JP2009302778A - Image capturing apparatus and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a sudden luminance change in an image to be displayed in an EVF (electronic view finder) when driving a diaphragm during using the EVF. <P>SOLUTION: This image capturing apparatus having an electronic view finder function includes: an image sensor (14) for converting an optical image of an object which is made incident through the diaphragm (312) into an electrical signal to store the electrical signal; a stopping switch (74) for entering instructions to drive the diaphragm; and a system control circuit for controlling so as to drive the diaphragm during storing electrical signals of frame images other than a frame image to be used for exposure control in the image sensor when the stopping switch instructs to drive the diaphragm during using the electronic view finder function. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly to an imaging apparatus having an electronic viewfinder function and a control method thereof.

  2. Description of the Related Art Conventionally, an electronic still camera having a moving image monitor function, that is, an electronic still camera provided with a monitor that can be used for an electronic viewfinder (hereinafter referred to as EVF) having a function of outputting a pre-photographed image on an image display device in real time. Are known.

  In such an electronic still camera, a video signal obtained by a CMOS sensor or a CCD sensor is subjected to predetermined processing by an imaging circuit or the like, and is then output as a moving image by a monitor.

  The frame rate for moving image output is 1/30 for the NTSC standard and 1/25 for the PAL standard (1/60 and 1/50 for the interlace method, respectively) as the TV output standard.

  During EVF display, in order to make it easier to observe the subject to be photographed, an image is acquired with an aperture value and exposure time that are different from the aperture and exposure time used when actually taking the image. In many cases, the aperture is driven to an aperture value used for shooting. However, since the focus range (depth of field) of the subject changes depending on the aperture, in order to confirm the depth of field and the degree of blur of the background, an instruction to actually drive the aperture is displayed at any time during EVF display. There are some that have a narrowing switch. In this way, by actually reducing the aperture during EVF display, it is possible to confirm by EVF display what depth of field the image obtained by shooting will be and what kind of blur.

  Japanese Patent Application Laid-Open No. H10-228561 discloses that when the aperture switch is operated during EVF use, actual aperture control is performed so that the Av value set in the camera is obtained. However, since the amount of incident light changes when the stop is narrowed, the luminance of the subject image displayed on the EVF changes. Therefore, in Patent Document 1, the digital gain is changed or the accumulation time and the frame rate are automatically switched according to the photometric result on the imaging surface so that the image displayed on the EVF has an appropriate brightness. is suggesting.

JP 2006-270426 A

  The aperture control during EVF display as described above is performed in conjunction with the aperture switch, but is not synchronized with the photometry timing or the image accumulation timing on the imaging surface, so a sudden change in luminance of the incident light amount immediately after the aperture control. The followability of the EVF display control with respect to was poor.

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress an abrupt luminance change of an EVF displayed image even when the diaphragm is driven when the EVF is used.

  In order to achieve the above object, an image pickup apparatus of the present invention having an electronic viewfinder function includes an image pickup element that converts an optical image of a subject incident through a diaphragm into an electric signal and stores the image, and an instruction for driving the diaphragm. When the electronic viewfinder function is used, when the instruction to drive the diaphragm is given by the instruction unit, the electrical signal of the frame image excluding the frame image used for exposure control is captured. Control means for controlling the diaphragm to be driven during accumulation in the element.

  In addition, the control method of the present invention of an imaging apparatus having an electronic viewfinder function that includes an imaging element that converts an optical image of a subject incident through the diaphragm into an electrical signal and stores the electrical signal, receives an instruction to drive the diaphragm And when the electronic viewfinder function is used, when the instruction to drive the diaphragm is received, the diaphragm is driven while the electrical signal of the frame image excluding the frame image used for exposure control is being accumulated in the imaging device. The process of carrying out.

  ADVANTAGE OF THE INVENTION According to this invention, when driving a diaphragm at the time of EVF use, the sudden brightness change of the image displayed by EVF can be suppressed.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

Configuration of Imaging System FIG. 1 is a block diagram showing a configuration of an imaging apparatus having an image processing function in the embodiment of the present invention.

  As shown in FIG. 1, the imaging apparatus according to the present embodiment mainly includes a camera body 100 and an interchangeable lens type lens unit 300.

