Imaging apparatus capable of detecting position of movable image pickup device at first resolving power and at second resolving power higher than first resolving power and, at which second resolving power, deviation amount is less than or equal to pixel shift amount

An imaging apparatus includes a camera shake correction unit which uses a coil and a magnet to move a movable portion including an image pickup device relative to a fixed portion. A position detection section detects the position of the movable portion. A setting section sets a resolving power of the detection of the position by the position detection section to a first or second resolving power which is a resolving power higher than the first resolving power and at which an amount of deviation from a target position is less than or equal to a pixel shift amount. A drive control section performs pixel shifts to move the movable portion with the second resolving power set by the setting section. A photography control section causes the image pickup device to perform exposures by timing of the pixel shifting and which composes images obtained by the exposures.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging apparatus comprising a camera shake correction unit.

2. Description of the Related Art

There is known a camera shake correction unit which moves an image pickup device to reduce an image blur generated in a taken image due to, for example, a camera shake. In recent years, various suggestions have been made to use such a function of moving the image pickup device by the camera shake correction unit for purposes other than the camera shake correction. For example, an imaging apparatus suggested in Jpn. Pat. Appln. KOKAI Publication No. 2014-224940 corrects a camera shake and also obtains an optical low pass filter effect by moving an image pickup device and thereby changing the focus position of a subject image. The imaging apparatus according to Jpn. Pat. Appln. KOKAI Publication No. 2014-224940 superimposes a modulation signal representing a minute vibration component of the imaging apparatus on a position detection signal from a position detection section which detects the position of the imaging apparatus to generate a superimposition position signal, and controls the position of the image pickup device on the basis of the superimposition position signal so that the position of the image pickup device can be controlled with a high degree of accuracy.

BRIEF SUMMARY OF THE INVENTION

The camera shake correction unit can also be used in super-resolution photography. The super-resolution photography that uses the camera shake correction unit is processing to perform multiple exposures while shifting the image pickup device by a unit less than or equal to a pixel pitch, and composes taken images obtained by the multiple exposures to generate a super-resolution image. To perform such super-resolution photography, it is necessary to control the position of the image pickup device with an extremely high degree of accuracy. However, to perform the super-resolution photography by the technique according to Jpn. Pat. Appln. KOKAI Publication No. 2014-224940, it is necessary to increase the accuracy of a position detection system.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an imaging apparatus capable of accurately controlling the position of a camera shake correction unit to perform super-resolution photography without using an accurate position detection element.

According to an aspect of the invention, there is provided an imaging apparatus comprising: a camera shake correction unit which uses a coil and a magnet to move a movable portion including an image pickup device relative to a fixed portion; a position detection section which detects the position of the movable portion; a setting section which sets a resolving power of the detection of the position by the position detection section to a first resolving power or to a second resolving power which is a resolving power higher than the first resolving power and at which an amount of deviation from a target position is less than or equal to a pixel shift amount; a drive control section which, performs pixel shifts to move the movable portion with the second resolving power set by the setting section; and a photography control section which causes the image pickup device to perform exposures by timing of the pixel shifting and which composes images obtained by the exposures.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.FIG. 1is a diagram showing a schematic configuration of an imaging apparatus according to the present embodiment. An imaging apparatus1shown inFIG. 1includes an interchangeable lens100and a body200. The interchangeable lens100is attached to the body200via a mount202provided in the body200. When the interchangeable lens100is attached to the body200, the interchangeable lens100and the body200are connected to each other to be able to communicate with each other. The interchangeable lens100and the body200cooperate to perform operations. The imaging apparatus1does not necessarily have to be a lens-interchangeable imaging apparatus. For example, the imaging apparatus1may be a lens-integrated imaging apparatus.

The interchangeable lens100includes an optical system102. The optical system102includes, for example, lenses and a diaphragm, and brings a light flux from an unshown subject into a camera shake correction unit206of the body200. Although the optical system102inFIG. 1comprises the lenses, the optical system102may comprise one lens. The optical system102may include a focus lens, or may be configured as a zoom lens. In these cases, some of the lenses of the optical system102are configured to be movable along a Z-direction which is a direction along an optical axis O.

The body200includes a shutter204, the camera shake correction unit206, a monitor208, and an operation section210.

