JP2007028211A - Imaging apparatus and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To charge a strobe with electricity during the display of an EVF (electronic view finder) and to prevent charging noise from being included in an image during the display of the EVF. <P>SOLUTION: In the imaging apparatus comprises an imaging device (14) for photoelectrically converting incident light and outputting image data, an image display part (28) functioned as the electronic view finder by periodically updating and displaying the image data outputted from the imaging device (14) and a strobe charging/light emitting part (48), in the case of charging the strobe charging/light emitting part (48) during the function of the electronic view finder, the updating frequency of image data displayed on the image display part (28) is reduced and the strobe charging/light emitting part is charged in a period excluding at least the output period of image data displayed on the image display part from the imaging device (14). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus and a control method thereof, and more particularly to strobe charge control during electronic viewfinder (EVF) display in the image pickup apparatus.

  In recent years, in order to monitor a subject before photographing, a compact digital camera equipped with an electronic viewfinder (EVF) function that captures a moving image and displays it on a display device as a basic function has become widespread. In such a camera, in general, after displaying an image taken after shooting a subject for a predetermined time (preview display) or when switched to the EVF mode, the EVF function is returned to display a moving image (hereinafter, “ This is called “EVF display”). In addition, there has been proposed one that starts charging during EVF display so that the next strobe shooting can be started immediately when the built-in strobe is used for shooting.

  On the other hand, if the strobe is charged during image reading, high-frequency noise (charging noise) is generated due to large current fluctuations, which adversely affects the read image. At present, it is difficult to prevent this charging noise in terms of hardware, for example, by arranging the image reading portion and the charging control portion on separate bases because of downsizing and cost problems of the camera. For this reason, Patent Document 1 discloses an imaging apparatus that prevents noise from occurring in recorded data of a captured image by stopping the strobe charging operation until digitization of the captured image (image to be recorded) is completed. Yes.

JP 2001-17393 A

  However, in Patent Document 1, there is no description about charging control during EVF display. For example, as described in Patent Document 1, a method of stopping the charging operation of a strobe until digitization of a captured image is completed. The following problems arise.

  First, even if EVF display is being performed, if control is performed so that charging is started with the end of digitization of a captured image, charging noise will appear on the EVF display image. In this case, when EVF display is performed while shooting an image with high sensitivity, such as when shooting a night view, not only charging noise is particularly noticeable, but the display device that will perform EVF display in the future will be further increased in size and high definition. In this case, charging noise may stand out.

  On the other hand, in many imaging apparatuses having an EVF function, EVF display is started immediately after a captured image is displayed for a predetermined time (preview display). For this reason, if control is performed so as not to charge the strobe even during digitization of an image that is continuously read out for EVF display, it becomes impossible to provide a period for charging the strobe during EVF display. Therefore, in this case, there arises a problem that the next flash photography cannot be performed immediately.

  The present invention has been made in view of the above problems, and an object thereof is to charge a strobe during EVF display and to prevent charging noise from appearing in an image during EVF display.

  To achieve the above object, an image sensor that photoelectrically converts incident light and outputs image data, and display means that functions as an electronic viewfinder by periodically updating and displaying image data output from the image sensor And the light emitting means for irradiating the subject with light, the image pickup device of the present invention displays the image data on the display means at a lower frequency when the light emitting means is charged during the electronic viewfinder function. When controlling the display control means to control, and charging the light emitting means during the electronic viewfinder function, except at least a period during which image data to be displayed on the display means is output from the imaging device, Charging control means for controlling the light emitting means to be charged.

  An image sensor that photoelectrically converts incident light and outputs image data; display means that functions as an electronic viewfinder by periodically updating and displaying image data output from the image sensor; and According to the control method of the present invention of the imaging apparatus having the light emitting means for irradiating, when the light emitting means is charged during the electronic viewfinder function, the image data is updated at a lower frequency and displayed on the display means. A display control step for controlling, and when the light emitting means is charged during the electronic viewfinder function, at least during a period in which image data to be displayed on the display means is output from the image sensor, A charge control step for controlling to perform charging.

