JP2010081351A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of photographing a still picture with proper exposure even when brightness of an image of a subject is made high by a smear component. <P>SOLUTION: In the imaging apparatus comprising an electronic shutter and a mechanical shutter, it is determined whether or not smear is caused from an actual light quantity level made incident on an imaging device 6 during live view imaging. In a case where it is determined that the smear is caused, after the lapse of a predetermined time from the start of charge storage, rear curtain traveling of the mechanical shutter 5 is performed regardless of charge transfer of the electronic shutter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly, to an imaging apparatus characterized by a technique for preventing smear that occurs during high-luminance imaging.

  As an electronic camera (imaging device) that uses both a so-called electronic shutter (electronic shutter function) and a mechanical shutter (mechanical shutter) for controlling the charge accumulation time of the image sensor, there is one disclosed in Patent Document 1, for example. .

  The electronic camera disclosed in Patent Document 1 uses only an electronic shutter when a preview video is monitored by a liquid crystal monitor or the like provided in the main body before shooting, or when exposure calculation (AE) is performed immediately before shooting. . Further, only when actually shooting (main shooting), the mechanical shutter and the electronic shutter are used together.

  In such an electronic camera, a preview image acquired using an electronic shutter (a moving image monitored in advance) is brighter than an image captured using a mechanical shutter due to leakage of unnecessary signals called smear. Become.

  For this reason, an image monitored before photographing is different from an image actually photographed using a mechanical shutter. For the same reason, when exposure calculation is performed using only an electronic shutter, AE becomes inaccurate due to smear.

  Patent Document 2 proposes an electronic camera having the following configuration and functions.

  That is, the electronic camera has both an electronic shutter that controls the charge accumulation time of the image sensor and a mechanical shutter that can shield / open the incident optical path to the image sensor. When capturing light amount data used for exposure calculation before imaging, the exposure time is controlled using only the electronic shutter with the mechanical shutter open. Further, during the actual photographing, the exposure time is controlled by using both an electronic shutter and a mechanical shutter.

  Then, when the exposure time is controlled only with an electronic shutter, when the smear component ratio included in the light amount data read from the image sensor is the effective smear rate, correction to reduce the effect of smear as follows I do.

In other words, the effective smear rate is used to control the effect of smear when performing exposure control that achieves proper exposure during actual shooting based on the light amount data acquired by controlling the exposure time using only the electronic shutter before imaging. Make corrections to reduce.
JP-A-9-83875 JP-A-11-234573

  In the image pickup apparatus, electrical correction is performed so that the light beam incident through the photographing lens has appropriate luminance with respect to the photographing region. However, when a light beam significantly exceeding a predetermined luminance is incident, the entire photographed image becomes a white blurred image due to leakage of an unnecessary signal called smear.

  In the proposal described in Patent Document 2, although the effect of smear is reduced using the effective smear rate, it is incomplete to perform highly reliable exposure calculation.

  An object of the present invention is to provide an imaging apparatus capable of taking a still image with an appropriate exposure even if an image of a subject has high brightness due to a smear component.

  In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus including an electronic shutter and a mechanical shutter, a live view shooting unit that performs still image shooting in live view, and a live view shooting by the live view shooting unit. Determining means for determining whether smear is generated from the actual light quantity level incident on the image sensor, reset means for resetting the image received by the image sensor, and after reset by the reset means A storage means for storing charge in the imaging device, and when the determination means determines that the smear has occurred, the electronic shutter after a predetermined time has elapsed from the start of the charge storage by the storage means Control means for performing the trailing curtain travel of the mechanical shutter regardless of the charge transfer.

  An image pickup apparatus according to the present invention is an image pickup apparatus including an electronic shutter and a mechanical shutter, and a live view shooting unit that performs moving image shooting in live view, and a still image that performs still image shooting during live view shooting by the live view shooting unit. An imaging unit, a determination unit that determines whether smear has occurred from the actual light amount level incident on the image sensor during still image shooting by the still image shooting unit, and light received by the image sensor A reset unit that resets an image; an accumulation unit that accumulates charges in the image sensor after reset by the reset unit; and when the determination unit determines that the smear is generated, the storage unit After the elapse of a predetermined time from the start of the charge accumulation, the rear shutter of the mechanical shutter travels regardless of the charge transfer of the electronic shutter. Characterized in that it comprises a control means for performing.

  According to the image pickup apparatus of the present invention, still image shooting can be performed with appropriate exposure even if the image of the subject becomes bright due to the smear component.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a mirror-down state of a digital single-lens reflex camera as an imaging apparatus according to an embodiment of the present invention.

