JP2013026662A - Imaging apparatus and imaging apparatus control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a release time lag while keeping accuracy of a correction signal for removing fixed pattern noise, even in an imaging apparatus configured to simultaneously reset electric charges of plural pixels.SOLUTION: The imaging apparatus performs simultaneous reset of the electric charges stored in the plural pixels 203 in a region including an aperture pixel part 220 of an imaging device 14 (a state of plural-pixel simultaneous reset 502). After the completion of this, the imaging apparatus simultaneously starts reading of the image signals of light-shielded pixels 203 (a correction data reading state 503) and storing of electric charges in the other pixels 203 (a storing state 504) and performs them in parallel.

Description

  The present invention relates to an imaging apparatus and an imaging apparatus control method, and is particularly suitable for use in removing fixed pattern noise.

  In the imaging device, an imaging device such as a CMOS is used. In the CMOS image sensor, the peripheral circuit can be on-chip. Therefore, a technique for realizing an on-chip amplifier circuit for each column and a technique for realizing a high S / N ratio for each column have been proposed. In this CMOS image sensor, a difference in characteristics occurs in each on-chip circuit due to variations in manufacturing processes and the like, and fixed pattern noise occurs in a captured image. If the characteristics of the amplifier circuits on-chip for each column are varied, vertical streaky fixed pattern noise appears in the captured image. Therefore, it is necessary to remove the fixed pattern noise and obtain a good image.

  Further, in the imaging apparatus, when the release button is operated, an exposure operation is performed to capture a still image. The period from when the shutter button is operated until the start of exposure (release) is called the release time lag. If the release time lag is long, an image of a scene at a point later than the scene intended by the user is recorded. For this reason, it is desirable that the release time lag is short.

  In order to achieve both the removal of the fixed pattern noise and the reduction of the release time lag, Patent Document 1 detects correction data for each column from an unexposed image, stores it in a memory, and stores the memory from the exposed image. The correction data stored in is subtracted. Further, when the correction data is acquired, it is necessary to remove random noise such as amplifier noise. In order to remove this random noise, it is necessary to acquire an unexposed image a plurality of times. In this regard, in Patent Document 1, in order to shorten the release time lag, the number of readings and the accumulation time are controlled according to the shooting conditions.

  In Patent Document 2, in order to correct the above-mentioned vertical streak-like fixed pattern noise (column noise) without using pixels of the image sensor, the output from the pixels of the image sensor to the vertical output line is stopped, and column noise is acquired. Perform the action. Since signals are not read from the pixels in this column noise acquisition operation, the state of the image sensor can be changed to the accumulation state for the exposure operation, and the release time lag can be shortened.

JP 2003-1116064 A JP 2010-28676 A

However, as in Patent Document 1, in order to remove fixed pattern noise such as column noise, detection of correction data for each column and accumulation of aperture images are performed at different timings from an unexposed image. This makes it difficult to reduce the release time lag.
In Patent Document 2, there is no description of an operation for simultaneously resetting a plurality of pixels, which is performed before the opening image accumulation operation. If the fixed pattern noise detection operation for removing the fixed pattern noise is performed at the same timing as the operation of simultaneously resetting the plurality of pixels, the fluctuation of the power source becomes large. For this reason, the accuracy of the correction data obtained by detecting the fixed pattern noise may be deteriorated.
The present invention has been made in view of such problems, and in an imaging apparatus configured to simultaneously reset the charges of a plurality of pixels, while maintaining the accuracy of a correction signal for removing fixed pattern noise. The purpose is to shorten the release time lag.

An imaging device according to the present invention includes an imaging device having a plurality of pixels arranged in a two-dimensional matrix, a charge accumulation operation in the plurality of pixels after simultaneously resetting the plurality of pixels, And control means for controlling to perform a correction signal reading operation for reading a correction signal for correcting the fixed pattern noise from the image sensor in parallel.
According to another aspect of the present invention, there is provided a control method for an image pickup apparatus including an image pickup device having a plurality of pixels arranged in a two-dimensional matrix, wherein the plurality of pixels are simultaneously reset. A correction signal reading step for reading a correction signal for correcting the fixed pattern noise of the image pickup device from the image pickup device, a charge storage step for storing charges in the plurality of pixels, and a charge storage step. An image signal readout step of reading out the generated charges as an image signal, and simultaneously resetting the plurality of pixels by the reset step and then performing the charge accumulation step and the correction signal readout control step in parallel. It is characterized by that.

