JP2010098416A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device capable of suppressing a flicker caused by a fluorescent lamp and acquiring a moving image with few frames dropped.
An imaging apparatus includes an imaging element, an electronic shutter, an imaging element driving unit, an exposure control unit, a flicker detection unit, and an accumulation time control unit. The imaging element captures a subject image. The electronic shutter has a plurality of shutter functions. The image sensor driving unit causes the image sensor to capture a moving image, and causes the image sensor to capture the flicker detection image using the interval between successive moving image capturing. The exposure control unit sequentially performs exposure control by alternately switching the first shutter speed and the second shutter speed for each predetermined line of the image sensor when capturing the flicker detection image. The flicker detection unit detects the presence or absence of flicker based on the first image captured at the first shutter speed and the second image captured at the second shutter speed. The accumulation time control unit controls the accumulation time of the image sensor for capturing a moving image.
[Selection] Figure 1

Description

  The present invention relates to an imaging apparatus such as an electronic camera.

  Conventionally, in an imaging apparatus including a complementary metal-oxide semiconductor (CMOS) type imaging device, in moving image shooting under a fluorescent lamp, it is caused by a periodic luminance change of the fluorescent lamp (light source) by an AC power supply (50 Hz or 60 Hz). Flicker may occur. For example, it is assumed that rolling shutter control is performed in which a shutter is sequentially released for each line (pixel row) of the image sensor in a live view mode in which a live image of the image sensor is displayed on a liquid crystal monitor. In this case, depending on the balance between the frequency of the AC power supply and the storage time of the image sensor, flicker (luminance unevenness) occurs periodically in one screen.

  Thus, an imaging apparatus that suppresses the flicker has been proposed (see, for example, Patent Document 1).

In the imaging apparatus of Patent Document 1, first, when using a rolling shutter, two images with shutter speeds of 1/100 sec and 1/120 sec are acquired continuously using the interval between successive moving image imaging, and they are common. Compare brightness values of image areas. Subsequently, in this imaging apparatus, when flicker is detected from the comparison result, global shutter control for reading all pixel signals at once is performed. Thereby, the occurrence of flicker is suppressed. (Note that the fluorescent lamp causes a luminance change twice in each cycle of the power supply frequency. In other words, this luminance change is repeated in a cycle corresponding to a frequency twice the power supply frequency. (In the case of / 100 sec and 60 Hz, the cycle is 1/120 sec.)
JP 2007-329658 A

  However, in the imaging apparatus of Patent Document 1, two images are continuously acquired for flicker detection when the rolling shutter is used, which leads to a decrease in the frame rate. Therefore, in the case of a moving subject, there may be a problem that it looks unnatural.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an imaging apparatus that can suppress the occurrence of flicker due to a fluorescent lamp and can acquire a moving image with less frame dropping.

  An image pickup apparatus according to a first invention includes an image pickup device, an electronic shutter, an image pickup device driving unit, an exposure control unit for detecting flicker, a flicker detection unit, and an accumulation time control unit. The imaging element can two-dimensionally arrange a plurality of pixels and perform line reading by addressing. The electronic shutter has a plurality of shutter functions for electronically controlling exposure to the image sensor. The image sensor driving unit causes the image sensor to capture a moving image at a predetermined frame rate, and also detects a flicker detection image for detecting flicker due to a periodic change in luminance of the light source between consecutive moving image capturing. The image sensor is caused to take an image using The flicker detection exposure control unit sequentially switches the exposure between the first shutter speed and the second shutter speed at which the shutter speed of the electronic shutter is different for each predetermined line by address designation when capturing a flicker detection image. To do. The flicker detection unit detects the presence or absence of flicker based on a flicker detection image composed of a first image captured at the first shutter speed and a second image captured at the second shutter speed. The accumulation time control unit controls the accumulation time of the image sensor for capturing a moving image using an electronic shutter according to the detection result of the flicker detection unit.

  In a second aspect based on the first aspect, when the flicker detection unit detects flicker, the accumulation time control unit controls the accumulation time by reading all pixel signals at once.

  In a third aspect based on the first aspect, the accumulation time control unit controls the accumulation time by sequentially releasing the shutter for each line and reading the pixel signal for each line when the flicker detection unit does not detect flicker. To do.

  In a fourth aspect based on the first aspect, when the flicker detection unit detects flicker, the accumulation time control unit calculates the power supply frequency of the light source based on the flicker detection image, and sets the accumulation time as an arbitrary power supply frequency. The accumulation time is controlled by setting an integral multiple and sequentially releasing the shutter for each line and reading the pixel signal for each line.

