JP2017161891A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus that properly corrects decrease in peripheral light quantity associated with shake correction.SOLUTION: The imaging apparatus comprises: an optical system including a plurality of lenses; an imaging element imaging a subject formed by the optical system; a peripheral light quantity correction unit correcting a peripheral light quantity of an image imaged by the imaging element; a shake detection unit detecting a shake of the imaging apparatus; and a drive control unit moving, based on an output signal of the shake detection unit, at least one of the lens and the imaging element on a plane perpendicular to an optical axis for shake correction. The peripheral light quantity correction unit extracts a predetermined frequency component of the shake and changes a correction amount of the peripheral light quantity according to a predetermined frequency component of the shake.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an imaging apparatus having a blur correction function in one or both of a lens and a camera body.

  2. Description of the Related Art Conventionally, there is an imaging apparatus equipped with detection means (such as a gyro sensor) that detects a shake of the own apparatus. In the case of a camera with an interchangeable lens, detection means for detecting a shake of the imaging device is provided on at least one of the interchangeable lens and the camera body (for example, see Patent Document 1). In the case where the detection unit is provided in the interchangeable lens, the position of the lens for blur correction provided in the interchangeable lens is shifted based on the detection result of the detection unit. On the other hand, when the detection means is provided in the camera body, the position of the image sensor (image sensor) provided in the camera body is shifted based on the detection result of the detection means.

  In such an image pickup apparatus, vibration in a frequency band of about 1 to 10 Hz due to camera shake of the photographer is detected by the detection means. Based on this detection result, the influence of blurring in the captured image is reduced by driving either or both of the lens in the interchangeable lens and the imaging sensor in the camera body.

JP 2009-251492 A

  In an imaging apparatus, a subject image projected onto an imaging element through a lens has a characteristic that the amount of light decreases toward the periphery of the imaging element. When the correction lens or the image sensor is shifted according to the blur of the imaging device to reduce the influence of the blur in the captured image, the image is projected onto the image sensor by the shift by the correction lens or the shift of the image sensor. In the subject image, the amount of light is further reduced toward the periphery of the image sensor. As a result, there is a problem that the quality of the captured image is lowered. The present disclosure relates to an image pickup apparatus that reduces the influence of blurring during shooting by shifting a correction lens or an image pickup device, and the quality of a shot image due to a decrease in the amount of light projected on the image pickup device around the image pickup device. An object is to prevent a decrease and provide a good captured image.

  In particular, the present disclosure prevents a deterioration in the quality of a captured image due to a decrease in the amount of light projected onto the image sensor around the image sensor, and provides a good video captured image at the time of video recording. With the goal.

  An imaging apparatus according to the present disclosure includes an optical system including a plurality of lenses, an imaging element that captures a subject image formed by the optical system, a peripheral light amount correction unit that corrects a peripheral light amount of an image captured by the imaging element, Have Also, a shake detection unit that detects the shake of the image pickup device, and a drive control unit that corrects the shake by moving at least one of the lens or the image pickup element on a plane perpendicular to the optical axis based on the output signal of the shake detection unit And having. The peripheral light amount correction unit extracts a predetermined frequency component of blur and changes the correction amount of the peripheral light amount according to the predetermined frequency component of blur.

  According to the present disclosure, it is possible to prevent deterioration in quality of a captured image due to a decrease in the amount of light projected on the image sensor in the imaging apparatus, and provide a good captured image. In particular, the present disclosure can prevent deterioration in quality of a captured image during moving image shooting and provide a good moving image captured image.

1 is a block diagram illustrating a configuration of a digital camera according to a first embodiment. FIG. 2 is a block diagram illustrating a configuration of an OIS processing unit in the digital camera according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of a BIS processing unit in the digital camera according to the first embodiment. Explanatory drawing of the peripheral light amount drop in the digital camera of Embodiment 1 Peripheral light quantity drop principle diagram in the digital camera of Embodiment 1 Characteristic graph of peripheral light amount drop in the digital camera of Embodiment 1 Characteristic graph of peripheral light amount correction gain in the digital camera of Embodiment 1 Characteristic graph after peripheral light amount correction in the digital camera of Embodiment 1 Explanatory drawing of the peripheral light quantity characteristic at the time of OIS lens shift in the digital camera of Embodiment 1 Principle of camera shake correction by OIS lens shift in the digital camera of Embodiment 1 Explanatory drawing of the principle of the peripheral light quantity characteristic at the time of CCD shift in the digital camera of Embodiment 1 Principle of camera shake correction by CCD shift in the digital camera of Embodiment 1 Peripheral light quantity characteristic graph after OIS lens shift in the digital camera of Embodiment 1 Characteristic graph of peripheral light amount correction gain after OIS lens shift in the digital camera of Embodiment 1 Characteristic graph after correction of peripheral light quantity after OIS lens shift in the digital camera of Embodiment 1 Peripheral light quantity characteristic graph after CCD shift in the digital camera of Embodiment 1 Characteristic graph of peripheral light amount correction gain after CCD shift in the digital camera of Embodiment 1 Characteristic graph after correction of peripheral light quantity after CCD shift in the digital camera of Embodiment 1 Waveform diagrams of a shake detection signal and a shake control signal in the shake correction process of the second embodiment FIG. 6 is a waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction in the shake correction processing of the second embodiment. Waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction that is updated every exposure period Tk in the blur correction process of the reference example Waveform diagram showing temporal change of peripheral light amount correction gain updated for each exposure period Tk in the blur correction process of the reference example The waveform diagram showing the temporal change of the peripheral light amount ratio after the peripheral light amount correction updated every exposure period Tk in the blur correction process of the reference example The characteristic graph of the peripheral light amount ratio before the peripheral light amount correction during the CCD shift in the exposure period T2 in the digital camera of the reference example Characteristic graph of peripheral light amount correction gain in exposure period T2 in the digital camera of the reference example Characteristic graph of the peripheral light amount ratio after the peripheral light amount correction in the exposure period T2 in the digital camera of the reference example FIG. 6 is a waveform diagram showing a temporal change in the peripheral light amount ratio updated for each exposure period Tk in the shake correction processing according to the second embodiment. The wave form diagram showing the time change of the peripheral light amount correction gain updated for every exposure period Tk in the shake correction process of Embodiment 2 The wave form diagram showing the time change of the peripheral light quantity ratio after the peripheral light quantity correction | amendment updated for every exposure period Tk in the blurring correction process of Embodiment 2. FIG. Characteristic graph of peripheral light amount ratio during CCD shift in exposure period T2 in the digital camera of the second embodiment Characteristic graph of peripheral light amount correction gain in exposure period T2 in the digital camera of Embodiment 2 Characteristic graph of the peripheral light amount ratio after the peripheral light amount correction in the exposure period T2 in the digital camera of the second embodiment 7 is a flowchart showing peripheral light amount correction processing by CCD shift in the shake correction processing of the digital camera according to the second embodiment. FIG. 6 is a waveform diagram showing a temporal change in the peripheral light amount ratio updated for each frame number k in the shake correction processing of the second embodiment. FIG. 6 is a waveform diagram showing a temporal change in the peripheral light amount correction gain updated for each frame number k in the shake correction processing according to the second embodiment. FIG. 6 is a waveform diagram showing a temporal change in the peripheral light amount ratio after the peripheral light amount correction updated for each frame number k in the shake correction processing of the second embodiment. 8 is a flowchart showing peripheral light amount correction processing by OIS lens shift in the shake correction processing of the digital camera according to the second embodiment. FIG. 6 is a waveform diagram showing temporal changes in the peripheral light amount ratio before the peripheral light amount correction that is updated every six frames in the shake correction process of the third embodiment. The wave form diagram showing the time change of the peripheral light quantity correction gain updated for every 6 frames exposure period in the blurring correction process of Embodiment 3

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

  The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims. Hereinafter, a digital camera will be described as an example of the imaging apparatus.

(Embodiment 1)
The digital camera according to the present embodiment includes a shake correction function (function for performing image shake correction) that reduces the influence of camera shake on a captured image in each of the interchangeable lens and the camera body. Hereinafter, the configuration and operation of the camera of the present embodiment will be described in detail.

  In the following description, the function of correcting the blur by shifting the correction lens in the interchangeable lens is referred to as an “OIS (Optical Image Stabilizer) function”. The function of correcting the blur by shifting the image sensor in the camera body is referred to as a “BIS (Body Image Stabilizer) function”.

1. Configuration FIG. 1 is a block diagram showing a configuration of a digital camera 1 according to the first embodiment. The digital camera 1 includes a camera body 100 and an interchangeable lens 200 that can be attached to and detached from the camera body 100.

1-1. Camera Body The camera body 100 includes a CCD (Charge Coupled Device) 110, a liquid crystal monitor 120, a camera controller 140, a body mount 150, a power supply 160, and a card slot 170.

  The camera controller 140 controls the operation of the entire digital camera 1 by controlling components such as the CCD 110 in accordance with an instruction from the release button 130. The camera controller 140 transmits a vertical synchronization signal to a timing generator (TG) 112. In parallel with this, the camera controller 140 generates an exposure synchronization signal. The camera controller 140 periodically transmits the generated exposure synchronization signal to the lens controller 240 via the body mount 150 and the lens mount 250. The camera controller 140 uses a DRAM (Dynamic Random Access Memory) 141 as a work memory during a control operation or an image processing operation.

  The CCD 110 captures a subject image incident through the interchangeable lens 200 and generates image data. The generated image data is digitized by an AD converter (Analog-to-digital Converter (ADC)) 111. The digitized image data is subjected to predetermined image processing by the camera controller 140. The predetermined image processing is, for example, gamma correction processing, white balance correction processing, scratch correction processing, YC conversion processing, electronic zoom processing, or JPEG (Joint Photographic Experts Group) compression processing.

  The CCD 110 operates at a timing controlled by the timing generator 112. Examples of the operation of the CCD 110 include a still image capturing operation and a through image capturing operation. The through image is mainly a moving image, and is displayed on the liquid crystal monitor 120 in order for the user to determine a composition for capturing a still image.

  The liquid crystal monitor 120 displays an image indicated by the display image data image-processed by the camera controller 140. The liquid crystal monitor 120 can selectively display both moving images and still images.

  The card slot 170 can be loaded with a memory card 171 and controls the memory card 171 based on the control from the camera controller 140. The digital camera 1 can store image data in the memory card 171 and read image data from the memory card 171.

  The power supply 160 supplies power to each element in the digital camera 1.