  According to the present invention, even in an imaging apparatus configured to simultaneously reset the charges of a plurality of pixels, the release time lag can be shortened while maintaining the accuracy of a correction signal for removing fixed pattern noise.

It is a figure which shows the structure of an imaging device. It is a figure which shows the structure of an image pick-up element. It is a figure which shows the structure of a pixel. It is a figure which shows fixed pattern noise. It is a figure explaining the drive sequence of the image pick-up element of 1st Embodiment. 3 is a flowchart for explaining the operation of the imaging apparatus according to the first embodiment. It is a figure which shows the structure of a pixel and its periphery. It is a flowchart explaining operation | movement of the imaging device of 2nd Embodiment. It is a figure explaining the drive sequence of the image pick-up element of 3rd Embodiment. 10 is a flowchart for explaining the operation of the imaging apparatus according to the third embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, the first embodiment will be described.
FIG. 1 is a block diagram illustrating an example of the configuration of the imaging apparatus.
In the present embodiment, the imaging apparatus includes an image processing apparatus 100, a recording medium 200 such as a memory card or a hard disk, and a lens unit 300. Details of these blocks will be described.

First, the inside of the image processing apparatus 100 will be described.
The shutter 12 controls the exposure amount. The image sensor 14 converts the optical image into an electrical signal. The image sensor 14 is, for example, a CMOS image sensor. The A / D converter 16 converts the analog signal output from the image sensor 14 into a digital signal.
The timing generation circuit 18 is a circuit that supplies a clock signal and a control signal to the image sensor 14, the A / D converter 16, and the D / A converter 26, and is controlled by the system control circuit 50. The timing generation circuit 18 includes a multiple pixel simultaneous reset control circuit 1801, a first correction readout control circuit 1802, an accumulation control circuit 1803, an image readout control circuit 1804, and a second correction readout control circuit 1805. . In the present embodiment, the second correction reading control circuit 1805 is not used.

The image processing / correction circuit 22 performs predetermined correction processing, pixel interpolation processing, and color conversion processing on the data (digital signal) obtained by the A / D converter 16. The image memory 24 stores data (image data) processed by the image processing / correction circuit 22. The D / A converter 26 converts the digital signal output from the image processing / correction circuit 22 into an analog signal.
The image display unit 28 displays a live view image or the like. The image display unit 28 is, for example, a TFT LCD (Liquid Crystal Display). The display image data written in the image memory 24 is displayed on the image display unit 28 via the D / A converter 26.

The compression / decompression circuit 32 compresses / decompresses image data.
The system control circuit 50 controls the entire image processing apparatus 100. The system control circuit 50 incorporates a known CPU or the like.
The mode dial switch 60 is a switch for the user to set various function photographing modes. The system control circuit 50 detects the operation state of the mode dial switch 60 and switches and sets the functional shooting mode to any one of the automatic shooting mode, the program shooting mode, the shutter speed priority shooting mode, the aperture priority shooting mode, and the like. It is possible.

The shutter switch (SW2) 64 is a switch operated by the user when shooting. The system control circuit 50 detects the operation state of the shutter switch (SW2) 64 and starts capturing a still image based on the operation state.
The moving image recording / stop switch 67 is a switch operated by the user when recording and stopping a moving image. The system control circuit 50 detects the operation state of the moving image recording / stop switch 67. The system control circuit 50 starts moving image recording when the moving image recording / stop switch 67 is pressed, and stops moving image recording when the moving image recording / stop switch 67 is pressed again.

The ISO sensitivity setting switch 68 is a switch operated by the user when setting the ISO sensitivity. The system control circuit 50 detects the operation state of the ISO sensitivity setting switch 68, and sets the ISO sensitivity by changing the gain setting in the image sensor 14 or the image processing / correction circuit 22 based on the operation state.
The shutter time setting switch 69 is a switch operated by the user when setting the shutter time (time for opening and closing the shutter 12). The system control circuit 50 detects the operation state of the shutter time setting switch 69, and sets the shutter time by changing the opening / closing timing of the shutter 12 based on the operation state.

