JP6728010B2 - Imaging device and method for controlling imaging device - Google Patents

Description

The present invention relates to an imaging device and a method for controlling the imaging device.

In many image pickup devices such as digital cameras, a display image generated from an image signal picked up by an image pickup element is sequentially displayed in live view on a display device such as a liquid crystal display device as an electronic viewfinder for framing an object. Live view display cannot be displayed in real time because multiple image processes such as reading the image signal captured by the image sensor and generating a display image from the read image signal must be performed through the memory. It is displayed with a delay of several frames. Therefore, it is known that live view display can be performed in almost real time by reading an image from the memory for displaying the image in addition to writing the image signal read from the image sensor to the memory. There is. This can be achieved by operating the image sensor and the display device asynchronously, rather than operating them asynchronously. Further, there is a digital camera capable of performing live view display with proper exposure even in a low-luminance environment by reducing the image capture frame rate according to the exposure time of the image sensor.

There is disclosed an image pickup apparatus capable of performing live view display almost in real time even when the image pickup frame rate is variable (see Patent Document 1). The image pickup apparatus disclosed in Patent Document 1 sets the display frame rate according to the image pickup frame rate, and adjusts the operation timings of the image pickup element and the display device according to the set display frame rate so as to have a predetermined phase difference.

JP, 2009-159067, A

However, the above-described image pickup apparatus does not take into consideration processing such as AF processing that uses an evaluation value generated from imaged image data over a plurality of frames. When the evaluation value used for the processing is generated from the captured image data, the interval for generating the evaluation value is determined according to the imaging frame rate. Therefore, the processing time of the processing using the evaluation value over a plurality of frames is the imaging frame rate. It becomes longer with the decrease of. In other words, in order to perform live view display with proper exposure in a low-luminance environment, when the imaging frame rate is reduced in time with the exposure time, the interval at which the evaluation value is generated increases as the imaging frame rate decreases, The processing time of the processing using the evaluation value also becomes long. However, when adjusting the operation timing of the image sensor and the display device to a predetermined phase difference in consideration of the display delay, it is necessary to consider the synchronization with the display device as well, and the fastest exposure time that fits the exposure time can be set. It cannot be set to the imaging frame rate. Therefore, there is a problem that the frame rate becomes slower than the imaging frame rate determined by the exposure time for performing live view display of proper exposure, and the processing time of the process of using the evaluation value over a plurality of frames becomes longer than the exposure time. is there.

An object of the present invention is to provide an imaging device and a method for controlling the imaging device that can perform live view display with an appropriate exposure time even in a low-luminance environment while suppressing a delay in live view display.

The image pickup apparatus of the present invention picks up an image of each frame according to an exposure time, and outputs the picked-up image of each frame one frame at a time in one vertical scanning period, and the image pickup unit outputs the image. An exposure time determination unit that determines the exposure time of the imaging unit based on the image, and if the exposure time determined by the exposure time determination unit is longer than a reference value of one vertical scanning period, output by the imaging unit In the first state in which a predetermined evaluation value is acquired from the captured image, a unit of a period shorter than the reference value of the one vertical scanning period so that one vertical scanning period of the imaging unit is equal to or longer than the exposure time. In the second state in which one vertical scanning period of the image capturing unit is set and a predetermined evaluation value is not acquired from the image output by the image capturing unit, one vertical scanning period of the image capturing unit is the exposure time. As described above, the image pickup unit includes a period setting unit that sets one vertical scanning period to an integral multiple of a reference value of the one vertical scanning period.

According to the present invention, it is possible to perform live view display with an appropriate exposure time even in a low-luminance environment while suppressing a delay in live view display.

It is an external view of an imaging device. It is a block diagram which shows the structural example of an imaging device. It is a flow chart which shows the control method of an imaging device. 6 is a timing chart showing a control method of the imaging device.