  According to the present invention, the strobe can be charged during EVF display, and charging noise can be prevented from appearing in an image during EVF display.

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

  FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus having an image processing function according to an embodiment of the present invention.

  In FIG. 1, reference numeral 100 denotes an imaging device. Reference numeral 10 denotes a photographing lens, 12 denotes a shutter having a diaphragm function, 14 denotes an image sensor that converts an optical image into an electrical signal, and 16 denotes an A / D converter that converts an analog signal output from the image sensor 14 into a digital signal.

  A timing generation circuit 18 supplies a clock signal and a control signal to the image sensor 14, the A / D converter 16, and the D / A converter 26, respectively, and is controlled by the memory control circuit 22 and the system control circuit 50.

  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 performs TTL (through the lens) type autofocus (AF) processing, automatic exposure (AE) on the exposure control unit 40 and the distance measurement control unit 42. ) Processing and flash pre-emission (EF) processing. 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.

  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, 28 denotes an image display unit including a TFT LCD, and the image data for display written in the image display memory 24 passes through the D / A converter 26. Displayed by the image display unit 28. An electronic viewfinder (EVF) function can be realized by sequentially displaying captured image data using the image display unit 28 (hereinafter referred to as “EVF display”). Further, the image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50. When the display is turned off, the power consumption of the imaging apparatus 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. Thereby, even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, it is possible to write a large amount of images to the memory 30 at high speed. 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 an exposure control unit that controls the shutter 12 having an aperture function. Reference numeral 42 denotes a distance measurement control unit that controls focusing of the photographing lens 10, 44 denotes a zoom control unit that controls zooming of the photographing lens 10, and 46 denotes a barrier control unit that controls the operation of the barrier 102. Reference numeral 48 denotes a flash charging / light emitting unit having a function of projecting AF auxiliary light and a flash light control function for illuminating a subject. The strobe charging / light emitting unit 48 includes a main capacitor that is charged by a booster circuit (not shown) and a strobe light emitting circuit (not shown) that emits strobe light in accordance with a light emission signal from a strobe control unit 47 (to be described later). Reference numeral 49 denotes a strobe charge detection unit that detects the charge voltage of the main capacitor of the strobe charge / light emitting unit 48. A strobe control unit 47 controls the strobe charging / light emitting unit 48 according to the charging voltage of the strobe charging / light emitting unit 48 from the strobe charging detection unit 49 based on the control from the system control circuit 50.

  The exposure control unit 40 and the distance measurement control unit 42 are controlled using the TTL method. That is, as described above, first, the calculation result obtained by calculating the image data obtained from the image sensor 14 via the A / D converter 16 by the image processing circuit 20 is output to the system control circuit 50. The system control circuit 50 calculates the aperture value, shutter speed, and strobe main light emission amount during exposure according to the calculation result. Then, the exposure control unit 40, the distance measurement control unit 42, and the strobe control unit 47 are controlled according to these calculation results. Note that a photometric sensor may be provided separately. In this case, the system control circuit 50 does not use image data obtained from the image sensor 14 but based on image data obtained from the photometric sensor. The controller 47 is controlled.

  Reference numeral 50 denotes a system control circuit that controls the entire imaging apparatus 100, and 52 denotes a memory that stores constants, variables, programs, and the like for operation of 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, the display unit is installed at one or a plurality of locations near the operation unit 70 of the imaging apparatus 100 that are easily visible. In addition, the notification unit 54 has a part of its function 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 related to the shooting mode such as single shot / continuous 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, macro shooting display, buzzer setting display, battery level display for clock, battery level display, error display, information display with multiple digits, display status of recording media 200 and 210, communication I / F operation display In addition, date and time are displayed.

  Among the display contents of the notification unit 54, what is displayed in the optical viewfinder 104 includes in-focus display, camera shake warning display, flash charge display, shutter speed display, aperture value display, exposure correction display, and the like.

  Reference numeral 56 denotes an electrically erasable / recordable nonvolatile memory such as an EEPROM.