  In FIG. 1, the present digital single lens reflex camera includes a camera body 1. A mount 2 for enabling the taking lens 3 to be attached to and detached from the camera body 1 has an interface unit for communicating various signals and supplying driving power.

  The interchangeable photographic lens 3 has a focus lens group, a zoom lens group, and a diaphragm device (not shown) inside. In FIG. 1, each lens group is shown as a single lens for the sake of convenience, but in actuality, it is composed of a complex combination of lens groups with a large number of lenses.

  The main mirror 4 composed of a half mirror can be rotated according to the operating state of the camera. When the subject is observed with the viewfinder, the main mirror 4 is obliquely installed in the photographing optical path, and the light beam from the photographing lens 3 is bent. It leads to the finder optical system described later. Further, when taking an image, the image is retracted from the imaging optical path, and the light beam from the imaging lens 3 is guided to the imaging element 6 described later.

  The mechanical shutter 5 is for controlling the incidence of a light beam from the photographing lens 3 on an image sensor 6 described later, and details of the mechanism will be described later. The image sensor 6 is composed of a CCD, a CMOS, or the like.

  The sub mirror 7 that rotates together with the main mirror 4 is formed of a half mirror. When the main mirror 4 is obliquely installed in the photographing optical path, the light beam that has passed through the main mirror 4 is bent and guided to an AF sensor 8 described later. The light beam is divided into a light beam and a light beam that is transmitted and guided to the image sensor 6.

  The AF sensor 8 includes a secondary imaging lens, an area sensor composed of a plurality of CCDs, and the like, and can detect a focus by a known phase difference method.

  A Fresnel lens (condenser lens) is provided on the entrance surface of the focusing plate 9 arranged on the primary image formation surface of the photographic lens 3, and a subject image (finder image) is formed on the exit surface.

  The finder optical path changing pentaprism 10 corrects the subject image formed on the exit surface of the focus plate 9 into an erect image.

  Here, an optical system including the focus plate 9, the pentaprism 10, and the eyepieces 11 and 12 is referred to as a finder optical system.

  The AE sensor 13 serving as a luminance detecting unit is configured by photodiodes corresponding to the respective areas in the multi-divided shooting screen, and measures the luminance of the subject image formed on the exit surface of the focusing screen 9. The liquid crystal monitor 14 displays captured images and various types of shooting information.

  Here, the configuration of the mechanical shutter 5 will be described.

  FIG. 2 is a schematic front view of the mechanical shutter 5 in FIG.

  In FIG. 2, the shutter base plate 51 has an aperture 51 a that allows the photographing light beam to pass therethrough, and the charge lever 52 charges a drive spring for driving the mechanical shutter 5.

  The front curtain drive lever 53 drives the front curtain of the mechanical shutter 5, and a front curtain drive spring (not shown) is provided on the same rotation axis. The front curtain armature 54 is fixed to the front curtain drive lever 53.

  The front curtain armature shaft 55 fixes the front curtain armature 54 to the front curtain drive lever 53. The front-curtain absorbing rubber 56 exists between the front-curtain armature shaft 55 and the front-curtain drive lever 53 and absorbs an impact.

  The front curtain yoke 57 electromagnetically holds the front curtain armature 54. The front curtain coil 58 generates an electromagnetic force in the front curtain yoke 57. The front curtain bobbin 59 holds the front curtain coil 58.

  The rear curtain drive lever 61 drives the rear curtain of the mechanical shutter 5 and is provided with a rear curtain drive spring (not shown) on the same rotation axis. The rear curtain armature 62 is fixed to the rear curtain drive lever 61.

  The trailing curtain armature shaft 63 fixes the trailing curtain armature 62 to the trailing curtain drive lever 61. The rear curtain absorbing rubber 64 exists between the rear curtain armature shaft 63 and the rear curtain drive lever 61 and absorbs an impact.

  The rear curtain yoke 65 electromagnetically holds the rear curtain armature 62. The rear curtain coil 66 generates an electromagnetic force in the rear curtain yoke 65. The rear curtain bobbin 67 holds the rear curtain coil 66.

  FIG. 3 is a rear view showing the blades of the mechanical shutter 5 of FIG.

  In FIG. 3, the front curtain arm 101 holds the front blade group constituting the front curtain of the mechanical shutter 5, engages with the foot portion 53 a of the front curtain drive lever 53, and interlocks with the front curtain drive lever 53. And rotate (rotate) about the rotation center 101a.