FIG. 1 is an external view showing an imaging device 10 according to an embodiment of the present invention. The connector 112 connects the connection cable and the imaging device 10. The recording medium 20 is a memory card, a hard disk, or the like. The recording medium slot 201 is a slot for storing the recording medium 20. The recording medium 20 stored in the recording medium slot 201 can communicate with the imaging device 10. The lid 203 is a lid of the recording medium slot 201. The imaging device 10 is provided with a display unit 13 and an operation unit 14. The image pickup apparatus 10 can be applied to a smartphone, a tablet, an industrial camera, a medical camera, etc., as well as a digital camera and a video camera.

FIG. 2 is a block diagram showing a configuration example of the image pickup apparatus 10. The imaging device 10 includes a CPU (central processing unit) 11, a ROM 12, a display unit 13, an operation unit 14, a DRAM 15, a recording medium interface 16, an imaging unit 17, an image processing circuit 18, an image compression/expansion circuit 19, and an internal bus 30. ..

The CPU 11 controls each processing unit, data flow, and the like described later. The ROM 12 stores a program (firmware) related to the processing procedure of the CPU 11 and various kinds of information. The display unit 13 is a color liquid crystal display device or the like, displays an image, and displays a graphic user interface. The display unit 13 also includes a terminal that outputs a video signal to an external display device such as a television. The operation unit 14 has various buttons such as a release button (SW1/SW2) and a power button for receiving an instruction from a user, a cross key, a control wheel, a mode dial, and the like. When the release button is half-pressed, the switch SW1 is turned on, and when the release button is fully pressed, the switch SW2 is turned on.

The DRAM 15 is used as a work area of the CPU 11 and has a buffer function of temporarily storing image data, display data, image-compressed data, and the like. The CPU 11 writes/reads data to/from the DRAM 15 via the memory controller. Further, the imaging device 10 may be provided with a DMA controller for performing DMA (Direct Memory Access) transfer between each processing unit and the DRAM 15.

The recording medium interface 16 writes and reads image data to and from the recording medium 20 according to an instruction from the CPU 11. The recording medium 20 is a randomly accessible recording medium such as a memory card, an optical disk, or a hard disk, and is attachable to and detachable from the imaging device 10. The CPU 11, the DRAM 15, and the recording medium interface 16 function as recording means for recording still images and moving images, which are captured images, on the recording medium 20.

The image pickup unit 17 has a lens, a diaphragm, a shutter, and an image pickup element such as a CCD sensor or a CMOS sensor, and generates image data of a still image or a moving image by photoelectric conversion. The image processing circuit 18 performs processing such as white balance adjustment and pixel interpolation on the image data generated by the image pickup unit 17, converts the image data into YUV data, and resizes it to an arbitrary size. The image processing circuit 18 also generates display image data to be displayed on the display unit 13 and compression image data to be compressed by the image compression/expansion circuit 19. Further, the image processing circuit 18 obtains the luminance information of the subject for the AE processing and the evaluation value based on the high frequency component of the luminance signal of the subject for the AF processing based on the image data generated by the imaging unit 17. To generate. The AE process is an automatic exposure adjustment process, and the AF process is an automatic focus adjustment process.

The image compression/decompression circuit 19 converts the YUV data into JPEG or H.264. H.264 format image data is compressed to JPEG or H.264. The compressed image data of H.264 format is expanded to YUV data. The CPU 11, the ROM 12, the display unit 13, the operation unit 14, the DRAM 15, the recording medium interface 16, the image pickup unit 17, the image processing circuit 18, and the image compression/expansion circuit 19 communicate with each other via the internal bus 30.

In the present embodiment, the imaging device 10 processes the output of the image for one frame by the imaging unit 17 and the YUV data conversion and the display image data generation by the image processing circuit 18 in parallel. In the imaging apparatus 10, the display unit 13 starts reading the image data for display from the time when the imaging unit 17 starts outputting the image to the time when the output is completed, thereby delaying the display of the live view. Can be shortened and the live view can be displayed in near real time. Further, the imaging device 10 can perform live view display of proper exposure even in a low-luminance environment by lowering the imaging frame rate of the imaging unit 17 and extending the exposure time of the imaging unit 17 when the brightness is low.