  Reference numerals 60, 62, 64, and 70 are operation means for inputting various operation instructions of the system control circuit 50, and may be a single or a combination of a switch, a dial, a touch panel, pointing by line-of-sight detection, a voice recognition device, or the like. Composed.

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

  Reference numeral 60 denotes a mode dial switch, which can switch and set various function modes such as power-off, automatic shooting mode, program shooting mode, panoramic shooting mode, playback mode, multi-screen playback / erase mode, and PC connection mode.

  Reference numeral 62 denotes a shutter switch SW1, which is turned on by a first stroke (for example, half-press) of a shutter button (not shown), and instructs to start operations such as AF processing, AE processing, AWB processing, and EF processing.

  A shutter switch SW2 64 is turned on by a second stroke (for example, full press) of a shutter button (not shown), and instructs the start of a series of processing operations 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 unit 20 and the memory control circuit 22 is performed. Development processing using is performed. Further, a recording process is performed in which the image data is read from the memory 30, compressed by the compression / decompression circuit 32, and the image data is written to the recording medium 200 or 210.

  An operation unit 70 includes various buttons and a touch panel. For example, the menu button, set button, macro button, multi-screen playback pagination button, flash setting button, single shooting / continuous shooting / self-timer switching button, menu movement + (plus) button, menu movement-(minus) button Including. Furthermore, 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, a built-in flash pop-up switch, and the like are also included. By pressing the built-in strobe pop-up switch, the light emitting portion of the strobe charging / light emitting portion 48 is exposed, and strobe photography can be performed.

  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 presence / absence of the battery, the type of battery, and the remaining battery level are detected, and the DC-DC converter is controlled based on the detection result and the instruction of the system control circuit 50, and the necessary voltage is included for the necessary period. Supply to each part.

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

  Reference numerals 90 and 94 denote interfaces with recording media such as memory cards and hard disks, and reference numerals 92 and 96 denote connectors for connecting to recording media such as memory cards and hard disks. A recording medium attachment / detachment detection circuit 98 detects whether or not the recording medium 200 or 210 is attached to the connectors 92 and / or 96. The recording medium attachment / detachment detection circuit 98 can also detect whether a connector 92 and / or 96 is equipped with, for example, various communication cards described later other than the recording medium 200 or 210.

  In the present embodiment, it is assumed that there are two interfaces and connectors for attaching a recording medium. Of course, the interface and the connector for attaching the recording medium may have a single or a plurality of systems and any number of systems. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.

  Reference numeral 102 denotes a barrier that is a protective device that prevents the imaging unit from being soiled or damaged by covering the imaging unit including the lens 10 of the imaging device 100.

  Reference numeral 104 denotes an optical viewfinder, which can take an image using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28. In addition, 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.

  A communication circuit 110 has various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication.

  Reference numeral 112 denotes a connector for connecting the imaging apparatus 100 to another device by the communication unit 110 or an antenna in the case of wireless communication.

  Reference numerals 200 and 210 denote recording media such as a memory card and a hard disk. Each of the recording media 200 and 210 includes recording units 202 and 212 configured by a semiconductor memory, a magnetic disk, and the like, interfaces 204 and 214 with the imaging device 100, and connectors 206 and 216 for connecting to the imaging device 100, respectively. Yes.

<First Embodiment>
Next, with reference to FIG. 2 to FIG. 5, the photographing processing operation of the image pickup apparatus 100 having the above-described configuration in the first embodiment will be described. The shooting processing operation described here is performed when the mode dial switch 60 is set to the shooting mode.

  When the mode dial switch 60 is set to the photographing mode, EVF display is started on the image display unit 28 in step S101. In the EVF display state, data sequentially written in the image display memory 24 via the image sensor 14, the A / D converter 16, the image processing circuit 20, and the memory control circuit 22 are stored in the memory control circuit 22, D / D Images are sequentially displayed by the image display unit 28 via the A converter 26. This realizes an image monitor function.