  In a fifth aspect based on the first aspect, the exposure control unit performs the first shutter speed and the second shutter speed for each predetermined line with respect to the number of readout lines that are pre-addressed and capable of detecting at least flicker. Are alternately switched to sequentially control exposure.

  In a sixth aspect based on any one of the first to fifth aspects, the first shutter speed is n / 100 sec, the second shutter speed is m / 120 sec, and n and m are arbitrary integers. It is.

  According to a seventh aspect of the invention, in any one of the first to sixth aspects, the number of bits of the output signal of the analog / digital conversion is reduced when the flicker detection image is captured as compared with the time when the moving image is captured and output. A bit number control unit is further provided.

  According to the imaging apparatus of the present invention, it is possible to suppress the occurrence of flicker due to a fluorescent lamp and to obtain a moving image with few frames dropped.

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

  FIG. 1 is a block diagram illustrating a configuration of an electronic camera 1 that is an imaging apparatus according to the present embodiment. As shown in FIG. 1, the electronic camera 1 includes a photographing optical system 11, an image sensor 12, a timing generator (TG) 13, an A / D converter 14, a signal processor 15, and a RAM (Random Access Memory). 16, a recording interface (recording I / F) 17, a display unit 18, an operation unit 19, a CPU (Central processing Unit) 20, a ROM (Read Only Memory) 21, and a bus 22. Among them, the signal processing unit 15, the RAM 16, the recording interface (recording I / F) 17, the display unit 18, the CPU 20, and the ROM 21 are connected to each other via a bus 22. The operation unit 19 is connected to the CPU 20.

  The photographic optical system 11 includes a plurality of lens groups including a focus lens and a zoom lens. For the sake of simplicity, FIG. 1 shows the photographing optical system 10 as a single lens.

  The image sensor 12 generates an image by photoelectrically converting a subject image formed on the imaging surface. In the present embodiment, the image sensor 12 uses a CMOS in which a plurality of pixels are two-dimensionally arranged and line reading is possible by address designation.

  The image pickup device 12 selects a global shutter (not shown) that sequentially releases the shutter for each line and reads all pixel signals at once, and a rolling shutter (not shown) that reads the pixel signal for each line. Thus, a subject image is captured. The details of the global shutter and the rolling shutter are the same as those of the known art, and thus the description thereof is omitted.

  The timing generator (TG) 13 sends a drive signal to each of the image sensor 12 and the A / D converter 14 according to an instruction from the CPU 20, thereby controlling the drive timing of both. More specifically, the timing generator (TG) 13 causes the image sensor 12 to capture a moving image at a predetermined frame rate in accordance with an instruction from the CPU 20, and continuously generates flicker detection images for flicker detection. The image pickup device 12 is caused to take an image using the interval between the image pickup operations.

  The A / D converter 14 converts the analog signal generated by the image sensor 12 into a digital signal and outputs the digital signal. The digital signal output from the A / D converter 14 is temporarily stored in the frame memory of the RAM 16 as a moving image or flicker detection image.

  The signal processing unit 15 reads a digital signal (RGB signal distribution) stored in the frame memory of the RAM 16 and performs predetermined signal processing. For example, the signal processing unit 15 converts image data of RGB signals into image data of YC signals represented by luminance (Y) and color (C) as necessary. The reverse conversion is also performed.

  Further, the signal processing unit 15 is provided with an image changeover switch, an image separation circuit, an image subtraction circuit, and a determination circuit (not shown) separately from a circuit used for normal signal processing such as a clamp circuit. .

  The image switching switch is a switch that switches between a moving image read from the RAM 16 and a flicker detection image at a predetermined timing in accordance with an instruction from the CPU 20. When the image changeover switch is set to a moving image, the moving image is sequentially recorded on the recording medium 23 via the bus 22, or the moving image is sequentially displayed on the display unit 18 as a through image.

  On the other hand, when the image changeover switch is set to the flicker detection image, the flicker detection image is sent to the image separation circuit. The image separation circuit separates the flicker detection image into a first image (YC signal image data) captured at the first shutter speed and a second image (YC signal image data) captured at the second shutter speed. .

  The image subtraction circuit calculates a difference in luminance value between the first image and the second image (details will be described later). The determination circuit detects the presence or absence of flicker based on the difference in luminance value between the first image and the second image, and notifies the detection result to a flicker detection unit 20b described later.