FIG. 3 is a flowchart showing the control method of the image pickup apparatus 10 according to the present embodiment. The CPU 11 controls each unit so as to realize the processing shown in FIG. When the start-up of the imaging device 10 or the transition from the reproduction mode or the like to the imaging mode is instructed by the operation of the power button or the mode dial of the operation unit 14, the imaging device 10 starts the process illustrated in FIG. 3.

In step S101, the CPU 11 controls the vertical synchronization signal of the image pickup unit 17, which is the drive timing of the image pickup unit 17, and the vertical synchronization signal of the display unit 13, which is the drive timing of the display unit 13, to have a predetermined phase difference. Then, driving of the image pickup unit 17 for live view is started. The CPU 11 controls the image pickup unit 17 and the display unit 13 so that the display unit 13 starts reading the image data for display before the image pickup unit 17 starts outputting the image for one frame and before the output is completed. The driving of the image pickup unit 17 is started by synchronizing the vertical synchronization signal with a predetermined phase difference. The predetermined phase difference is a reference phase difference. By doing so, the image pickup apparatus 10 can reduce the delay from the image pickup by the image pickup unit 17 to the display of the live view based on the image, and can perform live view display almost in real time.

Next, in step S<b>102, the CPU (exposure time determination unit) 11 performs AE processing based on the image data output by the imaging unit 17, and determines the exposure time Exp_cur of the imaging unit 17. Specifically, the CPU 11 uses the image processing circuit 18 to obtain the luminance information of the subject based on the image data captured by the image capturing unit 17, performs a predetermined calculation so that the subject has an appropriate luminance, and captures the image. The exposure time Exp_cur of the unit 17 is determined. Further, since the image data captured by the image capturing unit 17 does not exist in the first frame when the live view is started, the CPU 11 sets the exposure time Exp_cur of the initial value.

In step S103, when the switch SW1 is turned on by half-pressing the release button of the operation unit 14, the CPU 11 is in the AF process (autofocus process) as the still image shooting preparation process started by using the switch SW1 as a trigger. Determine whether. In the AF process, the CPU 11 obtains an evaluation value based on the high frequency component of the luminance signal of the subject using the image processing circuit 18 based on the image data picked up by the image pickup unit 17. Then, the CPU 11 obtains an evaluation value over a plurality of frames over the entire range of the AF process while moving the focus lens of the imaging unit 17, and determines the lens position having the maximum evaluation value as the focus position. The focus lens of the image pickup unit 17 is moved to the in-focus position.

In step S103, when it is determined that the AF process is being performed, the CPU 11 advances the process to step S104. In step S104, the CPU 11 determines whether or not the exposure time Exp_cur determined in step S102 is longer than the length T of the reference value of the 1 V period (1 vertical scanning period) of the imaging unit 17. That is, the CPU 11 determines whether Exp_cur>T. For example, when the reference value of the frame rate of the imaging unit 17 is 60 fps (frames/second), the length T of the reference value of the 1V period is T=1/60 seconds. The length T of the reference value of the 1V period is one frame time.

In step S104, when the CPU 11 determines that the exposure time Exp_cur is longer than the length T of the reference value of the 1V period, the CPU 11 advances the process to step S105. In step S105, the CPU (first period setting unit) 11 sets the length V_cur of the 1V period of the imaging unit 17 as the shortest settable 1V period in which the exposure time Exp_cur determined in step S102 falls. Set. For example, the CPU 11 adjusts the length V_cur of the 1V period in units of the length of the 1H period (1 horizontal scanning period) shorter than the length T of the reference value of the 1V period. In the CPU 11, the length V_cur of the 1V period is the exposure time or longer (exposure time Exp_cur or longer), and the length V_cur of the 1V period is the shortest length unit of the length of the 1H period (1 horizontal scanning period). As described above, the length V_cur of the 1V period is set. For example, when the exposure time Exp_cur determined in step S102 is 1/50 second, the 1V period length V_cur is also about 1/50 second.