  In the lens unit 300, 310 is an imaging lens composed of a plurality of lenses, 312 is a diaphragm, and 306 is a lens mount that mechanically couples the lens unit 300 to the camera body 100. The lens mount 306 includes various functions for electrically connecting the lens unit 300 to the camera body 100. Reference numeral 320 denotes an interface for connecting the lens unit 300 to the camera body 100 in the lens mount 306, and 322 denotes a connector for electrically connecting the lens unit 300 to the camera body 100.

  The connector 322 transmits a control signal, a status signal, a data signal, and the like between the camera body 100 and the lens unit 300, and also has a function of supplying or supplying a current of various voltages. The connector 322 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  A diaphragm control unit 340 controls the diaphragm 312. Based on the photometric information from the photometric control unit 46 or the calculation result obtained by calculating the image data picked up by the image sensor 14 by the image processing circuit 20, it cooperates with the shutter control unit 40 that controls the shutter 12 of the camera body 100 described later. Meanwhile, the diaphragm 312 is controlled. A focus control unit 342 controls the focusing of the imaging lens 310.

  A lens system control circuit 350 controls the entire lens unit 300. The lens system control circuit 350 includes a memory for storing operation constants, variables, programs, and the like. Further, a non-volatile memory that holds identification information such as a number unique to the lens unit 300, management information, function information such as an open aperture value, a minimum aperture value, and a focal length, and current and past setting values is also provided.

  Next, the configuration of the camera body 100 will be described.

  Reference numeral 106 denotes a lens mount that mechanically couples the camera body 100 and the lens unit 300, and reference numerals 130 and 132 denote mirrors, which guide light rays incident on the imaging lens 310 to the optical viewfinder 104 by a single-lens reflex system. The mirror 130 may be either a quick return mirror or a half mirror. Reference numeral 12 denotes a shutter having an aperture function, and reference numeral 14 denotes an image sensor that converts an optical image of a subject into an electric signal. The light beam incident on the imaging lens 310 is guided by the single-lens reflex system through the aperture 312 that is a light amount limiting unit, the lens mounts 306 and 106, the mirror 130, and the shutter 12, and forms an optical image on the imaging element 14.

  Reference numeral 16 denotes an A / D converter that converts an analog signal output from the image sensor 14 into a digital signal. Reference numeral 18 denotes a timing generation circuit that supplies a clock signal and a control signal to the image pickup device 14, the A / D converter 16, the D / A converter 26, and the system control circuit 50. The memory control circuit 22 and the system control circuit 50 Be controlled.

  An image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22. Further, the image processing circuit 20 performs a predetermined calculation process using the image data output from the A / D converter 16. Then, based on the obtained calculation result, the system control circuit 50 controls the shutter control unit 40 and the focus adjustment unit 42, TTL (through the lens) type autofocus (AF) processing, automatic exposure ( AE) processing and flash pre-emission (EF) processing are performed. Further, the image processing circuit 20 performs predetermined arithmetic processing using the image data output from the A / D converter 16, and also performs TTL auto white balance (AWB) processing based on the obtained arithmetic result. ing.

  In the example shown in FIG. 1 in the present embodiment, the focus adjustment unit 42 and the photometry control unit 46 are provided exclusively. Accordingly, when the optical viewfinder is used, AF processing, AE processing, and EF processing are performed using the focus adjustment unit 42 and the photometry control unit 46, and when EVF is used, AF processing and AE using the image processing circuit 20 are performed. A configuration in which each of the processing and the EF processing is automatically performed may be employed. In any case, the aperture value and shutter time suitable for shooting can be acquired by the AE process. When the imaging system has an aperture priority mode or a shutter speed priority mode, the user sets a desired aperture or shutter time in advance, and the shutter speed suitable for the set aperture or shutter time is set by AE processing. Ask for time or aperture.

  A memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32.

  Image data output from the A / D converter 16 is written into the image display memory 24 or the memory 30 via the image processing circuit 20, the memory control circuit 22, or only through the memory control circuit 22.

  Reference numeral 24 denotes an image display memory, 26 denotes a D / A converter, and 28 denotes an image display unit made up of a TFT type LCD or the like. Display image data written in the image display memory 24 is stored in the D / A converter 26. Via the image display unit 28. The EVF function can be realized by sequentially displaying the captured image data using the image display unit 28. Further, the image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50, and when the display is turned off, the power consumption of the camera body 100 can be significantly reduced. it can.

  Reference numeral 30 denotes a memory for storing captured still images and moving images, and has a storage capacity sufficient to store a predetermined number of still images and a moving image for a predetermined time. This makes it possible to write a large amount of images to the memory 30 at high speed even in continuous shooting or panoramic shooting in which a plurality of still images are continuously shot. The memory 30 can also be used as a work area for the system control circuit 50.