  The power switch 70 is a switch set by the user when the imaging apparatus is turned on / off. The system control circuit 50 can detect the operation state of the power switch 70 and switch between the power-on and power-off modes of the image processing apparatus 100 based on the operation state. Further, the system control circuit 50 also switches the power-on and power-off modes of various accessory devices such as the lens unit 300 and the recording medium 200 connected to the image processing device 100 based on the operation state of the power switch 70. Is possible.

The 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 system control circuit 50 detects the presence / absence of a battery, the type of battery, and the remaining battery level via the power supply control unit 80, and controls the DC-DC converter based on the detection result. A voltage is supplied to each unit including the recording medium 200 for a necessary period.
The power supply unit 86 includes a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a Li battery, and an AC adapter. The connector 82 is a connector for connecting to the main body side of the image processing apparatus 100. The connector 84 is a connector that connects to the power supply unit 86. The main body of the image processing apparatus 100 and the power supply unit 86 are electrically connected to each other through the connectors 82 and 84.

The interface 90 is an interface with the recording medium 200 such as a memory card or a hard disk. The connector 92 is a connector for connecting to a recording medium such as a memory card or a hard disk.
Light rays from the imaging lens 314 are incident on the optical viewfinder 104 via the mirrors 130 and 132. The optical viewfinder 104 forms an image of incident light when the mirror 130 is on the optical axis. Thereby, the user can confirm the composition of the still image to be shot. The lens mount 106 is a connection part that physically connects the image processing apparatus 100 and the lens unit 300. The interface 120 is an interface for communicating with the lens unit 300 using an electrical signal. The connector 122 is a connector that electrically connects the image processing apparatus 100 to the lens unit 300.

Next, the inside of the lens unit 300 will be described.
The connector 322 is a connector that electrically connects the lens unit 300 to the image processing apparatus 100. The lens control unit 320 receives a signal from the image processing apparatus 100 via the connector 322. Based on this signal, the lens control unit 320 changes the position of the imaging lens 314 on the optical axis and controls the focus. Similarly, the lens control unit 320 receives a signal from the image processing apparatus 100 and controls the size of the diaphragm 312.
Next, the inside of the recording medium 200 will be described.
The recording unit 207 includes a semiconductor memory, a magnetic disk, and the like. The connector 206 connects to the image processing apparatus 100.

Next, an example of the operation of the imaging device when shooting a still image will be described.
First, when the power switch 70 is pressed, the system control circuit 50 turns on the power of the imaging apparatus. When the user presses the shutter switch (SW2) 64 after the power is turned on, the system control circuit 50 controls each unit for still image shooting. For example, the system control circuit 50 changes the position of the imaging lens 314 and the size of the diaphragm 312 via the lens control unit 320 based on settings by the user. Further, the system control circuit 50 moves the mirror 130 so as not to enter the optical path in order to guide the light to the image sensor 14. Furthermore, the system control circuit 50 controls the operation of the shutter 12 so that the shutter 12 opens for a period based on the shutter time setting.

The light beam that has entered the imaging lens 314 is formed as an optical image on the imaging device 14 through the aperture 312, the lens mounts 313 and 106, and the shutter 12. The image sensor 14 converts the imaged light signal into an electrical signal. This electrical signal is converted from an analog signal to a digital signal by the A / D converter 16 in accordance with an instruction from the system control circuit 50. The digital signal is subjected to correction processing and image processing by the image processing / correction circuit 22 and is written in the image memory 24 as image data.
The image data written in the image memory 24 is compressed by the compression / decompression circuit 32 based on an instruction from the system control circuit 50. The compressed image data is recorded in the recording unit 207 via the interface 90 and the connectors 92 and 206.