  The front curtain follower arm 102 holds the front blade group and interlocks with the front curtain arm 101 to rotate around the rotation center 102a. The front blades 103, 104, 105, and 106 are held by the front curtain arm 101 and the front curtain driven arm 102 and operate in conjunction with each other, and constitute a front curtain (front blade group) 150.

  The rear curtain arm 111 holds a rear blade group constituting the rear curtain of the mechanical shutter 5. The rear curtain arm 111 engages with a foot portion 61 a of the rear curtain drive lever 61 and interlocks with the rear curtain drive lever 61 to rotate the rotation center 111 a. Rotate around the center.

  The rear curtain follower arm 112 holds the rear blade group and interlocks with the rear curtain arm 111 to rotate around the rotation center 112a. The rear blades 113, 114, 115, 116 are held by the rear curtain arm 111 and the rear curtain driven arm 112 and operate in conjunction with each other, and constitute a rear curtain (rear blade group) 160.

  FIG. 4 is a block diagram showing an electrical configuration of the digital single-lens reflex camera of FIG.

  In FIG. 4, a microcomputer (central processing unit; hereinafter referred to as MPU) 20 controls the entire camera. The memory controller 21 performs various controls of image data. The EEPROM 22 stores settings for performing various controls, adjustment data, and the like.

  A lens control circuit 23 in the photographing lens 3 is connected to the MPU 20 via the mount 2 and performs focus adjustment (focus drive) and aperture drive of the focus lens based on each information described later.

  The focus detection circuit 24 performs accumulation control and readout control of the area sensor of the AF sensor 8 and outputs pixel information of each ranging point to the MPU 20.

  The MPU 20 performs focus detection by a known phase difference detection method from pixel information of each distance measuring point, and sends the detected focus detection information to the lens control circuit 23 to perform focus adjustment of the focus lens. A series of operations from the focus detection to the focus adjustment is referred to as an autofocus (hereinafter referred to as AF) operation.

  The photometry circuit 25 outputs the luminance signal from each area of the AE sensor 13 to the MPU 20. The MPU 20 performs A / D conversion of the luminance signal to obtain photometric information of the subject, and uses this photometric information to calculate and set the photographic exposure. A series of operations from obtaining this photometric information to setting the photographic exposure is called an AE operation.

  The motor drive circuit 26 controls a motor (not shown) that drives the main mirror 4 and a motor (not shown) that charges the mechanical shutter 5.

  The shutter drive circuit 27 performs power supply control to the front curtain coil 58 that holds the front curtain 150 of the mechanical shutter 5 in a charged state and the rear curtain coil 66 that holds the rear curtain 160 in a charged state.

  The DC / DC converter 28 converts the voltage of the power source 29 into a voltage necessary for each circuit. When an electronic dial 32 described later is operated while the mode button 30 is being operated, the shooting mode is changed according to the count, and when the operation is stopped, the shooting mode is determined.

  The release button 31 is turned on by a first stroke (half-press) operation, SW1 which is a switch for starting photometry (AE) and AF operations, and turned on by a second stroke (full-press) operation to perform an exposure operation. A signal of SW2, which is a switch for starting, is output to the MPU 20.

  The electronic dial 32 outputs an ON signal corresponding to a rotation click of the dial to an unillustrated up / down counter in the MPU 20, and the number thereof is counted. Various numerical values and data are selected according to this count.

  When the power button 33 is operated, the power of the camera is turned on / off. The moving image start button 34 switches the internal control of the camera to the moving image system, sets the aperture to the aperture priority mode, and starts recording the moving image.

  A CDS (correlated double sampling) / AGC (automatic gain adjustment) circuit 40 samples and holds an image signal output from the image sensor 6 and performs automatic gain adjustment. The A / D converter 41 converts the analog output of the CDS / AGC circuit 40 into a digital signal.

  A TG (timing generation) circuit 42 supplies a drive signal to the image sensor 6, a sample hold signal to the CDS / AGC circuit 40, and a sample clock signal to the A / D converter 41. Here, the memory controller 21 can receive the image signal output from the image sensor 6 through the CDS / AGC circuit 40 and the A / D converter 41, and perform focus detection of the subject image by a contrast detection method. .

  The TG (timing generation) circuit 42, the memory controller 21, and the MPU 20 have an electronic shutter function.

The SDRAM 43 is a memory for temporarily recording an image or the like digitally converted by the A / D converter 41. The image processing circuit 44 performs Y / C (luminance signal / color difference signal) separation, white balance correction, γ correction, and the like of the image.
The image compression / decompression circuit 45 compresses an image according to a format such as JPEG, and decompresses the compressed image. Here, the memory controller 21 can obtain photometric information of the subject by performing image processing on the image signal output from the image sensor 6 by the image processing circuit 44.