  The body mount 150 can be mechanically and electrically connected to the lens mount 250 of the interchangeable lens 200. The camera body 100 and the interchangeable lens 200 can transmit and receive data via connectors mounted on the body mount 150 and the lens mount 250. The body mount 150 transmits the exposure synchronization signal received from the camera controller 140 to the lens controller 240 via the lens mount 250. The body mount 150 transmits other control signals received from the camera controller 140 to the lens controller 240 via the lens mount 250. The body mount 150 transmits the signal received from the lens controller 240 to the camera controller 140 via the lens mount 250. The body mount 150 supplies the power from the power source 160 to the entire interchangeable lens 200 via the lens mount 250.

  The camera body 100 is configured to realize a BIS function that corrects camera shake by shifting the CCD 110, and a gyro sensor 184 that detects camera shake and a BIS that controls camera shake correction processing based on the detection result of the gyro sensor 184. And a processing unit 183. The camera body 100 further includes a CCD drive unit 181 that moves the CCD 110 and a position sensor 182 that detects the position of the CCD 110. The CCD drive unit 181 can be realized by a magnet and a flat coil, for example. The position sensor 182 is a sensor that detects the position of the CCD 110 in a plane perpendicular to the optical axis of the optical system. The position sensor 182 can be realized by a magnet and a hall element, for example. The BIS processing unit 183 controls the CCD driving unit 181 based on the signal from the gyro sensor 184 and the signal from the position sensor 182 so that the CCD 110 is a surface perpendicular to the optical axis so as to cancel out the camera body 100 shake. Shift within. Here, the imaging sensor provided in the camera body 100 is a CCD, but another imaging sensor such as a CMOS (Complementary Metal Oxide Semiconductor) sensor may be used. The CCD driving unit 181 may use another actuator such as a stepping motor or an ultrasonic motor. When a stepping motor is used as the actuator, open control can be performed, and accordingly, a position sensor can be dispensed with.

1-2. Interchangeable Lens The interchangeable lens 200 includes an optical system, a lens controller 240, and a lens mount 250. The optical system includes a zoom lens 210, an OIS lens 220, and a focus lens 230.

  The zoom lens 210 is a lens for changing the magnification of a subject image formed by the optical system. The zoom lens 210 is composed of one or a plurality of lenses. The zoom lens driving unit 211 includes a zoom ring or the like that can be operated by the user, transmits the operation by the user to the zoom lens 210, and moves the zoom lens 210 along the optical axis direction of the optical system.

  The focus lens 230 is a lens for changing the focus state of the subject image formed on the CCD 110 in the optical system. The focus lens 230 is composed of one or a plurality of lenses.

  The focus lens driving unit 233 includes a motor. The focus lens driving unit 233 moves the focus lens 230 along the optical axis of the optical system based on the control of the lens controller 240. The focus lens driving unit 233 can be realized by a DC motor, a stepping motor, a servo motor, an ultrasonic motor, or the like.

  The OIS lens 220 is a lens for correcting blur of a subject image formed by the optical system of the interchangeable lens 200 in an OIS function that corrects camera shake by shifting the OIS lens 220. The OIS lens 220 moves in a direction that cancels out the blur of the digital camera 1, thereby reducing the blur of the subject image on the CCD 110. The OIS lens 220 is composed of one or a plurality of lenses. Under the control of the OIS processing unit 223, the OIS driving unit 221 shifts the OIS lens 220 within a plane perpendicular to the optical axis of the optical system.

  The OIS drive unit 221 can be realized by a magnet and a flat coil, for example. The position sensor 222 is a sensor that detects the position of the OIS lens 220 in a plane perpendicular to the optical axis of the optical system. The position sensor 222 can be realized by a magnet and a Hall element, for example. The OIS processing unit 223 controls the OIS driving unit 221 based on the output of the position sensor 222 and the output of the gyro sensor 224 (blur detector). Here, other actuators such as an ultrasonic motor may be used as the OIS drive unit 221.

  The gyro sensor 184 or the gyro sensor 224 detects shake (vibration) in the yawing direction and the pitching direction based on an angular change per unit time of the digital camera 1, that is, an angular velocity. The gyro sensor 184 or the gyro sensor 224 outputs an angular velocity signal indicating the detected blur amount (angular velocity) to the OIS processing unit 223 or the BIS processing unit 183. The angular velocity signal output by the gyro sensor 184 or the gyro sensor 224 may include a wide range of frequency components due to camera shake or mechanical noise. In this embodiment, a gyro sensor is used as the angular velocity detection means, but other sensors can be used as long as they can detect the shake of the digital camera 1 instead of the gyro sensor.

  The camera controller 140 and the lens controller 240 may be configured with a hard-wired electronic circuit or a microcomputer using a program.

  The digital camera 1 can store image data in the flash memory 242 and read image data from the flash memory 242.

  The lens controller 240 uses the DRAM 241 as a work memory during a control operation or an image processing operation.

1-3. OIS Processing Unit FIG. 2 is a block diagram showing the configuration of the OIS processing unit 223 in the digital camera of the first embodiment. The configuration of the OIS processing unit 223 in the interchangeable lens 200 will be described with reference to FIG. The OIS processing unit 223 includes an ADC (analog / digital conversion) / LPF (low pass filter, low pass filter) 305, an HPF (high pass filter, high pass filter) 306, a phase compensation unit 307, An integrator 308, an LPF 309, an adder 310, and a PID control unit (Proportional-Integral-Differential Controller) 311 are included.

  The ADC / LPF 305 converts the angular velocity signal from the gyro sensor 224 from an analog format to a digital format. Further, the ADC / LPF 305 blocks high-frequency components of the angular velocity signal converted into the digital format in order to eliminate noise and extract only the blur of the digital camera 1. The frequency of camera shake of the photographer is a low frequency greater than 0 Hz and less than or equal to 10 Hz. Considering this point, the cutoff frequency of the LPF is set. If noise is not a problem, the LPF function can be omitted.

  The HPF 306 blocks a predetermined low frequency component included in the signal received from the ADC / LPF 305 in order to block the drift component. The phase compensation unit 307 corrects a phase lag caused by the OIS driving unit 221 or lens-body communication (described later) with respect to the signal received from the HPF 306.

  The integrator 308 integrates the signal indicating the angular velocity of vibration (vibration) input from the phase compensation unit 307, and generates a signal indicating the angle of vibration (vibration). Hereinafter, the signal generated by the integrator 308 is referred to as a “blur detection signal”.

  The shake detection signal from the integrator 308 is input to the LPF 309 and the adder 310. The LPF 309 cuts the high frequency component of the blur detection signal and passes the low frequency component (hereinafter referred to as “first blur signal”). The first blur signal is a signal indicating a blur correction amount related to blur in the low frequency region. Here, the cutoff frequency of the LPF 309 is set to 1 Hz, for example, in consideration of the camera shake frequency (greater than 0 Hz and 10 Hz or less). Here, the LPF is used to generate the low-frequency component blur signal. However, any filter may be used as long as it is a filter that cuts high-frequency components such as another filter such as an LSF (Low-Shelf Filter). May be. The filter configuration is not limited to this configuration, and may be another configuration such as, for example, changing the order of the HPF 306 and the integrator 308.

  The adder 310 subtracts the low-frequency component of the shake detection signal extracted by the LPF 309 from the shake detection signal input from the integrator 308, so that the high-frequency component of the shake detection signal (hereinafter “second shake signal”). Extract). The second blur signal is a signal indicating a blur correction amount related to blur in a high frequency region (1 Hz to 10 Hz). The second shake signal is input to the PID control unit 311. On the other hand, the first blur signal is transmitted to the camera body 100.

  The PID control unit 311 performs PID control based on the difference between the input second shake signal and the current position information of the OIS lens 220 received from the position sensor 222. The PID control unit 311 generates a drive signal for the OIS drive unit 221 and sends it to the OIS drive unit 221. The OIS drive unit 221 drives the OIS lens 220 based on the drive signal.

1-4. BIS Processing Unit FIG. 3 is a block diagram illustrating a configuration of the BIS processing unit 183 in the digital camera 1 according to the first embodiment. The configuration of the BIS processing unit 183 in the camera body 100 will be described with reference to FIG. The BIS processing unit 183 includes an ADC / LPF 405, an HPF 406, a phase compensation unit 407, an integrator 408, a selector 412, and a PID control unit 410.

  The basic functions of the ADC / LPF 405, the HPF 406, the phase compensation unit 407, the integrator 408, and the PID control unit 410 are the same as the functions of the corresponding elements in the OIS processing unit 223.

  The BIS processing unit 183 is based on either one of the output of the gyro sensor 184 provided in the camera body 100 (the output of the integrator 408) and the first blur signal received from the interchangeable lens 200, in particular. The camera is configured to perform shake correction processing. Therefore, the BIS processing unit 183 outputs either one of the output of the gyro sensor 184 (the output of the integrator 408) provided in the camera body 100 and the first blur signal received from the interchangeable lens 200. A selector 412 for selecting and outputting to the PID control unit 410 is provided. The selector 412 selects the output of the gyro sensor 184 (the output of the integrator 408) when realizing the shake correction function on the camera body 100 side, such as when the interchangeable lens 200 does not have a shake correction function. The selector 412 is controlled by the camera controller 140.

  The PID control unit 410 generates a drive signal for shifting the CCD 110 based on the output from the position sensor 182 and the output from the integrator 408 or the first blur signal from the interchangeable lens 200, and the CCD Output to the drive unit 181. The CCD drive unit 181 drives the CCD 110 based on the drive signal.

2. Operation 2-1. Camera shake correction process The camera shake correction process in the digital camera 1 configured as described above will be described. In the following description, an example of driving the OIS lens 220 and the CCD 110 based on a signal from the gyro sensor 224 provided on the lens side among the two gyro sensors 224 and 184 will be described. That is, the digital camera 1 uses a gyro sensor 224 provided on the lens side. At this time, the selector 412 in the BIS processing unit 183 is controlled to select the first blur signal and output it to the PID control unit 410. At this time, the digital camera 1 operates with the interchangeable lens 200 having the gyro sensor 224 to be used as a master and the other camera body 100 as a slave.

  The OIS processing unit 223 receives the detection signal from the gyro sensor 224 and generates a shake detection signal from the received detection signal. The OIS processing unit 223 separates the shake detection signal into a second signal and a first shake signal. The OIS processing unit 223 generates a drive signal for shifting the OIS lens 220 based on the second shake signal and the position information from the position sensor 222, and outputs the drive signal to the OIS drive unit 221. The OIS driving unit 221 moves the OIS lens 220 on a surface perpendicular to the optical axis so as to cancel high-frequency vibration (1 Hz to 10 Hz) detected by the gyro sensor 224 according to the driving signal from the OIS processing unit 223. Shift with.