  The recording interface (recording I / F) 17 provides a communication interface so that a moving image can be recorded on the recording medium 23.

  The display unit 18 displays an operation menu of the electronic camera 1 and the like. In the live view mode, a live image of the image sensor 12 is displayed.

  The operation unit 19 is a release button, a command dial, or the like, and gives a signal to the CPU 20 in accordance with the content of operation by the user.

  The CPU 20 is a processor that performs overall control of the electronic camera 1. The CPU 20 controls each part of the electronic camera 1 by executing a sequence program stored in advance in the ROM 21. Further, the CPU 20 of this embodiment also functions as an exposure control unit 20a for flicker detection, a flicker detection unit 20b, an accumulation time control unit 20c, and a bit number control unit 20d.

  The exposure control unit 20a sequentially controls exposure by alternately switching the first shutter speed and the second shutter speed for each predetermined line according to the address designation of the image sensor 12 when capturing the flicker detection image. The first shutter speed is n / 100 sec, the second shutter speed is m / 120 sec, and n and m are arbitrary integers. Here, for convenience of explanation, it is assumed that n = 1 and m = 1.

  The flicker detection unit 20b instructs the signal processing unit 15 to perform flicker detection processing using the image separation circuit, the image subtraction circuit, and the determination circuit, and receives the determination result of the determination circuit. The hardware configuration of the flicker detection unit 20b is handled by the signal processing unit 15.

  The accumulation time control unit 20c controls the accumulation time of the image sensor for capturing a moving image via the timing generator (TG) 13 according to the detection result of the flicker detection unit 20b. For example, the accumulation time control unit 20c controls the accumulation time using a global shutter when the flicker detection unit 20b detects flicker.

  The accumulation time control unit 20c controls the accumulation time using a rolling shutter when the flicker detection unit 20b does not detect flicker.

  The bit number control unit 20d outputs an instruction to the A / D conversion unit 14, and reduces the number of bits of the output signal of the A / D conversion unit 14 when capturing a flicker detection image compared to when capturing a moving image. Let

  Next, an operation example in the flicker suppression mode for suppressing flicker in the electronic camera 1 of the present embodiment will be described.

  FIG. 2 is a flowchart illustrating an example of an operation example in the flicker suppression mode. The flowchart shown in FIG. 2 starts when the user sets the flicker suppression mode to ON and selects moving image shooting or live view display.

  Step S101: First, the CPU 20 acquires a moving image. That is, the CPU 20 drives the timing generator (TG) 13 to cause the image sensor 12 to capture a moving image at a predetermined frame rate. Here, when this processing routine starts, it is assumed that a moving image is first picked up by the rolling shutter. In addition, the line reading by the rolling shutter is performed every two lines in consideration of the RGB Bayer arrangement of the image sensor 12.

  Step S102: The CPU 20 acquires a flicker detection image. That is, the CPU 20 drives the timing generator 13 to cause the image sensor 12 to capture the flicker detection image. At this time, the exposure control unit 20a sequentially controls the exposure by alternately switching the first shutter speed and the second shutter speed every two lines by the rolling shutter. Since the frame rate is defined by the frame rate of the moving image, the exposure control unit 20a appropriately adjusts the flicker detection image accumulation time using a blanking time or the like.

  FIG. 3 is a diagram illustrating an example of moving image shooting using flicker detection in the first embodiment. The horizontal direction represents elapsed time, and the vertical direction represents each horizontal line.

  FIG. 3A is a diagram illustrating moving image shooting using a rolling shutter when flicker detection is not performed as a comparative example. As shown in FIG. 3A, images are taken at different times when signal charge accumulation starts for each line direction of the image sensor 12. Then, moving images are sequentially acquired at a predetermined frame rate.

  FIG. 3B shows imaging in the case of flicker detection disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2007-329658) as a comparative example. As shown in FIG. 3B, after acquiring one moving image frame, two images with shutter speeds of 1/100 sec and 1/120 sec are acquired continuously for flicker detection. As described above, since two images are continuously acquired for flicker detection when the rolling shutter is used, the frame rate is lowered. Therefore, in the case of a moving subject, there may be a problem that it looks unnatural.

  FIG. 3C illustrates an example of flicker detection according to the first embodiment of the present invention. As shown in FIG. 3C, after one frame of the moving image is acquired, one flicker detection image is acquired. Here, the bit number control unit 20d performs processing for reducing the number of bits of the output signal of the A / D conversion unit 14 when capturing the flicker detection image compared to when capturing the moving image. Thereby, for example, the A / D converter 14 outputs a 12-bit output signal when capturing a moving image, and outputs an 8-bit output signal when capturing a flicker detection image.