The shutter204is, for example, a focal plane shutter disposed in front of the camera shake correction unit206(on a positive side in the Z-direction). When opened, the shutter204exposes the camera shake correction unit206. When closed, the shutter204shields the camera shake correction unit206.

The camera shake correction unit206generates an image of the unshown subject by imaging the subject. The camera shake correction unit206moves a movable portion relative to a fixed portion by a voice coil motor (VCM) that uses a coil and a magnet, and thereby corrects an image blur that occurs in the taken image due to, for example, a camera shake. The configuration of the camera shake correction unit206will be described in detail later.

The monitor208is, for example, a liquid crystal display, and displays an image based on the taken image generated in the camera shake correction unit206. The monitor208displays a menu screen for a user to perform various settings of the imaging apparatus1. The monitor208may include a touch panel.

The operation section210is, for example, a release button. The release button is a button for the user to instruct to start photography by the imaging apparatus1. The operation section210also includes various operation portions in addition to the release button.

Next, the configuration of the camera shake correction unit206is further described.FIG. 2shows a diagram of an assembly state of the camera shake correction unit206. As shown inFIG. 2, the camera shake correction unit206roughly comprises two fixed portions301and302and a movable portion303disposed between the fixed portions301and302. In such a configuration, the camera shake correction unit206translates the movable portion303in a plane (an X-direction and a Y-direction inFIG. 3) perpendicular to the optical axis O. The camera shake correction unit206also moves the movable portion303in a rotation direction around the optical axis O.

First, the configuration regarding the movement of the movable portion303in the camera shake correction unit206is described.FIG. 3is an exploded perspective view of the camera shake correction unit206. As shown inFIG. 3, the fixed portion301disposed on the side of the monitor208when seen from the movable portion303is a substantially rectangular plate member and is fixed to the body200. A magnet3011for X-direction movement and a magnet3012for both X-direction and Y-direction movement are respectively adhesively bonded to the outer periphery of the fixed portion301.

The magnet3011includes a first magnet which is in the shape of a rectangular parallelepiped having its longitudinal direction in the Y-direction and which is disposed so that its north pole faces toward the movable portion303and a second magnet which is in the shape of a rectangular parallelepiped having its length in the Y-direction that is the longitudinal direction shorter than that of the first magnet and which is disposed so that its south pole faces toward the movable portion303. The second magnet of the fixed portion301is disposed adjacent to the center of the right surface of the first magnet when seen from the movable portion303. The magnet3012includes a first magnet which is in the shape of a rectangular parallelepiped having its longitudinal direction in the Y-direction and which is disposed so that its north pole faces toward the movable portion303and a second magnet which is in the shape of a rectangular parallelepiped having its length in the Y-direction shorter than that of the first magnet and having its longitudinal direction in the X-direction and which is disposed so that its south pole faces toward the movable portion303. The second magnet is disposed adjacent to the center of the right surface of the first magnet when seen from the movable portion303.

The magnet3012includes a third magnet which is in the shape of a rectangular parallelepiped having its length in the X-direction that is the longitudinal direction shorter than that of the second magnet and which is disposed so that its north pole faces toward the movable portion303. The third magnet is disposed on the lower surface of the second magnet when seen from the movable portion303. That is, the second magnet that constitutes the magnet3012is combined with the first magnet function as a magnet for X-direction movement, and is combined with the third magnet to function as a magnet for Y-direction movement.

The fixed portion302disposed on the side of the shutter204when seen from the movable portion303is a substantially L-shaped plate member in which an opening for holding an image pickup device unit3034in the movable portion303is formed. A magnet3021for X-direction movement and a magnet3022for both X-direction and Y-direction movement are respectively adhesively bonded to the positions of the fixed portion302corresponding to the magnets3011and3012of the fixed portion301. The magnet3021has the same configuration as that of the magnet3011, and is disposed so that a different pole faces toward the magnet3011. The magnet3022has the same configuration as that of the magnet3012, and is disposed so that a different pole faces toward the magnet3012.

The movable portion303is a substantially L-shaped plate member in which an opening for mounting the image pickup device unit3034similar to that of the fixed portion302is formed. Coils3031and3032afor X-direction movement and a coil3032bfor Y-direction movement are disposed in the outer periphery of the movable portion303. The coil3031is disposed at a position corresponding to the magnet3011and the magnet3021in a plate-shaped portion of the movable portion303extending in the Y-direction. The coil3032ais disposed at a position corresponding to the first magnet and the second magnet of the magnet3012and the magnet3022in the plate-shaped portion of the movable portion303extending in the Y-direction. The coil3032bis disposed at a position corresponding to the second magnet and the third magnet of the magnet3012and the magnet3022in the plate-shaped portion of the movable portion303extending in the X-direction.