  Next, in step S102, the state of the shutter switch SW1 is confirmed. When the shutter switch SW1 is pressed, the process proceeds to step S103 to perform distance measurement / photometry processing. Here, distance measurement / photometry processing will be described with reference to FIG.

  First, in step S201, the system control circuit 50 reads out a charge signal from the image sensor 14, and sequentially reads captured image data into the image processing circuit 20 via the A / D converter 16 (step S201). Using the sequentially read image data, the image processing circuit 20 performs predetermined calculations used for TTL AE processing, EF processing, and AF processing.

  In each process here, a specific part of the total number of captured pixels is extracted according to necessity and extracted and used for calculation. This makes it possible to perform optimum calculations for different modes such as the center-weighted mode, the average mode, and the evaluation mode in each of the TTL method AE, EF, AWB, and AF processes.

  The system control circuit 50 performs AE control using the exposure control unit 40 until the exposure (AE) is determined to be appropriate using the calculation result in the image processing circuit 20 (until YES in step S202) ( Step S203). In step S204, the system control circuit 50 determines whether or not shooting is performed using a strobe. For example, the strobe is used when it is determined from the measurement data obtained by the AE control in step S203 that the brightness of the subject is low or when the user is instructed to take a strobe by pressing a strobe pop-up switch (not shown). And decide to shoot. If a strobe is necessary (YES in step S204), a strobe flag is set and the strobe charging / light emitting unit 48 is charged (step S205). In step S205, the strobe control unit 47 controls charging based on the charging voltage of the main capacitor of the strobe charging / light emitting unit 48 detected by the strobe charging detection unit 49. Accordingly, when the charging voltage necessary for light emission has already been reached by strobe charging during EVF display described later, it is not necessary to charge here. When the strobe control unit 47 determines that the charging voltage necessary for light emission has been reached, it notifies the system control circuit 50 that charging has ended.

  If it is determined that the exposure (AE) is appropriate (YES in step S202), the measurement data and / or setting parameters are stored in the internal memory or the memory 52 of the system control circuit 50. Next, the system control circuit 50 performs distance measurement (AF) using the calculation result in the image processing circuit 20 and the measurement data obtained by the AE control, and until the result is determined to be in focus (step S208). During NO, AF control is performed using the distance measurement control unit 42 (step S209).

  If it is determined that the subject is in focus as a result of the distance measurement (AF) (YES in step S208), the measurement data and / or setting parameters are stored in the internal memory of the system control circuit 50 or the memory 52, and the distance measurement / photometry processing routine is performed. (Step S103) is terminated.

  In the above example, the case where distance measurement (AF) is performed after exposure (AE) control has been described, but it goes without saying that it may be reversed or performed in parallel.

  When the distance measurement / photometry processing in FIG. 4 is thus completed, the process proceeds to step S104 in FIG. If the shutter switch SW2 is not pressed (OFF in step S104) and the shutter switch SW1 is also released (OFF in step S105), the process returns to step S102. If the shutter switch SW2 is pressed (ON in step S104), the process proceeds to step S106.

  Next, in step S106, instead of EVF display, fixed color display for displaying a predetermined color (fixed color) on the entire surface of the image display unit 28 is performed. Instead of the fixed color, the EVF display image obtained immediately before pressing the shutter switch SW2 may be continuously displayed. In addition to switching to fixed color display, according to the photometric data stored in the internal memory of the system control circuit 50 or the memory 52, the exposure controller 40 sets the shutter 12 having the aperture function to an aperture value corresponding to the obtained photometric data. To do. In step S107, exposure of the image sensor 14 is started.

  In step S108, it is checked whether or not the strobe flag is set, and it is determined whether or not the strobe charging / light emitting unit 48 performs strobe shooting. When performing flash photography, the flash charging / light emitting unit 48 is caused to emit light according to the flash emission amount stored in the internal memory of the system control circuit 50 or the memory 52 (step S109). In step S110, the system control circuit 50 waits for the end of exposure of the image sensor 14 according to the photometric data, and after the exposure ends, closes the shutter 12 and reads the charge signal from the image sensor 14 (step S111). The read charge signal is taken to the image data memory 30 via the A / D converter 16, the image processing circuit 20, the memory control circuit 22, or directly from the A / D converter 16 via the memory control circuit 22. Write the data.