  The D / A converter 46 converts the image into an analog signal in order to display an image recorded on the SDRAM 43 or a medium 48 described later on the liquid crystal monitor 14. An I / F (interface) 47 is connected to a medium 48 for recording and storing images.

  Next, the operation of the camera will be described using a flowchart.

(First embodiment)
FIG. 5 (FIGS. 5a and 5b) is a flowchart showing a procedure of still image shooting processing executed by the digital single-lens reflex camera of FIG.

  This flowchart is executed under the control of the MPU 20. The same applies to the flowchart of FIG. 9 described later.

  In FIG. 5, in step S101, the power button 33 is operated to turn on the camera.

  In step S102, various buttons are operated to perform various camera settings. Here, the mode button 30 is operated to set the shooting mode to shutter speed priority AE, and then the electronic dial 32 is operated to set the shutter speed.

  In step S103, it is determined whether or not the live view is used for shooting. If the live view shooting is ON, the process proceeds to step S121 of the live view shooting routine. If not, the process proceeds to step S104 of the normal shooting routine. move on.

  First, an operation routine when normal shooting is selected will be described.

  In step S104, the release button 31 is pressed halfway to turn on SW1.

  In step S105, a predetermined AF operation is performed.

  In step S106, a predetermined AE operation is performed.

  In step S107, it is determined whether or not the release button 31 is fully pressed and the SW2 is turned on. If it is turned on, the process proceeds to step S108, and if not, the process returns to step S104.

  In step S108, the lens control circuit 23 drives the diaphragm of the photographing lens 3 in accordance with the calculated photographing exposure value.

  In step S109, the shutter drive circuit 27 controls the energization of the front curtain coil 58 and the rear curtain coil 66. When energized, the front curtain yoke 57 and the front curtain armature 54, and the rear curtain yoke 65 and the rear curtain armature 62 are adsorbed to each other.

  In step S110, the motor drive circuit 26 controls energization of the motor, and the charge lever 52 is driven to release the mechanical shutter 5 from the charged state. The state of the mechanical shutter 5 at this time is shown in FIGS.

  In step S111, the motor is controlled by the motor drive circuit 26, and the main mirror 4 and the sub mirror 7 are retracted from the photographing optical path (so-called mirror up).

  In step S112, the memory controller 21 starts reading an image received by the image sensor 6.

  In step S <b> 113, in order to run the front curtain 150 of the mechanical shutter 5, the energization of the front curtain coil 58 is turned off by the shutter drive circuit 27. As a result, the electromagnetic force generated in the front curtain yoke 57 disappears, the electromagnetic attraction between the front curtain yoke 57 and the front curtain armature 54 is eliminated, and the front curtain drive lever 53 is moved by a front curtain drive spring (not shown). Turn right by the biasing force.

  Then, the front curtain 150 linked with the front curtain drive lever 53 travels from the position covering the aperture 51a to the retracted position. FIG. 6 shows the state of the camera at this time, and FIGS. 7 and 8 show the state of the mechanical shutter 5.

  In step S <b> 114, the image sensor 6 starts charge accumulation.

  In step S115, the elapsed time from the front curtain 150 running (the front curtain coil 58 is turned off) is measured, and it is determined whether or not the time corresponding to the set shutter speed has elapsed. If time has elapsed, the process proceeds to step S116.

  In step S116, in order to run the rear curtain 160 of the mechanical shutter 5, the energization of the rear curtain coil 66 is turned off by the shutter drive circuit 27. As a result, the electromagnetic force generated in the rear curtain yoke 65 disappears, the electromagnetic attraction between the rear curtain yoke 65 and the rear curtain armature 62 disappears, and the rear curtain drive lever 61 is driven by a not-shown rear curtain drive spring. Turn right by the biasing force.

  Then, the rear curtain 160 interlocked with the rear curtain drive lever 61 travels from the position retracted from the aperture 51a to the position covered.

  Here, if the shutter speed is not a long time, the time period from step S109 for starting energization to the trailing curtain coil 66 to ending step S115 is several tens of milliseconds to several hundreds of milliseconds. The temperature rise at 66 is small. Therefore, the travel start timing and the travel curve of the rear curtain 160 do not change, and accuracy unevenness and exposure unevenness do not occur.

  In step S117, reading of the image received by the image sensor 6 by the memory controller 21 is terminated, and the image temporarily recorded in the SDRAM 43 is stored and recorded in the medium 48.