The image pickup device unit3034is mounted in the opening of the movable portion303. The image pickup device unit3034is a unit including an image pickup device and its control circuit. The image pickup device unit3034in the present embodiment includes the image pickup device, a signal processing section, an A/D conversion section, and an image processing section. The image pickup device images the subject to generate an image signal regarding the subject. The signal processing section subjects the image signal to analog processing such as amplification processing. The A/D conversion section converts, into a digital signal, the image signal processed in the signal processing section. The image processing section subjects the image signal to image processing to generate an image. The image processing section also composes multiple images to generate a super-resolution image.

Two screw receivers3015are formed in the fixed portion301, and screw receiver holes3025are formed in the parts of the fixed portion302corresponding to the screw receivers3015. The fixed portion302is screwed so that the movable portion303is put between the fixed portion301and the fixed portion302. In this instance, the coil3031, the coils3032aand3032b, the magnet3011, the magnet3012, the magnet3021, and the magnet3022are out of contact to maintain a predetermined space therebetween.

In such a configuration, if the application of electricity to one of the coils3031,3032a, and3032bis started, the movable portion303becomes afloat between the fixed portion301and the fixed portion302. The intensity of a drive electric current to apply electricity to the coils3031,3032a, and3032bin this state is controlled so that the movable portion303is translated or rotated.

Next, the configuration regarding the position detection of the movable portion303is described. Three position detection magnets3013are disposed in the fixed portion301. One of the position detection magnets3013is disposed in the upper part of the fixed portion301. One of the position detection magnets3013is disposed in the lower part of the fixed portion301. One of the position detection magnets3013is disposed in the left part of the fixed portion301. Moreover, as shown inFIG. 4, three hall elements3033are provided at the positions on the rear surface of the movable portion303corresponding to the position detection magnets3013. The position detection magnet3013provided in the upper part of the fixed portion301and the hall element3033provided in the upper part of the movable portion303detect in pairs a first displacement amount of the movable portion303in the X-direction as a change amount of a magnetic field. The position detection magnet3013provided in the lower part of the fixed portion301and the hall element3033provided in the lower part of the movable portion303detect in pairs a second displacement amount of the movable portion303in the X-direction as a change amount of the magnetic field. The position detection magnet3013provided in the left part of the fixed portion301and the hall element3033provided in the left part of the movable portion303detect in pairs a displacement amount of the movable portion303in the Y-direction as a change amount of the magnetic field. The position of the movable portion303is detected by the difference of the signals detected by the respective hall elements3033.

FIG. 5is a functional block diagram of the imaging apparatus1according to the present embodiment. The imaging apparatus1according to the present embodiment performs a camera shake correction, normal still image photography, and super-resolution photography. The camera shake correction is processing to move the movable portion303to inhibit an image blur that occurs in the image due to, for example, camera shake. The normal still image photography is processing to perform one exposure to obtain one taken image. The super-resolution photography is processing to perform multiple exposures while shifting the movable portion303by a pixel shift amount less than or equal to a pixel pitch, and composes images obtained by the multiple exposures to obtain an image higher in resolution than the original number of pixels of the image pickup device.

As shown inFIG. 5, the imaging apparatus1has, as functional blocks, the camera shake correction unit206, a position detection section402, a camera shake detection section404, a photography control section406, a target position generation section408, a subtraction section410, a drive control section412, a determination section414, and a setting section416. Among these functional blocks, the photography control section406, the target position generation section408, the subtraction section410, the drive control section412, the determination section414, and the setting section416comprise CPUs and ASICs.

The position detection section402amplifies a position detection signal from the hall elements3033of the camera shake correction unit206, acquires the amplified position detection signal as a digital signal to generate a present position signal indicating the position of the movable portion303, and outputs the generated present position signal to the subtraction section410.

