cam groove.

Further, as shown in FIGS. 1 and 2, a straight guide cylinder 502 is provided on the inner peripheral side of the moving cam ring 503 to regulate rotation when each lens group moves. The straight guide cylinder 502 and the moving cam ring 503 are so-called bayonet-coupled and move substantially integrally in the optical axis direction. The moving cam ring 503 is rotatable relative to the straight guide cylinder 502. The straight guide cylinder 502 is provided with long grooves 502a, 502b, 502c (FIG. 3) extending in the optical axis direction. The group 1 ground plate 12, the diaphragm unit 21, and the group 2 ground plate 32 move straight along the optical axis direction by being restricted in rotation by the long grooves 502a, 502b, and 502c, respectively.

A cam groove 504a and a straight guide groove 504b, which is a linear groove, are formed on the inner peripheral surface portion of the fixed cam cylinder 504. As shown in FIG. 3, the follower pin 503d formed on the outer peripheral surface portion of the moving cam ring 503 engages with and follows the cam groove 504a. The guide groove 504b is slidably fitted with the straight-moving restricting portion 502d of the straight-moving guide cylinder 502. The gear portion 503e formed on the outer peripheral surface portion of the moving cam ring 503 meshes with the final gear 606 of the gear rows 603 to 606. By driving the zoom motor 601 the driving force is transmitted from the final gear 606 to the gear portion 503e, so that the moving cam ring 503 rotates in the optical axis direction while engaging with and following the cam groove 504a of the fixed cam cylinder 504. Moving.

As shown in FIG. 4, the gear portion 503e of the moving cam ring 503 meshes with the small diameter gear that is a part of the final gear 606, and the large diameter gear is located behind the small diameter gear in the optical axis direction (on the image pickup element side). It meshes with the gear 605. The small-diameter gear portion (long gear portion) of the final gear 606 is formed long in the optical axis direction in accordance with the extension amount of the moving cam ring 503 so as to correspond to the movement of the moving cam ring 503 in the optical axis direction. The straight guide cylinder 502 moves integrally with the moving cam ring 503 in the optical axis direction. The straight guide cylinder 502 is provided with a straight guide portion 502d on the outer peripheral portion on the rear end side (FIG. 3). Since the rotation of the straight guide portion 502d is restricted by slidably fitting into the straight guide groove 504b of the fixed cam cylinder 504, the straight guide cylinder 502 only moves straight in the optical axis direction.

In the present embodiment, as the moving cam ring 503 rotates, the first group unit, the aperture unit 21, and the second group unit following the moving cam ring 503 move in the optical axis direction while being restricted from going straight. Since the fixed cam cylinder 504 is integrally formed by fastening the sensor holder 501 with a screw, it does not move in the optical axis direction or the rotation direction.

Next, the image stabilization device will be described with reference to FIG. The image shake correction device includes a two-group unit and a driving unit thereof. FIG. 5A is a front view of the group 2 unit when viewed from the subject side. FIG. 5B is a cross-sectional view when the group 2 unit is cut at the center of the lens, and the cutting position is shown in FIG. 5A.

A lens driving unit of the 2nd group unit is provided on the outer peripheral side of the 2nd group ground plate 32. The second group lens 2 functions as a correction lens (so-called shift lens). The lens driving unit includes a magnet 37 and a coil 38, and moves the group 2 lens holding frame 31 in a direction orthogonal to the optical axis. A shutter drive unit (not shown) for driving the shutter mechanism is provided on the outer peripheral side of the second group lens 2 in the second group base plate 32. An ND drive unit (not shown) for driving an ND (Neutral Density) filter is provided on the image plane side (rear side) of the group 2 base plate 32.

The second group lens holding frame 31 and the second group base plate 32 are connected in the optical axis direction by two tension springs (not shown). Due to the urging force of the two tension springs, the second group lens holding frame 31 is offset with respect to the second group base plate 32 with a plurality of balls 35 sandwiched in the optical axis direction. The rolling of the ball 35 causes the group 2 lens holding frame 31 to move in a direction orthogonal to the optical axis.

A Hall element holding portion 34 is arranged in front of the second group ground plate 32. The shutter FPC (flexible wiring member) 33 is routed over the Hall element holding unit 34 in a state of being connected to the lens driving unit, the shutter driving unit, and the ND driving unit, and is formed on the outer peripheral portion of the Hall element holding unit 34. It is pulled out toward the image plane along the pull-out plane. Hall elements 36 for detecting the positions of the second group lens 2 and the second group lens holding frame 31 are mounted on the shutter FPC 33 at two locations separated from each other by 90 ° in the circumferential direction. Each Hall element 36 is connected to a lens barrel FPC (not shown) via a shutter FPC 33. The shutter FPC 33 is fixed to the Hall element holding portion 34, and the Hall element holding portion 34 is locked to the second group base plate 32 by a snap-fit coupling with the second group lens 2 sandwiched between them.