  FIG. 4 is a diagram illustrating an example of capturing the flicker detection image illustrated in FIG. The horizontal direction represents elapsed time, and the vertical direction represents each horizontal line.

  As described above, the exposure control unit 20a controls the rolling shutter by alternately switching the first shutter speed (1/100 sec) and the second shutter speed (1/120 sec) every two lines. That is, under the control of the exposure control unit 20a, images of 1/100 sec and 1/120 sec are alternately captured on one image. 3 (d) and 3 (e) will be described later.

  Step S103: The CPU 20 sends a predetermined timing signal to the signal processing unit 15, and sorts the moving image and the flicker detection image by the image changeover switch. The image separation circuit of the signal processing unit 15 separates the flicker detection image into a first image captured at the first shutter speed (1/100 sec) and a second image captured at the second shutter speed (1/120 sec). To do.

  Step S104: First, the CPU 20 calculates the difference between the luminance values of the first image and the second image. This will be specifically described below.

  FIG. 5 is a diagram conceptually showing the processes of step S103 and step S104. FIG. 5A is an image diagram of the flicker detection image 100. FIG. 5B is an image diagram of the first image 101 captured at the first shutter speed (1/100 sec) and the second image 102 captured at the second shutter speed (1/120 sec). In the figure, solid lines and dotted lines represent flicker components. Here, the dotted line portion represents a line with a thick flicker component, and the solid line represents a line with a thin flicker component.

  As shown in FIGS. 5A and 5B, the first image 101 and the second image 102 are compressed images captured with half the number of lines as compared to the flicker detection image 100.

  As an example, a case where imaging is performed under a 50 Hz fluorescent lamp is assumed. For example, when the accumulation time of the image sensor 12 is the first shutter speed (1/100 sec), this accumulation time is an integral multiple (1 time) of the frequency twice the power supply frequency (1/100 sec). Therefore, the accumulated brightness (luminance) is constant for each line. Therefore, no flicker occurs.

  On the other hand, when the accumulation time of the image sensor 12 is the second shutter speed (1/120 sec), this accumulation time does not become an integral multiple of twice the power supply frequency (1/100 sec). Accordingly, the accumulated brightness (brightness) is not constant for each line, and a light and dark stripe pattern is generated as flicker (brightness unevenness).

  Therefore, the image subtraction circuit of the signal processing unit 15 extracts the flicker by taking the difference between the first image 101 and the second image 102. FIG. 5C shows an image 103 from which flicker is extracted. Further details will be described with reference to FIG.

  FIG. 6 is a diagram for explaining the flow of flicker extraction. The horizontal axis represents lines, and the vertical axis represents the luminance value for each line.

  FIG. 6A shows the case of an image when there is flicker (second image 102). FIG. 6B shows an image (first image 101) when there is no flicker. Here, the image subtraction circuit of the signal processing unit 15 calculates the difference between the luminance value in the line direction of the second image 102 and the luminance value in the line direction of the first image 101. In this case, for example, a luminance value is obtained for each pixel of the line, and a difference between the average values is calculated. Since a difference between two images having different exposure times is taken, correction such as increasing the gain is performed on an image having a short exposure time. If both the first image 101 and the second image 102 are dark, the gain is appropriately increased so that flicker can be detected.

  FIG. 6C shows a state after the difference is calculated. The determination circuit of the signal processing unit 15 determines that flicker exists if the difference value is greater than or equal to a certain value. The above-described flicker detection method is an example, and is not limited to the above-described method.

  In this way, the flicker detection unit 20b receives the determination result of the determination circuit of the signal processing unit 15. If there is flicker (step S104: Yes), the processing routine proceeds to step S105.

  Step S105: The accumulation time control unit 20c of the CPU 20 issues an instruction to the timing generator (TG) 13 and performs all pixel collective reset processing using a global shutter. As shown in FIG. 3D, the accumulation time control unit 20c switches from the rolling shutter to the global shutter. Then, the processing routine proceeds to step S107.

  Step S107: The CPU 20 determines the presence / absence of a shooting end command based on a user input. If the photographing end command is not accepted (step S107: No), the process returns to step S101. On the other hand, when the photographing end command is received (step S107: Yes), this processing routine ends.

  On the other hand, if there is no flicker in step S104 (step S104: No), the processing routine proceeds to step S106.

