JP2018148311A - Imaging apparatus and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus for realizing an image with low power consumption and low noise in a function that obtains a dynamic range moving image by combining images having different exposure amounts.SOLUTION: An imaging apparatus that acquires a plurality of images with different exposure amounts and performs synthesis with an image with a wide dynamic range includes a pixel part in which a plurality of pixels 201 are arranged in a matrix, an imaging element including an amplifier 208 for amplifying signals output from the plurality of pixels 201, exposure amount control means 107 for controlling the exposure amount, and synthesis means 106 for performing switching between a first addition mode in which a plurality of images are synthesized in the preceding stage of the amplifier 208 and a second addition mode in which the plurality of images are synthesized in the subsequent stage of the amplifier 208 in accordance with the exposure amount controlled by the exposure amount control means 107.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an imaging apparatus and a control method for the imaging apparatus, and more particularly, to driving for a wide dynamic range.

  2. Description of the Related Art Conventionally, a camera capable of acquiring a moving image with a wide dynamic range and a good S / N without black crushing or overexposure in both a dark part and a bright part has been desired. As an example for a wide dynamic range, a moving image having a different exposure amount for each frame is acquired at a predetermined double frame rate, and a tone can be saved from two moving images having different exposure amounts in a later stage. Combine images. By doing so, cameras having a function of acquiring a moving image with a wide dynamic range are widely used. However, there is a concern about power consumption because this function requires reading at twice the speed.

  On the other hand, in Patent Document 1, when shooting is performed based on the first exposure amount, only A / D conversion of a pixel signal having a preset first level or less is performed. When shooting based on a second exposure amount that is smaller than the first exposure amount, only A / D conversion of a pixel signal having a preset second level or higher is performed, thereby reducing power consumption. An imaging apparatus has been proposed.

  In addition, in a driving method for moving images, with a camera capable of acquiring still images / moving images, moving images have predetermined formats such as FHD, HD, and 4k2k for still images that do not have a predetermined format. For this reason, it is common to reduce the number of pixels so as to match the format according to the moving image mode. To reduce the number of pixels, all pixels are read from the sensor, and the same color pixel signals that are adjacent in the subsequent stage are digitally mixed, or the same color pixel signals that are adjacent in the sensor are mixed as analog signals to reduce the number of pixels in the sensor. The method of outputting from is known. In the former method, since it is necessary to output data for all pixels from the sensor, power consumption is large. In addition, there is a concern in terms of reading speed for moving images that need to be read at high speed. On the other hand, the latter method is advantageous in terms of power consumption and readout speed because the number of pixels can be reduced in the sensor.

  In the latter method, Patent Document 2 has an amplifier configured for each pixel column and a mixing circuit arranged in the subsequent stage of the amplifier, and the signal of each pixel column passes through the amplifier and is then transmitted in the column direction by the mixing circuit. A sensor configured to perform mixing and reduce the number of pixels for output is described. In addition, circuit noise in which pixel noise generated in the pixel portion, thermal noise from an amplifier, and the like are superimposed appears in the light-shielded image. This is a noise that does not depend on the exposure amount. On the other hand, it is known that in light images, light shot noise that increases in proportion to the exposure amount becomes dominant with respect to the circuit noise that does not depend on the exposure amount, and the circuit noise becomes inconspicuous.

JP 2014-57189 A JP 2005-333462 A

  In the function of obtaining a moving image having a wide dynamic range by combining two images having different exposure amounts, the tone of the dark portion is stored for an image with a large exposure amount, and the tone of a bright portion is stored for an image with a small exposure amount. At the time of image composition, partial information in which gradation is stored is used for composition. With respect to this feature, Patent Document 1 does not discuss noise. Further, in Patent Document 2, since mixing is performed after passing through an amplifier, there is an effect that noise generated in the amplifier can be reduced. On the other hand, since it is necessary to drive all the amplifiers according to the pixel column to be read, In terms of surface, there is little reduction effect.

  In view of the above problems, an object of the present invention is to provide an imaging device that realizes a low-power consumption and low-noise image in a function of obtaining a dynamic image having a wide dynamic range by combining images with different exposure amounts. .