  In step S118, the motor is controlled by the motor drive circuit 26 to drive the main mirror 4 and the sub mirror 7 retracted from the photographing optical path to an observation position that reflects and guides the photographing light flux to the viewfinder (so-called mirror down).

  In step S119, the motor drive circuit 26 controls energization of the motor, and the charge lever 52 is driven to charge the mechanical shutter 5.

  In step S120, the power button 33 is operated to determine whether or not the camera is turned off. If not, the process returns to step S102 to prepare for the next shooting, and if it is turned off, a series of shooting operations are performed. finish.

  Next, an operation routine when live view shooting is selected will be described.

  In step S121, the release button 31 is pressed halfway to turn on SW1.

  In step S122, the shutter drive circuit 27 controls energization of the front curtain coil 58 and the rear curtain coil 66. When energized, the front curtain yoke 57 and the front curtain armature 54, and the rear curtain yoke 65 and the rear curtain armature 62 are adsorbed to each other.

  In step S123, the motor drive circuit 26 controls energization of the motor, drives the charge lever 52, and releases the mechanical shutter 5 from the charged state. The state of the mechanical shutter 5 at this time is shown in FIGS.

  In step S124, the motor is controlled by the motor drive circuit 26, and the main mirror 4 and the sub mirror 7 are mirrored up.

  In step S125, in order to run the front curtain 150 of the mechanical shutter 5, the energization of the front curtain coil 58 is turned off by the shutter drive circuit 27. As a result, the electromagnetic force generated in the front curtain yoke 57 disappears, the electromagnetic attraction between the front curtain yoke 57 and the front curtain armature 54 is eliminated, and the front curtain drive lever 53 is moved by a front curtain drive spring (not shown). Turn right by the biasing force.

  Then, the front curtain 150 linked with the front curtain drive lever 53 travels from the position covering the aperture 51a to the retracted position. FIG. 8 shows the state of the camera at this time, and FIGS. 7 and 8 show the state of the mechanical shutter 5.

  In step S126, reading and temporary recording of an image received by the image sensor 6 by the memory controller 21 is started.

  In step S127, the live view is started by continuously displaying the images temporarily recorded in the SDRAM 43 by the memory controller 21 on the liquid crystal monitor 14.

  In step S128, since the AF sensor 8 cannot be used due to the mirror up, a contrast detection AF (so-called TV-AF) operation using the image sensor 6 is performed.

  In step S129, since the AE sensor 13 cannot be used due to mirror-up, an AE (so-called TV-AE) operation using the image sensor 6 is performed.

  In step S130, it is determined whether or not the release button 31 is fully pressed and the SW2 is turned on. If it is turned on, the process proceeds to step S131, and if it is not turned on, the process returns to step S128.

  Steps S121, S127, and S130 function as a live view shooting unit that performs still image shooting in live view.

  In step S131, the actual light amount level incident on the image sensor 6 is measured. When a predetermined amount of light is incident on the image sensor 6, the image sensor 6 is saturated, that is, when a light amount more than necessary is incident on the image sensor 6, an unnecessary signal is generated, causing a phenomenon called smear. Therefore, it is determined whether smear occurs from the amount of light that smear occurs, the reading time of the image sensor 6, and the imaging time of the electronic shutter.

  Step S131 functions as a determination unit that determines whether smear has occurred from the actual light amount level incident on the image sensor 6 during live view shooting by the live view shooting unit.

  If smear does not occur, the process proceeds to step S132. If it is determined that smear occurs, the process proceeds to step S138.

  In step S132, the live view ends.

  In step S133, the lens control circuit 23 drives the aperture of the photographic lens 3 in accordance with the photographic exposure calculated from the TV-AE result.

  In step S134, the image received by the image pickup device 6 by the memory controller 21 is reset, and the light receiving state of the image pickup device 6 is returned to the initial state, that is, the state where nothing is picked up.

  In step S135, charge accumulation in the image sensor 6 is started.

  In step S136, the elapsed time from the reset operation of the image sensor 6 is measured, and it is determined whether or not the time corresponding to the set shutter speed has elapsed. If not, the time is continuously measured. If it passes, it will progress to step S137.

  In step S 137, reading of the image received by the image sensor 6 by the memory controller 21 is finished, and the image temporarily recorded in the SDRAM 43 is stored and recorded in the medium 48. Thereafter, the process proceeds to step S118. That is, if it is determined in step S131 that smear does not occur, the image is stored and recorded without running the shutter rear curtain.