  Step S106: The accumulation time control unit 20c issues an instruction to the timing generator (TG) 13 and performs a reset process for each line by the rolling shutter. In this case, the state of FIG. 3C continues continuously.

  In this way, in the acquisition of moving images, the accumulation time control unit 20c appropriately switches between the global shutter and the rolling shutter according to the presence or absence of flicker. FIG. 3E shows a state in which, after switching to the global shutter, flicker is not detected, so that switching to the rolling shutter is performed again. This is applied, for example, when the illumination is changed from a fluorescent lamp to tungsten light while shooting a moving image under a fluorescent lamp. In addition, for example, the present invention is applied to a case where a subject moves out of the room into the garden while shooting a moving image under sunlight, while shooting a moving image of the subject in the room under a fluorescent lamp.

  As described above, according to the electronic camera 1 of the first embodiment, it is possible to suppress the occurrence of flicker due to a fluorescent lamp and to acquire a moving image with few frames dropped. Further, according to the electronic camera 1 of the first embodiment, the bit number control unit 20d compares the number of bits of the output signal of the A / D conversion unit 14 when capturing a flicker detection image as compared to when capturing a moving image. Since the output is reduced, the data processing speed can be increased.

The flicker detection unit 20b determines the presence / absence of flicker detection with an image of one frame. For example, when flicker is detected continuously for three frames, the accumulation time control unit 20c switches from the rolling shutter to the global shutter. It may be. That is, the number of frames used for flicker detection may be set arbitrarily.
(First modification)
Next, a first modification will be described. In the first modification, the CPU 20 captures a flicker detection image with a rolling shutter using a window detection function for reading a predetermined number of lines by addressing. Specifically, the exposure control unit 20a sets a first shutter speed and a second shutter speed, which have different shutter speeds, for each predetermined line with respect to the number of readout lines addressed in advance at which flicker can be detected at least. The exposure is sequentially controlled by switching alternately.

  FIG. 7 is a diagram illustrating an example of the window reading function. FIG. 7 shows a moving image (one frame) captured at a shutter speed n / 100 sec, for example. In this case, as described above, flicker does not occur under a 50 Hz fluorescent lamp. However, flickering occurs under a 60 Hz fluorescent lamp. In FIG. 7, the dotted line portion represents a dark line with a flicker component, and the solid line represents a thin line with a flicker component. As described above, a plurality of flickers occur in one screen according to the frame rate at the time of moving image shooting.

  Therefore, when detecting the presence or absence of flicker, it is understood that it is sufficient to image at least the number of lines that can detect flicker using the window reading function, without imaging one screen.

  Therefore, in step S102 shown in FIG. 2, the flicker detection image is not captured for one screen but is captured for at least the number of lines where the flicker can be detected. The number of lines varies depending on the frequency of the fluorescent lamp and the frame rate, but can be calculated by a known method.

  Then, the flicker detection unit 20b captures the flicker detection image captured with at least the number of lines capable of detecting flicker at the first shutter speed (1/100 sec) and the second shutter speed (1/120 sec). After being divided into captured images, the presence or absence of flicker is detected based on the difference in luminance values.

  FIG. 8 is a diagram illustrating an example of moving image shooting using flicker detection in the first modification. The horizontal direction represents elapsed time, and the vertical direction represents each horizontal line.

  As shown in FIG. 8A, after one frame of a moving image is captured, a flicker detection image in which at least the number of lines capable of detecting flicker is captured is captured. Here, when flicker is detected, as shown in FIG. 8B, the accumulation time control unit 20c switches to the global shutter. Further, when flicker is not detected thereafter, the accumulation time control unit 20c switches to the rolling shutter as shown in FIG.

  As described above, according to the electronic camera 1 of the first modification, flicker can be detected by shortening the imaging time of the flicker detection image, so that the frame rate is higher than that of the electronic camera 1 of the first embodiment. It is possible to raise. Therefore, even in the first modified electronic camera 1, it is possible to suppress the occurrence of flicker due to a fluorescent lamp and obtain a moving image with few frames dropped.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment of the present invention and the second embodiment of the present invention, the same elements are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, when the flicker detection unit 20b detects flicker, first, the accumulation time control unit 20c calculates the power supply frequency of the fluorescent lamp based on the flicker detection image. Subsequently, the accumulation time control unit 20c is characterized in that the accumulation time is set to an arbitrary integer multiple of the power supply frequency and the accumulation time is controlled by a rolling shutter.