  The first blur signal generated in the OIS processing unit 223 is transmitted to the camera body 100 using communication between the interchangeable lens and the camera body via the lens mount 250 and the body mount 150. At this time, in the BIS processing unit 183 of the camera body 100, the selector 412 is controlled to select the first blur signal from the interchangeable lens 200. The BIS processing unit 183 generates a drive signal for driving the CCD 110 based on the first shake signal from the interchangeable lens 200 and the position information from the position sensor 182, and transmits the drive signal to the CCD drive unit 181. The CCD drive unit 181 shifts the CCD 110 on a plane perpendicular to the optical axis so as to cancel the low-frequency blur (less than 1 Hz) detected by the gyro sensor 224 according to the drive signal from the BIS processing unit 183. Here, the communication between the interchangeable lens and the camera body is performed via the lens mount 250 and the body mount 150, but may be performed by optical communication or wireless communication.

  As described above, the digital camera 1 according to the present embodiment operates the shake correction function on the interchangeable lens 200 side based on the high-frequency component (1 Hz to 10 Hz) in the detected shake signal. The digital camera 1 activates the camera shake correction function on the camera body 100 side based on the low frequency component (less than 1 Hz) in the detected camera shake signal. As described above, in the present embodiment, the camera shake correction function is shared between the camera body 100 and the interchangeable lens 200, so that only the high-frequency component of the shake signal needs to be corrected on the interchangeable lens 200 side. Therefore, the correction range of the OIS lens 220 can be effectively used on the interchangeable lens 200 side.

2-2. As described above, the digital camera 1 according to the present embodiment includes the interchangeable lens 200 and the camera main body 100, and cooperates with the OIS function on the interchangeable lens 200 side and the BIS function of the camera main body 100. By doing so, image blur is corrected. The basic principle of peripheral light amount correction in the digital camera 1 will be described below.

  FIG. 4 is a diagram for explaining the principle of the decrease in the amount of peripheral light in the digital camera 1 according to the first embodiment. The optical system includes a zoom lens 210, an OIS lens 220, and a focus lens 230. The image sensor is composed of a CCD 110. The OIS lens 220 has a function of correcting camera shake by shifting in a direction perpendicular to the optical axis. Here, an example in which the OIS lens 220 is held at the center is shown. L1 and L2 indicate the boundaries of the light beam range where the subject image can be captured. The light ray range for capturing the subject image indicated by L1 and L2 corresponds to the light ray range indicated by L3 and L4 on the CCD 110 side. On the other hand, L30 and L40 on the CCD 110 side indicate the boundaries of the light range captured by the CCD 110, and correspond to the light range indicated by L10 and L20 on the subject side (left side of the zoom lens 210). A in FIG. 4 indicates an intersection between the extended line on the surface of the CCD 110 and the light beam range L3. B in FIG. 4 indicates the intersection of the end point of the CCD 110 and the light beam range L30. Details regarding these intersections A and B will be described with reference to FIG.

  In a general optical system, the amount of light that is imaged decreases toward the periphery of the image sensor. Specifically, in FIG. 4, the amount of light gradually decreases from L30 to L3 in the vertical direction upward from the center of the optical axis indicated by the alternate long and short dash line along the CCD 110. The light quantity gradually decreases from L40 to L4 in the vertical direction downward from the center of the optical axis indicated by the alternate long and short dash line along the CCD 110.

  FIG. 5 is a diagram illustrating the peripheral light amount drop principle in the digital camera 1 according to the first embodiment. FIG. 5B shows a characteristic graph of the peripheral light amount drop. In FIG. 5A, C represents the light amount distribution of the subject image on the CCD 110 side through the zoom lens 210, the OIS lens 220, and the focus lens 230, and D represents the outer shape of the CCD 110. The light amount distribution C of the subject image on the CCD 110 side is referred to as an effective image circle, and so-called vignetting occurs in which an appropriate light amount cannot be obtained outside the effective image circle. A point A where the alternate long and short dash line and the outer shape of the light quantity distribution C intersect corresponds to the intersection A in FIG. 4 described above. A point B where the alternate long and short dash line intersects the outer shape D of the CCD 110 corresponds to the intersection B in FIG. 4 described above.

  In FIG. 5B, the horizontal axis indicates the image height and corresponds to the coordinates along the alternate long and short dash line in FIG. The vertical axis represents the peripheral light amount ratio. The center of the light quantity distribution C in FIG. 5A is set to an image height of 0, the peripheral light quantity ratio is set to 1.0, and the peripheral light quantity decreases as the image height along the alternate long and short dash line in FIG. . Here, an image height of 1.0 is defined as a point B at which the alternate long and short dash line of FIG. Note that the area outside the intersection A (area where the image height exceeds 1.2) indicates an area where vignetting occurs and a normal amount of light cannot be obtained, and is omitted from the characteristic graph of FIG. In the characteristic graph of the peripheral light amount drop in FIG. 5B, as a specific example, the peripheral light amount ratio when the image height is 1.0 is 0.5, and the peripheral light amount ratio when the image height is 1.2. 0.35. The characteristic graph of the decrease in the amount of peripheral light with the image height as the center is a symmetrical shape. The characteristic graph from the image height of 0 to the image height of −1.2 to 0 is shown with the image height from 0 to the left coordinate being negative.

  Next, a specific example in which the peripheral light amount correction is performed will be described with reference to FIGS. 6A, 6B, and 6C. FIG. 6A is a characteristic graph of a peripheral light amount drop in the digital camera 1 according to the first embodiment. FIG. 6B is a characteristic graph of the peripheral light amount correction gain in the digital camera 1 according to the first embodiment. FIG. 6C is a characteristic graph after the peripheral light amount correction in the digital camera 1 of the first embodiment. FIG. 6A is the same as the characteristic graph of the peripheral light amount drop in FIG. 5B described above. However, since the graph is limited to the light amount projected onto the CCD 110, the image height on the horizontal axis is −1. It is limited to 0.0 to 1.0. FIG. 6B is a characteristic graph of the peripheral light amount correction gain when the peripheral light amount correction is performed in accordance with the peripheral light amount drop characteristic of FIG. 6A. In the camera controller 140 in FIG. 1, image data input to the camera controller 140 through the CCD 110 and the ADC 111 is increased in accordance with the image height and the correction gain, thereby correcting the peripheral light amount. In FIG. 6C, the peripheral light amount ratio of FIG. 6A and the peripheral light amount correction gain characteristic of FIG. 6B are multiplied for each image height, thereby correcting the peripheral light amount ratio to 1.0 regardless of the image height. An example is possible. In FIG. 6C, the characteristic graph of the peripheral light amount drop indicated by the broken line (same as the characteristic graph of FIG. 6A) becomes a characteristic graph after the peripheral light amount correction of the solid line by the correction.

2-3. The principle of peripheral light amount correction in the camera shake correction system Here, the subject image projected on the CCD 110 by a shift by a correction lens (hereinafter referred to as an OIS lens) or a shift by an image sensor (hereinafter referred to as a CCD) is A specific embodiment for solving the problem that the quality of a photographed image is deteriorated by further reducing the amount of light near the periphery of the CCD 110 will be described.

2-3-1. FIG. 7A is a diagram for explaining the principle of the peripheral light amount characteristic when the OIS lens 220 is shifted in the digital camera 1 according to the first embodiment. FIG. 7B is a diagram illustrating the principle of camera shake correction using the OIS lens 220 shift. In FIG. 7B, only the requirements that are the points of explanation are described as the digital camera 1 including the CCD 110 in the camera body 100 and the OIS lens 220 in the interchangeable lens 200. Assuming that the digital camera 1 is rotated by θ about the OIS lens 220 due to camera shake with respect to the optical axis L5, the optical axis L5 rotates about the OIS lens 220 by θ as shown by L50. In this case, the rotated optical axis L50 is aligned with the optical axis L5 on the right side of the OIS lens 220 by shifting the OIS lens 220 by X1 in accordance with the rotation θ of the digital camera 1 due to camera shake. Correct as follows. Thereby, even when the digital camera 1 rotates due to camera shake, the subject image can be formed on the CCD 110 without blurring. As an example, when the focal length f of the interchangeable lens 200 is 150 mm and the rotation θ due to camera shake of the digital camera 1 is 0.3 degrees, on the CCD 110, the optical axis L5 rotates to L50, so that only about 0.78 mm. The imaging position will shift. Therefore, the shift of the imaging position can be corrected by shifting the OIS lens 220. The shift amount of the OIS lens 220 in this case depends on the optical design. For example, when the shift amount X1 is set to 0.3 mm, the image formation position is returned by a shift of 0.78 mm, thereby correcting camera shake. Function can be realized.

  In FIG. 7A, the OIS lens 220 has a function of correcting camera shake by shifting in a direction perpendicular to the optical axis. When the OIS lens 220 is held at the center, L1 and L2 indicate the boundaries of the light beam range in which the subject image can be captured. The light ray range for capturing the subject image indicated by L1 and L2 corresponds to the light ray range indicated by L3 and L4 on the CCD 110 side. On the other hand, L30 and L40 on the CCD 110 side indicate the boundaries of the light range captured by the CCD 110, and correspond to the light range indicated by L10 and L20 on the subject side (left side of the zoom lens 210). Here, as described with reference to FIG. 7B, when the digital camera 1 is rotated by θ around the OIS lens 220 due to camera shake, the OIS lens 220 is moved by X1 in the vertical direction with respect to the optical axis. By shifting, it is possible to correct a shift in the imaging position of the subject image on the CCD 110 due to camera shake. At this time, the light ray ranges L10 and L20 on the subject side (left side of the zoom lens 210) corresponding to L30 and L40, which are light ray ranges projected onto the CCD 110, move as indicated by L100 and L200, respectively. As described above, when the light ray range on the subject side is moved by the camera shake correction by the shift of the OIS lens 220, the L20 moves to L200 and approaches the boundary L2 of the light ray range where the subject can be captured. The amount of the light beam L30 corresponding to the side is slightly reduced. On the other hand, when L10 moves to L100 and moves away from the boundary L1 of the light beam range where the subject can be captured, the light amount of the light beam L40 corresponding to the CCD 110 side slightly increases.