  In order to solve the above problems, an imaging apparatus of the present invention is an imaging apparatus that acquires a plurality of images with different exposure amounts and synthesizes an image with a wide dynamic range, and a plurality of pixels are arranged in a matrix. In accordance with the exposure amount controlled by the exposure amount control means, the image pickup device including the pixel unit, an amplifier for amplifying the signals output from the plurality of pixels, the exposure amount control means for controlling the exposure amount And a combining means for switching between a first addition mode for combining the plurality of images at the front stage of the amplifier and a second addition mode for combining the plurality of images at the subsequent stage of the amplifier.

  According to the present invention, it is possible to provide an imaging apparatus capable of realizing an image with low power consumption and low noise in a function of obtaining a moving image with a wide dynamic range by synthesizing images with different exposure amounts.

It is a schematic block diagram of the imaging device in this invention. It is an equivalent circuit diagram of the image sensor in the present invention. It is an equivalent circuit diagram of an image sensor pixel unit. It is a read timing chart at the time of non-mixing mode. It is a read timing chart at the time of the 1st mixed mode. It is a read timing chart at the time of the 2nd mixed mode. It is a graph showing the relationship between each mixed mode and noise. It is a timing chart of wide dynamic range mode. This is a configuration example in which the pixel sensitivity is changed every two rows.

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

[Imaging system]
FIG. 1 is a block diagram illustrating an example of an imaging system according to the present embodiment. In FIG. 1, a lens unit 101 is a lens that forms an optical image of a subject on an image sensor 105, and zoom control, focus control, aperture control, and the like are performed by a lens driving device 102. The mechanical shutter 103 is controlled by the shutter control means 104. The image sensor 105 captures the subject imaged by the lens unit 101 as an image signal. The imaging signal processing circuit 106 performs various corrections, data compression, and multiple image synthesis processing to obtain a wide dynamic range image on the image signal output from the imaging element 105. A timing generation circuit (exposure amount control means) 107 is a drive means for outputting various timing signals to the image sensor 105 and the image signal processing circuit 106. The control circuit 109 controls various calculations and the entire imaging apparatus. The memory 108 temporarily stores image data. The interface 110 performs recording or reading on a recording medium. The recording medium 111 is a detachable recording medium such as a semiconductor memory for recording or reading image data. The display unit 112 displays various information and captured images.

  Next, an operation at the time of shooting of the digital camera (image pickup apparatus) according to the present embodiment will be described. First, when the main power supply is turned on, the power supply for the control system is turned on, and further, the power supply for the imaging system circuit such as the imaging signal processing circuit 106 is turned on. Next, when a release button (not shown) is pressed, a shooting operation is started. When the photographing operation is completed, the image signal output from the image sensor 105 is subjected to correction calculation and image processing of the image sensor output described later in the photographing signal processing circuit 106 and written into the memory 108 according to an instruction from the control circuit 109. (Data is accumulated). The data stored in the memory 108 is recorded on a removable recording medium 111 such as a semiconductor memory through the recording medium control I / F unit 110 under the control of the control circuit 109. Further, the image may be processed by directly inputting to a computer or the like through an external I / F unit (not shown).

[Image sensor equivalent circuit diagram]
Next, the configuration of the image sensor 105 according to the present embodiment will be described in detail with reference to FIG. FIG. 2 shows an equivalent circuit diagram of the image sensor. In the present embodiment, it is assumed that the image pickup device has a configuration in which three adjacent pixels of the same color are horizontally mixed when the number of pixels is reduced in accordance with the moving image format during moving image driving. However, the number of mixing is not limited to three pixels. The present invention can also be applied to an arbitrary mixed number such as 2 pixels or 5 pixels.

  The unit pixel 201 includes a microlens (hereinafter referred to as ML), a photodiode (hereinafter referred to as PD), a floating diffusion (hereinafter referred to as FD), and the like, and a plurality of unit pixels 201 are arranged in a matrix in the pixel portion. The detailed configuration of the unit pixel 201 will be described later. R, G, and B described in the unit pixel 201 represent Red, Green, and Blue color filters, respectively, and are arranged in a Bayer array as shown in FIG. The vertical scanning circuit 202 supplies drive signals (PRES, PTX, PSEL) to each pixel in units of rows. The number at the end of each signal and n (an integer greater than or equal to 3) indicate a row number. For example, n indicates a signal supplied to each pixel in the n-th row. If there is no need to specify the number of lines, the character indicating the number of lines at the end is omitted. The drive signal will be described later together with the configuration of the unit pixel.