  When the reading of the charge signal from the image sensor 14 is completed, it is determined in step S121 in FIG. 3 whether or not flash photography has been performed in the immediately preceding photographing (steps S107 to S110). When the flash photography is performed, the flash charging / light emitting unit 48 is charged in step S122. In this way, when the flash photography is performed, the charge of the stroboscopic charge / light emitting unit 48 is charged after the readout of the charge of the photographed image is completed, so that charging noise is prevented from being included in the image data during the charge readout. be able to.

  Then, in step S123, preview display for displaying the image taken immediately before is started. In step S124, image processing and recording of the taken image are started. Here, the system control circuit 50 first reads the captured image data written in the image data memory 30 and performs various image processing using the memory control circuit 22 and, if necessary, the image processing circuit 20. Further, after the image compression processing corresponding to the set mode is performed by the compression / decompression circuit 32, the compressed image data is written to the recording medium 200 or 210 via the interface 90 or 94 and the connector 92 or 96.

  Next, in step S125, it is confirmed whether or not a predetermined time has elapsed since the preview display was started in step S123. If not, the process proceeds to step S126 to determine whether or not the shutter switch SW1 has been pressed. If the shutter switch SW1 is pressed, the process returns to step S103 in FIG. If not, the process returns to step S125.

  On the other hand, when a predetermined time has elapsed since the preview display was started (YES in step S125), the process proceeds to step S127, and it is determined again whether or not the flash photography was performed in the immediately preceding photography (steps S107 to S110). If the flash photography has not been performed, the process returns to step S101 in FIG. 2 to start normal EVF display.

  On the other hand, if flash photography has been performed (YES in step S127), in step S128, the EVF display frame rate is changed to a predetermined frame rate. The frame rate of EVF display refers to the update frequency of each frame image constituting a moving image during EVF display. Here, the frame rate is set to be lower than the frame rate of normal EVF display (for example, when the normal frame rate is 60 frames / second, the predetermined frame rate is 30 frames / second).

  Next, in step S129, in accordance with the EVF display frame rate changed in step S128, processing for alternately performing EVF display for one frame on the image display unit 28 and charging of the strobe charging / light emitting unit 48 is performed. . The timing control of charge storage and readout of the image sensor 14, EVF display on the image display unit 28, and charging of the strobe charging / light emitting unit 48 performed here will be described with reference to the timing chart of FIG. 5.

  In FIG. 5, (a) shows the timing of charge accumulation and readout during normal EVF display and EVF display when charging is not performed, and (b) is the charge accumulation during EVF display when charging is performed. And timings of readout, EVF display, and charging. FIG. 5 shows a case where the frame rate for normal EVF display is 60 frames / second and the frame rate for EVF display when charging is 20 frames / second. The numbers in the timing chart of FIG. 5 indicate the frame numbers.

  As can be seen from FIG. 5A, the stored charge is always transferred during normal EVF display. Therefore, if the strobe charging / light emitting unit 48 is charged while performing normal EVF display, charging noise is added to the image signal, and the EVF displayed image becomes difficult to see. On the other hand, in the first embodiment, when charging, the frame rate of EVF display is lowered, so that a time during which no charge is read occurs as shown in FIG. By controlling the strobe charging / light emitting unit 48 to be charged when the charge is not read, it is possible to prevent charging noise from being added to the image signal for EVF display.

  Note that FIG. 5B shows a case where the charge accumulation and readout of one frame image is not different from the normal through display, and the charge accumulation and readout of the image are not performed every other frame. Yes. However, the present invention is not limited to this. Accumulation and reading of charges are continuously performed as shown in FIG. 5A, and EVF display of the read image data is performed as shown in FIG. 5B. It may be. By doing so, charging can be performed at the timing of reading the charges of a frame that is not used for EVF display, so that the influence of charging noise on the image displayed by EVF can be eliminated.