FIG. 2 is a diagram schematically illustrating an example of the configuration of the image sensor 14. FIG. 2A is a diagram illustrating the entire configuration of the image sensor 14, and FIG. 2B is a diagram illustrating the pixels 203 of the image sensor 14 by type.
In FIG. 2A, the imaging device 14 includes a plurality of pixels 203 arranged in a two-dimensional matrix. Here, a matrix-like vertical arrangement is called a “column”, and a horizontal arrangement is called a “row”. The vertical scanning circuit 202 outputs a signal necessary for reading out charges in each row to the circuit of each pixel 203, and causes the image signal of each pixel to be output to a vertical output line 310 which is an example of a column output line. The image signal of each pixel output to the vertical output line 310 is output to the horizontal scanning circuit 201 via the column circuit 204 connected to each vertical output line 310. The horizontal scanning circuit 201 sequentially outputs the image signals of the pixels 203 for one row in the horizontal direction. In the present embodiment, the image signal reading operation is performed as described above.
Further, as shown in FIG. 2B, the pixel 203 of the image sensor 14 is shielded from light even when the shutter 12 is opened and is not exposed (that is, always shielded from light), and the shutter 12 is opened. It belongs to any one of the aperture pixel portions 220 to be exposed.

FIG. 3 is a diagram illustrating an example of the configuration of the pixel 203 in detail.
Charges generated and stored in the photodiode 304 are stored in the storage capacitor 307 by the operation of the transfer switch 305 based on the transfer control signal 301. The source follower amplifier 308 performs voltage amplification on the signal charge stored in the storage capacitor 307 and converts it to an amplified voltage. In the example shown in FIG. 3, the reset switch 306, the storage capacitor 307, and the source follower amplifier 308 form a floating diffusion amplifier.
The output of the source follower amplifier 308 is connected to the vertical output line 310 under the control of the row selection switch 309 based on the row selection control signal 303. When resetting unnecessary charges stored in the photodiode 304 or the storage capacitor 307, the reset is executed by the control of the reset switch 306 based on the reset control signal 302. The transfer control signal 301, the reset control signal 302, and the row selection control signal 303 are output from the vertical scanning circuit 202 to each row.

FIG. 4 is a diagram illustrating an example of fixed pattern noise of the image sensor.
As in the pixel signal readout procedure described above, the output of the group of pixels 203 is output to the vertical output line 310 connected to each pixel 203 and output to the horizontal scanning circuit 201 via the column circuit 204. Is done. At that time, the image signal of the pixel 203 in each column of one row passes through the vertical output line 310 and the column circuit 204 in each column. From the difference in manufacturing variation of the image sensor 14, all the pixels 203 are shielded and the image signal of each pixel 203 is read out, and the image signal of each pixel 203 is averaged for each column. A difference appears in the average level of the signal. This is called the dark shading level. Correction data is necessary to correct the dark shading level in each column.

For example, the average level of the image signal of each pixel 203 in a specific column y and z of the image sensor 14 shown in FIG. 2 is shown in FIGS. The level is corrected by the A / D converter 16 and the image processing / correction circuit 22 so that the level when the image sensor 14 is shielded from light becomes the target digital value. The target digital value is set as the target black level.
As shown in FIG. 4A, in the y column, the average level (output level) of the image signal of each pixel 203 when all the pixels 203 are shielded from light has a value larger than the target black level. Therefore, as shown in FIG. 4B, a correction level having a value smaller than the target black level is set for the y column. On the other hand, in the z column, as shown in FIG. 4A, the output level has a value smaller than the target black level. Therefore, as shown in FIG. 4B, a correction level having a value larger than the target black level is set for the z column. As described above, correction data is provided so that the corrected output becomes the target black level.
Hereinafter, an example of the operation of the imaging apparatus according to the present embodiment will be described based on the imaging apparatus, the configuration / process of the imaging element, and the phenomenon described with reference to FIGS.

FIG. 5 is a diagram illustrating an example of a driving sequence of the image sensor 14 of the imaging apparatus according to the present embodiment. FIG. 5A shows the driving of the image sensor 14 when the reading of the correction signal for generating the correction data is completed earlier than the charge accumulation in a plurality of pixels for forming an image. It is a figure explaining an example of a sequence. FIG. 5B shows the driving of the image sensor 14 when the accumulation of charges in a plurality of pixels for forming an image ends earlier than the reading of the correction signal for generating the correction data. It is a figure explaining an example of a sequence. In FIG. 5, the horizontal axis indicates time, and each block indicates the state of the image sensor 14. FIG. 6 is a flowchart for explaining an example of the operation of the imaging apparatus when taking a still image.
When the system control circuit 50 detects that the user has pressed the shutter switch 64, the system control circuit 50 places the image sensor 14 in the standby state 501 (step S601).