When it is determined in step S104 that the exposure time Exp_cur is equal to or less than the reference value length T of the 1V period (equal to or less than the reference value), the process proceeds to step S106. In step S106, the CPU (fourth period setting unit) 11 sets the length V_cur of the 1V period of the imaging unit 17 to the same length (V_cur=T) as the length T of the reference value of the 1V period. As a result, during the AF processing, the CPU 11 obtains the evaluation value based on the high frequency component of the luminance signal of the subject from the image data captured by the image capturing unit 17, and the length V_cur of the 1V period corresponding to the exposure time Exp_cur. Can be acquired at the imaging frame rate of. Therefore, even when the exposure time Exp_cur of the imaging unit 17 is set longer than the length T of the reference value of the 1V period so that the low-luminance subject has an appropriate brightness, the acquisition time of the evaluation value for AF processing is longer than necessary. The AF processing time can be shortened without extension.

When it is determined in step S103 that the AF process is not in progress, the CPU 11 advances the process to step S107. In step S107, the CPU 11 determines that the phase difference between the vertical synchronization signal of the image pickup unit 17, which is the drive timing of the image pickup unit 17, and the vertical synchronization signal of the display unit 13, which is the drive timing of the display unit 13, is a predetermined amount (reference phase difference). Or not. Specifically, the CPU 11 adjusts the length V_cur of the 1V period according to the exposure time Exp_cur during the AF process, so that the phase difference between the vertical synchronization signals of the imaging unit 17 and the display unit 13 starts live view. It is determined whether or not there is a deviation from the optimum phase difference at the time.

When it is determined in step S107 that the phase difference between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 is the predetermined amount, the CPU 11 advances the process to step S108. In step S108, the CPU 11 determines whether the exposure time Exp_cur determined in step S102 is longer than the length T of the reference value of the 1V period (Exp_cur>T). When it is determined that the exposure time Exp_cur is longer than the reference value length T of the 1V period, the CPU 11 advances the process to step S109. In step S109, the CPU (second period setting unit) 11 sets the 1V period length V_cur to the reference value of the 1V period so that the 1V period length V_cur becomes equal to or longer than the exposure time Exp_cur determined in step S102. Is set to an integral multiple of the length T. Specifically, the CPU 11 adjusts the length V_cur of the 1V period in units of the length T of the reference value of the 1V period, and sets V_cur=T×N≧Exp_cur. Here, N is an integer of 2 or more. For example, when the reference value of the frame rate of the imaging unit 17 is 60 fps and the exposure time Exp_cur determined in step S102 is 1/50 seconds, the length V_cur of the 1V period is 1/60×2=1/30. Seconds.

When it is determined in step S108 that the exposure time Exp_cur is equal to or less than the length T of the reference value of the 1V period, the CPU 11 advances the process to step S110. In step S110, the CPU (fourth period setting unit) 11 sets the length V_cur of the 1V period to the same length (V_cur=T) as the length T of the reference value of the 1V period. By doing so, the imaging apparatus 10 shortens the delay from the imaging by the imaging unit 17 to the display of the live view based on the image when the AF processing is not in progress, and displays the live view in almost real time. be able to. In addition, the imaging apparatus 10 similarly makes a live view almost in real time even when the exposure time Exp_cur of the imaging unit 17 is made longer than the reference value length T of the 1V period so that the low-luminance subject has an appropriate brightness. Can be displayed.

