WO2019189893A1 - Imaging element and imaging device - Google Patents

Abstract

This imaging element is provided with: a plurality of pixels each including a photoelectric conversion unit that generates electric charge by performing photoelectric conversion of light, a storage unit that stores the electric charge generated by the photoelectric conversion unit, a switch unit that performs switching between connection and disconnection between the storage unit and a supply unit that supplies a prescribed voltage, and an output unit that outputs a signal based on the electric charge stored in the storage unit; and a control unit that, while a signal based on the electric charge stored in the storage unit of a first pixel among the plurality of pixels is outputted from the output unit, performs control to cause the switch unit of a second pixel among the plurality of pixels to connect the supply unit and the storage unit.

Description

Imaging device and imaging apparatus

The present invention relates to an imaging element and an imaging apparatus.

An image sensor that performs a shutter operation by a rolling shutter method is known (for example, Patent Document 1). Patent Document 1 describes that dummy pixels are provided in order to suppress image noise and a shutter operation of the dummy pixels is performed. However, if a dummy pixel is provided, the area of the image sensor increases.

Japanese Unexamined Patent Publication No. 2014-57367

According to the first aspect of the invention, the imaging device supplies a predetermined voltage, a photoelectric conversion unit that photoelectrically converts light to generate a charge, a storage unit that stores the charge generated by the photoelectric conversion unit, and a predetermined voltage A plurality of pixels each having a switching unit that switches connection and disconnection between the supply unit and the storage unit, and an output unit that outputs a signal based on the charge stored in the storage unit, and the first of the plurality of pixels Control for connecting the supply unit and the storage unit to the switching unit of the second pixel among the plurality of pixels while outputting the signal based on the charge stored in the storage unit of the pixel from the output unit And a control unit for performing.
According to a second aspect of the invention, an imaging apparatus includes the imaging device according to the first aspect and a generation unit that generates image data based on a signal output from the output unit.

It is a block diagram which shows the structure of the imaging device which concerns on 1st Embodiment. It is a figure which shows the structural example of the pixel part of the image pick-up element which concerns on 1st Embodiment. It is a figure showing an example of composition of an image sensor concerning a 1st embodiment. It is a figure which shows the structural example of the pixel of the image pick-up element which concerns on 1st Embodiment. It is a figure which shows an example of operation | movement of the pixel which concerns on 1st Embodiment. It is a figure which shows another example of operation | movement of the pixel which concerns on 1st Embodiment. It is a figure which shows the structural example of a part of image pick-up element which concerns on 1st Embodiment. 3 is a timing chart illustrating an operation example of the image sensor according to the first embodiment. 6 is a timing chart illustrating another operation example of the image sensor according to the first embodiment. 6 is a timing chart illustrating another operation example of the image sensor according to the first embodiment. It is a figure which shows an example of operation | movement of the image pick-up element which concerns on 1st Embodiment. It is a figure which shows an example of operation | movement of the image pick-up element which concerns on 1st Embodiment.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of the imaging apparatus according to the first embodiment. FIG. 1 shows a configuration example of a camera 1 that is an example of an imaging apparatus according to the first embodiment. The camera 1 includes an imaging optical system (imaging optical system) 2, an imaging element 3, a control unit 4, a memory 5, a display unit 6, and an operation unit 7. The imaging optical system 2 includes a plurality of lenses including a focus adjustment lens (focus lens) and an aperture stop, and forms a subject image on the imaging element 3. Note that the imaging optical system 2 may be detachable from the camera 1.

The image sensor 3 is, for example, a CMOS image sensor. The imaging element 3 receives the light beam that has passed through the exit pupil of the imaging optical system 2 and captures a subject image. In the imaging device 3, a plurality of pixels having photoelectric conversion units are arranged in a two-dimensional manner (for example, in the row direction and the column direction). The photoelectric conversion unit is configured by, for example, a photodiode (PD). The image sensor 3 photoelectrically converts the received light to generate a signal, and outputs the generated signal to the control unit 4.

The image pickup device 3 has an image pickup pixel and an AF pixel (focus detection pixel). The imaging pixel outputs a signal (imaging signal) used for image generation. The AF pixel outputs a signal (focus detection signal) used for focus detection. As will be described later, the AF pixels are arranged so as to be replaced with a part of the imaging pixels, and are distributed over almost the entire imaging surface of the imaging element 3. In the following description, when simply referred to as a pixel, it refers to either one or both of an imaging pixel and an AF pixel.

The memory 5 is a recording medium such as a memory card, for example. Image data and the like are recorded in the memory 5. Writing of data to the memory 5 and reading of data from the memory 5 are performed by the control unit 4. The display unit 6 displays an image based on image data, information relating to shooting such as a shutter speed and an aperture value, a menu screen, and the like. The operation unit 7 includes various setting switches such as a release button and a power switch, and outputs an operation signal corresponding to each operation to the control unit 4.

The control unit 4 includes a processor such as a CPU, FPGA, ASIC, and a memory such as a ROM or a RAM, and controls each unit of the camera 1 based on a control program. The control unit 4 includes an imaging control unit 4a, an image data generation unit 4b, and a focus detection unit 4c.

The imaging control unit 4 a supplies a control signal to the imaging device 3 to control the operation of the imaging device 3. The imaging control unit 4a causes the imaging device 3 to repeatedly capture a subject image for each frame of a predetermined period when displaying a through image (live view image) of a subject on the display unit 6 or when capturing a moving image. An imaging signal and a focus detection signal are output. For example, the imaging control unit 4a performs so-called rolling shutter type readout control in which pixels of the imaging device 3 are sequentially selected in units of rows and signals are read from the selected pixels.

The imaging control unit 4a controls the imaging device 3 to read out signals from a row of pixels in which AF pixels are arranged (hereinafter referred to as AF pixel rows) and a row of pixels in which no AF pixels are arranged ( Hereinafter, a process of separately reading signals from the imaging pixel row) is performed. In addition, the imaging control unit 4a also performs processing of sequentially selecting pixel rows and reading signals of each pixel without separately performing AF pixel row signal readout and imaging pixel row signal readout.

For example, when the through image is displayed on the display unit 6 or when moving image shooting is performed, the imaging control unit 4a separates the readout of the signal of each pixel of the AF pixel row and the readout of the signal of each pixel of the imaging pixel row. Do it. In addition, when performing high-resolution still image shooting, the imaging control unit 4a does not separately read out the signal of each pixel in the AF pixel row and read out the signal of each pixel in the imaging pixel row. A process of reading out signals by sequentially selecting rows is performed.

The image data generation unit 4b performs various kinds of image processing on the imaging signal output from the imaging element 3 to generate image data. The image processing includes, for example, known image processing such as gradation conversion processing, color interpolation processing, and contour enhancement processing.

The focus detection unit 4c performs a focus detection process necessary for automatic focus adjustment (AF) of the imaging optical system 2 by a known phase difference detection method. Specifically, the focus detection unit 4 c detects the focus position of the focus lens for focusing the image by the imaging optical system 2 on the imaging surface of the imaging device 3. The focus detection unit 4 c detects the image shift amount between the first and second images based on the pair of focus detection signals output from the image sensor 3. The focus detection unit 4c calculates a shift amount (defocus amount) between the current position of the focus lens and the focus position based on the detected image shift amount. Focus adjustment is performed automatically by driving the focus lens in accordance with the defocus amount.

FIG. 2 is a diagram illustrating a configuration example of a pixel unit of the image sensor according to the first embodiment. The image sensor 3 includes a pixel unit 100 in which pixels are arranged two-dimensionally (row direction and column direction). The pixel unit 100 includes an effective pixel area 91 and an optical black (OB) pixel area 92. In the effective pixel region 91, an imaging pixel and a focus detection pixel that receive light from the subject are arranged. The effective pixel area 91 is an area where light from the outside enters the imaging pixel and the focus detection pixel. In the OB pixel area 92, for example, a pixel that outputs a correction signal used for correcting an imaging signal read from the imaging pixel is arranged. The OB pixel region 92 is a region that does not enter a pixel where light from the outside is arranged. For this reason, the OB pixel region 92 is provided with a light shielding film so as to cover all the arranged pixels. The pixels arranged in the OB pixel region 92 are pixels (OB pixels) that are shielded from light so that light does not enter from the outside. The OB pixel region 92 includes a PD-equipped OB pixel region 93 in which an OB pixel having a photoelectric conversion unit is disposed, and a PD-free OB pixel region 94 in which an OB pixel having no photoelectric conversion unit is disposed. The PD-equipped OB pixel is used for detecting a dark current component of a signal output from the imaging pixel. The PD-less OB pixel is used for detecting an offset component of a signal output from the imaging pixel.