  On the other hand, if it is determined in step S131 that smear will occur, the live view is immediately terminated in step S138 in order to prevent the image sensor 6 from further accumulating the amount of light.

  In step S139, the lens control circuit 23 drives the diaphragm of the photographing lens 3 in accordance with the photographing exposure calculated based on the result of TV-AE.

  In step S140, the image received by the image pickup device 6 by the memory controller 21 is reset, and the light receiving state of the image pickup device 6 is returned to the initial state, that is, the state where nothing is picked up.

  Step S140 functions as a reset unit that resets the image received by the image sensor 6 when the determination unit determines that smear has occurred.

  In step S141, charge accumulation of the image sensor 6 is started.

  Step S141 functions as an accumulation unit that accumulates charges in the image sensor 6 after being reset by the reset unit.

  In step S142, the elapsed time from the reset operation of the image sensor 6 is measured, and it is determined whether or not the time corresponding to the set shutter speed has elapsed. If not, the time is continuously measured. If it passes, it will progress to step S143.

  In step S143, the rear curtain 160 of the mechanical shutter 5 is caused to travel. By performing the rear curtain travel of the mechanical shutter 5 regardless of the rear curtain travel (charge transfer) of the electronic shutter, the light beam is shielded before the smear component is generated, and saturation of the exposure amount of the image sensor 6 is prevented. It is possible to perform charge accumulation that does not include a smear component.

  Step S143 functions as a control unit that performs the rear curtain travel of the mechanical shutter 5 regardless of the charge transfer of the electronic shutter after a lapse of a predetermined time from the start of charge accumulation by the accumulation unit.

  In step S144, reading of the image received by the image sensor 6 by the memory controller 21 is terminated, and the image temporarily recorded in the SDRAM 43 is stored and recorded in the medium 48. Thereafter, the process proceeds to step S118.

  As described above, in the first embodiment, when a high-brightness subject having a smear component is acquired when a still image is shot with an electronic shutter in live view, the mechanism is controlled by the rear curtain control of the electronic shutter. The shutter is driven with priority on the trailing curtain drive to shield the smear component. Thereby, it is possible to provide an imaging apparatus capable of performing still image shooting with appropriate exposure.

(Second Embodiment)
FIG. 9 (FIGS. 9a and 9b) is a flowchart showing the procedure of the moving image shooting process executed by the digital single-lens reflex camera of FIG.

  In FIG. 9, in step S201, the power button 33 is operated to turn on the camera.

  In step S202, various settings and recording for recording a series of moving images are started by turning on the moving image button 34 for starting moving images.

  In the moving image recording system, the subject light flux that has passed through the photographing optical system is directly imaged on the image sensor 6, where the subject image is converted into electrical image data by the image sensor 6 and is equivalent to one frame. Each image data is sequentially read at a predetermined time interval.

  Photometry is performed based on image data corresponding to the subject image read from the image sensor 6, and a shutter speed for obtaining an appropriate exposure state is determined according to the luminance of the subject. Then, the electronic shutter is turned on for a time corresponding to the shutter speed, and the charge accumulation time in the image sensor 6 is adjusted.

  The image data photoelectrically converted by the image sensor 6 is sequentially recorded frame by frame on a recording medium (not shown) as a moving image. Such a series of settings is executed in steps S203 and S204.

  In step S203, various setting buttons are operated to set the shooting category of the camera to the moving image setting.

  In step S204, the aperture setting is automatically switched to the aperture priority mode in order to perform moving image shooting.

  In step S205, since the moving image shooting mode is set, the mode is automatically switched to the live view mode, and the subject image is displayed as a moving image on the liquid crystal monitor 14 on the back of the camera body 1.

  Steps S202 to S205 function as live view shooting means for performing live view shooting with a moving image.

  In step S206, in order to perform still image shooting during movie shooting, the release button 31 is pressed halfway to turn on SW1.

  In step S207, the shutter drive circuit 27 controls the energization of the front curtain coil 58 and the rear curtain coil 66. When energized, the front curtain yoke 57 and the front curtain armature 54, and the rear curtain yoke 65 and the rear curtain armature 62 are adsorbed to each other.

  In step S208, the motor drive circuit 26 controls energization of the motor, drives the charge lever 52, and releases the mechanical shutter 5 from the charged state. The state of the mechanical shutter 5 at this time is shown in FIGS.

  In step S209, the motor is controlled by the motor drive circuit 26, and the main mirror 4 and the sub mirror 7 are mirrored up.