When it is determined in step S107 that the phase difference between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 is not the predetermined amount (reference phase difference), the CPU 11 advances the process to step S111. In step S111, the CPU 11 sets the length V_cur of the 1V period to be the exposure time Exp_cur or more and sets the phase difference between the vertical synchronization signals of the imaging unit 17 and the display unit 13 to be the optimum reference phase difference at the start of the live view. , The length V_cur of the 1 V period is set. Specifically, the CPU (third period setting unit) 11 sets V_cur=T×N+α≧Exp_cur, and the phase difference between the vertical synchronization signals of the imaging unit 17 and the display unit 13 is optimal at the start of live view. Α is adjusted so that the phase difference becomes as large as possible, and the length V_cur of the 1V period is set. Here, N is an integer of 1 or more. The imaging device 10 sets the exposure time Exp_cur of the imaging unit 17 longer than the length T of the reference value of the 1V period so that the brightness subject has an appropriate brightness during the AF process. As a result, the phase difference between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 is no longer optimal, but the image pickup apparatus 10 can restore the optimum phase after the AF process.

Next, in step S112, the CPU 11 reads out an image captured by the image capturing unit 17 based on the exposure time Exp_cur determined in step S102 as a moving image frame with a frame time of a length V_cur of 1V period. The image capturing unit 17 captures an image of each frame according to the exposure time Exp_cur, and outputs the captured image of each frame to the CPU 11 one frame at a time of V_cur of 1V period.

Next, in step S113, the CPU 11 uses the image processing circuit 18 to perform processing such as white balance adjustment and pixel interpolation on the image data of the moving image frame read in step S112, and converts it into YUV data. Then, the data is written in the DRAM 15.

Next, in step S114, the CPU 11 determines that the phase difference between the vertical synchronization signal of the image pickup unit 17 that is the drive timing of the image pickup unit 17 and the vertical synchronization signal of the display unit 13 that is the drive timing of the display unit 13 is a predetermined amount (reference Phase difference) or more. When it is determined in step S114 that the phase difference between the vertical synchronization signals of the imaging unit 17 and the display unit 13 is less than the predetermined amount (less than the reference phase difference), the CPU 11 advances the process to step S115. In step S115, the CPU (display image generation unit) 11 performs resizing processing or the like on the image data generated in step S113 using the image processing circuit 18, generates display image data, and displays the display image. Data is written in the DRAM (memory) 15. After the generation of the display image data is completed, in step S116, the CPU 11 sets the read address of the DRAM 15 from which the display unit 13 reads the display image data so that the display unit 13 displays the display image data generated in step S115. Update. The display unit 13 is, for example, an electronic viewfinder.

In step S114, when the CPU 11 determines that the phase difference between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 is equal to or more than a predetermined amount (equal to or more than the reference phase difference), the process proceeds to step S117. In step S117, the CPU 11 updates the read address of the DRAM 15 from which the display unit 13 reads the display image data so that the display unit (electronic viewfinder) 13 displays the display image data generated in step S115. Next, in step S118, the CPU (display image generation unit) 11 uses the image processing circuit 18 to resize the image data generated in step S113 to a display size, and displays the image data. Image data is generated and the display image data is written in the DRAM 15.

Here, the moving image frame reading in step S112, the YUV data conversion in step S113, and the display image data generation in step S115 or step S118 are processed in parallel. Further, in step S117, the CPU 11 updates the read address of the display image data in the DRAM 15 in order to display the display image data on the display unit 13 before or during the generation of the display image data in step S118. By doing so, in the imaging device 10, the display unit 13 can start reading the display-image data from when the imaging unit 17 starts outputting the image for one frame to before the output is completed. Live view can be displayed in near real time.

Next, in step S119, the CPU 11 determines whether or not an instruction to stop the live view such as termination of the imaging device 10 or transition to the reproduction mode is made by operating the power button or the mode dial of the operation unit 14. To do. When it is determined that the stop of the live view is instructed, the CPU 11 stops the live view and ends the process. When it is determined that the live view stop is not instructed, the CPU 11 returns the process to step S102 and continues the process of the next frame.