The second group lens holding frame 31 is provided with a magnet 37 magnetized so as to sandwich the Hall element 36 between the N pole and the S pole when viewed from the optical axis direction. The two Hall elements 36 detect the magnetic field generated by the magnet 37 and output the detection signal to the control unit inside the camera body. When the 2nd group lens holding frame 31 moves in a plane orthogonal to the optical axis, the magnetic field passing through the Hall element 36 changes and the output of the Hall element 36 changes. Therefore, the position of the 2nd group lens holding frame 31 is detected. Can be done.

The coil 38 is arranged at a position facing the magnet 37 on the image plane side in the optical axis direction, and is attached to the second group base plate 32. The coil 38 is connected to the lens barrel FPC via the shutter FPC 33, and receives power from the power supply unit of the camera body. An electromagnetic force is generated by energizing the coil 38, and the second group lens holding frame 31 is driven.

The focus drive mechanism unit will be described with reference to FIGS. 3 and 6. The focus drive mechanism unit is attached to the sensor holder unit. FIG. 6A is an exploded perspective view of the focus drive mechanism unit, and FIG. 6B is a front view showing a main part of the focus drive mechanism unit. The third lens group 3, which is a focus lens group, moves in the optical axis direction by a drive unit using a lead screw.

A group 3 lens holding frame 41 is supported on the sensor holder 501 so as to be movable straight in the optical axis direction. The main guide shaft 42 (FIG. 6) extending parallel to the shooting optical axis is press-fitted into the hole of the sensor holder 501 and fixed. Similarly, the rotation control sub-guide shaft 43 is press-fitted into the hole of the sensor holder 501 and fixed.

The focus drive motor 44 (FIG. 6) is fixed to the sensor holder 501 by fastening with screws. The sleeve 41a provided on the group 3 lens holding frame 41 is formed with sleeve holes that engage with the main guide shaft 42 at both ends, and a sleeve opening is formed at the center. Further, the third group lens holding frame 41 is formed with a U-shaped groove portion 41b that engages with the sub guide shaft 43. Further, the group 3 lens holding frame 41 is provided with a support hole portion 41c for supporting the rack 45 in the vicinity of the sleeve 41a.

The lead screw 44a is integrally formed with the output shaft of the focus drive motor 44. The rack 45 includes meshing teeth 45a that mesh with the lead screw 44a and urging teeth 45b that face the meshing teeth 45a. Further, the rack 45 is formed with a support shaft that engages with the support hole of the third group lens holding frame 41. The urging tooth 45b is pressed by the arm portion of the torsion coil spring 46 in a direction in which it meshes with the lead screw 44a. The arm portion of the torsion coil spring 46 is hooked on the back surface portion of the rack 45. As a result, the lead screw 44a is sandwiched between the urging tooth 45b and the meshing tooth 45a. That is, the urging tooth 45b and the meshing tooth 45a are always in a state of being meshed with the lead screw 44a.

Further, the torsion coil spring 46 urges the rack 45 toward the end face in the optical axis direction of the third group lens holding frame 41 to prevent rattling between the rack 45 and the third group lens holding frame 41. Therefore, the lens is driven stably and with high accuracy in the optical axis direction. In the focus drive mechanism section, when the lead screw 44a is rotated by the focus drive motor 44, the group 3 lens holding frame 41 moves forward and backward in the optical axis direction due to the screwing relationship between the rack 45 and the lead screw 44a, and the focus adjustment operation is performed. Will be.

The internal configuration of the image pickup apparatus will be described with reference to FIG. 7. FIG. 7 is a block diagram showing a configuration of a digital camera 100 as an example of an image pickup device. The lens barrel 101 includes various optical members. The zoom lens 102 optically changes the angle of view by adjusting the focal length. The correction lens 103 performs an image stabilization operation by eccentricizing the optical axis. The focus lens 104 performs a focus adjustment operation. The aperture and shutter 105 are used for exposure control to adjust the amount of light.

The image pickup unit includes an image pickup device 106 using a CCD (charge-coupled device), CMOS (complementary metal oxide semiconductor), or the like. The image pickup device 106 receives the light that has passed through the lens barrel 101 and outputs an electric signal by photoelectric conversion. The electric signal is input to the image processing circuit 107, subjected to pixel interpolation processing, color conversion processing, and the like, and then stored in the internal memory 108 as image data. The display unit 109 acquires image data, shooting information, and the like after shooting and displays them on the screen. The image processing circuit 107, the internal memory 108, and the display unit 109 are connected to the system control unit 119 and perform processing according to a control command from the system control unit 119.

The compression / decompression processing unit 110 acquires data stored in the internal memory 108 and performs compression / decompression processing according to a predetermined image format. The storage unit 111 stores various data such as parameters. The compression / decompression processing unit 110 and the storage unit 111 are connected to the system control unit 119, and perform processing according to a control command from the system control unit 119. The operation unit 112 is a user interface unit for performing various menu operations, mode switching operations, and the like. For example, the user can use the operation unit 112 to switch between a still image and a moving image, switch between manual focus and auto focus, and the like. The operation signal of the operation unit 112 is output to the system control unit 119. The runout detection unit 113 includes an angular velocity sensor or the like, detects runout applied to the image pickup device, and outputs a runout detection signal to the system control unit 119.