  Next, the system control circuit 50 completes the necessary setting from the standby state 501 to the multiple pixel simultaneous reset state 502 in which a plurality of pixels of the image sensor 14 are simultaneously reset, in order to acquire a still image, the image sensor 14. Is set to a multiple pixel simultaneous reset state 502. In the multiple pixel simultaneous reset state 502, the system control circuit 50 controls the multiple pixel simultaneous reset control circuit 1801 to execute the following multiple pixel simultaneous reset (step S602). That is, the system control circuit 50 reads the main image by controlling the reset control signal 302 and the transfer control signal 301 of the aperture pixel unit 220 of the image sensor 14. Therefore, the system control circuit 50 collectively resets (removes) unnecessary charges accumulated in the photodiode 304 and the storage capacitor 307 in each of the plurality of pixels. Here, the operation of simultaneously resetting a plurality of pixels is performed on the pixels 203 of the aperture pixel unit 220, but a part or all of the pixels 203 of the optical black pixel unit 210 may be reset together. The multi-pixel simultaneous reset state 502 includes a period during which the power supply after reset is stable.

In the multiple pixel simultaneous reset state 502, the reset switches 306 of all the pixels 203 that perform multiple pixel simultaneous reset (selected) operate, and a large number of charges are moved by resetting the charges. For this reason, the power supply (voltage) is likely to fluctuate. Therefore, it is desirable not to perform an image signal readout operation from the image sensor 14 when performing a multiple pixel simultaneous reset.
When the simultaneous reset of the plurality of pixels is completed and the power supply and the like are stabilized, the system control circuit 50 starts the correction signal readout operation and the charge accumulation operation simultaneously. The correction signal reading operation is an operation of reading a correction signal for correcting the fixed pattern noise of the image sensor 14 in the correction data read state 503 from the image sensor 14. The charge accumulation operation is performed in each of the plurality of pixels of the image sensor 14 in the accumulation state 504.

  In the correction data read state 503, the system control circuit 50 controls the first correction read control circuit 1802 to execute the following processing. The system control circuit 50 converts the charge stored in the storage capacitor 307 of the pixel 203 (optical black pixel unit 210) that is constantly shielded from light into an amplified voltage by the source follower amplifier 308. Then, the system control circuit 50 controls the row selection switch 309 based on the row selection control signal 303 to output the image signal of the pixel 203 to the vertical output line 310. The image signal output to the vertical output line 310 is output to the horizontal scanning circuit 201 via the column circuit 204 connected to each vertical output line 310. The horizontal scanning circuit 201 sequentially outputs image signals for one row in the horizontal direction as correction signals. This operation is repeated as many times as necessary (steps S603 and S604). If there are not as many rows of light-shielded pixels 203 as the number of times required for the investigation, the rows of light-shielded pixels 203 once read may be read repeatedly. When the reading of the correction signal is completed (Yes in step S604), the reading operation is stopped. As shown in FIG. 5A, when reading of the correction signal is completed, if the process of the accumulation state 504 that is executed in parallel with the process of the correction signal read state 503 is continued, the system control is performed. The circuit 50 stops the operation of the first correction readout control circuit 1802.

In the accumulation state 504, the system control circuit 50 controls the accumulation control circuit 1803 to execute the following processing. The system control circuit 50 controls the transfer control signal 301 for the pixels 203 that are not used for processing in the correction signal readout state 503 among the pixels 203 of the image sensor 14 and turns off the transfer switch 305. Then, the system control circuit 50 opens the shutter 12 for the shutter time period set by the user to be in an exposure state, and closes the shutter 12 when this period has elapsed (step S605). When the operation of the shutter 12 is finished (Yes in step S606), the system control circuit 50 controls the accumulation control circuit 1803 to complete the accumulation exposure.
As shown in FIG. 5B, when the correction signal readout state 503 continues even after the accumulation state 504 is completed, it waits in a state where it enters the image readout state 505 (a state in which the processing of the accumulation state 504 is completed). Keep it. Since the accumulation state 504 is a state where no exposure is performed, the accumulation state 504 may be continued.