The camera shake detection section404detects the amount of a camera shake that has occurred in the body200of the imaging apparatus1, and outputs a signal corresponding to the detected amount of the camera shake. For example, the camera shake detection section404detects a camera shake amount by an angular velocity sensor. The camera shake detection section404also detects a camera shake amount from the movement of the subject in the image generated in the camera shake correction unit206.

The photography control section406controls the driving of the image pickup device of the camera shake correction unit206. The photography control section406also outputs, to the target position generation section408, a signal indicating whether to perform a camera shake correction and/or super-resolution photography. When performing the super-resolution photography, the photography control section406indicates, to the target position generation section408, a signal representing a predetermined target position for each exposure for super-resolution photography. The photography control section406also indicates, to the setting section416, whether to perform the normal still image photography or the super-resolution photography.

The target position generation section408generates a target position signal indicating a target position to be the target of the position control of the movable portion303, and outputs the generated target position signal to the subtraction section410. When the camera shake correction is performed, the target position generation section408generates a target position signal on the basis of a camera shake correction signal based on a signal corresponding to the camera shake amount from the camera shake detection section404. When the super-resolution photography is performed, the target position generation section408generates a target position signal on the basis of a signal indicating a target position from the photography control section406. When both the camera shake correction and the super-resolution photography are performed, the target position generation section408combines (adds) the camera shake correction signal from the camera shake detection section404and the signal corresponding to the target position from the photography control section406to generate a target position signal.

The subtraction section410outputs a deviation signal of the target position signal generated in the target position generation section408and the present position signal generated in the position detection section402to the drive control section412.

The drive control section412generates drive currents to be supplied to the coils3031,3032a, and3032bof the camera shake correction unit206on the basis of the deviation signal output from the subtraction section410, and supplies the generated drive currents to the coils3031,3032a, and3032band thereby moves the movable portion303.

The determination section414determines whether a camera shake has occurred in the body of the imaging apparatus1in accordance with the camera shake amount detected in the camera shake detection section404, and outputs a signal indicating this determination result to the photography control section406and the setting section416.

The setting section416sets a resolving power of position detection in the position detection section402. When the normal still image photography is performed, the setting section416sets the resolving power of position detection in the position detection section402to a predetermined first resolving power. In contrast, when the super-resolution photography is performed, the setting section416sets the resolving power of position detection in the position detection section402to a second resolving power which is determined in accordance with the pixel pitch of the image pickup device.

The operation of the imaging apparatus1is described below.FIG. 6is a flowchart showing the operation of the imaging apparatus1. The processing inFIG. 6is started when the electric power supply of the imaging apparatus1is turned on.

In step S101, the determination section414determines whether the camera shake amount detected in the camera shake detection section404is less than or equal to a standard value. This standard value is a value of a camera shake amount such that an image blur is considered to have occurred, and is previously stored in the determination section414. When it is determined in step S101that the camera shake amount detected in the camera shake detection section404is not less than or equal to the standard value, the processing moves to step S102. When it is determined in step S101that the camera shake amount detected in the camera shake detection section404is less than or equal to the standard value, the processing moves to step S104.

In step S102, the setting section416sets the resolving power of position detection in the position detection section402to a still image resolving power which is the first resolving power. Here, the resolving power in the present embodiment refers to a unit length [μm/LSB] indicated by the least significant bit of a signal loaded as digital data from each of the hall elements3033of the camera shake correction unit206. The still image resolving power is a resolving power in a normal still image photography mode, and, for example, a resolving power stored as a fixed value in the setting section416is used.

In step S103, the photography control section406turns on a camera shake correction mode. The processing then moves to step S106. When it is determined in step S101that the camera shake amount is more than the standard value, that is, that a great image blur has occurred, the camera shake correction mode is turned on. As a result, the image blur that occurs in the image is reduced.

In step S104, the setting section416sets the resolving power of position detection in the position detection section402to a super-resolution resolving power which is the second resolving power. The super-resolution resolving power is a resolving power which is changed by the pixel pitch of the image pickup device. The processing for setting the super-resolution resolving power will be described in detail later.

In step S105, the photography control section406turns off the camera shake correction mode. The processing then moves to step S106. When it is determined in step S101that the camera shake amount is not more than the standard value, that is, that no image blur has occurred, the camera shake correction mode is turned off.

In step S106, the photography control section406sets a photography mode. The photography mode includes the normal still image photography mode for performing the normal still image photography and a super-resolution photography mode for performing the super-resolution photography. One of the modes is set by, for example, a user's operation on the menu screen displayed on the monitor208.