The aperture shutter drive unit 114, the focus lens drive unit 115, the image shake correction lens drive unit 116, and the zoom lens drive unit 118 drive each unit in charge according to a control command from the system control unit 119. The aperture shutter drive unit 114 drives the aperture and the shutter 105, and the focus lens drive unit 115 drives the focus lens 104. The image stabilization lens driving unit 116 drives the correction lens 103. The position detection unit 117 acquires the current position of the correction lens 103 and outputs a position detection signal to the system control unit 119. The zoom lens driving unit 118 drives the zoom lens 102.

The system control unit 119 includes a CPU (Central Processing Unit), executes various control programs stored in the internal memory 108 according to user operations, and performs AE (automatic exposure) control, AF (autofocus) control, and Performs image blur correction control, zoom control, etc. In FIG. 7, the function of the system control unit 119 is illustrated as a block element. The luminance signal calculation unit 121 calculates the luminance signal value of the subject based on the electric signal output from the image sensor 106. The exposure control unit 120 calculates the exposure control value (aperture value and shutter speed) based on the luminance signal value calculated by the luminance signal calculation unit 121, and outputs the calculation result to the aperture shutter drive unit 114. The evaluation value calculation unit 122 extracts a specific frequency component from the luminance signal by the luminance signal calculation unit 121 and calculates the AF evaluation value. Further, the evaluation value calculation unit 122 acquires the position information and the position correction information of the focus lens from the position correction unit 126 described later.

The focus control unit 123 outputs a control signal to the focus lens drive unit 115 to control the drive direction and drive amount of the focus lens 104. The scanning control unit 124 issues a drive command in a predetermined range to the focus control unit 123, and calculates the contrast by referring to the calculation result (evaluation value) of the evaluation value calculation unit 122 at the predetermined position of the focus lens 104. .. AF control is performed with the focus lens position where the contrast is highest as the focusing position.

The image shake correction control unit 125 calculates a correction direction and a correction amount for canceling the shake based on the detection information of the shake detection unit 113. The image shake correction control unit 125 acquires the current position of the correction lens 103 from the position detection unit 117 and drives the correction lens 103 to perform image shake correction control. The position correction unit 126 corrects the position of the focus lens 104 according to the current position of the correction lens 103 acquired via the image shake correction control unit 125. The zoom control unit 127 calculates the drive direction and the drive amount of the zoom lens 102 according to the zoom operation instruction by the operation unit 112, and controls the drive of the zoom lens 102.

The operation unit 112 includes a release button that turns on the first switch (SW1) and the second switch (SW2) in order according to the pushing amount. When the user half-presses the release button, the first switch SW1 is turned on. At that time, the exposure control unit 120 calculates the exposure control value (aperture value and shutter speed) based on the luminance information from the luminance signal calculation unit 121, and notifies the aperture shutter drive unit 114 of the calculation result. As a result, automatic exposure control is performed. The evaluation value calculation unit 122 calculates the AF evaluation value after extracting a specific frequency component from the luminance signal by the luminance signal calculation unit 121. When the user further operates the release button and pushes it all the way in, the second switch SW2 is turned on. The exposure control unit 120 performs exposure control based on the determined aperture value and shutter speed, and the image pickup image data acquired by the image pickup device 106 is stored in the storage unit 111.

The user can display a so-called live view image acquired by the image sensor 106 on the screen without pressing the release button. At that time, the system control unit 119 preliminarily determines the aperture value and the shutter speed at predetermined intervals based on the luminance information and the program diagram related to the video signal in preparation for the exposure at the time of still image shooting.

Here, with reference to FIG. 8, a phenomenon that may occur when the correction lens is greatly deviated from the optical axis, that is, subject focus deviation will be described. 8 (A) and 8 (B) are graphs showing the relationship between the focus lens position with respect to a predetermined subject and the fluctuation of the contrast evaluation value of the subject. The X-axis, which is the horizontal axis, represents the focus lens position, and the Y-axis, which is the vertical axis, represents the contrast evaluation value of the subject. 8 (C) and 8 (D) are schematic views showing a zoom lens 102, a correction lens 103, a focus lens 104 and an image pickup device 106, and FIG. 8 (C) corresponds to FIG. 8 (A) and is shown in FIG. 8 (A). D) corresponds to FIG. 8 (B). As shown in FIGS. 8A and 8B, the contrast evaluation value of the subject changes depending on the position of the focus lens 104, and the mountain shape changes due to the difference in contrast. The apex of the graph curve is the position where the contrast evaluation value is maximized, and when the focus lens 104 is located at this position, the subject is in focus.

8 (A) and 8 (C) show the case where the correction lens 103 is located on the same optical axis as the other lens groups. When the correction lens 103 is on the optical axis, as shown in FIG. 8A, the contrast evaluation value becomes the maximum value Y1 when the position of the focus lens 104 is X1. 8 (B) and 8 (D) show the case where the correction lens 103 is located off the optical axis. When the correction lens 103 is driven away from the center of the optical axis as shown in FIG. 8 (D) from the state of FIG. 8 (C), a mountain-shaped graph showing a contrast evaluation value is shown as shown in FIG. 8 (B). The curve shifts to the right. That is, the position of the focus lens 104 that maximizes the contrast evaluation value shifts from X1 to X2.