The image data generation unit 4b of the control unit 4 generates image data based on the imaging signal read from the imaging pixels in the effective pixel area 91. The OB pixel is used for detecting a dark current component and an offset component. The image data generation unit 4b removes the noise component due to the dark current from the imaging signal by subtracting the dark current component and the offset component from the imaging signal.

FIG. 3 is a diagram illustrating a configuration example of the image sensor according to the first embodiment. The imaging device 3 includes a pixel unit 100, a vertical control unit 30, a supply unit 35, and a plurality of readout units 40 (first readout unit 40a and second readout unit 40b) arranged above and below the pixel unit 100. And have. Note that the number and arrangement of the pixels arranged in the effective pixel region 91 of the pixel unit 100 are not limited to the illustrated example. In the effective pixel region 91, for example, millions to hundreds of millions of pixels or more are provided.

In the effective pixel area 91 of the pixel unit 100, a plurality of imaging pixels 10 and AF pixels 13 (13a, 13b) are arranged. In FIG. 3, the pixel at the upper left corner is the imaging pixel 10 (1, 1) in the first row and the first column, and the imaging pixel at the lower right corner is the imaging pixel 10 (19, 10) in the 19th row and the tenth column. 190 pixels from the imaging pixel 10 (1, 1) to the imaging pixel 10 (19, 10) are illustrated. Note that 190 pixels of 10 pixels in the row direction and 19 pixels in the column direction shown in FIG. 3 represent a pixel group arranged in an arbitrary area of the effective pixel area 91, and the first column to the first column in FIG. The names of the tenth column and the first to nineteenth rows are also given to 190 pixels. Therefore, in the imaging device 3, not only the right side of the pixel in the 10th column and the lower side of the pixel in the 19th row in FIG. 3, but also the left side of the pixel in the first column and the upper side of the pixel in the first row. There may also be pixels.

The imaging pixel 10 is provided with one of three color filters (color filters) 41 having different spectral characteristics of R (red), G (green), and B (blue), for example. The R color filter 41 mainly transmits light in the red wavelength band, the G color filter 41 transmits mainly light in the green wavelength band, and the B color filter 41 mainly transmits light in the blue wavelength band. Transparent. The pixels have different spectral characteristics depending on the arranged color filter 41. Accordingly, the imaging pixel 10 includes a pixel having red (R) spectral characteristics (hereinafter referred to as an R pixel), a pixel having green (G) spectral characteristics (hereinafter referred to as a G pixel), and a blue pixel. Some pixels have spectral characteristics (B) (hereinafter referred to as B pixels). The R pixel, the G pixel, and the B pixel are arranged according to a Bayer array.

The first and second AF pixels 13a and 13b are arranged by being replaced with a part of the R, G, and B imaging pixels 10 arranged in the Bayer arrangement as described above. A color filter 41 and a light shielding film 43 are provided in the first and second AF pixels 13a and 13b. For example, a G color filter is disposed as the color filter 41 in the first and second AF pixels 13a and 13b. The first AF pixel 13a and the second AF pixel 13b are different in the position of the light shielding portion 43. Thereby, the photoelectric conversion unit of the first AF pixel 13a receives the light beam that has passed through the first region of the first and second regions of the exit pupil of the imaging optical system 2. The photoelectric conversion unit of the second AF pixel 13b receives the light beam that has passed through the second region of the first and second regions of the exit pupil of the photographing optical system 2.

As shown in FIG. 3, the imaging device 3 includes a first imaging pixel row 401 in which R pixels 10r and G pixels 10g are alternately arranged in the left-right direction, that is, the row direction, G pixels 10g, and B pixels 10b. Have second imaging pixel rows 402 arranged alternately in the row direction. Further, in the imaging device 3, the first AF pixel row 403a in which the G pixel 10g and the first AF pixel 13a are alternately arranged in the row direction, and the G pixel 10g and the second AF pixel 13b in the row direction. The second AF pixel rows 403b are alternately arranged.

The vertical control unit 30 is controlled by the imaging control unit 4a of the camera 1 and supplies a control signal to each pixel to control the operation of each pixel. The supply unit 35 is controlled by the imaging control unit 4a and supplies a predetermined voltage (potential) to each pixel. As will be described later, the supply unit 35 supplies the power supply voltage VDD to the switching unit and the amplification unit of each pixel. Each of the first reading unit 40a and the second reading unit 40b includes an analog / digital conversion unit (AD conversion unit).

The signal of each pixel is output to the first vertical signal line VoutA or the second vertical signal line VoutB connected to the pixel. The pixel signal output to the first vertical signal line VoutA is converted to a digital signal by the first readout unit 40a and then output to the control unit 4. The pixel signal output to the second vertical signal line VoutB is converted to a digital signal by the second readout unit 40b and then output to the control unit 4.

FIG. 4 is a diagram illustrating a configuration example of pixels of the image sensor according to the first embodiment. Each pixel ( pixels 10a and 10b in FIG. 4) includes a photoelectric conversion unit 11 and a transfer unit 12, respectively. The pixel 10a has a photoelectric conversion unit 11a and a transfer unit 12a, and the pixel 10b has a photoelectric conversion unit 11b and a transfer unit 12b. The photoelectric conversion unit 11 is a photodiode PD, converts incident light into charges, and accumulates the photoelectrically converted charges.

In the imaging device 3 according to the present embodiment, as shown by a broken line 20 in FIG. 4, two adjacent pixels are a floating diffusion (FD) 15, a switching unit 16, an amplification unit 17, and a first selection unit. 18 and the second selection unit 19 are shared. The switching unit 16 includes a connection switch unit 16a and a reset unit 16b, and switches connection and disconnection between the supply unit 35 that supplies the power supply voltage VDD and the FD 15.

The transfer unit 12a of the pixel 10a includes a transistor M1 controlled by a signal TX0. When the transistor M4a of the connection switch unit 16a is off, the transfer unit 12a transfers the charge photoelectrically converted by the photoelectric conversion unit 11a to the FD 15. That is, the transfer unit 12a forms a charge transfer path between the photoelectric conversion unit 11a and the FD 15. When the transistor M4a of the connection switch unit 16a is on, the transfer unit 12a transfers the charges photoelectrically converted by the photoelectric conversion unit 11a to the FD 15 and the region 16c.

The transfer unit 12b of the pixel 10b includes a transistor M2 that is controlled by a signal TX1. When the transistor M4a of the connection switch unit 16a is off, the transfer unit 12b transfers the charge photoelectrically converted by the photoelectric conversion unit 11b to the FD 15. That is, the transfer unit 12b forms a charge transfer path between the photoelectric conversion unit 11b and the FD 15. When the transistor M4a of the connection switch unit 16a is on, the transfer unit 12b transfers the charge photoelectrically converted by the photoelectric conversion unit 11b to the FD 15 and the region 16c. The transistors M1 and M2 are transfer transistors, respectively.
The capacitor C of the FD 15 accumulates (holds) the charge transferred to the FD 15 and converts it into a voltage divided by the capacitance value.

The amplification unit 17 amplifies and outputs a signal based on the charge transferred from the photoelectric conversion unit 11. The amplifying unit 17 includes a supply unit 35 for supplying a power supply voltage VDD and a transistor M5 having a drain (terminal) and a gate (terminal) connected to the FD 15, respectively. The source (terminal) of the transistor M5 is connected to the first vertical signal line VoutA via the first selector 18 and is connected to the second vertical signal line VoutB via the second selector 19. The The amplifying unit 17 functions as a part of a source follower circuit using current sources (first current source 25a and second current source 25b in FIG. 7) described later as load current sources. The transistor M5 is an amplification transistor. The amplification unit 17, the first selection unit 18, and the second selection unit 19 constitute an output unit that generates and outputs a signal based on the charge generated by the photoelectric conversion unit 11.

The connection switch unit 16a includes a transistor M4a controlled by the signal GC, and electrically connects (couples) the FD 15 and the region 16c. The region 16c has a capacitance (parasitic capacitance) of each transistor connected to the region 16c and a wiring capacitance. The region 16c accumulates the charge transferred to the region 16c and converts it into a voltage divided by the capacitance value.