2-3-2. FIG. 8A is an explanatory diagram of the principle of the peripheral light amount characteristic at the time of CCD shift in the digital camera 1 according to the first embodiment. FIG. 8B is a principle of camera shake correction by CCD shift in the digital camera 1 of the first embodiment. In FIG. 8B, only the requirements that are the points of explanation are described as the digital camera 1 including the CCD 110 in the camera body 100 and the OIS lens 220 in the interchangeable lens 200. Assuming that the digital camera 1 is rotated by θ about the OIS lens 220 due to camera shake with respect to the optical axis L5, the optical axis L5 rotates about the OIS lens 220 by θ as shown by L50. In this case, by shifting the CCD 110 by X2 in accordance with the rotation θ of the digital camera 1 due to camera shake, the intersection coordinates on the CCD 110 by the optical axis L5 coincide with the intersection coordinates on the CCD 110 by the optical axis L50. Make corrections. Thereby, even when the digital camera 1 rotates due to camera shake, the subject image can be formed on the CCD 110 without blurring. As an example, when the focal length f of the interchangeable lens 200 is 150 mm and the rotation θ due to camera shake of the digital camera 1 is 0.3 degrees, on the CCD 110, the optical axis L5 rotates to L50, so that only about 0.78 mm. The imaging position will shift. Therefore, the shift of the imaging position can be corrected by shifting the CCD 110 by about 0.78 mm.

  In FIG. 8A, the CCD 110 has a function of correcting camera shake by shifting in a direction perpendicular to the optical axis. However, here, when the CCD 110 is held at the center, L1 and L2 indicate the boundaries of the light beam range that can capture the subject image, and the light beam range that captures the subject image indicated by L1 and L2 is L3 on the CCD 110 side. And L4. On the other hand, L30 and L40 on the CCD 110 side indicate the boundaries of the light range captured by the CCD 110, and correspond to the light range indicated by L10 and L20 on the subject side (left side of the zoom lens 210). Here, as described with reference to FIG. 8B, when the digital camera 1 is rotated about the OIS lens 220 by θ by camera shake, the CCD 110 is shifted by X2 in the direction perpendicular to the optical axis. Thus, it is possible to correct the shift of the imaging position of the subject image on the CCD 110 due to camera shake. Before the CCD 110 shift, L30 and L40, which are the light beam ranges projected onto the CCD 110, correspond to the light beam ranges L10 and L20 on the subject side (left side of the zoom lens 210). After the CCD 110 is shifted by X2, the light range projected on the CCD 110, L300 and L400, corresponds to the light range L100 and L200 on the subject side (left side of the zoom lens 210). The light beam ranges L100 and L200 are the same as those at the time of camera shake correction by the shift of the OIS lens 220 described above. That is, when the rotation due to camera shake of the digital camera 1 is θ, the angle of view to be captured on the subject side is the same. Here again, L10 in the light ray range on the subject side (left side of the zoom lens 210) is far from L1 that is the boundary of the light ray range where the subject can be captured by moving to L100. The amount of light projected on the side increases slightly. On the other hand, L20 in the light ray range on the subject side (left side of the zoom lens 210) approaches L2 that is the boundary of the light ray range where the subject can be captured by moving to L200. For this reason, the light quantity which the L200 light beam is projected on the CCD 110 side slightly decreases. After the CCD 110 is shifted by X2, the L300, which is the boundary of the light beam range projected onto the CCD 110, approaches the light beam L3 corresponding to the outer shape of the effective image circle. descend. That is, in addition to the decrease in the amount of light incident on the interchangeable lens 200 due to the light beam L200, the light amount of the light beam L300 corresponding to the light beam L200 is further decreased due to the decrease in the light amount. On the other hand, after shifting the CCD 110 by X2, L400, which is the boundary of the light beam range projected on the CCD 110, is far from the light beam L4 corresponding to the outer shape of the effective image circle. For this reason, the light quantity by the L400 light beam projected onto the CCD 110 further increases. That is, in addition to the increase in the amount of light incident on the interchangeable lens 200 due to the light beam L100, the light amount of the light beam L400 corresponding to the light beam L100 further increases as the light amount increases.

  Therefore, in a region where the peripheral light amount decreases due to the shift of the OIS lens or the CCD due to camera shake correction, the peripheral light amount decreases more greatly during the CCD shift than when the OIS lens shifts. On the other hand, in the region where the peripheral light amount increases due to the shift of the OIS lens or the CCD due to camera shake correction, the peripheral light amount increases more during the CCD shift than during the OIS lens shift.

2-3-3. Method for correcting peripheral light quantity characteristic by OIS lens shift A specific example of correcting a change in the peripheral light quantity characteristic caused by the OIS lens shift will be described with reference to FIGS. 9A, 9B, and 9C. FIG. 9A is a peripheral light quantity characteristic graph after the OIS lens shift in the digital camera 1 of the first embodiment. FIG. 9B is a characteristic graph of the peripheral light amount correction gain after the OIS lens shift in the digital camera 1 according to the first embodiment. FIG. 9C is a characteristic graph after the peripheral light amount correction after the OIS lens shift in the digital camera 1 of the first embodiment.

  In FIG. 9A, the horizontal axis indicates the image height at the center on the CCD 110 as 0 and the image height at the corners on the CCD 110 from −1.0 to 1.0. The vertical axis represents the peripheral light amount ratio corresponding to the image height. The broken line graph is a graph showing the characteristics of the peripheral light quantity before the OIS lens shift. The solid line graph is a graph showing the characteristics of the peripheral light amount after the OIS lens shift, that is, the state shifted by X1 in the direction perpendicular to the optical axis. In the graph, as described above, the OIS lens shift shows that the image height is slightly lower than the peripheral light amount before the OIS lens shift when the image height is 1.0, and the OIS lens when the image height is −1.0. It shows a slight increase from the peripheral light amount before the shift.

  FIG. 9B is a characteristic graph of the peripheral light amount correction gain when the peripheral light amount correction is performed according to the peripheral light amount drop characteristic of FIG. 9A. Here, an example is shown in which the peripheral light amount correction after the OIS lens shift is performed, and thus corresponds to the graph shown by the solid line in FIG. 9A. In the camera controller 140, the peripheral light quantity is corrected by increasing the gain of the image data input to the camera controller 140 through the CCD 110 and the ADC 111 in accordance with the image height and the correction gain. FIG. 9C corrects the peripheral light amount ratio to 1.0 regardless of the image height by multiplying the peripheral light amount drop characteristic shown by the solid line in FIG. 9A and the peripheral light amount correction gain characteristic of FIG. 9B for each image height. The peripheral light quantity ratio is shown. In FIG. 9C, the characteristic graph of the peripheral light amount drop of the broken line (same as the characteristic graph shown by the solid line in FIG. 9A) becomes the characteristic graph after the peripheral light amount correction of the solid line by the correction.

  In FIG. 9B, a gain at an image height of 1.0 is defined as G1, and a gain at an image height of −1.0 is defined as G2. The gain G1 and the gain G2 are used in the description of the correction method of the peripheral light amount characteristic by the CCD shift described later.

2-3-4. Method for correcting peripheral light quantity characteristics by CCD shift A specific example of correcting changes in peripheral light quantity characteristics caused by CCD shift will be described with reference to FIGS. 10A, 10B, and 10C. FIG. 10A is a peripheral light quantity characteristic graph after the CCD shift in the digital camera 1 of the first embodiment. FIG. 10B is a characteristic graph of the peripheral light amount correction gain after the CCD shift in the digital camera 1 according to the first embodiment. FIG. 10C is a characteristic graph after the peripheral light amount correction after the CCD shift in the digital camera 1 of the first embodiment.

  In FIG. 10A, the horizontal axis indicates the image height at the center on the CCD 110 as 0 and the image height at the corner on the CCD 110 from −1.0 to 1.0. The vertical axis represents the peripheral light amount ratio corresponding to the image height. The broken line graph is a graph showing the characteristics of the peripheral light amount before the CCD shift. The solid line graph is a graph showing the characteristics of the amount of peripheral light after the CCD shift, that is, in a state where it is shifted by X2 in the direction perpendicular to the optical axis. As described above, this graph shows a state in which the CCD light shift causes the light amount to fall below the peripheral light amount before the CCD shift when the image height is 1.0, and the peripheral area before the CCD shift when the image height is −1.0. It shows a slight increase from the amount of light. In particular, comparing FIG. 10A and FIG. 9A, when the image height is 1.0, the peripheral light amount after the CCD shift is larger than that after the OIS lens shift than the peripheral light amount before the CCD shift or before the OIS lens shift. It shows a decline. Comparing FIG. 10A and FIG. 9A, when the image height is −1.0, the peripheral light amount after the CCD shift is larger than that after the OIS lens shift, and the peripheral light amount increases before the CCD shift or before the OIS lens shift. It shows how they are doing.

  FIG. 10B is a characteristic graph of the peripheral light amount correction gain when the peripheral light amount correction is performed in accordance with the peripheral light amount drop characteristic of FIG. 10A. FIG. 10B shows an example in which the peripheral light amount correction after the CCD shift is performed, and therefore corresponds to the graph shown by the solid line in FIG. 10A. In the camera controller 140, the peripheral light quantity is corrected by increasing the gain of the image data input to the camera controller 140 through the CCD 110 and the ADC 111 in accordance with the image height and the correction gain. In FIG. 10C, the peripheral light amount ratio shown by the solid line in FIG. 10A and the peripheral light amount correction gain characteristic in FIG. 10B are multiplied for each image height, so that the peripheral light amount ratio becomes 1.0 regardless of the image height. Indicates the peripheral light amount ratio to be corrected. In FIG. 10C, the characteristic graph of the decrease in peripheral light amount indicated by the broken line (same as the characteristic graph indicated by the solid line in FIG. 10A) becomes a characteristic graph after correction of the peripheral light amount by the solid line.

  In FIG. 10B, a gain at an image height of 1.0 is defined as G3, and a gain at an image height of −1.0 is defined as G4. The magnitude relationship between the gains G1 and G2 defined in FIG. 9B and the gains G3 and G4 defined in FIG. 10B is compared. When the image height is 1.0, the relationship is G3> G1. When the image height is -1.0, the relationship is G4 <G2. That is, with respect to the same camera shake rotation amount θ of the digital camera 1, when the image height is 1.0, the decrease in the amount of peripheral light is greater after the CCD shift than after the OIS lens shift. Therefore, as a result, the peripheral light amount correction gain is set so that the CCD shift is larger than the OIS lens shift. On the other hand, when the image height is −1.0 with respect to the same camera shake rotation amount θ of the digital camera 1, the decrease in the amount of peripheral light is smaller after the CCD shift than after the OIS lens shift. Therefore, as a result, the peripheral light amount correction gain is set so that the CCD shift is smaller than the OIS lens shift.