It is assumed that the focus lens 104 moves to the position X1 when the correction lens 103 is on the optical axis, stops at this position, and is in focus on the subject. After that, when the correction lens 103 moves, the graph curve showing the contrast evaluation value shifts as shown in FIG. 8B. At this time, the contrast evaluation value drops from Y1 to Y2, so if shooting starts at this point, the shooting operation is performed with the contrast evaluation value low. Furthermore, if the camera shake caused by the photographer is not constant and changes from moment to moment, the movement of the correction lens 103 changes with this change. That is, the movement of the correction lens 103 is not constant, and the contrast evaluation value of the subject is constantly changing.

The operation of the correction lens and the focus lens before and after shooting will be described with reference to FIG. 9. FIG. 9 is a graph schematically showing the relationship between the movement amount of the correction lens 103 and the correction amount of the focus lens position. The vertical axis represents the amount of movement of the correction lens 103, that is, the displacement from the optical axis. The horizontal axis represents the correction amount of the focus lens 104 to be corrected when the correction lens 103 is driven, and the position correction unit 126 controls the position correction. When the position of the correction lens 103 is 0 degrees, that is, on the optical axis, it is expressed as Mov0. When the position of the correction lens is Mov0, the correction amount of the focus lens position is Comp0. As a concrete numerical value, Mov0 is 0 degrees and Comp0 is zero.

On the other hand, when the position of the correction lens 103 is farthest from the optical axis, it is referred to as Mov5. When the position of the correction lens 103 is Mov5, the correction amount of the focus lens position is Comp5. The correction amounts corresponding to Mov1 to Mov4 between the positions Mov0 and Mov5 are Comp1 to Comp4, respectively. The correction amount of the focus lens position corresponding to the movement amount of the correction lens 103 is stored in advance in the internal memory 108 as reference table data, and is referred to by the position correction unit 126. Therefore, at the time of shooting, the focus lens 104 moves according to the correction amount of the focus lens position corresponding to the position of the correction lens 103 corresponding to the camera shake amount of the photographer.

The numerical values of Mov1 to 5 and Comp1 to 5 vary depending on the characteristics of the imaging optical system. In the example of FIG. 9, the relationship between the correction lens position and the correction amount of the focus lens position is expressed by a linear expression, but it is not necessarily a linear relationship and is expressed by a curved expression due to the characteristics of the imaging optical system. There is also.

Next, a change in the MTF (Modulation Transfer Function) in the central portion and the peripheral portion of the image due to the drive of the correction lens in the image pickup optical system and the notification control to the user performed when the image quality is deteriorated due to the change in the MTF will be described. FIG. 10 is a diagram showing changes in MTF at four locations in the center and periphery of the photographing screen when the correction lens 103 is located at the center of the optical axis and when the correction lens 103 moves from the center of the optical axis. The illustrated MTF curve is an example and changes depending on the characteristics of the imaging optical system.

FIG. 10A is a diagram showing the positions of the central portion and the peripheral four locations with respect to the photographing screen. The central part of the shooting screen is represented by 0ch, and the peripheral portion is represented by 1ch, 2ch, 3ch, and 4ch in the clockwise direction from the upper right. FIG. 10B is a schematic diagram of an imaging optical system showing a state in which the correction lens 103 moves in the Y direction from the center of the optical axis. When it is detected that the image pickup device is shaken due to the camera shake of the operator or the like, the correction lens 103 moves in the Y direction of FIG. 10B and deviates from the center of the optical axis.

FIG. 10C is a diagram showing MTF values at four locations in the central portion and peripheral portions when the correction lens 103 is located at the center of the optical axis. FIG. 10D is a diagram showing MTF values at four locations in the central portion and peripheral portions when the correction lens 103 is farthest from the center of the optical axis. In FIGS. 10C and 10D, the vertical axis represents the MTF value, the horizontal axis represents the focus lens position, and the MTF value of each channel changes depending on the position of the focus lens.

The solid graph lines shown in FIGS. 10C and 10D represent the MTF values in the horizontal direction (X direction) of the subject, and the broken line graph lines represent the MTF values in the vertical direction (Y direction) of the subject. As can be seen from FIG. 10C, the horizontal and vertical MTF curves of the central portion 0ch and the peripheral four locations 1 to 4ch have maximum values at substantially the same focus lens position F1. The system control unit 119 of the present embodiment performs AF control so that the MTF value of the central portion 0ch becomes the maximum value. In other words, the focus lens 104 moves to the position F1 where the MTF value of the central portion 0ch is maximized by AF control. At this time, since the positions where the MTF values of the peripheral four locations 1 to 4 channels are maximized are substantially the same positions F1, good image quality with high contrast can be obtained over the entire shooting screen.