  When both the processing of the correction signal readout state 503 and the processing of the accumulation state 504 that have been executed in parallel as described above are completed (Yes in step S807), the processing proceeds to the processing of the image readout state 505 ( Step S608). In the image reading state 505, the system control circuit 50 controls the image reading control circuit 1804 to execute the following processing. First, the system control circuit 50 operates the transfer switch 305 based on the transfer control signal 301 to store the charge generated and stored in the photodiode 304 in the storage capacitor 307. The system control circuit 50 converts the charge stored in the storage capacitor 307 into an amplified voltage by the source follower amplifier 308, controls the row selection switch 309 based on the row selection control signal 303, and outputs an image signal based on the charge. Output to the vertical output line 310. The image signal output to the vertical output line 310 is output to the horizontal scanning circuit 201 via the column circuit 204 connected to each vertical output line 310. The horizontal scanning circuit 201 sequentially outputs the image signals for one row in the horizontal direction as captured image signals.

  As described above, in the present embodiment, the process of collectively resetting the charges accumulated in the plurality of pixels 203 in the region including the aperture pixel portion 220 of the image sensor 14 is performed (multiple pixel simultaneous reset state 502). After this is completed, readout of the image signal of the pixel 203 that has been shielded from light (correction data readout state 503) and accumulation of charges in the pixels 203 other than the pixel 203 (accumulation state 504) are started simultaneously. In parallel. Therefore, charge accumulation can be performed without waiting for the reading of the correction data. For this reason, the release time lag can be shortened. Further, the correction data reading state 503 is not performed in the multiple pixel simultaneous reset state 502, whereby accurate correction data can be acquired. Even in an imaging apparatus configured to simultaneously reset the charges of a plurality of pixels, the release time lag can be shortened while maintaining the accuracy of a correction signal (correction data) for removing fixed pattern noise.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment, in the correction signal readout state 503, the image signal of the pixel 203 that is always shielded from light is read out. On the other hand, in the present embodiment, the correction signal is read by fixing (clamping) the vertical output line 310 to a certain potential without reading the image signal from the pixel 203. As described above, the present embodiment and the first embodiment mainly differ in part of the processing in the correction signal readout state 503. Therefore, in the description of the present embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals as those in FIGS.

FIG. 7 is a diagram illustrating an example of the configuration of the pixel 203 and its periphery. FIG. 8 is a flowchart illustrating an example of the operation of the imaging apparatus when capturing a still image.
The system control circuit 50 controls the second correction readout control circuit 1805 to execute the following. First, the system control circuit 50 controls the vertical output line fixed voltage signal 701 to turn on the vertical output line fixed voltage switch 702. The system control circuit 50 outputs the output of the vertical output line 310 to the horizontal scanning circuit 201 via the column circuit 204 as a correction signal in a state where the vertical output line 310 is fixed to a predetermined potential. At this time, reading of the charges accumulated in the pixel 203 is stopped. The horizontal scanning circuit 201 sequentially outputs the image signals for one row in the horizontal direction (step S801). Other operations are the same as those in the first embodiment. In the present embodiment, the first correction read control circuit 1802 is not used.
As described above, in addition to the effects described in the first embodiment, it is necessary to provide the optical black pixel unit 210 in the image sensor 14 in order to obtain the correction signal in the correction signal readout operation. The effect of disappearing is obtained.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the first and second embodiments, reading of the image signal of the pixel 203 that is always shielded (correction signal reading state 503) and accumulation of electric charges for the pixels 203 other than the pixel 203 (accumulation state 504) are performed. Started at the same time. On the other hand, in this embodiment, reading of the image signal of the light-shielded pixel 203 (correction signal reading state 503) is started more than charge accumulation (accumulation state 504) for the pixels 203 other than the pixel 203. Try to delay. As described above, the present embodiment is different from the first and second embodiments mainly in the processing related to the start timing of the image signal reading (correction signal reading state 503) of the pixel 203 that is always shielded from light. Therefore, in the description of the present embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals as those in FIGS.