3. Summary In the present embodiment, it is possible to appropriately correct the decrease in the peripheral light amount at one corner of the CCD and the decrease in the peripheral light amount at the other corner of the CCD to prevent deterioration in the quality of the captured image, and to obtain a good captured image. The specific example which can provide is shown.

  The digital camera 1 that performs camera shake correction by shifting the OIS lens 220 and the CCD 110 in order to reduce the influence of camera shake on the captured image during shooting has been described. By shifting the OIS lens 220 with respect to a certain amount of camera shake, the amount of peripheral light on the CCD 110 falls compared to the case where camera shake correction is not performed. However, the amount of peripheral light on the CCD 110 is more greatly reduced by shifting the CCD 110 with respect to the same amount of camera shake. Therefore, in this case, the peripheral light amount correction caused by the CCD shift is made larger than the peripheral light amount correction caused by the OIS lens shift, thereby eliminating image quality degradation due to camera shake in the photographed image and a drop in the peripheral light amount. can do.

  On the other hand, by shifting the OIS lens 220 with respect to a certain amount of camera shake, the peripheral light amount on the CCD 110 may increase as compared with the case where camera shake correction is not performed. However, the amount of peripheral light on the CCD 110 is greatly increased by shifting the CCD 110 for the same amount of camera shake. Therefore, in this case, the peripheral light amount correction caused by the CCD shift is made smaller than the peripheral light amount correction caused by the OIS lens shift, thereby eliminating image quality degradation due to camera shake in the photographed image and a decrease in the peripheral light amount. can do.

  In particular, by combining both of these, it is possible to reduce the left and right heads of the peripheral light amount drop in the captured image, and to provide a higher quality image.

  That is, when the digital camera 1 switches from a correction based on the OIS lens shift to a correction based on the CCD shift for a certain amount of camera shake, or when switching from the correction based on the CCD shift to the correction based on the OIS lens shift, By changing the correction amount, it is possible to eliminate image quality degradation due to camera shake and a decrease in the amount of peripheral light in the captured image.

  As described above, the imaging apparatus corresponding to the digital camera 1 of the present embodiment is an imaging system corresponding to the optical system including the plurality of lenses 210, 220, and 230 and the CCD 110 that captures the subject image formed by the optical system. And a peripheral light amount correction unit corresponding to the BIS processing unit 183 that corrects the peripheral light amount of an image captured by the imaging device. Further, based on the shake detection unit corresponding to the gyro sensors 184 and 224 for detecting the shake of the image pickup device and the output signal of the shake detection unit, at least one of the lenses 210, 220, and 230 or the image pickup device is perpendicular to the optical axis. And a drive control unit corresponding to the CCD 110 or the OIS lens 220 which is moved on the surface and corrects the shake. The peripheral light amount correction unit extracts a predetermined frequency component of blur and changes the correction amount of the peripheral light amount according to the predetermined frequency component of blur.

  As a result, it is possible to prevent deterioration of the quality of the captured image due to a decrease in the amount of light projected onto the image sensor in the imaging apparatus, and to provide a good captured image. In particular, it is possible to prevent a deterioration in the quality of a captured image at the time of moving image shooting and provide a good moving image captured image.

  The peripheral light amount correction unit corresponding to the BIS processing unit 183 extracts a predetermined frequency component of blur from the output signal of the blur detection unit, and changes the correction amount of the peripheral light amount according to the predetermined frequency component of blur. May be. As a result, it is possible to prevent deterioration of the quality of the captured image due to a decrease in the amount of light projected onto the image sensor in the imaging apparatus, and to provide a good captured image.

  The peripheral light amount correction unit extracts a predetermined frequency component of blur from a drive control signal that moves at least one of the lens or the image sensor in the drive control unit, and corrects the peripheral light amount according to the predetermined frequency component of blur. The amount may vary. As a result, it is possible to prevent deterioration of the quality of the captured image due to a decrease in the amount of light projected onto the image sensor in the imaging apparatus, and to provide a good captured image.

  The imaging apparatus may include an interchangeable lens 200 including an optical system, and a camera body 100 including an imaging element and a peripheral light amount correction unit. Further, the interchangeable lens 200 and the camera body 100 may be detachable.

  Further, the optical system may include a correction lens corresponding to the OIS lens 220 for correcting blur.

(Embodiment 2)
1. Configuration Another example of a digital camera that realizes blur correction will be described. The configuration and basic operation of the digital camera of the present embodiment are the same as those of the first embodiment. In the digital camera of the present embodiment, various operations for improving the peripheral light amount correction performance during moving image shooting are newly added to the camera controller 140 and the lens controller 240.

2. Operation 2-1. Shake Correction Processing In this embodiment, the basic principle of the shake correction processing described in Embodiment 1 is the same, and thus detailed description of the principle is omitted. In the present embodiment, in order to make the explanation easy to understand, a detailed operation of the processing for correcting the peripheral light amount in addition to the processing for correcting the shake by shifting the CCD 110 will be described. On the other hand, in addition to the process of correcting the blur by shifting the OIS lens 220, the process of correcting the peripheral light quantity in the process of correcting the peripheral light quantity, in addition to the process of correcting the shake by shifting the CCD 110, There is a similar effect. The same effect can be obtained in the processing for correcting the peripheral light amount by operating both the processing for correcting the shake by shifting the CCD 110 and the processing for correcting the shake by shifting the OIS lens 220.

  In the present embodiment, a new process for improving the peripheral light amount correction performance is added to the camera controller 140 and the lens controller 240. A detailed description of the new processing will be given in section 2-3 onward.

2-2. Correction method for ambient light characteristics during image stabilization (reference example)
A correction method of the peripheral light amount characteristic during the camera shake correction operation in the reference example will be described with reference to FIGS. 11A, 11B, 12A, 12B, 12C, 13A, 13B, and 13C.

  FIG. 11A is a waveform diagram of a shake detection signal and a shake control signal in the shake correction process of the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the camera shake angle and the correction angle. For example, the frame number k is incremented every 1/30 [second]. The camera shake angle is calculated based on the output of the gyro sensor 184 provided in the camera body 100 (the output of the integrator 408). The correction angle is calculated based on the output of the position sensor 182 provided in the camera body 100. FIG. 11A shows an example of a camera shake angle and a correction angle when the frame number k is 0 to 16 (about 567 ms). Strictly speaking, the camera shake angle and the correction angle have different characteristics due to residual errors and response delays, and there are errors, but the errors are small, so they are graphed as having almost the same characteristics. Has been.

  FIG. 12A is a waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction that is updated every exposure period Tk in the blur correction process of the reference example. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio. For example, the frame number k is incremented every 1/30 [second]. The graph indicated by the broken line in FIG. 12A represents the transition in real time of the peripheral light amount ratio before the peripheral light amount correction during the camera shake correction operation, and the stepped graph indicated by the solid line represents the peripheral light amount before the peripheral light amount correction during the camera shake correction operation. It represents the transition of the ratio. Note that the peripheral light amount ratio in FIG. 12A represents the peripheral light amount ratio corresponding to the image height 1.0 on the CCD 110.

  FIG. 13A represents the peripheral light amount ratio before the peripheral light amount correction corresponding to the image height, where the center image height on the CCD 110 is 0 and the corner image height on the CCD 110 is −1.0 and 1.0. . 11A and 12A described above represent the peripheral light amount ratio before the peripheral light amount correction in the exposure period T2 in the frame number k = 2 in the shaded area. In FIG. 13A, a broken line graph is a graph showing the characteristic of the peripheral light amount before the peripheral light amount correction at time t2 in FIG. 11A. 13A, the alternate long and short dash line graph represents the characteristics of the peripheral light amount before the peripheral light amount correction at time t3 in FIG. 11A. In FIG. 13A, the solid line graph is a graph showing the characteristics of the peripheral light amount before the peripheral light amount correction in FIG. 11A.

  FIG. 11B is a waveform diagram illustrating a temporal change in the peripheral light amount ratio before the peripheral light amount correction in the shake correction processing according to the second embodiment. FIG. 11B shows a real-time transition of the peripheral light amount ratio before the peripheral light amount correction corresponding to the image height 1.0 on the CCD 110 during the camera shake correction operation.

  FIG. 12B is a waveform diagram illustrating a temporal change in the peripheral light amount correction gain updated for each exposure period Tk in the blur correction process of the reference example. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount correction gain. The graph indicated by the broken line in FIG. 12B represents the transition of the peripheral light amount correction gain in real time during the camera shake correction operation, and the stepped graph indicated by the solid line represents the peripheral light amount correction gain at the exposure start timing tk during the camera shake correction operation. Represents the transition. The peripheral light amount correction gain in FIG. 12B represents the peripheral light amount correction gain corresponding to the image height 1.0 on the CCD 110. Further, the real-time peripheral light amount correction gain indicated by a broken line in FIG. 12B represents a correction gain necessary for setting the original peripheral light amount ratio to 1.0.

  FIG. 13B shows the peripheral light amount correction gain corresponding to the image height, where the center image height on the CCD 110 is 0 and the corner image heights on the CCD 110 are indicated by −1.0 and 1.0. Explaining only the correction of the peripheral light amount ratio when the image height is 1.0, in FIG. 12B, the peripheral light amount at the start timing t2 of the exposure period T2 in the frame number k = 2 in the shaded area. The correction gain (about 3.3 times) corresponds to the peripheral light amount correction gain when the image height is 1.0 in FIG. 13B.

  FIG. 12C is a waveform diagram showing a temporal change in the peripheral light amount ratio after the peripheral light amount correction updated every exposure period Tk in the shake correction process of the reference example. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio after the peripheral light amount correction. The step-like graph shown by the solid line in FIG. 12C represents the transition of the peripheral light amount correction gain at the exposure start timing tk during the camera shake correction operation. The peripheral light amount ratio after the peripheral light amount correction in FIG. 12C represents the peripheral light amount ratio corresponding to the image height 1.0 on the CCD 110. In the reference example, since the peripheral light amount correction is performed using the camera shake angle or the camera shake correction angle detected only at a predetermined timing not related to the exposure period, the original aim of the peripheral light amount ratio (peripheral light amount ratio = 1.0). ) Is larger.