In FIG. 10D, the image stabilization operation causes the correction lens 103 to move significantly from the center of the optical axis, causing a change in the MTF value. In the central portion 0ch of the screen, the maximum value of the MTF value is lowered as a whole, and the peak position of the MTF value in the horizontal direction is shifted to the right in FIG. 10 (D). Further, with respect to the peripheral 4 locations 1 to 4ch, the peak positions of the horizontal and vertical MTF values of 1ch and 4ch are both greatly deviated to the right side of FIG. 10 (D). In particular, the peak position of the MTF value in the horizontal direction is deviated so as not to be confirmed from this figure. Further, in 2ch and 3ch, the maximum value of the MTF value decreases as a whole as in 0ch, and the maximum values in the horizontal direction and the vertical direction are slightly shifted to the right side. It can be seen that the focus lens position at which the MTF value is maximized shifts in the horizontal direction and the vertical direction in both the central portion 0ch and the peripheral four locations 1 to 4ch. In this embodiment, the change of the MTF curve when the correction lens 103 moves in the Y direction will be described. However, when the correction lens 103 moves in the X direction, or moves in the X direction and the Y direction, The degree of change in the MTF curve of each channel is different.

As described with reference to FIG. 9, the position of the focus lens 104 is changed according to the amount of movement (correction amount) of the correction lens 103. In FIG. 10D, the focus lens 104 moves from the position F1 indicated by the chain double-dashed line to the position F2 indicated by the solid line. The focus lens 104 moves to a position where the horizontal and vertical MTF values of the central portion 0ch are balanced. The image quality of the central portion 0ch is not as good as when the correction lens 103 is located at the center of the optical axis, but good image quality with high contrast can be obtained.

The MTF curve of the peripheral portions 1 to 4 channels when the focus lens 104 is moved to the position F2 will be described. For 2ch and 3ch, the position correction operation of the focus lens 104 changes the MTF value in both the horizontal direction and the vertical direction. In the vertical direction, as can be seen from the broken line graph curve, the position F2 is a position where the MTF value is almost the maximum value. Although the MTF value in the horizontal direction deviates slightly from the maximum value, good image quality with high contrast can be obtained.

On the other hand, for 1ch and 4ch, the MTF value in the vertical direction changes in the direction of improvement due to the position correction operation of the focus lens 104. However, since the MTF curve in the horizontal direction is greatly changed by driving the correction lens 103, it falls below the set reference, and the desired image quality cannot be obtained. In this case, a process of notifying the user of the deterioration in image quality due to the driving of the correction lens 103 is executed.

An example of notification to the user will be described with reference to FIG. 11 (A) and 11 (B) are schematic views of an imaging optical system similar to FIG. 10 (B). FIG. 11A shows how the correction lens 103 moves in the + Y direction, and FIG. 11B shows how the correction lens 103 moves in the −Y direction. 11 (C) and 11 (D) are views showing how the through image before the start of exposure is displayed on the screen of the display unit 109. 11 (C) shows a display example at the correction lens position shown in FIG. 11 (A), and FIG. 11 (D) shows a display example at the correction lens position shown in FIG. 11 (B). FIG. 11 (E) is a diagram showing a state in which the range of image quality deterioration is notified on the confirmation screen after the end of shooting. FIG. 11F is a diagram showing a state of notifying the cutout range of the image after shooting.

When camera shake or the like is detected in the display state of the through image before exposure and the correction lens 103 moves in the + Y direction as shown in FIG. 11A, the position correction of the focus lens 104 is performed in conjunction with the movement of the correction lens 103. It will be done. As described with reference to FIG. 10, if the amount of movement of the correction lens 103 is large, it is difficult to improve the MTF value in the peripheral portion even by correcting the position of the focus lens 104. The system control unit 119 determines that if the exposure is started as it is, the upper corner of the screen may not reach the standard image quality. As shown in FIG. 11C, the system control unit 119 performs a process of applying a gray mask to an image area in the + Y direction, that is, a predetermined area 1100 at the upper part of the screen. Further, as shown in FIG. 11B, the correction lens 103 moves in the −Y direction, and the system control unit 119 determines that the lower corner portion of the screen may not reach the standard image quality. In this case, as shown in FIG. 11D, the system control unit 119 performs a process of applying a gray mask to the image area in the −Y direction, that is, the predetermined area 1101 at the bottom of the screen. The criteria for determining whether or not to apply a gray mask and the method for determining the range of the gray mask will be described later.

The user can recognize camera shake and correct the shooting operation by seeing that a gray mask is applied to a predetermined area on the display screen in the display state of the through image before exposure. When the exposure operation is performed, the user recognizes the camera shake because the process of applying a gray mask to a predetermined area of the screen as shown in FIGS. 11C and 11D is performed according to the amount of camera shake as before the exposure. can do.

In FIG. 11 (E), in the confirmed image after exposure, gray masks are provided for the upper and lower peripheral regions 1102 and 1103 in which the MTF value of the peripheral image portion is determined to be low due to the movement of the correction lens 103 during exposure. Show how it was hung. By looking at the gray mask display, the user can immediately recognize that the image quality is partially deteriorated due to camera shake. After that, the system control unit 119 executes a process of asking the user to select whether or not to generate a cut-out image excluding the portion where the image quality is deteriorated in order to provide a high-quality image with little deterioration in image quality. At this time, the process of clearly indicating the cutout range is executed in FIG. 11F so that the cutout range of the image can be known. For example, the system control unit 119 performs a process of displaying a cutout range (see the broken line rectangular frame 1104) on the screen of the display unit 109. By displaying the cutout range in the area excluding the area where the image quality has deteriorated, the user can confirm the composition of the subject and the like. The user can also determine if a cropped image is needed. When the user determines that the cutout image is necessary and selects the cutout image, for example, an instruction operation with a finger on the touch panel is performed, the system control unit 119 generates data of the selected cutout image. Execute the process.