The reset unit 16b includes a transistor M4b controlled by the signal RST, and discharges charges accumulated in the regions 16c and FD15, and resets the voltages of the regions 16c and FD15. The transistor M4b is a reset transistor. In other words, the reset unit 16b is the discharge unit 16b, and discharges the charges accumulated in the region 16c and the FD 15 to the supply unit 35.

When the transistor M4b of the reset unit 16b is on, the connection switch unit 16a functions as a reset unit that discharges the charge accumulated in the FD 15 and resets the voltage of the FD 15. That is, the connection switch unit 16 a is also a discharge unit 16 a that discharges the charge accumulated in the FD 15 to the supply unit 35.

When the transistor M4a of the connection switch unit 16a is on, the FD 15 and the region 16c are electrically connected. Thereby, the charge transferred from the photoelectric conversion unit 11 is accumulated in the FD 15 and the region 16c. For this reason, the capacity | capacitance of the area | region where an electric charge is transferred from the photoelectric conversion part 11 becomes large. As a result, a large amount of charge generated by the photoelectric conversion unit can be accumulated by photoelectrically converting light from a high-luminance subject. On the other hand, when the transistor M4a of the connection switch unit 16a is off, the region 16c and the FD 15 are electrically disconnected. For this reason, the capacity | capacitance of the area | region where an electric charge is transferred from the photoelectric conversion part 11 becomes small. As a result, it is possible to increase the conversion gain when converting charge into voltage. The vertical control unit 30 can change the conversion gain by supplying the signal GC to the connection switch unit 16a and performing on / off control of the connection switch unit 16a.

The first selection unit 18 includes a transistor M6 controlled by the signal SELA, and electrically connects or disconnects the amplification unit 17 and the first vertical signal line VoutA. The transistor M6 of the first selection unit 18 outputs a signal from the amplification unit 17 to the first vertical signal line VoutA when in the on state. The second selection unit 19 includes a transistor M7 controlled by the signal SELB, and electrically connects or disconnects the amplification unit 17 and the second vertical signal line VoutB. The transistor M7 of the second selection unit 19 outputs a signal from the amplification unit 17 to the second vertical signal line VoutB when in the on state. The transistor M6 is a first selection transistor, and the transistor M7 is a second selection transistor.

As described above, a signal (pixel signal) corresponding to the charge transferred from the photoelectric conversion unit 11 is output to the first vertical signal line VoutA or the second vertical signal line VoutB. The pixel signal is an analog signal generated based on the charge photoelectrically converted by the photoelectric conversion unit 11. The pixel signal output from the imaging pixel 10 is subjected to signal processing by the reading unit 40 and then output to the control unit 4 as an imaging signal.

In the present embodiment, the circuit configurations of the first AF pixel 13a and the second AF pixel 13b are the same as the circuit configuration of the imaging pixel 10, respectively. Pixel signals output from the first AF pixel 13a and the second AF pixel 13b are output to the control unit 4 as a pair of focus detection signals after being subjected to signal processing by the reading unit 40.

In this embodiment, the vertical control unit 30 performs rolling shutter type readout control. That is, the imaging pixel row and AF pixel row of the imaging device 3 are sequentially selected by the vertical control unit 30. Specifically, in the imaging device 3, the discharge (reset operation) of the charge accumulated in the pixel and the read operation for reading a signal from the pixel are scanned, for example, from the top row to the bottom row for each row or every plurality of rows. While done.

In general, in the rolling shutter system, when the reset operation of all the pixel rows is completed during the readout period from the start of the readout operation of the uppermost row to the end of the readout operation of the lowermost row, the reset operation is performed at the same time. The number of pixel rows changes. When the supply of the signal for discharging the charge accumulated in the pixel is completed during the readout period, the load of the power supply changes. For this reason, the power supply voltage may fluctuate, and noise resulting from the fluctuation of the power supply voltage may be mixed into the pixel signal. For example, a pixel signal in which a reset operation of another pixel row is performed during the read operation and a pixel row in which the reset operation of the other pixel row is not performed during the read operation are caused by fluctuations in the power supply voltage in the pixel signal. Differences will occur. In this case, for example, a horizontal line pattern (electronic shutter flaw) occurs in the image generated using the pixel signal.

Therefore, the image pickup device 3 according to the present embodiment performs the same operation by performing a reset operation on a non-read target pixel, that is, a pixel that does not perform a read operation, while sequentially reading signals from the read target pixel. The number of pixel rows to be reset at the timing is controlled. In the present embodiment, as will be described later, the vertical control unit 30 reads out all the pixels in the effective pixel region 91 while reading signals from the pixels in the pixel row to be read out among all the pixels in the effective pixel region 91. A reset operation is performed on the pixels in the pixel row to be skipped.

Also, the vertical control unit 30 performs a reset operation on the non-read target pixel rows in accordance with a change in the number of read target pixel rows on which the reset operation is performed. Thereby, the number of pixel rows on which the reset operation is performed can be made constant during the period in which the readout operation for each pixel row to be read is performed. For this reason, it can suppress that a power supply voltage fluctuates, and can suppress that noise mixes in a pixel signal. As a result, it is possible to prevent an electronic shutter flaw from occurring in an image generated using the pixel signal. Hereinafter, the reset operation performed to adjust the number of pixel rows on which the reset operation is performed may be referred to as a dummy reset operation.

When simultaneously reading out signals from multiple pixel rows using multiple vertical signal lines, or when performing additive read out by adding signals from multiple imaging pixel rows, reset to multiple rows of pixels simultaneously, for example. Since the readout operation is performed after the operation is performed, the number of pixel rows on which the reset operation is performed simultaneously increases. In some cases, the reset operation for the imaging pixel row and the reset operation for the AF pixel row are performed in parallel. In this case, the number of pixel rows for which the reset operation is simultaneously performed further increases. Therefore, the vertical control unit 30 calculates the maximum number of pixel rows to be read for which the reset operation is performed at the same timing, and determines the number of non-read target pixel rows to be subjected to the dummy reset operation. Then, the vertical control unit 30 performs a dummy reset operation on the non-read target pixel rows so that the number of pixel rows on which the reset operation is performed in parallel with the period of the read operation of each pixel row is constant. Do. For this reason, even when the pixel signal readout method is changed, fluctuations in the power supply voltage can be suppressed to prevent noise from being mixed into the pixel signal.

In addition, it is conceivable to perform a dummy reset operation on the pixels (OB pixels) in the OB pixel region 92 to adjust the number of pixel rows in which the reset operation is performed. If it is increased, the pixel row in the OB pixel region 92 may not be sufficient. On the other hand, in this embodiment, since the dummy reset operation is performed on the non-read target pixels in the effective pixel region 91, it is possible to prevent the pixel rows for adjusting the number of reset rows from being insufficient. Further, since it is not necessary to separately arrange pixels for performing the dummy reset operation, it is possible to prevent the area of the image sensor from increasing. Further, since it is not necessary to separately arrange pixels for performing the dummy reset operation, it is possible to avoid an increase in the manufacturing cost due to an increase in the area of the imaging element.
Hereinafter, as an example of pixel control according to this embodiment, a reset operation for the pixel 10a and a signal read operation from the pixel 10a will be described with reference to FIGS.

FIG. 5 is a diagram illustrating an example of the operation of the pixel according to the first embodiment. In the timing chart illustrated in FIG. 5, the horizontal axis indicates time, and indicates a control signal input to the pixel of the image sensor 3. In FIG. 5, when the control signal is at a high level (for example, power supply voltage), the transistor to which the control signal is input is turned on, and when the control signal is at a low level (for example, ground voltage), the control signal is input. The transistor is turned off. FIG. 5 is also a diagram illustrating an example of the operation of a pixel when shooting a high-luminance subject. Therefore, in the example shown in FIG. 5, the signal GC is set to the high level, and the FD 15 and the region 16c are electrically connected.

At time t1 shown in FIG. 5, the signal RST goes high, turning on the transistor M4b of the reset unit 16b. Since both the signal RST and the signal GC are at a high level, the switching unit 16 electrically connects the supply unit 35 (power supply VDD), the region 16c, and the FD15. As a result, charges in the FD 15 and the region 16c are discharged, and the voltages of the FD 15 and the region 16c become the reset voltage.