FIG. 4 is a timing chart showing the control method of the imaging device 10 according to the present embodiment. Hereinafter, the live view display of the imaging device 10 will be described. The 1V period length 101 is the 1V period length V_cur of each frame. The exposure time 102 is the exposure time Exp_cur of each frame. The phase difference 103 is the phase difference between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 in each frame. Timing 104 is a display address update timing in each frame.

The 1V period length V_N is the length of the 1V period in the Nth frame. The exposure time Exp_N is the exposure time in the Nth frame. The phase difference t_N is the phase difference between the vertical synchronization signals of the imaging unit 17 and the display unit 13 in the Nth frame.

In the first frame, the exposure time Exp_1 is equal to or less than the length T of the reference value in the 1V period (Exp_1≦T). The length V_1 of the 1V period of the first frame is the same as the length T of the reference value of the 1V period (V_1=T).

In the second frame, the exposure time Exp_2 is longer than the length T of the reference value in the 1V period (Exp_2>T). At this time, since the AF process is not in progress, the length V_2 of the 1V period of the second frame is adjusted in units of the length T of the reference value of the 1V period, and is twice the length T of the reference value of the 1V period (V_2 = 2T).

Further, the phase differences t_1 and t_2 between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 in the first frame and the second frame are the same as the predetermined phase difference t at the start of live view (t_1=t, t_2= t). Therefore, in the first frame and the second frame, the display address is updated at the timing 104 before the generation of the display image data. As a result, the delay until the live view is displayed is short, and the live view is displayed almost in real time.

In the third frame, as in the second frame, the exposure time Exp_3 is longer than the length T of the reference value in the 1V period (Exp_3>T). In the third frame, since the AF process is being performed, the length V_3 of the 1V period of the third frame is adjusted by a unit shorter than the length T of the reference value of the 1V period, and is set to be the exposure time Exp_3 or more. (V_3≧Exp_3).

The same applies to the fourth frame to the seventh frame. Further, the phase difference between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 in the third frame to the seventh frame is represented by t_3 to t_7. In the fourth and fifth frames, the phase differences t_4 and t_5 between the vertical synchronization signals of the imaging unit 17 and the display unit 13 are equal to or larger than the predetermined phase difference t at the start of live view (t_4≧t, t_5≧t). The display address is updated at the timing 104 before the generation of the display image data.

In the third, sixth, and seventh frames, the phase differences t_3, t_6, and t_7 are less than the predetermined phase difference t at the start of live view (t_3<t, t_6<t, t_7<t), so the display address is The update is performed at the timing 104 after the generation of the display image data is completed. Therefore, by adjusting the length V_N of the 1V period according to the exposure time Exp_N during the AF process, the phase difference t_N between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 is not the predetermined phase difference t. Even if the proper live view is displayed.

The eighth frame is the first frame after the AF process is completed, and the phase difference t_8 between the vertical synchronization signals of the image pickup unit 17 and the display unit 13 becomes the same as the predetermined phase difference t at the start of live view (t_8=t). So that the length of the 1V period is V_8=T+α.

As described above, during the AF process, even when the exposure time of the image pickup unit 17 is set longer than the length T of the reference value of the 1V period so that the low-luminance subject has an appropriate brightness, the evaluation value for the AF process is obtained. Therefore, the AF processing time can be shortened without unnecessarily increasing the acquisition time of. Further, when the AF process is not being performed, the delay from the image pickup by the image pickup unit 17 to the display of the live view based on the image can be shortened, and the live view display can be performed almost in real time.

According to the present embodiment, while suppressing the time required for the processing based on the evaluation value generated from the captured image data such as the AF processing and the delay of the live view display, the live view with the proper exposure can be performed even in the low brightness environment. Can be displayed.