  In step S210, in order to run the front curtain 150 of the mechanical shutter 5, the energization of the front curtain coil 58 is turned off by the shutter drive circuit 27. As a result, the electromagnetic force generated in the front curtain yoke 57 disappears, the electromagnetic attraction between the front curtain yoke 57 and the front curtain armature 54 is eliminated, and the front curtain drive lever 53 is moved by a front curtain drive spring (not shown). Turn right by the biasing force.

  Then, the front curtain 150 linked with the front curtain drive lever 53 travels from the position covering the aperture 51a to the retracted position. FIG. 6 shows the state of the camera at this time, and FIGS. 7 and 8 show the state of the mechanical shutter 5.

  In step S <b> 211, the memory controller 21 reads an image received by the image sensor 6 and starts temporary recording in the SDRAM 43.

  In step S212, the live view is started by continuously displaying the images temporarily recorded in the SDRAM 43 by the memory controller 21 on the liquid crystal monitor 14.

  In step S213, since the AF sensor 8 cannot be used due to mirror up, a contrast detection AF (so-called TV-AF) operation using the image sensor 6 is performed.

  In step S214, since the AE sensor 13 cannot be used due to mirror-up, an AE (so-called TV-AE) operation using the image sensor 6 is performed.

  In step S215, it is determined whether or not the release button 31 is fully pressed and the SW2 is turned on. If it is turned on, the process proceeds to step S216, and if it is not turned on, the process returns to step S213.

  Steps S206 and S215 function as a still image capturing unit that performs still image capturing during live view shooting by the live view capturing unit.

In step S216, the actual light amount level incident on the image sensor 6 is measured. When a predetermined amount of light is incident on the image sensor 6, the image sensor 6 is saturated, that is, when a light amount more than necessary is incident on the image sensor 6, an unnecessary signal is generated, causing a phenomenon called smear.
Therefore, it is determined whether smear occurs from the amount of light that smear occurs, the reading time of the image sensor 6, and the imaging time of the electronic shutter.

  In step S216, during still image shooting by the still image shooting means, it functions as a determination means for determining whether smear is generated from the actual light amount level incident on the image sensor.

  If smear does not occur, the process proceeds to step S217. If it is determined that smear occurs, the process proceeds to step S228.

  In step S217, the live view ends.

  In step S218, the lens control circuit 23 drives the aperture of the photographic lens 3 according to the photographic exposure calculated based on the result of TV-AE.

  In step S219, the image received by the image pickup device 6 by the memory controller 21 is reset, and the light receiving state of the image pickup device 6 is returned to the initial state, that is, the state where nothing is picked up.

  In step S220, the temporary recording of the image read in step S211 to the SDRAM 43 is started.

  In step S221, the elapsed time from the reset operation of the image sensor 6 is measured, it is determined whether or not the time corresponding to the set shutter speed has elapsed, and if it has not elapsed, the time measurement is continued. If it passes, it will progress to step S222.

  In step S222, reading of the image received by the image sensor 6 by the memory controller 21 is terminated, and the image temporarily recorded in the SDRAM 43 is stored and recorded in the medium 48. Thereafter, the process proceeds to step S223. That is, if it is determined in step S216 that smear does not occur, the image is stored and recorded without running the shutter rear curtain.

  If it is determined in step S216 that smear has occurred, the live view is immediately terminated in step S228 in order to prevent the image sensor 6 from further accumulating the amount of light. In step S229, the lens control circuit 23 drives the diaphragm of the photographing lens 3 in accordance with the photographing exposure calculated based on the result of TV-AE.

  In step S230, the image received by the image pickup device 6 by the memory controller 21 is reset, and the light receiving state of the image pickup device 6 is returned to the initial state, that is, the state where nothing is picked up.

  In step S231, charge accumulation in the image sensor 6 is started.

  In step S232, the elapsed time from the reset operation of the image sensor 6 is measured, it is determined whether the time corresponding to the set shutter speed has elapsed, and if not, the time is continuously measured. If it passes, it will progress to step S233.

  In step S233, the rear curtain 160 of the mechanical shutter 5 is caused to travel. In the mechanical shutter rear curtain travel control, the energization of the rear curtain coil 66 is turned off by the shutter drive circuit 27. As a result, the electromagnetic force generated in the rear curtain yoke 65 disappears, the electromagnetic attraction between the rear curtain yoke 65 and the rear curtain armature 62 disappears, and the rear curtain drive lever 61 is driven by a not-shown rear curtain drive spring. Turn right by the biasing force.

  Then, the rear curtain 160 interlocked with the rear curtain drive lever 61 travels from the position retracted from the aperture 51a to the position covered.