At time t2, the signal TX0 becomes high level, whereby the transistor M1 of the transfer unit 12a is turned on, and the photoelectric conversion unit 11a, the FD 15, and the region 16c are electrically connected. Thereby, the electric charge accumulated in the photoelectric conversion unit 11a is transferred to the FD 15 and the region 16c, and the voltages of the photoelectric conversion units 11a, FD15, and the region 16c are averaged. That is, it can be said that the electric charge of the photoelectric conversion unit 11a is discharged and the voltage of the photoelectric conversion unit 11a is reset. As described above, in the period from time t1 to time t3 in FIG. 5, the reset operation for discharging the charges of the FD 15, the region 16c, and the photoelectric conversion unit 11a is performed once.

From time t4 to time t6, the second reset operation is performed in the same manner as the first reset operation in the period from time t1 to time t3. From time t7 to time t9, from time t10 to time t12, and from time t13 to time t15, the third, fourth, and fifth reset operations are performed, respectively. In this way, by performing the reset operation a plurality of times, the charge of the photoelectric conversion unit 11a can be reliably discharged.

At time t16, the signal RST becomes high level, so that the transistor M4b of the reset unit 16b is turned on. As a result, charges in the FD 15 and the region 16c are discharged, and the voltages of the FD 15 and the region 16c become the reset voltage. Further, at time t16, the signal SELA becomes high level, so that a signal based on the reset voltage is output to the first vertical signal line VoutA by the amplifying unit 17 and the first selecting unit 18. That is, a signal (noise signal) when the voltages of the FD 15 and the region 16c are reset to the reset voltage is output to the first vertical signal line VoutA.

At time t17, the signal TX0 becomes high level, whereby the transistor M1a of the transfer unit 12a is turned on, and the electric charge photoelectrically converted by the photoelectric conversion unit 11a is transferred to the FD 15 and the region 16c. At time t17, since the signal SELA is at a high level, a signal based on the charges generated by the photoelectric conversion unit 11a is output to the first vertical signal line VoutA by the amplification unit 17 and the first selection unit 18. The

FIG. 6 is a diagram illustrating another example of the operation of the pixel according to the first embodiment. In the example shown in FIG. 6, the signal RST is at a high level, and the connection switch unit 16a functions as a reset unit.

At time t1 shown in FIG. 6, the signal GC becomes high level, so that the transistor M4a of the connection switch unit 16a is turned on. Since both the signal RST and the signal GC are at a high level, the switching unit 16 electrically connects the supply unit 35 (power supply VDD), the region 16c, and the FD 15. Thereby, the electric charge of FD15 is discharged and the voltage of FD15 becomes a reset voltage.

At time t2, the signal TX0 becomes high level, whereby the transistor M1 of the transfer unit 12a is turned on, and the photoelectric conversion unit 11a and the FD 15 are electrically connected. Thereby, the electric charge accumulated in the photoelectric conversion unit 11a is transferred to the FD 15, and the voltages of the photoelectric conversion unit 11a and the FD 15 are averaged. That is, the electric charge of the photoelectric conversion unit 11a is discharged, and the voltage of the photoelectric conversion unit 11a is reset. Thus, in the period from time t1 to time t3 in FIG. 6, the reset operation for discharging the charges of the FD 15 and the photoelectric conversion unit 11a is performed once.
From time t4 to time t6, from time t7 to time t9, from time t10 to time t12, and from time t13 to time t15, the second, third, fourth, and fifth reset operations are performed, respectively.

At time t16, the signal GC becomes high level, so that the transistor M4a of the connection switch section 16a is turned on. Thereby, the electric charge of FD15 is discharged and the voltage of FD15 becomes a reset voltage. Further, at time t16, the signal SELA becomes high level, so that a signal based on the reset voltage is output to the first vertical signal line VoutA by the amplifying unit 17 and the first selecting unit 18.

At time t17, the signal TX0 becomes a high level, whereby the transistor M1a of the transfer unit 12a is turned on, and the charge photoelectrically converted by the photoelectric conversion unit 11a is transferred to the FD15. At time t17, since the signal SELA is at a high level, a signal based on the charges generated by the photoelectric conversion unit 11a is output to the first vertical signal line VoutA by the amplification unit 17 and the first selection unit 18. The

In the above description, the example in which the signal of the pixel 10a is output to the first vertical signal line VoutA has been described. However, when the first selection unit 18 is in the off state and the second selection unit 19 is in the on state, A signal can be output from the pixel 10a to the second vertical signal line VoutB.
Further, the reset operation of the pixel 10a and the signal read operation of the pixel 10a have been described. However, when the transfer unit 12b is turned on instead of the transfer unit 12a being turned on in FIGS. Reset operation and signal readout operation of the pixel 10b are performed.

FIG. 7 is a diagram illustrating a configuration example of a part of the image sensor according to the first embodiment. In FIG. 7, among a plurality of pixels arranged in the column direction (vertical direction) which is the first direction and the row direction (horizontal direction) which is the second direction intersecting the first direction, a plurality of pixels arranged in the column direction. A part of one of the pixel columns is shown. The configuration of the other pixel columns is the same as that of the pixel column in FIG. Note that the vertical control unit 30 and the supply unit 35 are provided in common for a plurality of pixel columns.

The imaging device 3 is provided with a first vertical signal line VoutA and a second vertical signal line VoutB for a pixel column that is a column of a plurality of pixels arranged in the column direction, that is, the vertical direction. In addition, a first current source 25a and a first readout unit 40a are provided for the first vertical signal line VoutA, and a second current source 25b and a second readout are provided for the second vertical signal line VoutB. A portion 40b is provided. In the example shown in FIG. 7, only the pixel in the row direction × 6 pixels in the column direction is shown for simplicity of explanation. In FIG. 7, among the plurality of pixels shown in FIG. 3, the G pixel 10 g (1, 1) in the first row and first column, the R pixel 10 r (2, 1) in the second row and first column, and the third The G pixel 10g (3, 1) in the first row, the R pixel 10r (4, 1) in the fourth row, first column, the G pixel 10g (5, 1) in the fifth row, first column, An R pixel 10r (6, 1) in 6 rows and 1 columns is illustrated.

The first current source 25a is connected to each pixel via a first vertical signal line VoutA, and the second current source 25b is connected to each pixel via a second vertical signal line VoutB. The first current source 25a and the second current source 25b generate a current for reading a signal from each pixel. The first current source 25a supplies the generated current to the first vertical signal line VoutA, the first selection unit 18 and the amplification unit 17 of each pixel. Similarly, the second current source 25b supplies the generated current to the second vertical signal line VoutB, the second selection unit 19 and the amplification unit 17 of each pixel.

The first readout unit 40a includes an AD conversion unit, and converts an analog signal input from each pixel through the first vertical signal line VoutA into a digital signal. The second readout unit 40b includes an AD conversion unit, and converts an analog signal input from each pixel via the second vertical signal line VoutB into a digital signal.

The vertical control unit 30 supplies the signal TX0, the signal TX1, the signal GC, the signal RST, the signal SELA, and the signal SELB to each pixel to control the operation of each pixel. Specifically, the vertical control unit 30 supplies a signal to the gate of each transistor of the pixel to turn the transistor on (connected, conductive, short-circuited) or off (disconnected, non-conductive, open). State, shut-off state).

The vertical control unit 30 sequentially selects all the imaging pixel rows and individually reads the signals of the pixels (first reading process), and some of the imaging pixels (hereinafter, selected pixels). Are sequentially selected and the signal of each pixel is read out separately (second readout process). The vertical control unit 30 also performs a process (third read process) of adding (mixing) and reading signals from a plurality of imaging pixels.

The imaging control unit 4a of the camera 1 controls the vertical control unit 30 to switch the pixel signal readout method. When reading signals from the imaging pixel rows (the first imaging pixel row 401 and the second imaging pixel row 402 in FIG. 3), the imaging control unit 4a causes the vertical control unit 30 to perform the first, second, or third. Is read out. In addition, when the imaging control unit 4a reads signals from the AF pixel rows (the first AF pixel row 403a and the second AF pixel row 403b in FIG. 3), the vertical control unit 30 sets one AF pixel row. Alternatively, a process of reading out pixel signals by selecting a plurality of rows is performed.
Hereinafter, the first reading process, the second reading process, and the third reading process will be described.

The first readout process has a one-row readout method for reading out signals for each row of imaging pixel rows and a two-row simultaneous readout method for reading out signals simultaneously in two rows. In the one-row readout method, the image sensor 3 outputs a pixel signal to, for example, the first vertical signal line VoutA. Hereinafter, the one-row reading method will be described with reference to FIG.