  A signal of each pixel is transmitted to a subsequent circuit via a vertical signal line 203 arranged for each unit pixel column, and a constant current circuit 204 is connected to each vertical signal line 203 as shown in the figure. The vertical signal line 203 is further connected to the front stage mixing changeover switches 205 and 206, and the front stage mixing changeover switches 205 and 206 are driven by the signal PHADD_f. A column amplifier 208 arranged corresponding to the pixel column to be read is connected to the other end of the previous-stage mixing changeover switch 205, and a mixing circuit 207 is connected to the other end of the previous-stage mixing changeover switch 206. The mixing circuit 207 is a circuit that performs horizontal mixing of three pixels for each color, and one is provided for each unit mixing column.

  The front mixing switch 205 is a pMOS switch, and the front mixing switching switch 206 is an nMOS switch. When the signal PHADD_f is “L”, the front mixing switch 205 is turned on and the front mixing switching switch 206 is turned off, and the pixel signal is input to the column amplifier 208 which is an amplifier corresponding to the vertical signal line. The column amplifier 208 has a function of amplifying a signal. At this time, the column amplifier 208 may be a gain amplifier capable of multiplying a plurality of different gains. When the signal PHADD_f is “H”, the front mixing switch 205 is turned off and the front mixing switching switch 206 is turned on, so that the signal on the vertical signal line is input to the mixing circuit 207.

  The column memory 211 stores an analog signal provided for each column. The sample hold switch 209 is turned on when the signal PSH is “H”, and has a function of sampling and holding the output signal of the column amplifier 208 using the column memory 211. The post-mixing changeover switch 210 is turned on when the signal PHADD_e is “H”, and is turned on after the output signal of the column amplifier 208 is sampled and held in the column memory 211, so that 3 for each color in the signal after the column amplifier output. Has the function of horizontally mixing pixels.

  The comparator 212 is provided corresponding to each column, and receives a pixel signal and a ramp signal VRAMP that fluctuates with a certain slope supplied from the DAC circuit 213, and compares the two signals. The comparator 212 has a function of inverting the output signal at the timing when the two input signals match. The counter 214 performs a count operation during the AD conversion period based on the input reference clock CLK. The digital memory 215 receives the count value from the counter 214 and the output signal from the comparator 212. The digital memory 215 holds the count value of the counter 214 at that time using the inversion of the output signal of the comparator 212 as a trigger. The value held in the digital memory 215 is output from the output circuit 216. The output signal is input to the imaging signal processing circuit 106 shown in FIG.

[Unit pixel unit equivalent circuit diagram]
Next, the unit pixel will be described in detail with reference to FIG. The unit pixel includes one ML (not shown), one PD, one FD, and four transistors. A PD (photoelectric conversion element) 301 performs photoelectric conversion. The transistor 302 is a transfer switch, and transfers the charge photoelectrically converted by the PD 301 to the FD 303. The FD 303 has a function of converting transferred charges into a potential. The transistor 304 forms a source follower amplifier together with a constant current source connected to the vertical signal line. The transistor 302 is driven by the signal PTX. The FD 303 is connected to the potential VDD via the transistor 306 driven by the signal PRES, and when the PRES becomes “H”, the FD 303 is reset to the potential VDD. The transistor 305 is driven by the signal PSEL and functions as a switch that transmits the output of the transistor 304 to the vertical signal line.

[Driving method in non-mixing mode]
Next, a driving method when reading the signals of each column independently without horizontally mixing the signals of each column will be described. This driving method, for example, reduces the number of mixed pixels by cutting out a part of the sensor and reading out the signals in each column independently, such as still image shooting and enlarged movie, which may have higher resolution and lower frame rate. Used for the mode to perform. In the present embodiment, this driving is called a non-mixing mode because it is not necessary to perform any mixing.