  In step S234, reading of the image received by the image sensor 6 by the memory controller 21 is terminated, and the image temporarily recorded in the SDRAM 43 is stored and recorded in the medium 48. Thereafter, the process proceeds to step S223.

  In step S223, reading of the image received by the image sensor 6 by the memory controller 21 is terminated, and the image temporarily recorded in the SDRAM 43 is stored and recorded in the medium 48.

  In step S224, the motor is controlled by the motor drive circuit 26 to drive the main mirror 4 and the sub mirror 7 retracted from the photographing optical path to an observation position that reflects and guides the photographing light flux to the viewfinder (so-called mirror down).

  In step S225, the motor drive circuit 26 controls energization of the motor, and the charge lever 52 is driven to charge the mechanical shutter 5.

  In step S226, the moving image button 34 is turned OFF to stop or interrupt the moving image shooting.

  In step S227, it is determined whether or not the power of the camera is turned off by operating the power button 33. If it is not turned off, the process returns to step S202 to prepare for the next shooting. Exit.

  FIG. 10 shows a shutter curtain travel curve.

  As described above, in the second embodiment, when a high-luminance subject having a smear component is acquired when a still image is captured while a moving image is being captured in live view, after the electronic shutter The mechanical shutter rear curtain drive is driven with priority over curtain control to shield the smear component. Thereby, it is possible to provide an imaging apparatus capable of performing still image shooting with appropriate exposure.

It is a schematic block diagram of the mirror down state of the digital single-lens reflex camera as an imaging device concerning an embodiment of the invention. It is a schematic front view of the mechanical shutter 5 in FIG. It is a rear view which shows the blade | wing of the mechanical shutter 5 of FIG. It is a block diagram which shows the electrical structure of the digital single-lens reflex camera of FIG. 5 is a flowchart illustrating a procedure of still image shooting processing executed by the digital single-lens reflex camera of FIG. 4. 5 is a flowchart illustrating a procedure of still image shooting processing executed by the digital single-lens reflex camera of FIG. 4. It is a schematic block diagram of the mirror up state of the digital single-lens reflex camera as an imaging device concerning an embodiment of the invention. It is a schematic front view of the mechanical shutter 5 in FIG. It is a rear view which shows the blade | wing of the mechanical shutter 5 of FIG. 5 is a flowchart illustrating a procedure of a moving image shooting process executed by the digital single-lens reflex camera of FIG. 4. 5 is a flowchart illustrating a procedure of a moving image shooting process executed by the digital single-lens reflex camera of FIG. 4. It is a figure which shows a shutter curtain travel curve.

Explanation of symbols

5 Mechanical shutter 6 Image sensor 14 Liquid crystal monitor 20 MPU
21 Memory controller 31 Release button 42 TG circuit 150 Front curtain 160 Rear curtain

Claims (4)

In an imaging device comprising an electronic shutter and a mechanical shutter,
Live view shooting means for shooting still images in live view;
Determining means for determining whether smear has occurred from the actual light quantity level incident on the image sensor during live view shooting by the live view shooting means;
Resetting means for resetting an image received by the image sensor;
Accumulation means for accumulating charges in the image sensor after reset by the reset means;
If the determination means determines that the smear has occurred, after the elapse of a predetermined time from the start of the charge accumulation by the accumulation means, the trailing shutter travel of the mechanical shutter regardless of the charge transfer of the electronic shutter. Control means for performing
An imaging apparatus comprising:   2. The imaging according to claim 1, wherein, when the determination unit determines that the smear has not occurred, the control unit performs control so as not to perform a rear curtain travel of the mechanical shutter. apparatus. In an imaging device comprising an electronic shutter and a mechanical shutter,
Live view shooting means for shooting videos in live view;
Still image shooting means for shooting still images during live view shooting by the live view shooting means;
Determining means for determining whether smear is generated from the actual light amount level incident on the image sensor during still image shooting by the still image shooting means;
Resetting means for resetting an image received by the image sensor;
Accumulation means for accumulating charges in the image sensor after reset by the reset means;
If the determination means determines that the smear has occurred, after the elapse of a predetermined time from the start of the charge accumulation by the accumulation means, the trailing shutter travel of the mechanical shutter regardless of the charge transfer of the electronic shutter. Control means for performing
An imaging apparatus comprising:   4. The imaging according to claim 3, wherein, when the determination unit determines that the smear has not occurred, the control unit performs control so as not to perform a rear curtain travel of the mechanical shutter. 5. apparatus.

Images