The vertical control unit 30 includes the first selection unit 18 of the G pixel 10g (1,1) which is the pixel in the first row, that is, the G pixel 10g (1,1) in the first row and the second row. The first selection unit 18 shared by the R pixel 10r (2, 1) is turned on. The vertical control unit 30 also includes a second selection unit 19 of the G pixel 10g (1,1), that is, a second shared by the G pixel 10g (1,1) and the R pixel 10r (2,1). The selection unit 19 is turned off. The vertical control unit 30 turns off the first selection unit 18 and the second selection unit 19 of pixels in other rows different from the first row and the second row, respectively. As a result, the pixel signal based on the charge generated by the photoelectric conversion unit 11a of the G pixel 10g (1,1) in the first row passes through the first selection unit 18 of the G pixel 10g (1,1). It is output to the first vertical signal line VoutA.

After reading out the pixel signal from each pixel in the first row, the vertical control unit 30 performs the first selection unit 18 of the R pixel 10r (2, 1) that is the pixel in the second row, that is, the first row. The first selector 18 shared by the G pixel 10g (1, 1) of the eye and the R pixel 10r (2, 1) of the second row is turned on. The vertical control unit 30 turns off the second selection unit 19 of the R pixel 10r (2, 1). In addition, the vertical control unit 30 turns off the first selection unit 18 and the second selection unit 19 of pixels in other rows different from the first row and the second row, respectively. Thus, the pixel signal of the R pixel 10r (2,1) in the second row is output to the first vertical signal line VoutA via the first selection unit 18 of the R pixel 10r (2,1). .

After reading out the pixel signal from each pixel in the second row, the vertical control unit 30 performs the first selection unit 18 of the G pixel 10g (3, 1) that is the pixel in the third row, that is, the third row. The first selection unit 18 shared by the G pixel 10g (3, 1) of the eye and the R pixel 10r (4, 1) of the fourth row is turned on. The vertical control unit 30 turns off the second selection unit 19 of the G pixel 10g (3, 1). In addition, the vertical control unit 30 turns off the first selection unit 18 and the second selection unit 19 of pixels in other rows different from the third row and the fourth row, respectively. Accordingly, the pixel signal of the G pixel 10g (3, 1) in the third row is output to the first vertical signal line VoutA via the first selection unit 18 of the G pixel 10 g (3, 1). .
Similarly, in the fourth and subsequent rows, the imaging pixel rows are sequentially selected one by one, and pixel signals are read out. The vertical control unit 30 sequentially selects all the imaging pixel rows and reads out pixel signals from each pixel in all the imaging pixel rows.

The example in which the pixel signal of the imaging pixel is output to the first vertical signal line VoutA has been described. However, when the first selection unit 18 is in the off state and the second selection unit 19 is in the on state, the imaging pixel Can output the pixel signal to the second vertical signal line VoutB.

As described above, in the case of the one-row readout method of the first readout process, the imaging device 3 selects the imaging pixel rows one by one, and the first vertical signal line VoutA ( Alternatively, a pixel signal is output to the second vertical signal line VoutB). Next, the two-row simultaneous reading method will be described with reference to FIG.

In the two-row simultaneous readout method, pixel signals are output from the pixels in one row to the first vertical signal line VoutA and the pixel signals are output from the pixels in the other row to the second row. To the vertical signal line VoutB. Hereinafter, the two-row simultaneous reading method will be described by taking as an example a case where pixel signals of the R pixel 10r (2, 1) and the G pixel 10 g (3, 1) are simultaneously read.

The vertical control unit 30 turns on the first selection unit 18 of the R pixel 10r (2, 1) and turns off the second selection unit 19 of the R pixel 10r (2, 1). In addition, the vertical control unit 30 turns on the second selection unit 19 of the G pixel 10g (3, 1) and turns off the first selection unit 18 of the G pixel 10g (3, 1). Furthermore, the vertical control unit 30 includes the first selection unit 18 and the second selection unit 19 for pixels in other rows different from the first row, the second row, the third row, and the fourth row. Are turned off.

The pixel signal based on the charge generated by the photoelectric conversion unit 11b of the R pixel 10r (2,1) is transferred to the first vertical signal line VoutA via the first selection unit 18 of the R pixel 10r (2,1). Is output. Further, the pixel signal based on the electric charge generated by the photoelectric conversion unit 11a of the G pixel 10g (3, 1) is sent to the second vertical signal line via the second selection unit 19 of the G pixel 10g (3, 1). Output to VoutB. In this way, the pixel signal of the pixel in one row is output to the first vertical signal line VoutA, and at the same time, the pixel signal of the pixel in the other row is output to the second vertical signal line VoutB. The pixel signal of each pixel in one row can be read out simultaneously.

In addition, although the example which reads the signal of the pixel which mutually adjoins simultaneously was demonstrated, it can perform similarly when reading the pixel (for example, each pixel of the 1st row and the 3rd row) of the row | line | columns mutually separated simultaneously.

As described above, in the case of the two-row simultaneous readout method of the first readout process, the imaging device 3 selects the imaging pixel rows two by two, and the pixels from one row to the first vertical signal line VoutA. A signal is output, and at the same time, a pixel signal is output from the pixel in the other row to the second vertical signal line VoutB. For this reason, a signal can be read out at high speed from each imaging pixel arranged in the imaging device 3. That is, the image sensor 3 can shorten the signal readout time of the imaging pixel.

In addition, pixel signals sequentially output to the first vertical signal line VoutA are input to the first readout unit 40a, and pixel signals sequentially output to the second vertical signal line VoutB are input to the second readout unit 40b. Is input. Therefore, the pixel signal output to the first vertical signal line VoutA and the pixel signal output to the second vertical signal line VoutB can be processed simultaneously (in parallel). The pixel signal output from each imaging pixel 10 is converted into a digital signal by the reading unit 40 and then output to the control unit 4 as an imaging signal.

Next, a second reading process for reading a pixel signal from a selected pixel that is a part of all the imaging pixels will be described. The vertical control unit 30 designates a pixel from which a pixel signal is to be read out of all the imaging pixels. Specifically, the vertical control unit 30 selects a selected pixel by thinning out pixels in a specific row or column among all the imaging pixels, and reads a pixel signal from the selected pixel. That is, the vertical control unit 30 performs skip reading to skip pixels in a specific row or column, and performs control to read out pixel signals at a higher speed than in the first reading process.

Also, the second reading process has a one-row reading method and a two-row simultaneous reading method, as in the case of the first reading process. In the one-row readout method, the vertical control unit 30 selects a selected pixel for each row and outputs a signal of the selected pixel to the first vertical signal line VoutA or the second vertical signal line VoutB. In the two-row readout method, a selected pixel is selected every two rows, a pixel signal is output from the selected pixel in one row to the first vertical signal line VoutA, and a second pixel is output from the selected pixel in the other row. A pixel signal is output to the vertical signal line VoutB.

Next, a third reading process in which signals from a plurality of imaging pixels are added (mixed) and read will be described. For example, the vertical control unit 30 determines a selected pixel from among all the imaging pixels, and adds the pixel signals of each of the two selected pixels in which the same color filter 41 in the same column is arranged. That is, the vertical control unit 30 adds and reads out the signals of the same color pixels for every two pixels in the column direction. In the example illustrated in FIG. 7, the imaging device 3 selects, for example, the G pixel 10 g (1, 1) in the first row and the G pixel 10 g (3, 1) in the third row as selection pixels. The signals are added and the added pixel signal is output to the control unit 4. An example of pixel signal addition processing will be described below.

The vertical control unit 30 turns on the first selection unit 18 of the G pixels 10g (1, 1) and (3, 1) in the first row and the third row, and sets the second selection unit 19 in the on state. Turn off. When the first selection unit 18 of each of the G pixel 10g (1,1) and the G pixel 10g (3,1) is turned on, the G pixel 10g (1,1) and the G pixel 10g (3,1) ) Is electrically connected to the first vertical signal line VoutA. The current of the first current source 25a connected to the first vertical signal line VoutA is divided (distributed) into the G pixel 10g (1,1) and the G pixel 10g (3,1). In the first vertical signal line VoutA, the pixel signal of the G pixel 10g (1,1) and the pixel signal of the G pixel 10g (3,1) are added to form an added pixel signal.