  Further, in the example shown in FIG. 5B, the strobe charging / light emitting unit 48 is not charged only at the time of reading out the charge, but it may be controlled not to be performed even during the charge accumulation time. Good.

  In addition, the frame rate of EVF display when charging is 1/3 of the frame rate of normal EVF display, but it is of course possible to make it 1/2, 1/4, etc.

  Returning to FIG. 3, in step S130, it is determined whether or not the charging is completed. When charging is completed, the process returns to step 101 to start normal through display, and the above-described processing is repeated. On the other hand, if the charging is not completed, the process proceeds to step S131 to determine whether or not SW1 is pressed. If it has been pressed, the process returns to step S103, and if it has not been pressed, the process returns to step S129 to repeat the above processing.

  As described above, according to the first embodiment, when the flash is charged after the flash photography, the EVF display frame rate is lowered, and charging is performed at the timing of reading the charges of the frame that is not used for EVF display. Can do. Thereby, the influence of the charging noise on the image displayed by EVF can be eliminated.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.

  In the first embodiment, when EVF display after flash photography is performed, the EVF display frame rate is changed to a predetermined frame rate set in advance. On the other hand, in the second embodiment, the frame rate is changed according to the change of the image during EVF display. Other than this point, the second embodiment is the same as the first embodiment, and a description thereof will be omitted. Differences will be described in detail below.

  FIG. 6 is a diagram showing a part of the photographing process in the second embodiment, and the processes performed before step S121 are the same as those in FIG. 2 described in the first embodiment. 6 is different from FIG. 3 in that the through display frame rate is determined every predetermined time or every predetermined frame in steps S228 and S232, but the other processes are the same as those in FIG. Therefore, the same reference numerals are given and explanations are omitted.

  In step S228, first, the brightness of the latest frame image is compared with the brightness of the immediately preceding frame image, and the frame rate is determined according to the difference. As an example, assuming that the standard frame rate for EVF display is 60 frames / second, if the difference in APEX value is one step or less, it is determined that there is little motion between images (no scene change) and 10 frames / second. And In the case of three or more stages, it is determined that the motion between images is large (the scene has changed), and is set to 30 frames / second. Note that the present invention is not limited to the luminance and APEX values, and it is only necessary to determine whether the subject is moving (the scene is changed) based on the latest frame image and the immediately preceding frame image. By determining the frame rate in this way, it is possible to display the image more smoothly by decreasing the frame rate when the motion is small (there is no scene change) and increasing the frame rate as the motion increases. .

  Thereafter, according to the EVF display frame rate determined in step S228, EVF display and charging are performed in step S129 as described with reference to FIG. 5B. In step S130, the charging is completed. In step S131, it is determined whether the shutter switch SW1 is pressed. If both are “NO”, the process proceeds to step S232. In step S232, it is determined whether or not a predetermined time has elapsed since the last EVF display frame rate was determined. If it has not elapsed, the process returns to step S129, and if it has elapsed, the process returns to step S128 to repeat the above processing. Note that the determination may be based on whether a predetermined number of frame images are displayed in EVF instead of time.

  In this way, by periodically determining the frame rate of EVF display, it becomes possible to change the frame rate as appropriate according to the state of the image during live view display, and to make EVF display easier to see. It becomes possible.

It is a block diagram which shows the structure of the imaging device in embodiment of this invention. It is a flowchart which shows the imaging | photography process in the 1st Embodiment of this invention. It is a flowchart which shows the imaging | photography process in the 1st Embodiment of this invention. It is a flowchart which shows the distance measurement and photometry process in the 1st Embodiment of this invention. 3 is a timing chart showing timings of charge accumulation and readout of the image sensor, EVF display on the image display unit, and strobe charging / light emitting unit charging in the first embodiment of the present invention. It is a flowchart which shows the imaging | photography process in the 2nd Embodiment of this invention.