  A compression / decompression circuit 32 compresses / decompresses image data using a known compression method such as adaptive discrete cosine transform (ADCT). The compression / decompression circuit 32 reads an image stored in the memory 30, performs a compression process or an expansion process, and writes the processed data to the memory 30 again.

  Reference numeral 40 denotes a shutter control unit that controls the shutter 12 in cooperation with an aperture control unit 340 that controls the aperture 312 based on photometric information from the photometry control unit 46. A focus adjusting unit 42 performs AF (autofocus) processing. A light beam incident on the imaging lens 310 in the lens unit 300 is incident as a single-lens reflex system through a diaphragm 312, lens mounts 306 and 106, a mirror 130, and a focus adjustment submirror (not shown), thereby forming an optical image. The in-focus state of the imaged image is measured.

  A photometry control unit 46 performs AE processing. A light beam incident on the imaging lens 310 in the lens unit 300 is incident on the single lens reflex system through the diaphragm 312, the lens mounts 306 and 106, the mirror 130, and the photometric sub mirror (not shown), thereby forming an optical image. Measure the exposed state of the captured image. A flash 48 has an AF auxiliary light projecting function and a flash light control function. The photometry control unit 46 also has an EF (flash dimming) processing function in cooperation with the flash 48.

  As described above, the EVF performs automatic exposure control and AF control based on the calculation result calculated by the image processing circuit 20 using the image data from the A / D converter 16. In this case, the system control circuit 50 can perform automatic exposure control and AF control using the video TTL system for the shutter control unit 40, the aperture control unit 340, and the focus control unit 342.

  Further, the AF control may be performed using the measurement result by the focus adjustment unit 42 and the calculation result obtained by calculating the image data from the A / D converter 16 by the image processing circuit 20. Furthermore, exposure control may be performed using the measurement result obtained by the photometry control unit 46 and the calculation result obtained by calculating the image data from the A / D converter 16 by the image processing circuit 20.

  Reference numeral 50 denotes a system control circuit that controls the entire camera body 100, and incorporates a known CPU. A memory 52 stores constants, variables, programs, and the like for operating the system control circuit 50.

  Reference numeral 54 denotes a notification unit for notifying the outside of an operation state, a message, and the like using characters, images, sounds, and the like in accordance with execution of a program in the system control circuit 50. As the notification unit 54, for example, a display unit that performs visual display using an LCD, an LED, or the like, or a sound generation element that performs voice notification, etc., is used, and the notification unit 54 is configured by a combination of one or more of these. In particular, in the case of the display unit, it is installed at one or a plurality of locations near the operation unit 70 of the camera body 100 that are easy to see. In addition, the notification unit 54 has a part of its functions installed in the optical viewfinder 104.

  Among the display contents of the notification unit 54, the following are displayed on the LCD or the like. First, there are displays relating to shooting modes such as single-shot / continuous-shot shooting display, self-timer display, and the like. In addition, there are displays relating to recording such as compression rate display, recording pixel number display, recording number display, and remaining image number display. In addition, there are displays relating to shooting conditions such as shutter speed display, aperture value display, exposure correction display, flash display, and red-eye reduction display. In addition, there are a macro shooting display, a buzzer setting display, a clock battery remaining amount display, a battery remaining amount display, an error display, an information display by a multi-digit number, and an attachment / detachment state display of the recording media 200 and 210. Furthermore, the attachment / detachment state display of the lens unit 300, the communication I / F operation display, the date / time display, the display indicating the connection state with the external computer, and the like are also performed.

  In addition, among the display contents of the notification unit 54, examples of what is displayed in the optical finder 104 include the following. In-focus display, photographing preparation completion display, camera shake warning display, flash charge display, flash charge completion display, shutter speed display, aperture value display, exposure correction display, recording medium writing operation display, and the like.

  Further, among the display contents of the notification unit 54, examples of what is displayed by an LED or the like include the following. In-focus display, shooting preparation completion display, camera shake warning display, flash charge display, flash charge completion display, recording medium writing operation display, macro shooting setting notification display, secondary battery charge display, and the like.

  Further, among the display contents of the notification unit 54, what is displayed on the lamp or the like includes, for example, a self-timer notification lamp. This self-timer notification lamp may be shared with AF auxiliary light.