  FIG. 4 is a timing chart when reading out the signal of each pixel after exposure for a predetermined period, a graph showing the potential VCAMP of the column memory on the time axis and the potential VRAMP output from the DAC 213, and a graph showing the count value of the counter. Each is shown. In the unmixed mode, the signals PHADD_f and PHADD_e are always “L”. That is, the mixing switch 205 is turned on, the mixing switch 206 is turned off, and the rear mixing switch 210 is turned off.

  First, all pixels are collectively reset, and after a predetermined period of accumulation, PSEL1 is set to “H”, and a signal in the first row is output to the vertical signal line 203. Further, PRES1 is set to “H”, and the FD is reset by the potential VDD. At time t401, PRES1 is set to “L”, and the FD reset is released. Further, PSH is set to “H”, and a signal is written in the column memory 211. Since the signal PHADD_f is “L” after the reset is released (hereinafter referred to as a reset signal), the signal is input to the column memory 211 via the column amplifier 208 and the sample hold switch 209 arranged in the column corresponding to the pixel to be read. Is communicated. When the reset signal is transmitted to the column memory 211 and the stable time t402, PRES1 and PSH become “L”, the reset signal is held in the column memory 211, the DAC 213 outputs the RAMP signal, and starts AD conversion of the reset signal. . The counter 214 counts from the timing when AD conversion is started until VC and VRAMP match and the output signal of the comparator is inverted, and the digital memory 215 holds the count value at that time. The count value held in the digital memory 215 at the time t403 when the AD conversion period ends is output to the outside of the sensor in a column sequence by the output circuit 216. The counter is reset to an initial value after outputting a reset signal.

  Next, at time t404, the signal PTX1 becomes “H”, and the accumulated charge of the PD is transferred in addition to the FD in which the reset signal is held. Further, PSH becomes “H” and the signal is again written in the column memory 211. A signal corresponding to the amount of light received (hereinafter referred to as an optical signal) is transmitted to the column memory 211 via the column amplifier 208 and the sample hold switch 209 arranged in the column corresponding to the pixel to be read out, similarly to the reset signal. At time t405 when the optical signal is transmitted to the column memory 211 and stabilized, PTX1 and PSH become “L”, the optical signal is held in the column memory 211, the DAC 213 outputs the RAMP signal, and starts AD conversion of the optical signal. . The counter 214 counts from the timing when the AD conversion is started until VC and VRAMP match and the output signal of the comparator is inverted, and the digital memory 215 holds the count value at that time. At time t406 when the AD conversion period ends, PSEL1 becomes “L”. In addition, the count value held in the digital memory is output to the outside of the sensor in a column order by the output circuit 216. The counter is reset to the initial value after outputting the optical signal to the output line. The above operation is sequentially performed up to the nth row, and the read operation is completed. The reset signal and the optical signal output from the imaging element are subjected to arithmetic processing by the subsequent imaging signal processing circuit 106 to obtain an optical signal from which the reset noise has been removed.

[Driving method in the first mixed mode]
Next, a description will be given of a driving method when reading out by reducing the number of pixels by horizontally mixing three adjacent signals of the same color in the mixing circuit 207 configured in the previous stage of the column amplifier 208. In this embodiment, this driving is the first mixed mode (first addition mode). FIG. 5 is a timing chart at the time of signal reading in the first mixed mode. Similarly to FIG. 4, the graph shown at the bottom of the figure shows a graph indicating the potential VCAMP of the column memory and the potential VRAMP output from the DAC 213 on the time axis, and a graph indicating the count value of the counter.

  In this driving, the signal PHADD_f is always “H” and the signal PHADD_e is always “L”. That is, the front stage mixing changeover switch 205 is turned off, the front stage mixing changeover switch 206 is turned on, and the rear stage mixing changeover switch 210 is turned off. Here, comparing the timing chart of the unmixed mode described in FIG. 4 with FIG. 5, only the signal PHADD_f is different. Therefore, in the present embodiment, only portions different from the unmixed mode will be described. At time t501, the reset signal is output to the vertical signal line 203. Since the signal PHADD_f is “H”, the corresponding reset signal of the adjacent three pixels of the same color is input to the shared mixing circuit 207. The mixing circuit 207 holds the signal obtained by mixing the three input signals in the column memory 211 via the column amplifier 208 and the sample hold switch 209 that are connected corresponding to the mixing circuit. The same applies to the optical signal at time t504. With this operation, it is possible to obtain an image with a reduced number of pixels by mixing in the previous stage of the column amplifier. In the first mixing mode, if the number of columns located at the center of the horizontally mixed columns is m, the column amplifiers, comparators, and digital memories of the columns positioned at m-2 and m + 2 are not used. Save.