When the voltage difference between the FD 15 of each of the G pixel 10g (1,1) and the G pixel 10g (3,1) is small, the first current source 25a includes the G pixel 10g (1,1) and the G pixel. A current of approximately the same magnitude is supplied to 10 g (3, 1). Thereby, the addition pixel signal output to the first vertical signal line VoutA corresponds to the average (value) of the voltage of the FD 15 of each of the G pixel 10 g (1, 1) and the G pixel 10 g (3, 1). It becomes a signal level (voltage) signal.

The readout of the added pixel signal from the selected pixels for the two rows of the first row and the third row is performed by the readout method described above. The vertical control unit 70 reads the added pixel signals from the selected pixels in the first and third rows, and then selects the next two rows of selected pixels (for example, the selected pixels in the fourth and sixth rows). The addition pixel signal is read out from. As described above, in the third readout process, the addition pixel signal is sequentially read out for each of a plurality of rows. The added pixel signal obtained by adding the signals of the plurality of selected pixels in the column direction is output to the control unit 4 after being subjected to signal processing by the reading unit 40. The image data generation unit 4 b of the control unit 4 generates image data (for example, moving image data) using the addition pixel signal output from the image sensor 3. Although an example in which pixel signals of two pixels in the column direction are added has been described, the number of pixels to be added may be an arbitrary number.

FIG. 8 is a timing chart showing an example of a reset operation of the image sensor 3 according to the first embodiment. In the timing chart shown in FIG. 8, the horizontal axis shows time, and shows control signals input to each part of the image sensor 3 in FIG. 7. In the example shown in FIG. 8, the signals GC <0>, GC <1>, and GC <2> are set to the high level, and the FD 15 and the region 16c are electrically connected.

At time t1 shown in FIG. 8, the signal RST <0> and the signal RST <1> are at a high level. When the signal RST <0> becomes high level, the transistor M4b of the reset unit 16b shared by the G pixel 10g (1,1) in the first row and the R pixel 10r (2,1) in the second row. Is turned on. As a result, the electric charges of the FD 15 and the region 16c shared by the G pixel 10g (1, 1) and the R pixel 10r (2, 1) are discharged, and the voltage of the FD 15 and the region 16c becomes the reset voltage.
Further, when the signal RST <1> becomes high level, the reset unit 16b shared by the G pixel 10g (3, 1) in the third row and the R pixel 10r (4, 1) in the fourth row. The transistor M4b is turned on. As a result, the charges of the FD 15 and the region 16c shared by the G pixel 10g (3, 1) and the R pixel 10r (4, 1) are discharged, and the voltage of the FD 15 and the region 16c becomes the reset voltage.

At time t2, the signal TX1 <0> and the signal TX0 <1> are at a high level. When the signal TX1 <0> becomes high level, the transistor M2 of the transfer unit 12b is turned on in the R pixel 10r (2, 1), and the photoelectric conversion unit 11b, the FD 15, and the region 16c are electrically connected. The Thereby, the electric charge of the photoelectric conversion unit 11b is discharged, and the voltage of the photoelectric conversion unit 11b is reset.
Further, when the signal TX0 <1> is set to the high level, the transistor M1 of the transfer unit 12a is turned on in the G pixel 10g (3, 1), and the photoelectric conversion unit 11a, the FD 15, and the region 16c are electrically connected. Connected. Thereby, the electric charge of the photoelectric conversion unit 11a is discharged, and the voltage of the photoelectric conversion unit 11a is reset.
As described above, the reset operation for discharging the charges of the FD 15, the region 16 c, and the photoelectric conversion unit 11 is performed once in the pixels in the second row and the third row.

At time t3, the signal RST <1> and the signal RST <2> are at a high level. When the signal RST <1> becomes high level, the charges of the FD 15 and the region 16c shared by the G pixel 10g (3, 1) and the R pixel 10r (4, 1) are discharged, and the voltage of the FD 15 and the region 16c is discharged. Becomes the reset voltage.
Further, when the signal RST <2> becomes high level, the charges of the FD 15 and the region 16c shared by the G pixel 10g (5, 1) and the R pixel 10r (6, 1) are discharged, and the FD 15 and the region 16c are discharged. Becomes the reset voltage.

At time t4, the signal TX1 <1> and the signal TX0 <2> are at a high level. When the signal TX1 <1> becomes high level, the transistor M2 of the transfer unit 12b is turned on in the R pixel 10r (4, 1), and the photoelectric conversion unit 11b, the FD 15, and the region 16c are electrically connected. The Thereby, the electric charge of the photoelectric conversion unit 11b is discharged, and the voltage of the photoelectric conversion unit 11b is reset.
Further, when the signal TX0 <2> is set to the high level, in the G pixel 10g (5, 1), the transistor M1 of the transfer unit 12a is turned on, and the photoelectric conversion unit 11a, the FD 15, and the region 16c are electrically connected. Connected. Thereby, the electric charge of the photoelectric conversion unit 11a is discharged, and the voltage of the photoelectric conversion unit 11a is reset.
As described above, the reset operation for discharging the charges of the FD 15, the region 16 c, and the photoelectric conversion unit 11 is performed once in the pixels in the fourth row and the fifth row.

Next, an example of the read operation will be described with reference to FIGS. FIG. 9 is a timing chart showing an example of a reading operation of the image sensor 3 according to the first embodiment.

At time t11 shown in FIG. 9, the signal RST <0> and the signal RST <1> are at a high level. When the signal RST <0> becomes high level, the charges of the FD 15 and the region 16c shared by the G pixel 10g (1,1) and the R pixel 10r (2,1) are discharged, and the voltage of the FD 15 and the region 16c is discharged. Becomes the reset voltage.
Further, when the signal RST <1> becomes high level, the charges of the FD 15 and the region 16c shared by the G pixel 10g (3, 1) and the R pixel 10r (4, 1) are discharged, and the FD 15 and the region 16c are discharged. Becomes the reset voltage.

At time t11, the signal SELA <0> and the signal SELB <1> are at a high level. When the signal SELA <0> is set to the high level, a signal based on the reset voltage of the R pixel 10r (2,1) is generated by the amplification unit 17 and the first selection unit 18 of the R pixel 10r (2,1). 1 to the vertical signal line VoutA. That is, a signal (reset signal) after discharging the charge of the FD 15 of the R pixel 10r (2, 1) is output to the first vertical signal line VoutA.
Further, when the signal SELB <1> is set to the high level, the reset signal of the G pixel 10g (3, 1) is transmitted to the second selection unit 19 by the amplification unit 17 and the second selection unit 19 of the G pixel 10g (3, 1). Are output to the vertical signal line VoutB.

In this way, the R pixel 10r (2,1) in the second row and the G pixel 10g (3,1) in the third row are respectively connected to the first vertical signal line VoutA and the second vertical signal line VoutB. The reset signal is output simultaneously. The reset signals output to the first vertical signal line VoutA and the second vertical signal line VoutB are input to the first readout unit 40a and the second readout unit 40b, respectively, and converted into digital signals.

At time t12, the signal TX1 <0> and the signal TX0 <1> become high level. When the signal TX1 <0> becomes high level, the transistor M2 of the transfer unit 12b is turned on in the R pixel 10r (2, 1), and the charge photoelectrically converted by the photoelectric conversion unit 11b is transferred to the FD15. . Further, when the signal TX0 <1> becomes high level, the transistor M1 of the transfer unit 12a is turned on in the G pixel 10g (3, 1), and the charge photoelectrically converted by the photoelectric conversion unit 11a is transferred to the FD15. Is done.

At time t12, since the signal SELA <0> is at a high level, the pixel signal based on the charge generated by the photoelectric conversion unit 11b of the R pixel 10r (2, 1) is converted into the amplification unit 17 and the first selection. The signal is output to the first vertical signal line VoutA by the unit 18. Further, since the signal SELB <1> is at a high level, the pixel signal of the G pixel 10g (3, 1) is output to the second vertical signal line VoutB by the amplifying unit 17 and the second selecting unit 19.

In this way, the R pixel 10r (2,1) in the second row and the G pixel 10g (3,1) in the third row are respectively connected to the first vertical signal line VoutA and the second vertical signal line VoutB. ) Output pixel signals simultaneously. Pixel signals output to the first vertical signal line VoutA and the second vertical signal line VoutB are input to the first readout unit 40a and the second readout unit 40b, respectively, and converted into digital signals. The reset signal and the pixel signal converted into a digital signal are input to a signal processing unit (not shown). The signal processing unit performs signal processing such as correlated double sampling for performing difference processing between the reset signal and the pixel signal, and then outputs the processed pixel signal to the control unit 4.