  Reference numeral 56 denotes an electrically erasable / recordable non-volatile memory in which programs and the like to be described later are stored. For example, an EEPROM or the like is used.

  Reference numerals 60, 62, 64, 66, 70, and 74 denote operation means for inputting various operation instructions of the system control circuit 50, which may be a single unit such as a switch, dial, touch panel, pointing by line-of-sight detection, or a voice recognition device. Consists of multiple combinations.

  Here, a specific description of these operating means will be given.

  Reference numeral 60 denotes a mode dial switch which can be used to switch and set each function shooting mode such as an automatic shooting mode, a program shooting mode, a shutter speed priority shooting mode, an aperture priority shooting mode, a manual shooting mode, and a depth of focus priority (depth) shooting mode. it can. In addition, each function shooting mode such as portrait shooting mode, landscape shooting mode, close-up shooting mode, sports shooting mode, night view shooting mode, panoramic shooting mode, and the like can be switched and set.

  Reference numeral 62 denotes a shutter switch SW1, which is turned on while a shutter button (not shown) is being operated (for example, half-pressed), and instructs to start operations such as AF processing, AE processing, AWB processing, and EF processing.

  A shutter switch SW2 64 is turned on when a shutter button (not shown) is completed (for example, fully pressed), and instructs the start of a series of processes including exposure processing, development processing, and recording processing. First, in the exposure process, the signal read from the image sensor 14 is written into the memory 30 via the A / D converter 16 and the memory control circuit 22, and further the calculation in the image processing circuit 20 and the memory control circuit 22 is performed. Development processing using is performed. Further, in the recording process, image data is read from the memory 30, compressed by the compression / decompression circuit 32, and written to the recording medium 200 or 210.

  Reference numeral 66 denotes a playback switch, which instructs to start a playback operation for reading an image shot in the shooting mode state from the memory 30 or the recording medium 200 or 210 and displaying it on the image display unit 28. Reference numeral 68 denotes a viewfinder changeover switch, which can be set to switch between the optical viewfinder and the EVF.

  An operation unit 70 includes various buttons and a touch panel. As an example, there are a menu button, a set button, a macro button, and a multi-screen playback page break button. Also, a shutter setting button for setting the shutter speed when the shutter speed priority shooting mode is set with the mode dial 60, and an aperture value when the aperture priority shooting mode is set with the mode dial 60. There is an aperture value setting button. Also included are a flash setting button, a single shooting / continuous shooting / self-timer switching button, a menu movement + (plus) button, and a menu movement− (minus) button. Further, a playback image movement + (plus) button, a playback image movement-(minus) button, a shooting image quality selection button, an exposure correction button, a date / time setting button, and the like are also included. The functions of the plus button and the minus button can be selected more easily with numerical values and functions by providing a rotary dial switch. Also included is an ISO sensitivity setting button that can set the ISO sensitivity by changing the gain setting in the image sensor 14 or the image processing circuit 20.

  In addition, a selection / switch button that sets selection and switching of various functions when performing shooting and playback in panorama mode, etc., and determination and execution of various functions when performing shooting and playback in panorama mode and the like There is a decision / execution button. In addition, there is an image display ON / OFF switch for setting ON / OFF of the image display unit 28, and a quick review ON / OFF switch for setting a quick review function for automatically reproducing image data taken immediately after shooting. Further, there is a compression mode switch that is a switch for selecting a compression rate of JPEG compression, or for selecting a CCD RAW mode in which a signal from an image sensor is directly digitized and recorded on a recording medium. In addition, there are a playback switch that can set each function mode such as a playback mode, a multi-screen playback / erase mode, and a PC connection mode, and an AF mode setting switch that can set a one-shot AF mode and a servo AF mode. In the one-shot AF mode, an autofocus operation is started when the shutter switch SW1 (62) is pressed, and once focused, the focused state is maintained. In the servo AF mode, the autofocus operation is continued while the shutter switch SW1 (62) is being pressed.

  Reference numeral 72 denotes a power switch, which can switch and set the power-on and power-off modes of the camera body 100. Also, the power on and power off settings of various accessory devices such as the lens unit 300, the external flash, and the recording media 200 and 210 connected to the camera body 100 can be switched.

  Reference numeral 74 denotes an aperture switch. When this switch is operated, the aperture 312 of the lens unit 300 is decreased so that the aperture value displayed on the notification unit 54 is obtained.