In step S107, the photography control section406starts the driving of the image pickup device of the camera shake correction unit206to perform a live-view display. The photography control section406then sequentially, displays, on the monitor208, the images obtained in the camera shake correction unit206.

In step S108, the photography control section406determines whether an instruction to start the normal still image photography has been issued. That is, the photography control section406determines whether the present photography mode is the normal still image photography mode and whether an instruction to start photography has been issued by the user. The instruction to start photography is an operation of depressing the release button or a touch release operation. When it is determined in step S108that the instruction to start the normal still image photography has been issued, the processing moves to step S109. When it is determined in step S108that the instruction to start the normal still image photography has not been issued, the processing moves to step S110.

In step S109, the photography control section406starts the driving of the image pickup device of the camera shake correction unit206to perform the normal still image photography. The photography control section406then records the image obtained in the camera shake correction unit206in an unshown recording medium. The processing then moves to step S116. Although not described, the camera shake correction is performed together with the normal still image photography when the camera shake correction mode is on.

In step S110, the photography control section406determines whether an instruction to start the super-resolution photography has been issued. That is, the photography control section406determines whether the present photography mode is the super-resolution photography mode and whether an instruction to start photography has been issued by the user. As in the normal still image photography, the instruction to start photography is the operation of depressing the release button or the touch release operation. When it is determined in step S110that the instruction to start the super-resolution photography has been issued, the processing moves to step S111. When it is determined in step S110that the instruction to start the super-resolution photography has not been issued, the processing moves to step S116.

In step S111, the setting section416sets the resolving power of position detection in the position detection section402to the super-resolution resolving power which is the second resolving power. The processing for setting the super-resolution resolving power will be described in detail later.

In step S112, the photography control section406determines whether the camera shake correction mode is on at present. When it is determined in step S112that the camera shake correction mode is not on, the processing moves to step S113. When it is determined in step S112that the camera shake correction mode is on, the processing moves to step S114.

In step S113, the photography control section406performs the super-resolution photography. The processing of the super-resolution resolving power will be described in detail later. After the end of the super-resolution photography, the processing moves to step S115.

In step S114, the photography control section406performs the super-resolution photography involving the camera shake correction. The processing of the super-resolution photography involving the camera shake correction will be described in detail later. After the end of the super-resolution photography involving the camera shake correction, the processing moves to step S115.

In step S115, the setting section416sets the resolving power of position detection in the position detection section402to the still image resolving power which is the first resolving power. The processing then moves to step S116.

In step S116, the photography control section406determines whether the electric power supply of the imaging apparatus1has been turned off. When it is determined in step S116that the electric power supply of the imaging apparatus1has not been turned off, the processing returns to step S101. When it is determined in step S116that the electric power supply of the imaging apparatus1has been turned off, the processing inFIG. 6ends.

Next, the processing for setting the super-resolution resolving power is described.FIG. 7is a flowchart showing the processing for setting the super-resolution resolving power. The processing inFIG. 7can be applied to both step S104and step S111.

In step S201, the setting section416calculates a super-resolution target resolving power. The calculation of the super-resolution target resolving power is described below.

FIG. 8shows the concept of pixel shifting according to the present embodiment. InFIG. 8, the pixel pitch is an opening-inter-central distance P between a pixel PIX1and a pixel PIX2that are adjacent to each other. The pixel shifting is processing for shifting the position of the movable portion303(image pickup device) by a pixel shift amount within the pixel pitch. Thus, the pixel shift amount has a relation: 0<pixel shift amount<pixel pitch. For example, the pixel shifting in which the pixel shift amount is a pixel pitch of 0.5 is processing for shifting the pixel PIX1and the pixel PIX2by a pixel pitch of 0.5 in a predetermined direction (rightward direction inFIG. 8) to produce a pixel PIX1′ and a pixel PIX2′.

When the position of the movable portion303is controlled by the VCM, the amount of deviation of the movable portion303from the target position is equal to or more than three times the resolving power of the detection of the position by the position detection section402. This is because the movable portion303slightly vibrates due to the operating principle of the VCM. The position deviates from the target position in each of the positive and negative directions due to the vibration, so that the amount of deviation of the movable portion303from the target position is equal to or more than three times the resolving power of the detection of the position by the position detection section402.