  FIG. 13C is a characteristic graph of the peripheral light amount ratio after the peripheral light amount correction in the exposure period T2 in the digital camera of the reference example. FIG. 13C shows the image height at the center on the CCD 110 as 0, the image height at the corners on the CCD 110 as −1.0 and 1.0, and the characteristics of the peripheral light amount after the peripheral light amount correction corresponding to the image height. It is a represented graph. The graph indicated by the broken line in FIG. 13C represents the peripheral light amount correction before the peripheral light amount correction, and corresponds to the graph indicated by the solid line in FIG. 13A. A graph indicated by a dotted line in FIG. 13C is a graph showing the characteristics of the peripheral light amount after the peripheral light amount correction. The graph indicated by the dotted line in FIG. 13C is a graph obtained by multiplying the values indicated by the vertical axis for each image height of the graph indicated by the broken line in FIG. 13C (the same as the graph indicated by the solid line in FIG. 13A) and the graph indicated by the broken line in FIG. It becomes. In the reference example, since the peripheral light amount correction is performed using the camera shake angle or the camera shake correction angle detected only at a predetermined timing not related to the exposure period, the peripheral light amount ratio after the peripheral light amount correction is between each frame. The relative error is also large.

  From this result, when the peripheral light amount correction is performed using the camera shake angle or the camera shake correction angle detected at a predetermined timing (time point t2 in this example), as shown in FIG. It can be seen that the marginal light amount ratio has a large error from the original target (peripheral light amount ratio = 1.0). Further, as shown in FIG. 12C, when attention is paid to the temporal change in the peripheral light amount ratio after the peripheral light amount correction at the image height of 1.0, the exposure period Tk (where k = 0, 1, 2, 3,... It can be seen that the temporal change in the peripheral light amount ratio after the peripheral light amount correction becomes large every time.

  Therefore, in the peripheral light amount correction of the shake correction process in the reference example, when the peripheral light amount correction is performed using the camera shake angle or the camera shake correction angle detected only at a predetermined timing not related to the exposure period, the peripheral light amount correction is performed. Therefore, an error from the original target (peripheral light amount ratio = 1.0) becomes large. Furthermore, at the time of moving image shooting, the marginal light amount ratio after the peripheral light amount correction for each exposure period becomes large from the original aim (peripheral light amount ratio = 1.0), so that even between each frame, The error of the peripheral light amount ratio after the peripheral light amount correction becomes large. For this reason, the periphery of the moving image appears as flickering, and the quality of the moving image is significantly reduced.

2-3. Explanation of the correction principle of the peripheral light quantity characteristic (this embodiment: CCD shift example 1)
A method for correcting the peripheral light amount characteristic during the camera shake correction operation in this embodiment will be described with reference to FIGS. 11A, 11B, 14A, 14B, 14C, 15A, 15B, and 15C. In this embodiment, the principle of the peripheral light quantity characteristic and the peripheral light quantity correction described in the first embodiment is the same, and thus the detailed description of the principle is omitted in this embodiment.

  FIG. 11A is a waveform diagram of a camera shake detection signal and a camera shake control signal. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the camera shake angle and the correction angle. For example, the frame number k is incremented every 1/30 [second]. The camera shake angle is calculated based on the output of the gyro sensor 184 provided in the camera body 100 (the output of the integrator 408). The correction angle is calculated based on the output of the position sensor 182 provided in the camera body 100. FIG. 11A shows an example of a camera shake angle and a correction angle when the frame number k is 0 to 16 (about 567 ms). Strictly speaking, the camera shake angle and the correction angle have different characteristics due to residual errors and response delays, and there are errors, but the errors are small, so they are almost the same characteristics. It has become.

  FIG. 14A is a waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction that is updated every exposure period Tk in the shake correction processing of the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio. For example, the frame number k is incremented every 1/30 [second]. The graph indicated by the broken line in FIG. 14A represents the transition in real time of the peripheral light amount ratio before the peripheral light amount correction during the camera shake correction operation, and the stepped graph indicated by the solid line is averaged during the exposure period Tk during the camera shake correction operation. This represents the transition of the peripheral light amount ratio before the peripheral light amount correction. Note that the peripheral light amount ratio in FIG. 14A represents the peripheral light amount ratio corresponding to the image height 1.0 on the CCD 110.

  FIG. 15A is a characteristic graph of the peripheral light amount ratio during the CCD shift in the exposure period T2 in the digital camera of the second embodiment. FIG. 15A shows the peripheral light amount ratio before the peripheral light amount correction corresponding to the image height, where the center image height on the CCD 110 is 0 and the corner image heights on the CCD 110 are −1.0 and 1.0. . 11A and 14A described above represent the peripheral light amount ratio before the peripheral light amount correction in the exposure period T2 in the frame number k = 2 of the shaded area. In FIG. 15A, a broken line graph is a graph showing the characteristics of the peripheral light amount before the peripheral light amount correction at time t2 in FIG. 11A. 15A, the alternate long and short dash line graph represents the characteristics of the peripheral light amount before the peripheral light amount correction at time t3 in FIG. 11A. In FIG. 15A, the solid line graph is a graph showing the characteristics of the peripheral light amount before the peripheral light amount correction when the peripheral light amount is averaged in the exposure period T2 in FIG. 11A.

  FIG. 11B is a waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction, and the peripheral light amount ratio before the peripheral light amount correction corresponding to the image height 1.0 on the CCD 110 during the camera shake correction operation. It represents a real-time transition.

  FIG. 14B is a waveform diagram illustrating a temporal change in the peripheral light amount correction gain updated for each exposure period Tk in the shake correction processing according to the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount correction gain. A graph indicated by a broken line in FIG. 14B represents a real-time transition of the peripheral light amount correction gain during the camera shake correction operation. Further, the staircase graph indicated by the solid line represents the transition of the peripheral light amount correction gain obtained using the camera shake angle detected during the exposure period Tk or the average value of the camera shake correction angles during the camera shake correction operation. Here, paying attention to the fact that the exposed image is averaged over the exposure period Tk, the peripheral light amount correction gain is also averaged over the camera shake angle or camera shake correction angle detected during the exposure period Tk. That is the point. That is, the low frequency component included in the information on the detected camera shake angle or camera shake correction angle is extracted. The camera shake angle before averaging generally includes a frequency component greater than 0 Hz and not greater than 30 Hz. By averaging the detected camera shake angle, a frequency component greater than 0 Hz and 15 Hz or less (low-frequency component of shake) is extracted, and a peripheral light amount correction gain is obtained using this component.

  Note that the peripheral light amount correction gain in FIG. 14B represents the peripheral light amount correction gain corresponding to the image height 1.0 on the CCD 110. Further, the real-time peripheral light amount correction gain indicated by a broken line in FIG. 14B represents a correction gain necessary for setting the original peripheral light amount ratio to 1.0.

  FIG. 15B is a characteristic graph of the peripheral light amount correction gain in the exposure period T2 in the digital camera of Embodiment 2. FIG. 15B shows the peripheral light amount correction gain corresponding to the image height, where the center image height on the CCD 110 is 0 and the corner image heights on the CCD 110 are indicated by −1.0 and 1.0. Explaining only the correction of the peripheral light amount ratio when the image height is 1.0, the camera shake angle or camera shake correction angle detected during the exposure period T2 in the frame number k = 2 in the shaded area in FIG. 14B. The peripheral light amount correction gain (about 2.5 times) obtained by using the average value of these corresponds to the peripheral light amount correction gain when the image height is 1.0 in FIG. 15B.

  FIG. 14C is a waveform diagram illustrating a temporal change in the peripheral light amount ratio after the peripheral light amount correction that is updated every exposure period Tk in the shake correction processing according to the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio after the peripheral light amount correction. The graph shown by the solid line in FIG. 14C represents the transition of the peripheral light amount correction gain obtained using the camera shake angle or the average value of the camera shake correction angles detected during the exposure period Tk during the camera shake correction operation. The peripheral light amount ratio after the peripheral light amount correction in FIG. 14C represents the peripheral light amount ratio corresponding to the image height 1.0 on the CCD 110. In the present embodiment, the peripheral light amount correction is performed by obtaining the peripheral light amount correction gain by using the average value within the exposure period for the detected camera shake angle or camera shake correction angle. The characteristic is as intended by the ratio (peripheral light quantity ratio = 1.0).

  FIG. 15C is a characteristic graph of the peripheral light amount ratio after the peripheral light amount correction in the exposure period T2 in the digital camera of Embodiment 2. FIG. 15C shows the image height at the center on the CCD 110 as 0, the image heights at the corners on the CCD 110 as −1.0 and 1.0, and the characteristics of the peripheral light amount after peripheral light amount correction corresponding to the image height. It is a graph. The graph indicated by the broken line in FIG. 15C represents the peripheral light amount correction before the peripheral light amount correction, and corresponds to the graph indicated by the solid line in FIG. 15A. The graph shown by the solid line in FIG. 15C is a graph showing the characteristics of the peripheral light amount after the peripheral light amount correction. The graph shown by the solid line in FIG. 15C is obtained by multiplying the numerical values on the vertical axis for each image height of the graph shown by the broken line in FIG. 15C (same as the graph shown by the solid line in FIG. 15A) and the graph shown by the solid line in FIG. It becomes a graph. In this embodiment, when the peripheral light amount correction gain is obtained using the detected camera shake angle or camera shake correction angle, the peripheral light amount correction is performed using the average value of the detected camera shake angle or camera shake correction angle within the exposure period. The peripheral light amount correction is performed by obtaining the gain. For this reason, accurate peripheral light amount correction can be performed on an image picked up during the exposure period, so that the peripheral light amount ratio becomes the characteristic as originally intended (peripheral light amount ratio = 1.0).

  From this result, for the detected camera shake angle or camera shake correction angle, the peripheral light amount correction is performed by obtaining the peripheral light amount correction gain using a value averaged within the exposure period. As shown in FIG. 15C, it can be seen that the peripheral light amount ratio after the peripheral light amount correction can be obtained as originally intended (peripheral light amount ratio = 1.0). 14C, when attention is paid to the temporal change in the peripheral light amount ratio after the peripheral light amount correction at the image height of 1.0, the exposure period Tk (where k = 0, 1, 2, 3,... It can be seen that there is no temporal change in the peripheral light amount ratio after the peripheral light amount correction every time.

  Therefore, in the imaging apparatus according to the present embodiment, it is possible to perform accurate peripheral light amount correction on an image captured during the exposure period, and thus provide an image with a target light amount ratio as desired. Can do. Furthermore, since accurate peripheral light amount correction can be performed for each exposure period at the time of moving image shooting, an error in the peripheral light amount ratio after peripheral light amount correction is small between frames. For this reason, the periphery of the moving image, which was a problem in the reference example, does not appear as flickering, and the image quality can be improved.