Explanation of symbols

10: photographing lens, 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 / expansion circuit, 34: shutter control unit, 40: exposure control unit, 42: distance measurement control unit, 46: barrier control unit, 47: strobe control 48: Strobe charging / light emitting unit 49: Strobe charging detection unit 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, 70: Operation unit, 80: Power supply control unit, 82, 84: Connector, 86: Power supply unit, 90, 94: I / F, 92, 96: Connector 98: recording medium attachment detection circuit, 100: imaging device, 200, 210: recording medium, 202, 212: recording section, 204 and 214: I / F, 206, 216: connector

Claims (12)

An image sensor that photoelectrically converts incident light and outputs image data, a display unit that functions as an electronic viewfinder by periodically updating and displaying image data output from the image sensor, and irradiating the subject with light An imaging device having a light emitting means,
Display control means for controlling to display the display means at a reduced frequency of updating image data when charging the light emitting means during the electronic viewfinder function;
When charging the light emitting means during the electronic viewfinder function, control is performed so that the light emitting means is charged at least during a period in which image data to be displayed on the display means is output from the image sensor. An image pickup apparatus comprising: a charge control unit.   The display control means includes setting means for setting the update frequency, and the setting means compares the latest image data with the immediately preceding image data, and when the difference between the two image data is small, The imaging apparatus according to claim 1, wherein the update frequency is set to be lower than that in the case of being larger.   The imaging apparatus according to claim 2, wherein the setting unit compares the brightness of the latest image data with the brightness of the immediately preceding image data, and the difference is a brightness difference between the two image data. .   The imaging apparatus according to claim 2, wherein the setting unit resets the update frequency every predetermined time or every predetermined frame.   The charging control means terminates charging of the light emitting means when the light emitting means reaches a voltage sufficient for light emission, and the setting means performs charging of the light emitting means with the update frequency according to completion of charging. The imaging apparatus according to claim 2, wherein the update frequency is set to the update frequency when there is no update. Determining means for determining whether to charge the light emitting means during the electronic viewfinder function;
The determination unit is configured to use the electronic view when the light emitting unit is used in shooting performed immediately before the display unit functions as an electronic viewfinder, and when an instruction is given from the outside to use the light emitting unit. 6. The imaging apparatus according to claim 1, wherein it is determined that the light emitting unit is charged during a finder function. An image sensor that photoelectrically converts incident light and outputs image data, a display unit that functions as an electronic viewfinder by periodically updating and displaying image data output from the image sensor, and irradiating the subject with light A method for controlling an imaging apparatus having a light emitting means,
A display control step for controlling to reduce the update frequency of image data displayed on the display means when charging the light emitting means during the electronic viewfinder function;
When charging the light emitting means during the electronic viewfinder function, control is performed so that the light emitting means is charged at least during a period in which image data to be displayed on the display means is output from the image sensor. And a charge control step. The display control step further includes a setting step for setting the update frequency,
8. The setting step is characterized in that the latest image data is compared with the immediately preceding image data, and when the difference between the two image data is small, the update frequency is set lower than when it is large. The control method described in 1.   9. The control method according to claim 8, wherein in the setting step, the brightness of the latest image data is compared with the brightness of the immediately preceding image data, and the difference is a brightness difference between the two image data. .   10. The control method according to claim 8, wherein in the setting step, the update frequency is reset every predetermined time or every predetermined frame. Determining whether the light emitting means has reached a sufficient voltage for light emission by charging in the charging control step, and ending charging of the light emitting means when reaching a sufficient voltage;
11. The control according to claim 7, further comprising a step of resetting the update frequency to an update frequency when charging of the light emitting unit is not performed in accordance with the end of the charging. Method. A determination step of determining whether to charge the light emitting means during the electronic viewfinder function;
In the determination step, the electronic view is used when the light emitting unit is used in photographing performed immediately before the display unit functions as an electronic viewfinder, and when the outside is instructed to use the light emitting unit. The control method according to claim 7, wherein it is determined that the light emitting unit is charged during a finder function.

Images