FIG. 9is a graph showing the change of the position detection signal when the movable portion303is moved from a predetermined target position1to another target position2which is 0.5 pixel pitch away. Even if a position detection signal indicating that the position of the movable portion303is the target position1is output, the actual position of the movable portion303changes within a deviation amount1inFIG. 9due to a deviation that occurs when the movable portion303is moved by the VCM. If photography is performed in this state, an image will be an image taken at any position within the deviation amount1from the target position1.

Similarly, even if a position detection signal indicating that the position of the movable portion303is the target position2is output, the actual position of the movable portion303changes within a deviation amount2inFIG. 9. If photography is performed in this state, an image will be an image taken at any position within the deviation amount2from the target position2.

When the deviation amount is greater than the pixel shift amount, the positions of the movable portion303overlap as indicated in a part A inFIG. 9, so that the actual position of the movable portion303may be reversed before and after the pixel shifting. If two exposures are performed while the position of the movable portion303is reversed, an image in which the image pickup device is located at the pixel PIX1′ and the pixel PIX2′ is acquired in the first exposure, and an image in which the image pickup device is located at the pixel PIX1and the pixel PIX2is acquired in the next exposure. If such images are composed, the resolving power in a super-resolution image to be finally obtained deteriorates.

Therefore, according to the present embodiment, the super-resolution target resolving power (the resolving power of the detection of the position by the position detection section402in the super-resolution photography) is set so that the deviation amount may be smaller than the pixel shift amount. Specifically, the super-resolution resolving power is less than or equal to ⅓ of the pixel shift amount. Thus, even if a deviation which is equal to or more than three times the resolving power has been made from the target position of the movable portion303as a result of the movement of the VCM, the actual position of the movable portion303can be within the pixel pitch.

Furthermore, to finally move the movable portion303to a correct target position, it is necessary that the super-resolution target resolving power be a fraction of the integer of the pixel shift amount. Therefore, the setting section416sets the super-resolution resolving power to be less than or equal to ⅓ of the pixel shift amount and to be a fraction of the integer of the pixel shift amount. When the pixel shift amount is a pixel pitch of 0.5, the setting section416sets, for example, the super-resolution resolving power to 0.5 pixel pitch/3 [μm/LSB]. Since there is a possibility that the deviation amount may be more than three times the resolving power of the detection of the position, the super-resolution resolving power is preferably a fraction of the integer more than a pixel shift amount of 4.

Here, the explanation returns toFIG. 7. In step S202, the setting section416respectively acquires a still image amplification factor and a still image resolving power. The still image amplification factor is an amplification factor of the position detection signal from the hall elements3033by the position detection section402in the normal still image photography mode. For example, an amplification factor stored in the position detection section402as a fixed value is used.

In step S203, the setting section416calculates a super-resolution amplification factor. The super-resolution amplification factor is an amplification factor of the position detection signal from the hall elements3033by the position detection section402in the super-resolution photography mode. For example, the super-resolution amplification factor is calculated as follows.
(Super-resolution amplification factor [magnification])=(still image amplification factor [magnification])×(still image resolving power [μm/LSB])/(super-resolution target resolving power [μm/LSB])

FIG. 10is a graph showing the relation between the actual position of the movable portion303and the position detection signal when the position detection signal from the hall elements3033is amplified at the still image amplification factor. In contrast,FIG. 11is a graph showing the relation between the actual position of the movable portion303and the position detection signal when the position detection signal from the hall elements3033is amplified at the super-resolution amplification factor. As obvious from the above equation, the super-resolution amplification factor is higher in value than the still image amplification factor. If the position detection signal is amplified at such a super-resolution amplification factor, the deviation amount can be less than or equal to the pixel shift amount. As a result, a super-resolution image that is high in resolution can be generated.

In step S204, the setting section416sets the calculated super-resolution amplification factor in the position detection section402. The processing inFIG. 7then ends.

Next, the processing for the super-resolution photography is described.FIG. 12is a flowchart showing the processing for the super-resolution photography.