  A power control unit 80 includes a battery detection circuit, a DC-DC converter, a switch circuit that switches a block to be energized, and the like. The power supply control unit 80 detects the presence / absence of a battery, the type of battery, and the remaining battery level, controls the DC-DC converter based on the detection result and an instruction from the system control circuit 50, and requires a necessary voltage. It is supplied to each part including the recording medium for a period.

  Reference numerals 82 and 84 denote connectors, 86 denotes a primary battery such as an alkaline battery or lithium battery, a secondary battery such as a NiCd battery, NiMH battery, Li-ion battery, or Li polymer battery, an AC adapter, or the like.

  Reference numeral 90 denotes an interface with a recording medium such as a memory card or hard disk, and reference numeral 92 denotes a connector for connecting to a recording medium such as a memory card or hard disk. A recording medium attachment / detachment detection circuit 98 detects whether or not the recording medium 200 is attached to the connector 92.

  In the present embodiment, the description has been made assuming that one interface and connector for attaching the recording medium are provided. However, the interface and connector for attaching the recording medium may have a plurality of systems. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.

  As the interface and the connector, it is possible to configure using interfaces that comply with various storage medium standards. For example, a PCMCIA (Personal Computer Memory Card International Association) card, a CF (Compact Flash (registered trademark)) card, an SD card, or the like. When the interface 90 and the connector 92 are configured using a standard conforming to a PCMCIA card, a CF (registered trademark) card, or the like, various communication cards can be connected. Communication cards include LAN cards, modem cards, USB (Universal Serial Bus) cards, and IEEE (Institute of Electrical and Electronic Engineers) 1394 cards. In addition, there are P1284 card, SCSI (Small Computer System Interface) card, PHS, and the like. By connecting these various communication cards, image data and management information attached to the image data can be transferred to and from other computers and peripheral devices such as a printer.

  Reference numeral 104 denotes an optical viewfinder, which guides a light beam incident on the imaging lens 310 through an aperture 312, lens mounts 306 and 106, and mirrors 130 and 132 by a single-lens reflex method, and forms an optical image for display. it can. Thereby, it is possible to perform photographing using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28. Further, in the optical viewfinder 104, some functions of the notification unit 54, for example, in-focus state, camera shake warning, flash charging, shutter speed, aperture value, exposure correction, and the like are displayed.

  Reference numeral 120 denotes an interface for connecting the camera body 100 to the lens unit 300 in the lens mount 106.

  A connector 122 electrically connects the camera body 100 to the lens unit 300. Whether or not the lens unit 300 is attached to the lens mount 106 and / or the connector 122 is detected by a lens attachment / detachment detection unit (not shown). The connector 122 transmits a control signal, a status signal, a data signal, and the like between the camera body 100 and the lens unit 300, and has a function of supplying currents of various voltages. Further, the connector 122 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  Reference numeral 200 denotes a recording medium such as a memory card or a hard disk. The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, and the like, an interface 204 with the camera body 100, and a connector 206 that connects to the camera body 100.

  As the recording medium 200, a memory card such as a PCMCIA card or compact flash (registered trademark), a hard disk, or the like can be used. Of course, it may be constituted by a micro DAT, a magneto-optical disk, an optical disk such as CD-R or CD-WR, a phase change optical disk such as DVD, or the like.

  The imaging system in the present embodiment has been described as an interchangeable lens single-lens reflex digital camera. However, if the EVF function is provided, a digital camera in which a lens and a lens barrel are integrated with the main body. It may be.

EVF Display Operation FIGS. 2 and 3 are flowcharts for explaining the image display operation in the EVF according to the embodiment of the present invention.

  As described above, display on the image display unit 28 is performed by outputting image data of an image formed on the image sensor 14 to the image display unit 28 at a frame rate for outputting a moving image.

  In FIG. 2, when EVF display is started, first, an aperture fixing flag is initialized (step S101). This fixed aperture flag is a flag indicating that the aperture 312 has been narrowed down to the aperture value displayed on the notification unit 54 (that is, the aperture value obtained by the AE process). Next, a counter that prohibits display update (display update prohibition counter) is cleared to 0 (step S102). As will be described later, the display update prohibition counter represents the number of times that EVF display display update is prohibited. Next, the mirror is raised (step S103), subject light is incident on the shutter 12, the shutter 12 is opened to expose the image sensor 14 (step S104), and charge accumulation of the image sensor 14 is started (step S105). ).