  As described above, in the first mixing mode, since the number of pixels is reduced by mixing in the previous stage of the column amplifier, the circuit configured for each column that is not used can perform power saving. Low power. Then, it is used in a moving image mode or the like that reads out the entire angle of view at a high frame rate. In addition, because of the feature of low power consumption, it is more effective when used in a mode with particularly large heat generation in moving images.

[Driving method in the second mixed mode]
Next, a description will be given of a driving method when reading by reducing the number of pixels by horizontally mixing three adjacent columns of the same color signal by using a rear stage mixing changeover switch and a column memory 211 arranged at the rear stage of the column amplifier 208. In this embodiment, this driving is referred to as a second mixed mode (second addition mode). FIG. 6 is a timing chart at the time of signal reading in the second mixed mode. Similarly to FIG. 4, the graph shown at the bottom of the figure shows a graph indicating the potential VCAMP of the column memory and the potential VRAMP output from the DAC 213 on the time axis, and a graph indicating the count value of the counter.

  In this driving, the signal PHADD_f is always “L”. That is, the pre-mixing changeover switch 205 is turned on and the pre-mixing changeover switch 206 is turned off. Here, when the timing chart of the unmixed mode described in FIG. 4 is compared with FIG. 6, only the signal PHADD_e is different. Therefore, only the points different from the unmixed mode will be described here. After the reset signal is held in the column memory 211 at time t602, the signal PHADD_e becomes “H” for a period up to time t603. As a result, column memories each holding signals of adjacent three pixels of the same color are connected, and a mixed signal is generated. The same driving is performed for the optical signal. In the second mixing mode, if the number of columns positioned at the center of the horizontally mixed columns is m, the comparators and digital memories of the columns positioned at m−2 and m + 2 are not used. After shutting down the input terminal, perform power saving.

  As described above, in the second mixing mode, since the number of pixels is reduced by mixing in the subsequent stage of the column amplifier, in addition to the noise generated in the pixel portion, the noise generated in the column amplifier can also be reduced by mixing. Therefore, a high-quality image with little noise can be obtained. Further, like the first mixed mode, it is used for a moving image mode or the like for reading out the entire angle of view at a high frame rate. In addition, because of its low noise feature, it is more effective when used in a mode that requires a particularly high-quality image among moving images.

[Characteristics of the first and second mixed modes]
Next, features of the first and second mixed modes will be described. First, paying attention to noise, σL is optical shot noise, σ1 is circuit noise in the first mixed mode, and σ2 is circuit noise in the second mixed mode. It is known that σL increases in proportion to the square root of the exposure amount. On the other hand, the circuit noise of σ1 and σ2 is generated regardless of the exposure amount. Here, it is assumed that random noise generated in the pixel portion is σpix, random noise generated in the column amplifier is σamp, and random noise generated in the AD conversion circuit is σad. The circuit noise on which these are superimposed is the sum of squares of σpix, σamp, and σad, with a square root. Further, it is known that random noise is mixed to reduce the square root of the number of mixing. That is, in the first mixed mode, the pixel noise is mixed by 3 pixels, which is 1 / √3 times. In the second mixed mode, the pixel noise and the amplifier noise are mixed by 3 pixels, respectively. / √3 times. Therefore, when σ1 and σ2 are expressed by mathematical expressions using σpix, σamp, and σad, they are as follows.
σ1 = √ (σ _pix / √3) ² + σ _amp ² + σ _ad ² ) Equation 1
σ 2 = √ (σ _pix / √3) ² + (σ _amp / √3) ² + σ _ad ² ) Equation 2