It should be noted that each of the above-described embodiments is merely an example of an embodiment for carrying out the present invention, and the technical scope of the present invention should not be limitedly interpreted by these. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

10: image pickup device, 11: CPU (central processing unit), 12: ROM, 13: display unit, 14: operation unit, 15: DRAM, 16: recording medium I/F, 17: image pickup unit, 18: image processing circuit , 19: image compression/expansion circuit, 20: recording medium, 30: internal bus

Claims (7)

An image pickup unit for picking up an image of each frame according to the exposure time and outputting the picked-up image of each frame one frame at a time in one vertical scanning period;
An exposure time determining unit that determines an exposure time of the image capturing unit based on the image output by the image capturing unit;
If the exposure time determined by the exposure time determination unit is longer than the reference value for one vertical scanning period, and if the first state in which a predetermined evaluation value is acquired from the image output by the imaging unit, One vertical scanning period of the image capturing unit is set in units of a period shorter than the reference value of the one vertical scanning period so that the one vertical scanning period of the image capturing unit is equal to or longer than the exposure time, and is output by the image capturing unit. In the second state in which the predetermined evaluation value is not acquired from the image, the one vertical scanning period of the imaging unit is set to the one vertical scanning period so that the one vertical scanning period of the imaging unit is equal to or longer than the exposure time. And a period setting unit that sets an integer multiple of the reference value of 1. The image pickup apparatus according to claim 1, wherein the predetermined evaluation value is an evaluation value used for autofocus. The image pickup apparatus according to claim 1, wherein the unit of the period shorter than the reference value of the one vertical scanning period is a unit of one horizontal scanning period. The period setting unit is in the second state, and when the phase difference between the vertical synchronization signal of the image pickup unit and the vertical synchronization signal of the display unit is not the reference phase difference, The image pickup apparatus according to claim 3, wherein one vertical scanning period of the image pickup unit is set such that a phase difference between the display unit and a vertical synchronization signal becomes the reference phase difference. When the exposure time determined by the exposure time determination unit is less than or equal to the reference value of the one vertical scanning period, the period setting unit sets one vertical scanning period of the imaging unit to the reference value of the one vertical scanning period. The image pickup device according to claim 1, wherein the image pickup device is set to have the same length. Furthermore, when the phase difference between the vertical synchronization signal of the image pickup unit and the vertical synchronization signal of the display unit is less than a reference phase difference, a display image is generated based on the image output by the image pickup unit, A display image generation unit that updates the read address of the display image in the memory in order to display the display image on the display unit after writing the display image in the memory and generating the display image. Then
When the phase difference between the vertical synchronization signal of the image pickup unit and the vertical synchronization signal of the display unit is equal to or larger than a reference phase difference, the display image generation unit displays based on the image output by the image pickup unit. Generating a display image, writing the display image in a memory, and before or during the generation of the display image, a read address of the display image in the memory for displaying the display image on a display unit. The imaging apparatus according to claim 1, wherein the imaging apparatus is updated. A control method for an image pickup apparatus having an image pickup section for picking up an image of each frame according to an exposure time and outputting the picked-up image of each frame one frame at a time in a vertical scanning period,
An exposure time determining step of determining an exposure time of the image capturing section by the exposure time determining section based on the image output by the image capturing section;
When the exposure time determined by the period setting unit in the exposure time determining step is longer than a reference value for one vertical scanning period, a first state in which a predetermined evaluation value is acquired from the image output by the imaging unit If so, one vertical scanning period of the image pickup unit is set in units of a period shorter than a reference value of the one vertical scanning period so that one vertical scan period of the image pickup unit is equal to or longer than the exposure time. In the second state in which the predetermined evaluation value is not acquired from the image output by the image pickup unit, one vertical scan period of the image pickup unit is set so that one vertical scan period of the image pickup unit is equal to or longer than the exposure time. And a period setting step of setting an integral multiple of a reference value of the one vertical scanning period.

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