FIG. 9 is a diagram illustrating an example of a driving sequence of the image sensor 14 of the imaging apparatus according to the present embodiment. FIG. 10 is a flowchart for explaining an example of the operation of the imaging apparatus when capturing a still image.
When the time necessary for reading out the correction signal is known in advance, the system control circuit 50 determines the timing for starting the reading out of the correction signal based on the time and the set accumulation time. At this time, the start timing of the correction signal reading state 503 is set to be later than the start timing of the accumulation state 504.

In the present embodiment, the system control circuit 50 calculates the end timing of the accumulation state 504 from the timing when the multi-pixel simultaneous reset state 502 ends and the set accumulation time. Then, the system control circuit 50 calculates the start timing of the correction signal readout state 503 so that the correction signal readout state 503 ends at the same timing as the end timing of the accumulation state 504. Then, the system control circuit 50 starts control of the first correction readout control circuit 1802 based on the calculation result. Until the operation of the first correction readout control circuit 1802 is started, the first correction readout control circuit 1802 is kept in a standby state (step S1001). Other operations are the same as those in the first embodiment. In this embodiment as well, as in the first embodiment, the processing in the accumulation state 504 is started when the simultaneous reset of a plurality of pixels is completed and the power source or the like is stabilized.
FIG. 9 shows an example in which the process of the correction signal readout state 503 is started so that the correction signal readout state 503 and the accumulation state 504 are completed at the same time.
In this manner, in addition to the effects described in the first and second embodiments, the influence of simultaneously resetting the plurality of pixels 203 can be reduced to the reading of the correction signal. An effect is obtained.
The correction signal reading state 503 and the accumulation state 504 need not be terminated at the same time. The correction signal reading state 503 may end before or after the accumulation state 504 processing. Good. However, the processing in the correction signal readout state 503 and the processing in the accumulation state 504 are completed before the processing in the image readout state 505 is started.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

(Other examples)
The present invention is also realized by executing the following processing. That is, first, software (computer program) for realizing the functions of the above embodiments is supplied to a system or apparatus via a network or various storage media. Then, the computer (or CPU, MPU, etc.) of the system or apparatus reads and executes the computer program.

  14 image sensor, 100 image processing device, 203 pixels

Claims (7)

An image sensor comprising a plurality of pixels arranged in a two-dimensional matrix;
After simultaneously resetting the plurality of pixels, a charge accumulation operation in the plurality of pixels and a correction signal read operation for reading out a correction signal for correcting fixed pattern noise of the image sensor from the image sensor. Control means for performing control in parallel;
An imaging device comprising: The image sensor has an optical black pixel that is always shielded from light, and an aperture pixel.
The image pickup apparatus according to claim 1, wherein the control unit reads a signal based on the electric charge accumulated in the optical black pixel as the correction signal. A plurality of column output lines provided for each column of the two-dimensional matrix, each having a pixel connected to the same column;
Clamping means for clamping the potential of the column output line to a predetermined potential;
The control means outputs a signal of the column output line clamped at a predetermined potential by the clamping means in a state where output to the column output line of a signal based on charges accumulated in the plurality of pixels is stopped. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is read out as the correction signal.   4. The control unit according to claim 1, wherein the control unit controls the readout of the correction signal and the accumulation of the electric charges simultaneously after resetting the plurality of pixels at the same time. The imaging apparatus according to item 1.   The imaging apparatus according to claim 1, wherein the control unit performs control so that reading of the correction signal is started after a timing of starting to accumulate the charge. .   6. The control unit according to claim 1, wherein the control unit controls the reading of the correction signal to be completed before reading of the image signal based on the charges accumulated in the plurality of pixels is started. The imaging device according to any one of the above. A method for controlling an imaging apparatus having an imaging device including a plurality of pixels arranged in a two-dimensional matrix,
A reset step of simultaneously resetting the plurality of pixels;
A correction signal readout step of reading out a correction signal for correcting the fixed pattern noise of the image sensor from the image sensor;
A charge storage step of storing charge in the plurality of pixels;
An image signal readout step of reading out the charge accumulated in the charge accumulation step as an image signal,
An image pickup apparatus control method, comprising: simultaneously resetting the plurality of pixels in the resetting step, and performing the charge accumulation step and the correction signal reading step in parallel.

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