In the second mixed mode, it can be seen that there is a relationship expressed by the following Equation 3 because σamp is mixed as compared with the first mixed mode because noise is reduced.
σ1> σ2 Formula 3

  The graph of FIG. 7 is a schematic graph showing the above relationship as the exposure amount on the horizontal axis and the noise amount on the vertical axis. The exposure amount E shown in the graph has a light shot noise sufficiently larger than the difference between σ1 and σ2 in the range where the exposure amount is larger than the exposure amount E. When viewed as an image, the first mixed mode and the second exposure amount E are shown. The point where the noise difference is not known in the mixed mode is shown. As for the exposure amount E, for example, σL is about 10 times the difference between σ1 and σ2. On the contrary, in the range where the exposure amount is smaller than the exposure amount E, the range in which the noise difference can be visually recognized by the mixed mode when viewed as an image is shown. Focusing on power consumption, the first mixed mode consumes less power than the second mixed mode because the number of column amplifiers to be driven may be 1/3. In view of the characteristics of the first and second mixed modes described above, a driving method capable of obtaining a wide dynamic range moving image with low power consumption and high quality will be described next.

[Driving method in wide dynamic range mode]
A driving method for obtaining a moving image having a particularly wide dynamic range in driving in which pixels are reduced by mixing will be described. In this embodiment, this driving is set to a wide dynamic range mode. FIG. 8 is a timing chart when a known slit rolling drive is performed in the wide dynamic range mode. The signal VD_R and the signal VD_S are signals input to the image sensor 105 from the timing generation unit 107 in FIG. The signal VD_R is a readout start signal, and readout scanning starts with the falling edge of the signal VD_R as a trigger. The signal VD_S is a reset start signal, and reset scanning starts with the falling edge of the signal VD_S as a trigger. A dotted line is a reset line indicating that the reset is performed in the row order. The alternate long and short dash line indicates that the above-described first mixed mode readout drive is performed in a row sequence, and the alternate long and two short dashes line indicates that the above-described second mixed mode readout drive is performed in a row sequential manner.

  As shown in the figure, the signal VD_S is controlled so that the image read in the even frame has a longer accumulation time than the image read in the odd frame. In other words, even-numbered frames are stored without causing dark images to be obtained with dark images. On the other hand, in the odd-numbered frame, a dark image is obtained and the gradation of the bright part is preserved without overexposure. In even frames in which dark portions are used during synthesis, circuit noise is conspicuous, so reading is performed in the second mixed mode with less circuit noise. In an odd frame in which a bright part is used at the time of synthesis, there is no need to care for circuit noise due to the relationship with light shot noise, so reading is performed in the first mixed mode with lower power consumption. At this time, it is desirable that the signal threshold value of the dark part and the bright part used for the synthesis is larger than the exposure amount E shown in FIG. The two frames of moving images with different exposure amounts acquired by the above-mentioned driving are synthesized in the image signal processing circuit 106 of FIG. Can be obtained. By performing the above driving, it is possible to realize a wide dynamic range moving image with low power consumption and good S / N.

  In the present embodiment, when obtaining a moving image with a wide dynamic range, the exposure amount is changed by changing the accumulation time for each frame, but the present invention is not limited to this. That is, it is only necessary to shift the dynamic range obtained in one frame for each frame, and the means may be sensitivity, a diaphragm, an optical filter, or the like. Also, it is not always necessary to shift the dynamic range for each frame. For example, the sensitivity is controlled to be switched every two rows (every Bayer unit row), and the first mixed mode and the second are switched every two rows accordingly. Alternatively, the mixed mode may be switched. As means for shifting the dynamic range every two rows, the pixel sensitivity may be changed by changing the pixel opening area every two rows, or the capacitance of the FD (pixel capacitance) is set to 2 without changing the opening area. You may change the sensitivity of a pixel by making it differ for every line (it distinguishes).

  FIG. 9 shows an example of a configuration (first pixel group and second pixel group) in which the opening area of the pixels is different every two rows. A hatched portion 901 indicates a light shielding portion, and indicates that light corresponding to the area of the opening 902 enters the PD. As shown in the figure, the present invention can be applied to a configuration in which the sensitivity is changed by changing the opening area of the PD every two rows, that is, every Bayer unit row. With such a configuration, the resolution in the vertical direction is lowered, but it is not necessary to read out at a rate twice the predetermined frame rate, so that the power consumption can be further reduced. In the case of a camera having a plurality of sensors, the first and second mixed modes may be performed in accordance with the dynamic range of each sensor by shifting the dynamic range by any of the above means for each sensor. .