In the period from time t13 to time t15, as in the period from time t11 to time t13, the pixels in the fourth row are selected in FIG. Reading is performed.

Next, an example of the dummy reset operation will be described with reference to FIGS. FIG. 10 is a timing chart showing an example of the dummy reset operation of the image sensor 3 according to the first embodiment. Hereinafter, the dummy reset operation will be described by taking as an example a case where a dummy reset operation is performed on the R pixel 10r (2, 1), the G pixel 10g (3, 1), and the R pixel 10r (4, 1). In the example shown in FIG. 10, the signal GC is set to the high level, and the FD 15 and the region 16c are electrically connected.

At time t21 shown in FIG. 10, the signal RST <0> and the signal RST <1> are at a high level. When the signal RST <0> becomes high level, the charges of the FD 15 and the region 16c shared by the G pixel 10g (1,1) and the R pixel 10r (2,1) are discharged, and the voltage of the FD 15 and the region 16c is discharged. Becomes the reset voltage.
Further, when the signal RST <1> becomes high level, the charges of the FD 15 and the region 16c shared by the G pixel 10g (3, 1) and the R pixel 10r (4, 1) are discharged, and the FD 15 and the region 16c are discharged. Becomes the reset voltage.

At time t22, the signal TX1 <0>, the signal TX0 <1>, and the signal TX1 <1> are at a high level. When the signal TX1 <0> becomes high level, the charge of the photoelectric conversion unit 11b is discharged in the R pixel 10r (2, 1), and the voltage of the photoelectric conversion unit 11b is reset.
Further, when the signal TX0 <1> and the signal TX1 <1> are at a high level, the photoelectric conversion unit 11a of the G pixel 10g (3, 1) and the photoelectric conversion unit 11b of the R pixel 10r (4, 1) , FD15 and region 16c are electrically connected. Thereby, the electric charges of the photoelectric conversion units 11a and 11b are discharged, and the voltages of the photoelectric conversion units 11a and 11b are reset.
Thus, in the pixels of the second row, the third row, and the fourth row, the dummy reset operation for discharging the charges of the FD 15, the region 16 c, and the photoelectric conversion unit 11 is performed once.

From time t23 to time t25, the pixels in the second row, third row, and fourth row are the same as in the first dummy reset operation in the period from time t21 to time t23. A second dummy reset operation is performed.

FIG. 11 is a diagram schematically illustrating pixel signal readout processing and dummy reset processing by the image sensor according to the first embodiment. FIG. 11 schematically illustrates the addition pixel signal read from the imaging pixel row and the pixel signal read from the AF pixel row.

The vertical control unit 30 includes, for example, the imaging pixels 10 surrounded by a thick line in FIG. 11 among all the imaging pixels 10, that is, the fourth row, the sixth row, the seventh row, the ninth row, and the tenth row. The imaging pixels 10 in the row, the twelfth row, the thirteenth row, the fifteenth row, the sixteenth row, and the eighteenth row are determined as selection pixels. When the signal is read from the imaging pixel row, the vertical control unit 30 performs the above-described third reading process, and adds and reads the signals of the two selected pixels of the same color arranged in the column direction.

In the first column, for example, the pixel signals of the two R pixels of the R pixel 10r (4, 1) and the R pixel 10r (6, 1) are added to generate an added pixel signal, and the G pixel 10g (7 , 1) and the G pixel 10g (9, 1) are added together to generate an added pixel signal. In the second column, for example, pixel signals of two G pixels of the G pixel 10 g (4, 2) and the G pixel 10 g (6, 2) are added to generate an added pixel signal, and the B pixel 10 b The pixel signals of two B pixels of (7, 2) and B pixel 10b (9, 2) are added to generate an added pixel signal.

Similarly, in the 10th and 12th rows, the 13th and 15th rows, the 16th and 18th rows, pixel signals of two same color pixels in the column direction are added and added. A pixel signal is generated. By adding the signals of the selected pixels in this way, the generated added pixel signal also becomes a signal corresponding to the Bayer array.

When the signal is read from the AF pixel row, the vertical control unit 30 selects the fifth AF pixel row 403a and the 17th second AF pixel row 403b, Read the signal.

In the case of the example shown in FIG. 11, the imaging pixel rows of the eighth row, the eleventh row, and the fourteenth row are in either case of reading signals from the imaging pixel rows and reading signals from the AF pixel rows. In other words, the pixel row does not output a pixel signal, that is, a skipped row. As described above, the vertical control unit 30 sequentially selects each pixel row to be read and reads out the pixel signal, and among the pixel rows to be skipped during the reading operation of each pixel row. A dummy reset operation is performed on any of the pixel rows. As a result, it is possible to suppress fluctuations in the number of pixel rows on which the reset operation is performed, and to prevent noise caused by fluctuations in the power supply voltage from being mixed into the pixel signal.

FIG. 12 is a diagram illustrating an operation example of the image sensor according to the first embodiment, and illustrates an operation example in the case where the third readout process is performed and signals are read from the imaging pixel rows as illustrated in FIG. 11. ing. The vertical axis represents the pixel row, and the horizontal axis represents the timing (time t) at which the reset operation and readout operation of each pixel row are performed. FIG. 12 schematically illustrates pixel row transition in which the reset operation and the read operation are performed. In the example illustrated in FIG. 12, the pixel signal is read from the pixel after the reset operation is performed five times for the pixel to be read (selected pixel).

In the fourth, sixth, seventh, and ninth pixel rows, the period from time t1 to time t2, the period from time t3 to time t4, and from time t5 to time t6 During the period, the period from time t7 to time t8, and the period from time t9 to time t10, the first, second, third, fourth, and fifth reset operations R1 to R5 are performed, respectively. .
In the tenth, twelfth, thirteenth, and fifteenth pixel rows, the period from time t2 to time t3, the period from time t4 to time t5, and from time t6 to time t7 During the period, the period from time t8 to time t9, and the period from time t10 to time t11, the first, second, third, fourth, and fifth reset operations R1 to R5 are performed, respectively. .
In the 16th, 18th, 19th, and 21st pixel rows, the period from time t3 to time t4, the period from time t5 to time t6, and from time t7 to time t8 During the period, the period from time t9 to time t10, and the period from time t11 to time t12, the first, second, third, fourth, and fifth reset operations R1 to R5 are performed, respectively. .

In the period from time t20 to time t21, the vertical control unit 30 performs the reading operation T1 of the fourth row, the sixth row, the seventh row, and the ninth row to be read, and skips the reading. A dummy reset operation is performed on some of the pixel rows.
An added pixel signal obtained by adding the signals of the imaging pixels in the fourth row and the sixth row is output to, for example, the first vertical signal line VoutA connected to these imaging pixels, and the seventh row and the ninth row. An added pixel signal obtained by adding the signals of the respective imaging pixels in the row is output to the second vertical signal line VoutB connected to these imaging pixels.

During the period from time t21 to time t22, the vertical control unit 30 performs the reading operation T2 of the tenth row, the twelfth row, the thirteenth row, and the fifteenth row to be read and also skips the reading. A dummy reset operation is performed on some of the pixel rows.
An added pixel signal obtained by adding the signals of the imaging pixels in the 10th and 12th rows is output to, for example, the first vertical signal line VoutA connected to these imaging pixels, and the 13th and 15th rows. An added pixel signal obtained by adding the signals of the respective imaging pixels in the row is output to the second vertical signal line VoutB connected to these imaging pixels.

In the period from time t22 to time t23, the vertical control unit 30 performs the reading operation T3 of the 16th row, the 18th row, the 19th row, and the 21st row to be read and also skips the reading. A dummy reset operation is performed on some of the pixel rows.
An added pixel signal obtained by adding the signals of the imaging pixels in the 16th and 18th rows is output to, for example, the first vertical signal line VoutA connected to these imaging pixels, and the 19th and 21st rows. An added pixel signal obtained by adding the signals of the respective imaging pixels in the row is output to the second vertical signal line VoutB connected to these imaging pixels.

The number of skipped rows in which the dummy reset operation is performed in each of the period from the time t20 to the time t21, the period from the time t21 to the time t22, and the period from the time t22 to the time t23, In the readout period until the end of the operation, it is determined based on the maximum number of rows in which the reset operation is simultaneously performed. As a result, the number of rows in which the reset operation is performed at the same timing in the period of the readout operation of each pixel row is the same. For this reason, it can suppress that a power supply voltage fluctuates, and can prevent that noise mixes in a pixel signal.