In this way, by displaying the image region in which the image quality deteriorates with respect to the through image before exposure and the image after imaging, the user can recognize the occurrence of camera shake and the like. Further, by extracting the image data in the image range having good image quality and presenting the cut-out image to the user, it is possible to prevent the failure of shooting.

11 (C) to 11 (E) illustrate the process of covering the image quality deterioration area due to the driving of the correction lens 103 with a gray mask, but the notification method to the user is not limited, and the image quality deterioration area can be obtained by any method. Can be displayed. Further, in the example of FIG. 11F, the data of the cut-out image is generated with the same aspect ratio as the original image at the time of shooting, but the image region may be extracted with an aspect ratio different from that of the original image. .. Further, in addition to the method of selectively acquiring the original image and the cut-out image, there is a method of acquiring only the cut-out image or acquiring the original image and the cut-out image.

The image quality determination method in the present embodiment will be described with reference to FIG. 12. In the image quality determination, the image quality is determined not by confirming the actual image but by the position of the correction lens 103. FIG. 12 is a graph showing an example of the movement of the correction lens 103.

FIG. 12A is a diagram showing an example of the movement of the correction lens in the display state of the through image before exposure. The vertical axis represents the position of the correction lens 103, and the horizontal axis is the time axis. The correction lens 103 moves to correct image shake due to camera shake or the like of the operator, but the amount of shake correction differs depending on the degree of camera shake or the like. Z1 indicates the movable range of the correction lens 103, and Z2 indicates the image quality allowable range when the correction lens 103 moves. The image quality allowable range is a range (range within a threshold value) that does not affect the image quality even if the correction lens 103 moves.

When the through image is displayed before exposure, the correction lens 103 moves to a position exceeding the image quality allowable range Z2, and the position detection unit 117 detects the current position of the correction lens 103. At this time, the user can recognize camera shake or the like by displaying the display in FIG. 11 or giving a warning or an alarm on the screen of the display unit 109. For example, when the position of the correction lens 103 exceeds the image quality allowable range Z2 (see ranges 1201 and 1202), a warning or notification process is executed each time.

FIG. 12B illustrates the movement of the correction lens 103 during exposure, and the settings of the vertical axis and the horizontal axis are the same as those in FIG. 12A. If the correction lens 103 moves to a position exceeding the image quality allowable range Z2 even during exposure as before exposure, the user can recognize the occurrence of camera shake or the like by a warning or notification. However, in this case, even if a warning or the like is issued, it has already been exposed. Therefore, the system control unit 119 calculates the image quality deterioration range from the amount in which the position of the correction lens 103 exceeds the allowable range Z2 and the exposure time as shown by the shaded areas 1203 and 1204 in FIG. 12 (B). Executes the process of displaying the image quality deterioration range on the screen after shooting. The image quality allowable range Z2 shown in FIG. 12 is an example, and the image quality allowable range may be narrowed or widened as necessary.

[First Embodiment]
The processing of the image pickup apparatus according to the first embodiment will be described with reference to FIGS. 13 and 14. 13 and 14 are flowcharts for explaining the notification process of the image quality deterioration range and the cutout process of the captured image according to the movement amount of the correction lens. The following notification control to the user and image extraction processing are performed under the control of the system control unit 119.

When the power of the image pickup device is turned on (S301), the runout detection unit 113 detects the runout of the image pickup device. The image shake correction control unit 125 calculates the shake correction amount of the correction lens 103 for the detected shake (S302). The system control unit 119 starts image shake correction control according to the amount of shake correction, and the correction lens 103 is driven by the image shake correction lens drive unit 116 (S303). Then, the system control unit 119 starts correction and movement control of the focus lens position according to the movement amount of the correction lens 103. The position correction unit 126 acquires a movement amount corresponding to the correction amount of the correction lens 103 from the image blur correction control unit 125, calculates the correction amount of the focus lens position, and outputs the correction amount to the scanning control unit 124. The focus control unit 123 controls the focus lens drive unit 115 in order to move the focus lens 104 to a position corrected according to a control command from the scan control unit 124. As a result, the focus lens 104 moves on the optical axis according to the drive target value corresponding to the in-focus position (S304).

Subsequently, the system control unit 119 determines whether or not the position of the correction lens 103 is within a predetermined range with respect to the center of the optical axis (S305). When the position of the correction lens 103 is within a predetermined range with respect to the center of the optical axis, that is, when the calculation result of the shake correction amount is not more than the predetermined amount, the process proceeds to S308. If the calculation result of the runout correction amount is larger than the predetermined amount, the process proceeds to S306. The predetermined amount is a preset threshold value. The movement amount of the correction lens 103 may be compared with a predetermined threshold value to make a determination. In S306, the system control unit 119 executes a process of calculating the image quality deterioration range in the peripheral portion of the screen. Next, a process of notifying the user of the image quality deterioration range calculated in S306 is executed (S307). After that, the process proceeds to S308.