The photography control section406performs loop processing for repeating i times of exposures for super-resolution photography. First, in step S301, the photography control section406indicates a target position to the target position generation section408to move the movable portion303of the camera shake correction unit206to the i-th position. Accordingly, the target position generation section408generates a target position signal. The drive control section412then moves the movable portion303to the target position in accordance with a drive signal generated on the basis of a deviation signal of the target position signal and the present position signal. Here, for example, a preset fixed value is used for the target position of the super-resolution photography.FIG. 13AandFIG. 13Bshow an example of the target position of the super-resolution photography. In the example ofFIG. 13A, the movable portion303is moved 8 times in a quadrate shape from an initial position1(corresponding to i=0). In this example, 8 target positions of i=0 to i=7 are set. In contrast, in the example ofFIG. 13B, an oblique movement of the movable portion303is also included, and the movable portion303is moved 9 times from the initial position1. In this example, 9 target positions of i=0 to i=8 are set. The settings inFIG. 13AandFIG. 13Bare illustrative only. How to set target positions is not particularly limited as long as upward, downward, leftward, rightward, and oblique movements are combined.

In step S302, the photography control section406starts the driving of the image pickup device of the camera shake correction unit206. The photography control section406then records the image obtained in the camera shake correction unit206in an unshown RAM. If i exposures have not been finished, i is incremented, and the processing returns to step S301where the loop starts. If i exposures have been finished, the processing moves to step S303.

In step S303, the image processing section of the camera shake correction unit206composes i images obtained by the i exposures to generate a super-resolution image. The processing inFIG. 12then ends.

Next, the super-resolution photography involving the camera shake correction is described.FIG. 14is a flowchart showing the processing for the super-resolution photography involving the camera shake correction.

The photography control section406performs loop processing for repeating i exposures for super-resolution photography. First, in step S401, the photography control section406indicates a target position to the target position generation section408to move the movable portion303of the camera shake correction unit206to the i-th position. In contrast, when the camera shake correction mode is on, the camera shake detection section404outputs a signal corresponding to a camera shake amount to the target position generation section408. The target position generation section408combines the camera shake correction signal based on the signal corresponding to the camera shake amount from the camera shake detection section404and the signal corresponding to the target position from the photography control section406to generate a target position signal. The drive control section412then moves the movable portion303to the target position in accordance with the drive signal generated on the basis of the deviation signal of the target position signal and the present position signal. The drive signal generated in step S401takes the camera shake amount into consideration. Therefore, even if a camera shake or the like occurs and even if a high-precision position detection element is not used, it is possible to correctly move the movable portion303to the target position.

In step S402, the photography control section406starts the driving of the image pickup device of the camera shake correction unit206. The photography control section406then records the image obtained in the camera shake correction unit206in the unshown RAM. If i exposures have not been finished, i is incremented, and the processing returns to step S401where the loop starts. If i exposures have been finished, the processing moves to step S403.

In step S403, the image processing section of the camera shake correction unit206composes i images obtained by the i exposures to generate a super-resolution image. The processing inFIG. 14then ends.

As described above, according to the present embodiment, the resolving power of the detection of the position by the position detection section402in the super-resolution photography mode is a resolving power such that the amount of deviation of the movable portion303from the target position is less than or equal to the pixel shift amount. Thus, the accuracy of the position control for the movable portion303can be improved, and each exposure in the super-resolution photography mode can be performed in a situation where the position of the movable portion303is an accurate position. Therefore, and even if a high-precision position detection element is not used, it is possible to generate a super-resolution image having high resolution.

While the present invention has been described above in connection with the embodiment, it should be understood that the present invention is not limited to the embodiment described above, and various modifications and applications can be made within the spirit of the present invention. For example, the above-described configuration of the camera shake correction unit206is one example and can be suitably changed. For example, the configuration of the VCM may be different. In the embodiment described above, the super-resolution target resolving power is calculated whenever the electric power supply of the imaging apparatus1is turned on. The super-resolution target resolving power can be set if the pixel pitch of the image pickup device is determined. Therefore, the super-resolution target resolving power may be calculated at the time of the manufacture of the imaging apparatus1and then stored in the setting section416, and subsequently, the stored super-resolution target resolving power may be used.

Each process according to the embodiment described above may be stored as a program executable by, for example, a CPU or the like as a computer. Otherwise, each process can be stored and distributed in a storage medium of an external storage device such as a memory card, a magnetic disk, an optical disk, or a semiconductor memory. The CPU or the like can then read the program stored in the storage medium of the external storage device, and execute the above-described processes when the operation of the CPU or the like is controlled by the read program.