  FIG. 9 is a diagram illustrating an example of moving image shooting using flicker detection in the second embodiment. The horizontal direction represents elapsed time, and the vertical direction represents each horizontal line.

  In order to make the explanation easy to understand, it is assumed that a moving image is shot at an integer multiple of the second shutter speed (1/120 sec) under a 50 Hz fluorescent lamp. In this case, under a 50 Hz fluorescent lamp, flicker is generated in the second image captured at 1/120 sec in the flicker detection image. In this case, in the difference image obtained by taking the difference between the first image and the second image, the density of the flicker component changes periodically, so that the power supply frequency can be calculated from this cycle. That is, in this example, the power supply frequency is 50 Hz.

  Therefore, as shown in FIG. 9, when moving image shooting is performed by switching the shutter speed of moving image shooting to an integral multiple of the first shutter speed (1/100 sec), flicker does not appear in the frame of the moving image.

  As described above, according to the electronic camera 1 of the second embodiment, the power supply frequency of the fluorescent lamp can be calculated from the flicker detection image. As a result, in the electronic camera 1, if the accumulation time for capturing moving images is set to an integral multiple of the power supply frequency of the fluorescent lamp, there is no need to switch to the global shutter when flicker is detected. It becomes possible to raise compared to the camera 1. Therefore, also in the electronic camera 1 of the second embodiment, it is possible to suppress the occurrence of flicker due to a fluorescent lamp and to acquire a moving image with few frames dropped.

1 is a block diagram illustrating a configuration of an electronic camera 1 that is an imaging apparatus according to an embodiment. A flowchart showing an example of an operation example in the flicker suppression mode The figure which shows an example of the video recording using the flicker detection in 1st Embodiment. The figure which shows an example of imaging of the flicker detection image shown in FIG.3 (c). The figure which shows the process of step S103 and step S104 notionally Diagram explaining the flow of flicker extraction The figure explaining an example of a window reading function The figure which shows an example of the video recording using the flicker detection in a 1st modification. The figure which shows an example of the video recording using the flicker detection in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic camera, 12 ... Image sensor, 15 ... Signal processing part, 20a ... Exposure control part, 20b ... Flicker detection part, 20c .... Accumulation time control part, 20d ... Bit number control part

Claims (7)

An image sensor that two-dimensionally arranges a plurality of pixels and can read a line by addressing;
An electronic shutter having a plurality of shutter functions for electronically controlling exposure to the image sensor;
A flicker detection image for detecting a flicker caused by a periodic change in luminance of a light source is captured using the interval between successive capturing of the moving image while causing the image sensor to capture a moving image at a predetermined frame rate An image sensor driving unit that causes the image sensor to image;
At the time of capturing the flicker detection image, the first shutter speed and the second shutter speed at which the shutter speed of the electronic shutter is different are alternately switched for each predetermined line by the address designation to sequentially perform exposure control. An exposure control unit;
A flicker detection unit that detects the presence or absence of the flicker based on the flicker detection image composed of the first image captured at the first shutter speed and the second image captured at the second shutter speed;
An accumulation time control unit that controls an accumulation time of the image sensor for capturing the moving image by the electronic shutter according to a detection result of the flicker detection unit;
An imaging apparatus comprising: The imaging device according to claim 1,
The image pickup apparatus, wherein the accumulation time control unit controls the accumulation time by reading all pixel signals at once when the flicker detection unit detects the flicker. The imaging device according to claim 1,
The accumulation time control unit controls the accumulation time by sequentially releasing a shutter for each line and reading a pixel signal for each line when the flicker detection unit does not detect the flicker. Imaging device.   When the flicker detection unit detects the flicker, the accumulation time control unit calculates a power frequency of the light source based on the flicker detection image, and sets the accumulation time to an arbitrary integer multiple of the power frequency. In addition, the accumulation time is controlled by sequentially releasing the shutter for each line and reading the pixel signal for each line. The imaging device according to claim 1,
The exposure control unit alternately switches the first shutter speed and the second shutter speed for each predetermined line with respect to the number of readout lines that are pre-addressed and capable of detecting at least the flicker. An image pickup apparatus that performs sequential exposure control. In the imaging device according to any one of claims 1 to 5,
The first shutter speed is n / 100 sec, the second shutter speed is m / 120 sec, and the n and the m are arbitrary integers. The imaging apparatus according to any one of claims 1 to 6,
An image pickup apparatus, further comprising: a bit number control unit configured to reduce and output the number of bits of an output signal of analog / digital conversion when a flicker detection image is captured compared to when capturing a moving image.

Images