In S308, the system control unit 119 determines whether or not the second switch SW2 is turned on by operating the release button. If it is determined that the second switch SW2 is not on, the process returns to S302 in the live view image display state to continue the process. On the other hand, when it is determined that the second switch SW2 is turned on, the process proceeds to S309 in FIG.

In S309, the system control unit 119 starts a shooting operation, and the exposure control unit 120 starts exposure. The shake detection unit 113 detects the shake of the image pickup apparatus even during exposure, and the image shake correction control unit 125 calculates the shake correction amount of the correction lens 103 for the detected shake (S310). The system control unit 119 performs image stabilization control, and the image stabilization lens driving unit 116 drives the correction lens 103 according to a control signal from the image stabilization control unit 125 (S311). When the exposure is started, the system control unit 119 is in the shooting state and proceeds to S312 to perform focus adjustment control. That is, the focus control unit 123 controls the focus lens drive unit 115 according to the position correction amount corresponding to the movement amount of the correction lens 103. By moving the focus lens 104 in conjunction with the image stabilization operation, the focus position correction operation is performed. After that, the process proceeds to S313, and the exposure ends. After the end of the exposure, the system control unit 119 determines whether or not the amount of movement of the correction lens 103 during the exposure is within a predetermined range (S314). When the movement amount of the correction lens 103 is within a predetermined range, that is, when it is determined that the calculation result of the shake correction amount is equal to or less than the predetermined amount, the process proceeds to S319 and the shooting operation is terminated. If it is determined that the calculation result of the runout correction amount is larger than the predetermined amount, the process proceeds to S315.

In S315, the system control unit 119 executes a process of calculating the image quality deterioration range of the peripheral portion of the screen. Next, a process of notifying the operator of the calculated image quality deterioration range is performed (S316). Notification control is performed when a still image is taken, but notification control of the image quality deterioration range is not performed when a moving image is taken.

In S317, the system control unit 119 executes a display process for confirming whether or not the cut-out image is necessary for the operator (user). When it is determined by the operation unit 112 that the user has given an operation instruction that the cut-out image is necessary, the process proceeds to S318. In this case, the system control unit 119 generates the data of the instructed cutout image. At that time, the system control unit 119 controls to notify the user of the pixel size of the cut-out image. The data of the cut-out image, or the data and the image data before the cut-out, are stored in the storage medium according to the instruction of the user, and then the process proceeds to S319. On the other hand, when it is instructed by the user operation in S317 that the cut-out image is not necessary, the shooting ends (S319).

In the present embodiment, by notifying the range of image quality deterioration due to the driving of the correction lens, the user can recognize camera shake and the like and correct the camera operation. Therefore, the amount of runout correction is reduced, and a good image can be obtained. Further, on the shooting confirmation screen after shooting, the user is notified of the image quality deterioration range due to the driving of the correction lens, and the image data generated by cutting out the range with good image quality can be generated. The user can instruct the generation of the captured image (original image) or the data of the cut-out image, or the data of the captured image and the cut-out image and store the data in the storage medium. That is, the user can selectively acquire the cut-out image and reduce the probability of shooting failure.

According to the present embodiment, it is possible to acquire a captured image with good image quality while exhibiting the necessary image stabilization effect. In the present embodiment, an example will be described in which a change in image quality is determined by comparing the movement amount or shake correction amount of the correction lens as the position information of the image blur correction means with a threshold value, and notification control is performed when the image quality deteriorates. bottom. Not limited to this, the change in image quality may be determined by comparing the correction amount of the focus lens position with the threshold value, and notification control may be performed when the image quality deteriorates. The reason is that, as described with reference to FIG. 9, the movement amount of the correction lens and the correction amount of the focus lens position have a corresponding relationship. This also applies to the embodiments described later.

[Second Embodiment]
Next, the processing of the image pickup apparatus according to the second embodiment will be described with reference to FIGS. 15 and 16. In this embodiment, only the matters different from those in the first embodiment will be described. If the drive speed of the correction lens becomes faster than a predetermined value in shooting, the focus lens cannot be linked to the drive of the correction lens, and there is a possibility that the image quality correction operation cannot be performed. In this case, the image quality is deteriorated even if the correction lens is in a position corresponding to the allowable image quality range described with reference to FIG. 12. Therefore, in the present embodiment, a process of notifying the user of the image quality deterioration range according to the position information of the correction lens and the information of the driving speed and cutting out the image will be described.

15 and 16 are flowcharts showing the processing in the present embodiment. Hereinafter, processing different from that of FIGS. 13 and 14 will be described. In FIG. 15, the processing of S401 to S407 is the same as the processing of S301 to S307 of FIG. In S405, when the position of the correction lens is within a predetermined range with respect to the center of the optical axis, that is, when the calculation result of the runout correction amount is not more than the predetermined amount, the process proceeds to S408.

In S408, the system control unit 119 compares the drive speed of the correction lens 103 with a predetermined amount (threshold value). If it is determined that the drive speed of the correction lens 103 is higher than a predetermined amount (threshold speed), the process proceeds to S406, and the image quality deterioration range in the peripheral portion of the screen is calculated. If the drive speed of the correction lens 103 is equal to or less than a predetermined amount, the process proceeds to S409.