  In step S106, a timing pulse (hereinafter referred to as VD) for reading out the electric charge accumulated in the image sensor 14 output from the timing generation circuit 18 is checked to determine the display update timing. Here, it is examined whether VD has changed from High to Low. The VD cycle is the same as the frame rate at which the image display unit 28 outputs a moving image. At this VD output timing, charges are read from the image sensor 14, display image data is created, and stored in the image display memory 24.

  In step S107, a display update prohibition counter is checked. If the display update prohibition counter is 0, that is, if display update is permitted, the display image of the image display unit 28 is updated using the display image data stored in the image display memory 24 in step S108.

  If the counter is not 0, that is, if updating of the display image is prohibited, the display update prohibition counter is decremented by 1 in step S109.

  Next, it is confirmed whether or not the narrowing switch 74 is operated (step S110 in FIG. 3). If the aperture switch 74 is OFF, the aperture fixing flag is cleared (step S111), the process proceeds to step S123, and it is checked whether or not to continue the EVF display.

  On the other hand, if the aperture switch 74 is operated, the aperture fixed flag is checked, and it is confirmed whether the aperture 312 has already been decreased to the aperture value (the aperture value obtained by the AE process) displayed on the notification unit 54. (Step S112). If the aperture fixing flag is ON, the aperture 312 is not driven any more, so the process proceeds to step S123, and it is checked whether or not to continue the EVF display.

  On the other hand, if the aperture fixing flag is OFF, that is, if the aperture 312 has not been reduced to the aperture value displayed on the notification unit 54, it is checked whether or not VD has changed from High to Low (step S113). ), If changed, the process proceeds to step S114. Normally, during the charge reading of a certain frame image from the image sensor 14, charge accumulation for the next frame image is performed. In this embodiment, an image obtained every other frame is used for photometric calculation. In step S114, it is checked whether the image of this frame is an image used for photometric calculation. If the image is a frame image used for photometry calculation, the aperture drive flag is set to 0 in step S115.

  On the other hand, if the image is not a frame image used for photometric calculation (NO in step S114), the diaphragm drive flag is confirmed (step S116). If the diaphragm drive flag is 1, the process proceeds to step S123. The process proceeds to step S117. In step S117, the aperture 312 is driven by a predetermined amount or for a predetermined time, and in step S118, the aperture drive flag is set to 1. Here, by setting the aperture drive flag to 1, the aperture drive is performed only once after the image of the frame used for the photometric calculation is acquired until the next frame image used for the photometric calculation is acquired. Will be done.

  In step S119, it is checked whether or not the aperture 312 has been driven to the aperture value displayed on the notification unit 54. When the diaphragm 312 is driven to the diaphragm value displayed on the notification unit 54, the diaphragm fixing flag is set in step S120, the diaphragm driving flag is set to 0 in step S121, and the process proceeds to step S122. On the other hand, if the aperture value displayed on the notification unit 54 has not been reached, the process proceeds to step S122 without setting the aperture fixed flag.

  Here, when the diaphragm 312 is driven in step S117, the brightness of the display image deviates from the converged state due to the diaphragm driving for a predetermined frame, and thus an unstable state continues. Accordingly, in order to prevent the frame image from being displayed on the image display unit 28 for the frame whose luminance becomes unstable, the display update prohibition counter is set with the number of frames for which display image update is prohibited (step S122). ). In step S107 described above, the value of the display update prohibition counter set in step S122 is checked. When the value is other than 0, the image displayed on the image display unit 28 is not updated. Then, it progresses to step S123 and it is checked whether EVF display is continued.

  If the EVF display is to be continued in step S123, the process returns to step S106 and the above-described series of operations is repeated. Then, by returning to step S106 and repeating the above processing, the driving of the diaphragm 312 that is insufficient is driven again in the next frame of the frame used for the next photometric calculation in step S117.

  When the EVF display is ended in step S123, the shutter 12 is closed (step S124), the mirror 130 is lowered (step S125), and the charge accumulation of the image sensor 14 is ended (step S126). Exit.

  The operation shown in FIGS. 2 and 3 will be described with reference to the timing chart of FIG. The horizontal direction of FIG. 4 is a time axis, and time passes as it goes to the right.

  VD represents a timing pulse for reading out the image data stored in the image sensor 14 from the timing generation circuit 18 from the image sensor 14, and a number written between the VD and VD indicates a frame number.

  The horizontal line of the diaphragm 312 indicates that the diaphragm 312 is being driven.