  Moreover, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

106 imaging signal processing circuit 107 timing generator 201 unit pixel 208 column amplifier

Claims (12)

An imaging device that acquires a plurality of images with different exposure amounts and synthesizes a wide dynamic range image,
An image sensor including a pixel portion in which a plurality of pixels are arranged in a matrix, and an amplifier that amplifies signals output from the plurality of pixels;
Exposure amount control means for controlling the exposure amount;
In accordance with the exposure amount controlled by the exposure amount control means, a first addition mode for combining the plurality of images before the amplifier and a second addition mode for combining the plurality of images at the subsequent stage of the amplifier. An imaging apparatus comprising: a combining unit for switching. The exposure amount control means controls a first exposure amount and a second exposure amount different from the first exposure amount,
The combining means combines the image in the first addition mode in the case of the first exposure amount, and combines the image in the second addition mode in the case of the second exposure amount. The imaging apparatus according to claim 1, wherein the imaging apparatus is characterized. The exposure amount control means controls the exposure amount based on an accumulation time, and controls the accumulation time in the first exposure amount to be shorter than the accumulation time in the second exposure amount;
The imaging apparatus according to claim 2. The imaging apparatus according to claim 2, wherein the exposure amount control unit controls the first exposure amount and the second exposure amount for each frame. The imaging apparatus according to claim 4, wherein the exposure amount control unit controls the first exposure amount in an odd frame and controls the second exposure amount in the even frame. An imaging device that acquires a plurality of images with different exposure amounts and synthesizes a wide dynamic range image,
An image sensor including a pixel portion in which a plurality of pixels are arranged in a matrix, and an amplifier that amplifies signals output from the plurality of pixels;
A combining unit that switches between a first addition mode for combining the plurality of images at the front stage of the amplifier and a second addition mode for combining the plurality of images at the subsequent stage of the amplifier;
The pixel portion is distinguished into at least a first pixel group and a second pixel group,
The synthesizing unit synthesizes the image output from the first pixel group in the first addition mode, and synthesizes the image output from the second pixel group. An image pickup apparatus that combines in the second addition mode. The imaging device according to claim 6, wherein the first pixel group and the second pixel group have different pixel opening areas. The imaging apparatus according to claim 7, wherein an opening area of the first pixel group is smaller than an opening area of the second pixel group. The pixel has a pixel capacity for converting the charge accumulated in the photoelectric conversion element into a potential,
The imaging device according to claim 6, wherein the first pixel group and the second pixel group have different pixel capacities. The image pickup apparatus according to claim 9, wherein a pixel capacity of the first pixel group is larger than a pixel capacity of the second pixel group. A pixel unit in which a plurality of pixels are arranged in a matrix to obtain a plurality of images with different exposure amounts and synthesize a wide dynamic range image, and an amplifier that amplifies signals output from the plurality of pixels. An imaging device control method comprising:
An exposure amount control step for controlling the exposure amount;
In accordance with the exposure amount controlled in the exposure amount control step, a first addition mode for combining the plurality of images before the amplifier and a second addition mode for combining the plurality of images at the subsequent stage of the amplifier. And a compositing step for switching. A pixel unit in which a plurality of pixels are arranged in a matrix to obtain a plurality of images with different exposure amounts and synthesize a wide dynamic range image, and an amplifier that amplifies signals output from the plurality of pixels. An imaging device control method comprising:
A combining step of switching between a first addition mode for combining the plurality of images at the front stage of the amplifier and a second addition mode for combining the plurality of images at the subsequent stage of the amplifier;
The pixel portion is distinguished into at least a first pixel group and a second pixel group,
In the synthesizing step, when synthesizing an image output from the first pixel group, when synthesizing in the first addition mode and synthesizing an image output from the second pixel group, A method for controlling an imaging apparatus, wherein the synthesis is performed in the second addition mode.

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