In S409, a determination process is performed as to whether or not the second switch SW2 is turned on. When it is determined that the second switch SW2 is off, the process returns to S402 with the live view image displayed, and the processes of S403 to S405 and S408 are repeatedly executed. On the other hand, if it is determined that the second switch SW2 is on, the process proceeds to S410 in FIG. Since the processes of S410 to S415 are the same as the processes of S309 to S314 of FIG. 14, the description thereof will be omitted.

If it is determined in S415 that the calculation result of the runout correction amount is equal to or less than the predetermined amount, the process proceeds to S418, and if it is determined to be larger than the predetermined amount, the process proceeds to S416. Since the processes of S416, S417, S419, S420, and S421 are the same as the processes of S315 to S319 in FIG. 14, the description thereof will be omitted.

In S418, the system control unit 119 compares the drive speed of the correction lens 103 with a predetermined amount (threshold value). If it is determined that the drive speed of the correction lens 103 is higher than a predetermined amount (threshold speed), the process proceeds to S416, and the image quality deterioration range in the peripheral portion of the screen is calculated. If the drive speed of the correction lens 103 is equal to or less than a predetermined amount, the process proceeds to S421 and shooting is terminated.
According to the present embodiment, it is possible to notify the user of the image quality deterioration range according to the movement amount and the driving speed of the correction lens, and to acquire a cut-out image as needed.

Although the example in which the present invention is applied to the image pickup apparatus has been described above, the present invention is not limited to these embodiments, and various forms within the range not deviating from the gist of the present invention are also the technical scope of the present invention. include. The image pickup apparatus is not limited to the example in which the lens barrel having a three-group configuration is provided, and the correction lens group for image blur correction is not limited to one, and two correction lens groups may be used. In that case, the image quality deterioration range is calculated from each movement amount or each correction amount of the two correction lens groups. Further, in an image pickup device having a moving mechanism unit of the image pickup element instead of the correction lens group, the image pickup element can move in a plane orthogonal to the optical axis. The image quality deterioration range is calculated from the amount of correction such as camera shake by the moving mechanism unit. An embodiment in which image blur correction by a correction lens group and image blur correction by a moving mechanism portion of an image sensor may be used in combination may be used. Further, the lens barrel may be attached to and detached from the image pickup apparatus main body, and the correction lens and the focus lens of the lens barrel may be controlled by the system control unit of the image pickup apparatus main body.

103 Correction lens 104 Focus lens 109 Display unit 119 System control unit 123 Focus control unit 125 Image stabilization control unit 126 Position correction unit

Claims (10)

An image shake correction control means that calculates a correction amount for correcting image blur from a detection signal by the shake detecting means and controls a correction means for correcting the image blur of an image captured by the image pickup means.
A focus adjustment control means for controlling the drive of a focus lens that adjusts the focus in conjunction with the drive of the correction means,
The image quality of the image captured by the imaging means was changed by the drive of the correction means when the display means displayed the image captured by the imaging means in live view before the shooting instruction accompanied by the image storage was given . An image pickup apparatus comprising: a notification control means for controlling an image range in which the image quality is lower than the standard image quality . The notification control means determines a change in image quality by comparing the movement amount of the correction means or the correction amount with a threshold value.
The image pickup apparatus according to claim 1. The correction means includes a correction lens for correcting image blur.
The image pickup apparatus according to claim 1 or 2, wherein the focus adjustment control means corrects the position of the focus lens based on the position information of the correction lens. The notification control means determines a change in image quality by comparing the position information of the correction means or the correction amount of the position of the focus lens with a threshold value.
The image pickup apparatus according to any one of claims 1 to 3. The notification control means determines a change in image quality by comparing the speed of the correction means with a threshold value.
The image pickup apparatus according to any one of claims 1 to 3. In the notification control means, when the image quality of the image captured by the image pickup means is changed by the driving of the correction means after the shooting instruction of the still image accompanied by the image storage is given, the image quality is lower than the reference image quality. Controls to notify the image range
The image pickup apparatus according to any one of claims 1 to 5. A cropping means for generating a cropped image obtained by cropping an image from a range excluding an image range whose image quality is lower than the standard image quality is provided.
The image pickup apparatus according to claim 6. The imaging device according to claim 7 , wherein the aspect ratio of the cut-out image is the same as the aspect ratio of the image before cutting . The image pickup apparatus according to claim 7 , wherein the notification control means controls to notify the pixel size of the cut - out image. A process of calculating a correction amount for correcting image blur from a detection signal by the shake detecting means and controlling a correction means for correcting image blur of an image captured by the imaging means.
The process of controlling the drive of the focus lens that adjusts the focus in conjunction with the drive of the correction means,
The image quality of the image captured by the imaging means was changed by the drive of the correction means when the display means displayed the image captured by the imaging means in live view before the shooting instruction accompanied by the image storage was given . A control method for an image pickup apparatus, comprising: a step of controlling to notify an image range in which the image quality is lower than the standard image quality .

Images