  The accumulated charge of the first frame is read when the VD of the second frame is output, and accumulation of the second frame is started. Display image data is generated and stored in the image display memory 24 while reading the charge of the first frame, and then displayed on the image display unit 28 at the timing when the VD of the third frame is output. Basically, these processes are sequentially repeated for each frame.

  Also, photometry is periodically performed using the read image data to obtain a Bv value for still image shooting or to calculate shooting parameters (accumulation time, aperture value, gain). In the example shown in FIG. 4, photometry is performed at intervals of 6 frames, and photometry is performed using the accumulation results of the first, seventh, thirteenth,... Frames. The imaging parameters obtained by this photometry are used as control parameters for image accumulation in the fourth frame when obtained from the accumulation data in the first frame.

  “Appropriate” and “Dark” in the column of the readout item indicate how the brightness of the image displayed on the image display unit 28 changes by controlling the aperture.

  As shown in FIG. 4, when the narrowing switch 74 is pressed at the timing t1, the VD timing (step S113) and the frame image used for the photometric calculation (step S114) are checked. In the example of FIG. 4, since the first frame image data started at the output timing of the next VD is used for photometric calculation (YES in step S114), the diaphragm 312 is driven during charge accumulation in the first frame. No (step S115). Accordingly, after waiting for the next VD timing, the diaphragm 312 is driven during the charge accumulation of the second frame (NO in step S114, “= 0” in step S116, step S117).

  In FIG. 4, it is assumed that the aperture drive control by the aperture switch 74 once does not end within one frame period for the reason described later and extends to a plurality of frames.

  After aperture control in the second frame, the image read out in the second and third frames is not reflected in the accumulation conditions and gains based on the photometric calculation result based on the image in the first frame, the exposure becomes indefinite, and the image becomes dark. Therefore, image updating of the image display unit 28 is prohibited until the photometric calculation result based on the first frame image is reflected in the accumulation condition. That is, in this case, in step S122, “2” is set as the value of the display update prohibition counter. As a result, since the value of the display update prohibition counter becomes other than 0 in step S107 after accumulation of the second frame and the third frame, the read image of the first frame is not updated with the read images of the second and third frames. Will continue to be displayed. Thereafter, when the image of the fourth frame is read out, the value of the display update counter becomes 0, so that the image of the fourth frame is displayed in step S108.

  Further, when controlling the diaphragm 312, the driving amount per one time is within the dynamic range for one metering, or the one time of the diaphragm 312 so that the driving time of the diaphragm 312 does not exceed one frame period. The driving amount is limited.

  This is because, for example, if the diaphragm 312 is controlled over a plurality of frames, the following inconvenience occurs. Suppose that the narrow-down switch 74 is pressed in the fifth frame. In this case, since the sixth frame is not an accumulation of an image used for the photometric calculation, the diaphragm 312 may be driven. However, if the diaphragm 312 is continuously driven, the image of the seventh frame used for the photometric calculation is accumulated, and the image accumulation for the photometric calculation is adversely affected.

  Also, by setting the drive amount of the diaphragm 312 within the dynamic range of photometry, the exposure control value (charge accumulation time, gain, etc.) at the time of charge accumulation in the next frame is taken into consideration at the time of photometry calculation by taking into account the influence of aperture control. Can be sought. Therefore, it is necessary to limit the drive of the diaphragm 312 so that it can be accommodated in one frame.

  When the diaphragm 312 is driven in a plurality of times, the second and subsequent diaphragm controls are performed from the next frame after the accumulation of the next photometric image, thereby minimizing image changes due to diaphragm driving. can do.

  That is, when the diaphragm 312 is driven during accumulation of the second frame (step S117), the diaphragm drive flag is set to 1 (step S119). As a result, the aperture drive flag remains 1 until the next photometric frame (“= 1” in step S116), and the aperture 312 is not driven. Since the aperture drive flag is 0 in the seventh frame in which the photometric image is stored, the remaining aperture drive is performed in the next eighth frame. When the driving of the diaphragm 312 is completed by this driving (YES in step S109), the diaphragm fixing flag is set (step S120), and the diaphragm driving flag is set to 0 (step S121).

  Note that read data of the eighth and ninth frames in which the image becomes dark by the second aperture control is not displayed as in the first aperture drive.

  In the description of the present embodiment, the photometric cycle has been described as being fixed. However, when the aperture is controlled in a plurality of times due to the above restrictions, the photometric cycle may be variable. For example, referring to FIG. 4, accumulation used for photometry calculation may be performed in the fourth frame, and the diaphragm may be driven while the image is accumulated in the fifth frame.