2-4. Explanation of flow of correcting peripheral light quantity characteristics (this embodiment: CCD shift example 1)
Next, the operation flow of the peripheral light amount correction during the blur correction operation in the digital camera 1 of the present embodiment will be described using the drawings. Digital cameras generally have a function of shooting a moving image in addition to a function of shooting a still image. Here, the operation flow of the peripheral light amount correction during the blur correction operation during moving image shooting, which is a feature of the present embodiment, will be described. Various methods are used to start moving image shooting in the digital camera. In this embodiment, moving image shooting is started by pressing (turning on) the release button. The still image shooting mode and the moving image shooting mode can be switched by operating a mode dial (not shown) or a menu (not shown).

  FIG. 16 is a flowchart (in the case of CCD shift processing) showing peripheral light amount correction processing in blur correction processing in the digital camera 1 of the present embodiment. The process within the solid line frame represents the process of the camera controller 140. The process within the broken line frame represents the process of the lens controller 240. When the moving image shooting mode is selected, a standby state for moving image shooting processing such as setting the frame rate is set (step S21). If it is determined in step S22 that the release button is turned on, the process proceeds to the next process, and the moving image shooting process is started. In a state where the release button is not pressed, the process of step S22 is repeated, and the standby state of the moving image shooting process is repeated. When the moving image shooting process is started, an exposure period Tk is set (step S23). For example, when the frame rate is set to 30 [fps] and the exposure period is set to 1/30 [second], Tk = 1/30 [second] is set. Based on this setting condition, exposure to the CCD 110 is started. The position of the CCD 110 during the blur correction operation in the exposure period Tk is detected, and the average value Qk is calculated (step S24). In order to perform the peripheral light amount correction, information regarding the peripheral light amount ratio corresponding to the image height on the CCD 110 is notified from the lens controller 240 to the camera controller 140 (step S25). In the design center, the peripheral light amount ratio is generally a numerical value that gradually decreases concentrically from the center on the CCD 110. The reciprocal of the notified peripheral light amount ratio becomes the peripheral light amount correction gain. This peripheral light amount correction gain is a table in which a numerical value is defined for each horizontal and vertical coordinate on the CCD 110 surface. The camera controller 140 acquires the image Dk of the exposure period Tk (step S26), and calculates the shift amount Ik of the table center position of the peripheral light amount correction gain based on the previously calculated average value Qk of the CCD 110 (step S26). Step S27). The camera controller 140 uses the peripheral light amount characteristic notified from the lens controller 240 to calculate the image Dk based on the calculated peripheral light amount correction gain table and the shift amount Ik of the CCD 110 moved in accordance with the shake correction operation. Corrected and recorded (step S28). It is determined whether or not to end the exposure by turning off the release button (step S29). If the exposure is not ended, the process returns to step S23, and the exposure in moving image shooting for the next frame is continued. On the other hand, in the process of step S29, when the release button is turned off to end the exposure, the moving image shooting is ended. Here again, paying attention to the fact that the exposed image is averaged during the exposure period Tk, the peripheral light amount correction gain is also averaged for the camera shake angle or camera shake correction angle detected during the exposure period Tk. Is the point. That is, the low frequency component included in the information on the detected camera shake angle or camera shake correction angle is extracted. The camera shake angle before averaging generally includes a frequency component greater than 0 Hz and not greater than 30 Hz. By averaging the detected camera shake angle, a frequency component greater than 0 Hz and 15 Hz or less (low-frequency component of shake) is extracted, and a peripheral light amount correction gain is obtained using this component.

  As described above, in the imaging apparatus according to the present embodiment, accurate peripheral light amount correction can be performed on an image captured during the exposure period. Therefore, it is possible to provide an image having the desired characteristics of the peripheral light amount ratio. Furthermore, during moving image shooting, accurate peripheral light amount correction can be performed for each exposure period. Accordingly, the error of the peripheral light amount ratio after the peripheral light amount correction is small between the frames. For this reason, the periphery of the moving image, which was a problem in the reference example, does not appear as flicker, and the quality of the image can be improved.

2-5. Explanation of the peripheral light quantity characteristic correction principle (this embodiment: CCD shift example 2)
A case where the exposure period Tk is shorter than the frame period in the peripheral light amount characteristic correction method during the camera shake correction operation in the present embodiment will be described with reference to FIGS. 17A, 17B, and 17C. Here, an example in which the frame period is 1/30 [second] (that is, the frame rate is 30 [fps]) and the exposure period is 1/60 [second] will be described.

  FIG. 17A is a waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction that is updated for each frame number k in the shake correction processing according to the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio. For example, the frame number k is incremented every 1/30 [seconds]. A graph indicated by a broken line in FIG. 17A represents a real-time transition of the peripheral light amount ratio before the peripheral light amount correction during the camera shake correction operation. The staircase graph shown by the solid line in FIG. 17A represents the transition of the peripheral light amount ratio before the peripheral light amount correction averaged during the exposure period Tk during the camera shake correction operation. In FIG. 14A, the exposure period Tk and the frame period are assumed to be equal. However, FIG. 17A differs from FIG. 14A in that the exposure period Tk (here 1/60 [second]) is shorter than the frame period (here 1/30 [second]). Note that the peripheral light amount ratio in FIG. 17A represents the peripheral light amount ratio corresponding to the image height 1.0 on the CCD 110.

  FIG. 17B is a waveform diagram illustrating a temporal change in the peripheral light amount correction gain updated for each frame number k in the shake correction processing according to the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount correction gain. A graph indicated by a broken line in FIG. 17B represents a real-time transition of the peripheral light amount correction gain during the camera shake correction operation. The staircase graph shown by the solid line in FIG. 17B represents the transition of the peripheral light amount correction gain obtained using the camera shake angle detected during the exposure period Tk or the average value of the camera shake correction angles during the camera shake correction operation. In FIG. 14B, the exposure period Tk and the frame period are assumed to be equal. However, FIG. 17B is different from FIG. 14B in that the exposure period Tk (here 1/60 [second]) is shorter than the frame period (here 1/30 [second]). Here again, paying attention to the fact that the exposed image is averaged during the exposure period Tk, the peripheral light amount correction gain is also averaged for the camera shake angle or camera shake correction angle detected during the exposure period Tk. Is the point. That is, the low frequency component included in the information on the detected camera shake angle or camera shake correction angle is extracted. The camera shake angle before averaging generally includes a frequency component greater than 0 Hz and not greater than 30 Hz. By averaging the detected camera shake angle, a frequency component greater than 0 Hz and 15 Hz or less (low-frequency component of shake) is extracted, and a peripheral light amount correction gain is obtained using this component.

  The peripheral light amount correction gain in FIG. 17B represents the peripheral light amount correction gain corresponding to the image height 1.0 on the CCD 110. The real-time peripheral light amount correction gain indicated by a broken line in FIG. 17B represents a correction gain necessary for setting the original peripheral light amount ratio to 1.0.

  FIG. 17C is a waveform diagram showing a temporal change in the peripheral light amount ratio after the peripheral light amount correction updated for each frame number k in the shake correction processing of the second embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio after the peripheral light amount correction. The graph indicated by the solid line in FIG. 17C represents the transition of the peripheral light amount correction gain obtained using the camera shake angle or the average value of the camera shake correction angles detected during the exposure period Tk during the camera shake correction operation. In FIG. 14C, the exposure period Tk and the frame period are assumed to be equal. However, FIG. 17C is different from FIG. 14C in that the exposure period Tk (here 1/60 [second]) is shorter than the frame period (here 1/30 [second]). The peripheral light amount ratio after the peripheral light amount correction in FIG. 17C represents the peripheral light amount ratio corresponding to the image height 1.0 on the CCD 110. In the present embodiment, the peripheral light amount correction is performed by obtaining the peripheral light amount correction gain by using the average value within the exposure period for the detected camera shake angle or camera shake correction angle. The characteristic is as intended by the ratio (peripheral light quantity ratio = 1.0).

  From this result, it can be seen that in the present embodiment, the peripheral light amount ratio after the peripheral light amount correction can obtain the characteristics as originally intended (peripheral light amount ratio = 1.0). As shown in FIG. 17C, when attention is paid to the temporal change in the peripheral light amount ratio after the peripheral light amount correction at the image height of 1.0, the frame number k (where k = 0, 1, 2, 3,... ), There is no temporal change in the peripheral light amount ratio after the peripheral light amount correction.

  Therefore, in the imaging apparatus according to the present embodiment, accurate peripheral light amount correction can be performed on an image captured during the exposure period. Accordingly, it is possible to provide an image with the peripheral light amount ratio having the desired characteristics. Furthermore, during moving image shooting, accurate peripheral light amount correction can be performed for each exposure period. Accordingly, the error of the peripheral light amount ratio after the peripheral light amount correction is small between the frames. For this reason, the periphery of the moving image, which was a problem in the reference example, does not appear as flickering, and the image quality can be improved.

2-6. Explanation of an operation flow for correcting the peripheral light quantity characteristic (this embodiment: an example of OIS lens shift)
With reference to the drawings, the operation flow of the peripheral light amount correction during the blur correction operation by the OIS lens shift in the digital camera 1 of the present embodiment will be described. In general, a digital camera has a function of shooting a moving image in addition to a function of shooting a still image. Here, the operation flow of the peripheral light amount correction during the blur correction operation at the time of moving image shooting, which is a feature of the present embodiment, will be described. In the digital camera, various methods are used for starting moving image shooting. In the present embodiment, moving image shooting is started by pressing (turning on) the release button. And The still image shooting mode and the moving image shooting mode can be switched by operating a mode dial (not shown) or a menu (not shown).