  Note that the photometry calculation at this time is performed in consideration of the movement of the aperture.

  In this way, when the aperture switch is operated during EVF, the aperture driving up to the set Av value is synchronized with the EVF image accumulation and readout switching timing (frame). Thereby, even if there is a sudden change in the amount of light due to the aperture control according to the operation of the aperture switch, it is possible to suppress a change in the luminance of the image, so that the quality of the EVF image can be improved.

It is a block diagram which shows the structure of the imaging device in embodiment of this invention. It is a flowchart for demonstrating the image display operation | movement by EVF in embodiment of this invention. It is a flowchart for demonstrating the image display operation | movement by EVF in embodiment of this invention. It is a timing chart in an embodiment of the invention.

Explanation of symbols

12: Shutter, 14: Image sensor, 16: A / D converter, 18: Timing generation circuit, 20: Image processing circuit, 22: Memory control circuit, 24: Image display memory, 26: D / A converter, 28 : Image display unit, 30: Memory, 32: Compression / decompression circuit, 40: Shutter control unit, 42: Focus adjustment unit, 46: Photometry control unit, 48: Flash, 50: System control circuit, 52: Memory, 54: Notification unit, 56: Non-volatile memory, 60: Mode dial switch, 62: Shutter switch SW1, 64: Shutter switch SW2, 66: Playback switch, 68: Single / continuous shooting switch, 70: Operation unit, 80: Power control Part, 82, 84: connector, 86: power supply, 90, 94: I / F, 92, 96: connector, 98: recording medium attachment / detachment detection part, 100: imaging device, 11 : I / F, 112: External flash, 200: Recording medium, 202: Recording unit, 204: I / F, 206: Connector, 300: Lens unit, 310: Imaging lens, 312: Aperture, 306: Lens mount, 320 : I / F, 322: Connector, 340: Aperture control unit, 342: Focus control unit, 350: Lens system control circuit

Claims (9)

An imaging apparatus having an electronic viewfinder function,
An image sensor for converting an optical image of a subject incident through a diaphragm into an electrical signal and storing the electrical signal;
Instruction means for inputting an instruction to drive the diaphragm;
When using the electronic viewfinder function, when an instruction to drive the diaphragm is given by the instruction means, the diaphragm is opened while the electric signal of the frame image excluding the frame image used for exposure control is being accumulated in the image sensor. An imaging apparatus comprising: control means for controlling to drive.   The image pickup apparatus according to claim 1, wherein a frame image obtained by the image pickup element is used for exposure control every plurality of frames.   The image pickup apparatus according to claim 1, wherein the control unit controls the diaphragm to have an aperture value based on automatic exposure control. Setting means for setting the aperture value of the aperture;
The imaging apparatus according to claim 1, wherein the control unit controls the aperture so that the aperture value is set by the setting unit.   The control means is configured such that the driving time per one stop does not exceed one frame period, and the driving amount per one time does not exceed a preset driving amount until the aperture value is reached. The imaging apparatus according to claim 3, wherein the diaphragm is controlled.   When the driving of the diaphragm does not end within one frame period, the control means controls to drive the diaphragm during the next frame period after accumulation of frame images used for the next exposure control. The imaging device according to claim 5. Further comprising a calculation means for calculating an exposure control value based on a frame image used for the exposure control,
7. The exposure unit according to claim 1, wherein when the instruction unit instructs to drive the diaphragm, the calculation unit calculates the exposure control value further taking into account the driving amount of the diaphragm. The imaging device according to any one of the above. Display means;
In order to realize the electronic viewfinder function, it further comprises display control means for sequentially displaying a frame image based on an electrical signal obtained by the imaging device on the display means,
When the instruction unit instructs to drive the diaphragm, the driving of the diaphragm is controlled so as not to update the display on the display unit with a frame image whose exposure is indefinite. The imaging device according to claim 1. A control method for an image pickup apparatus including an image pickup element that converts an optical image of a subject incident through a diaphragm into an electrical signal and stores the electric signal, and has an electronic viewfinder function,
Receiving an instruction to drive the diaphragm;
A step of driving the diaphragm while storing an electric signal of a frame image excluding a frame image used for exposure control in the imaging device when an instruction to drive the diaphragm is received when using the electronic viewfinder function; A control method characterized by comprising:

Images