  FIG. 18 is a flowchart showing a peripheral light amount correction process using an OIS lens shift in the shake correction process of the digital camera 1 according to the second embodiment. The process within the solid line frame represents the process of the camera controller 140. The process within the broken line frame represents the process of the lens controller 240. When the moving image shooting mode is selected, a moving image shooting process such as setting a frame rate is set in a standby state (step S31). If it is determined in step S32 that the release button is turned on, the process proceeds to the next process, and the moving image shooting process is started. In a state where the release button is not pressed, the process of step S32 is repeated, and the standby state of the moving image shooting process is repeated. When the moving image shooting process is started, an exposure period Tk is set (step S33). For example, when the frame rate is set to 30 [fps] and the exposure period is set to 1/30 [second], Tk = 1/30 [second] is set. Based on this setting condition, exposure to the CCD 110 is started. The position of the OIS lens 220 during the blur correction operation in the exposure period Tk is detected, and the average value Pk is calculated (step S34). In order to correct the average value Pk of the position of the OIS lens 220 and the peripheral light amount correction, information about the peripheral light amount ratio corresponding to the image height on the CCD 110 is notified from the lens controller 240 to the camera controller 140 (step S35). In the design center, the peripheral light amount ratio is generally a numerical value that gradually decreases concentrically from the center on the CCD 110. The reciprocal of the notified peripheral light amount ratio becomes the peripheral light amount correction gain. The peripheral light amount correction gain is a table in which a numerical value is defined for each horizontal and vertical coordinate on the CCD 110 surface. The camera controller 140 acquires the image Dk of the exposure period Tk (step S36), and based on the previously notified average value Pk of the position of the OIS lens 220, the shift amount Hk of the table center position of the peripheral light amount correction gain. Is calculated (step S37). The camera controller 140 generates an image Dk based on the peripheral light amount correction gain table calculated using the peripheral light amount characteristic notified from the lens controller 240 and the shift amount Hk of the OIS lens 220 moved in accordance with the shake correction operation. Corrected and recorded (step S38). In the process of step S39, it is determined whether or not to end the exposure by turning off the release button. If the exposure is not terminated, the process returns to step S33, and the exposure in moving image shooting for the next frame is continued. On the other hand, in the process of step S39, when the release button is turned off and the exposure is ended, the moving image shooting is ended. Here again, paying attention to the fact that the exposed image is averaged during the exposure period Tk, the peripheral light amount correction gain is also averaged for the camera shake angle or camera shake correction angle detected during the exposure period Tk. Is the point. That is, the low frequency component included in the information on the detected camera shake angle or camera shake correction angle is extracted. The camera shake angle before averaging generally includes a frequency component greater than 0 Hz and not greater than 30 Hz. By averaging the detected camera shake angle, a frequency component greater than 0 Hz and 15 Hz or less (low-frequency component of shake) is extracted, and a peripheral light amount correction gain is obtained using this component.

  Here, an example in which the lens controller 240 notifies the camera controller 140 of the average value Pk of the position of the OIS lens 220 is shown. However, for the position information of the OIS lens 220, the camera controller 140 may calculate the average value Pk. Further, the average value Pk is not limited to the position of the OIS lens 220, and may be shake detection information used for controlling the OIS lens 220 or information based thereon.

  As described above, in the imaging apparatus according to the present embodiment, accurate peripheral light amount correction can be performed on an image captured during the exposure period. Therefore, it is possible to provide an image having the desired characteristics of the peripheral light amount ratio. Furthermore, during moving image shooting, accurate peripheral light amount correction can be performed for each exposure period. Therefore, the error of the peripheral light amount ratio after the peripheral light amount correction is small between the frames. For this reason, the periphery of the moving image, which was a problem in the reference example, does not appear as flicker, and the quality of the image can be improved.

  In the present embodiment, an example of CCD shift and an example of OIS lens shift have been described separately. Even in the state where the CCD shift and the OIS lens shift described in the first embodiment are simultaneously operated, the peripheral light amount correction described in the second embodiment can be combined with the example of the CCD shift and the example of the OIS lens shift. Accurate peripheral light amount correction can be performed on an image captured during the exposure period. In addition, at the time of moving image shooting, even in the state where the CCD shift and the OIS lens shift described in the first embodiment are operated at the same time, the example of the CCD shift and the OIS lens shift in the peripheral light amount correction described in the second embodiment. Also by combining the example, it is possible to correct the peripheral light amount accurately for each exposure period.

  Therefore, in the present embodiment, it is possible to provide an image with the desired ratio of the peripheral light amount ratio even when the CCD shift and the OIS lens shift are simultaneously operated. Further, even when shooting a moving image, the periphery of the moving image, which was a problem in the reference example, does not appear as flickering, and the quality of the image can be improved.

3. Summary As described above, the digital camera 1 according to the present embodiment shifts the correction lens or the image sensor to reduce the influence of blur during shooting, and the amount of light projected onto the image sensor. Therefore, it is possible to prevent the quality of the captured image from being deteriorated due to the decrease in the vicinity of the imaging element, and to provide a good captured image. In particular, the digital camera 1 according to the present embodiment can prevent a deterioration in the quality of a captured image at the time of moving image shooting with respect to a deterioration in the quality of a captured image due to a decrease in the amount of light projected onto the image sensor around the image sensor. It is also possible to provide a good moving picture image.

  In the present embodiment, in order to obtain the peripheral light amount correction gain, an example in which the detected camera shake angle or information on the camera shake correction angle is averaged is shown. However, the present invention is not limited to this, and the peripheral light amount correction gain may be averaged, and as a result, it may be averaged with any of the signals related to the peripheral light amount correction. Further, the signal relating to the peripheral light amount correction may be smoothed without being limited to the process of averaging.

  In the imaging apparatus corresponding to the digital camera 1 of the present embodiment, the peripheral light amount correction unit corresponding to the BIS processing unit 183 has a plurality of correction data corresponding to the image height on the imaging element corresponding to the CCD 110. Also good.

(Embodiment 3)
FIG. 19A is a waveform diagram showing a temporal change in the peripheral light amount ratio before the peripheral light amount correction that is updated every six frames of the exposure correction process in the third embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount ratio. For example, the frame number k is incremented every 1/30 [second]. The graph shown by a broken line in FIG. 19A represents a real-time transition of the peripheral light amount ratio before the peripheral light amount correction during the camera shake correction operation, and the staircase graph shown by the solid line shows an exposure period of 6 frames during the camera shake correction operation. Represents the transition of the peripheral light amount ratio before correction of the peripheral light amount, Note that the peripheral light amount ratio in FIG. 19A represents the peripheral light amount ratio corresponding to an image height of 1.0 on the CCD 110.

  FIG. 19B is a waveform diagram showing a temporal change in the peripheral light amount correction gain updated every exposure period of 6 frames in the shake correction process of the third embodiment. The horizontal axis indicates the frame number k (where k = 0, 1, 2, 3...), And the vertical axis indicates the peripheral light amount correction gain. A graph indicated by a broken line in FIG. 19B represents a real-time transition of the peripheral light amount correction gain during the camera shake correction operation. Further, the staircase graph shown by the solid line represents the transition of the peripheral light amount correction gain obtained using the camera shake angle or the average value of the camera shake correction angles detected during the exposure period of 6 frames during the camera shake correction operation. . Here, paying attention to the fact that the exposed image is averaged over the exposure period of 6 frames, the camera shake angle or camera shake correction angle detected during the exposure period of 6 frames is also averaged for the peripheral light amount correction gain. That is the point. That is, the low frequency component included in the information on the detected camera shake angle or camera shake correction angle is extracted. In this case, the camera shake angle before averaging includes a frequency component of 5 Hz. By averaging the detected camera shake angle, a frequency component of 5 Hz (low frequency component of camera shake) is extracted, and a peripheral light amount correction gain is obtained using this component.

  Note that the peripheral light amount correction gain in FIG. 19B represents the peripheral light amount correction gain corresponding to the image height 1.0 on the CCD 110. Further, the real-time peripheral light amount correction gain indicated by a broken line in FIG. 19B represents a correction gain necessary for setting the original peripheral light amount ratio to 1.0.

  As described above, according to the present embodiment, an average process over a plurality of exposure periods Tk may be performed.

(Other embodiments)
The idea of the above embodiment is not limited to the embodiment described above. Various embodiments may be envisaged. Hereinafter, other embodiments to which the idea of the above embodiments can be applied will be described.

  In Embodiments 1 to 3, the example using the interchangeable lens and the camera body has been described, but a lens-integrated camera may be used.

  The embodiment has been described above as an example of the technique in the present disclosure. For this purpose, the detailed description and the accompanying drawings have been disclosed. Therefore, the constituent elements described in the detailed description and the accompanying drawings may include constituent elements that are not essential for solving the problem. Accordingly, just because those non-essential components are described in the detailed description and the accompanying drawings, those non-essential components should not be immediately recognized as essential.

  The above embodiment is for illustrating the technique in the present disclosure. Therefore, various changes, substitutions, additions and / or omissions may be made to the above-described embodiments within the scope of the claims or the equivalent scope thereof.

  The idea of the present disclosure can be applied to an electronic device (an imaging device such as a digital camera or a camcorder, a mobile phone, a smartphone, or the like) having a camera shake correction function.

1 Digital Camera 100 Camera Body 110 CCD
111 AD converter 112 Timing generator 120 LCD monitor 130 Release button 140 Camera controller 141 DRAM
150 Body mount 160 Power supply 170 Card slot 171 Memory card 181 CCD drive unit 182 Position sensor 183 BIS processing unit 184 Gyro sensor 200 Interchangeable lens 210 Zoom lens 211 Zoom lens drive unit 220 OIS lens 221 OIS drive unit 222 Position sensor 223 OIS processing unit 224 Gyro sensor 230 Focus lens 233 Focus lens driving unit 240 Lens controller 241 DRAM
242 Flash memory 250 Lens mount 305 ADC / LPF
306 HPF
307 Phase compensation unit 308 Integrator 309 LPF
310 Adder 311 PID Control Unit 405 ADC / LPF
406 HPF
407 Phase compensation unit 408 integrator 410 PID control unit 412 selector

Claims (6)

An optical system including a plurality of lenses;
An image sensor that captures a subject image formed by the optical system;
A peripheral light amount correction unit that corrects a peripheral light amount of an image captured by the image sensor;
A shake detection unit for detecting a shake of the imaging device;
A drive control unit that corrects the shake by moving at least one of the lens or the image sensor on a plane perpendicular to an optical axis based on an output signal of the shake detection unit;
The peripheral light amount correction unit extracts a predetermined frequency component of the blur and changes the correction amount of the peripheral light amount according to the predetermined frequency component of the blur;
Imaging device. The peripheral light amount correction unit extracts the predetermined frequency component of the blur from an output signal of the blur detection unit, and changes the correction amount of the peripheral light amount according to the predetermined frequency component of the blur. The imaging apparatus according to 1. The peripheral light amount correction unit extracts the predetermined frequency component of the blur from the drive control signal that moves at least one of the lens or the imaging element in the drive control unit, and converts the predetermined frequency component of the blur into the predetermined frequency component of the blur The imaging apparatus according to claim 1, wherein the correction amount of the peripheral light amount is changed accordingly. The imaging apparatus according to claim 1, wherein the peripheral light amount correction unit has a plurality of correction data corresponding to an image height on the imaging element. An interchangeable lens including the optical system;
A camera body including the image sensor and the peripheral light amount correction unit;
The imaging device according to any one of claims 1 to 4, wherein the interchangeable lens and the camera body are detachable. The optical system includes a correction lens for correcting the shake.
The imaging device according to claim 5.