In the above, an example has been described in which the number of pixel rows in which the reset operation is performed is the same in order to suppress fluctuations in the power supply voltage. However, even when the number of pixel rows on which the readout operation is performed at the same time changes, the load of the power supply changes and the power supply voltage may fluctuate. Therefore, the dummy reset operation may be performed based on the number of pixel rows on which the read operation is performed. In this case, for example, in the pixel signal readout period, the vertical control unit 30 performs the non-read target so that the number of pixel rows on which the readout operation is performed is the same as the number of pixel rows on which the dummy reset operation is performed. A dummy reset operation is performed on the pixel row.

According to the embodiment described above, the following operational effects can be obtained.
(1) The image pickup device 3 photoelectrically converts light to generate charges, a storage unit (FD 15) that stores charges generated by the photoelectric conversion unit 11, and a supply that supplies a predetermined voltage A switching unit 16 that switches connection and disconnection between the unit 35 and the storage unit, and an output unit (amplifier 17, first selection unit 18, and second selection unit 19 that outputs a signal based on the charge stored in the storage unit. ), And a signal is output from the output unit of the first pixel among the plurality of pixels, and a signal is not output from the output unit of the second pixel among the plurality of pixels, and the second pixel is switched. A control unit (vertical control unit 30) for controlling the supply unit 35 and the storage unit to be connected to the unit 16; In the present embodiment, the vertical control unit 30 reads out the pixel signal from the output unit of the pixel to be read, performs a dummy reset operation on the non-read target pixel, and supplies the pixel signal to the switching unit 16 of the non-read target pixel. The unit 35 and the FD 15 are connected. For this reason, the number of pixels on which the reset operation is performed can be controlled in a period in which pixel signals are read, and fluctuations in the power supply voltage can be suppressed. As a result, since it is not necessary to separately arrange dummy pixels, it is possible to prevent the area of the image sensor from increasing. It is possible to suppress noise from being mixed into the pixel signal, and to suppress deterioration in image quality of an image generated using the pixel signal.

(2) The image pickup device 3 photoelectrically converts light to generate charges, a photoelectric conversion unit 11 that generates charges, a storage unit (FD15) that stores charges generated by the photoelectric conversion unit 11, and a supply that supplies a predetermined voltage A switching unit 16 that switches between connection and disconnection between the unit 35 and the storage unit, and an output unit that outputs a signal based on the charge stored in the storage unit (amplifying unit 17, first selection unit 18, second selection unit) 19) and a signal is output from the output unit of the first pixel among the plurality of pixels, and the supply unit 35 and the storage unit are connected to the switching unit 16 of the second pixel among the plurality of pixels. And a control unit (vertical control unit 30) that changes the number of second pixels. In the present embodiment, the vertical control unit 30 reads the pixel signal from the readout target pixel and controls the number of non-readout target pixels on which the dummy reset operation is performed. For this reason, the number of pixels for which the reset operation is performed at the same timing can be adjusted, and fluctuations in the power supply voltage can be suppressed. As a result, it is possible to suppress a decrease in image quality.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.

(Modification 1)
In the above-described embodiment, the example in which the first vertical signal line VoutA and the second vertical signal line VoutB are arranged as the vertical signal lines has been described, but the present invention is not limited to this. For example, three or more vertical signal lines may be arranged. If there are 3 or more vertical signal lines, simultaneous readout of signals from 3 or more pixel rows using 3 or more vertical signal lines and addition readout for adding signals from multiple imaging pixel rows are possible. become. In that case, since the readout operation is performed after the reset operation is simultaneously performed on the pixels in three or more rows, the number of pixel rows on which the reset operation is simultaneously performed further increases. However, in this embodiment, since a dummy reset operation is performed on a pixel that is not to be read, it is possible to prevent a shortage of pixel rows for adjusting the number of reset rows. Further, since it is not necessary to separately arrange pixels for performing the dummy reset operation, it is possible to prevent a further increase in the area of the image sensor and a further increase in manufacturing cost.

(Modification 2)
In the first embodiment described above, an example in which two adjacent pixels share the FD 15 and the like has been described, but the configuration of the pixels is not limited to this. For example, each of the plurality of pixels provided in the imaging device 3 may include the FD 15, the switching unit 16, the amplification unit 17, the first selection unit 18, and the second selection unit 19.

(Modification 3)
In the above-described embodiment, the example in which the G color filter 41 is arranged in the AF pixel 13 has been described, but the present invention is not limited to this. For example, a W (white) color filter or a B color filter may be arranged as the color filter 41 in the AF pixel 13.

(Modification 4)
In the above-described embodiment, the case where a primary color (RGB) color filter is used for the image sensor 3 has been described. However, a complementary color (CMY) color filter may be used.

(Modification 5)
In the embodiment and the modification described above, the example in which the photodiode is used as the photoelectric conversion unit has been described. However, a photoelectric conversion film may be used as the photoelectric conversion unit.

(Modification 6)
The image pickup device 3 described in the above-described embodiments and modifications is applied to a camera, a smartphone, a tablet, a camera built in a PC, an in-vehicle camera, a camera mounted on an unmanned aircraft (such as a drone or a radio control machine), and the like. Also good.

(Modification 7)
You may apply the image pick-up element demonstrated by embodiment and the modification mentioned above to the lamination | stacking sensor (laminated | stacked imaging element) comprised by laminating | stacking a some board | substrate (for example, several semiconductor substrate). For example, the pixel unit 100 is arranged on the first layer substrate, the vertical control unit 30 and the readout unit 40 are arranged on the second layer substrate, and the vertical signal line Vout is arranged on the first layer substrate and the second layer substrate. Place between the board. The pixel unit 100 and the vertical control unit 30 may be disposed on the first layer substrate, and the reading unit 40 may be disposed on the second layer substrate. The laminated sensor may have three or more layers.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

The disclosure of the following priority application is hereby incorporated by reference.
Japanese Patent Application No. 2018-0012 (filed on March 30, 2018)

3 imaging device, 4 control unit, 4a imaging control unit, 4b image data generation unit, 4c focus detection unit, 10 imaging pixel, 11 photoelectric conversion unit, 13a first AF pixel, 13b second AF pixel, 15 FD, 17 amplification unit, 18 first selection unit, 19 second selection unit, 30 vertical control unit, 35 supply unit

Claims (18)

1. Switching between connection and disconnection of a photoelectric conversion unit that photoelectrically converts light to generate charges, a storage unit that stores charges generated by the photoelectric conversion unit, a supply unit that supplies a predetermined voltage, and the storage unit A plurality of pixels each having a switching unit and an output unit that outputs a signal based on the charge accumulated in the accumulation unit;
   Among the plurality of pixels, while the signal based on the charge accumulated in the accumulation unit of the first pixel is output from the output unit, the switching unit of the second pixel among the plurality of pixels and the supply unit A control unit that controls to connect the storage unit;
   An imaging device comprising:
2. The imaging device according to claim 1,
   While the control unit is outputting a signal from the output unit of the first pixel, the control unit does not output a signal from the output unit of the second pixel, and the switching unit of the second pixel is connected to the supply unit. An image sensor that controls to connect the storage unit.
3. The imaging device according to claim 1 or 2,
   The control unit is an image sensor that changes the number of the second pixels that connect the supply unit and the storage unit while outputting a signal from the output unit of the first pixel.
4. In the imaging device according to any one of claims 1 to 3,
   A plurality of the first pixels and the second pixels are provided in a first direction;
   The supply unit sequentially outputs signals from the output units of the plurality of first pixels in the first direction, and supplies the signals from the output unit based on the number of the first pixels. And an image sensor that changes the number of the second pixels that connect the storage unit.
5. In the image sensor according to any one of claims 1 to 4,
   The control unit is an image sensor that changes the number of the second pixels that connect the supply unit and the storage unit based on the number of the first pixels that output a signal from the output unit.
6. In the image sensor according to any one of claims 1 to 5,
   The control unit is an imaging device that changes the number of the second pixels that connect the supply unit and the storage unit when the number of the first pixels that output signals from the output unit changes.
7. In the image sensor according to any one of claims 1 to 6,
   The control unit increases the number of the second pixels that cause the switching unit to connect the supply unit and the storage unit when the number of the first pixels outputting a signal from the output unit decreases. .
8. In the imaging device according to any one of claims 1 to 7,
   The control unit sets the number of the second pixels so that the total number of the first pixels that output signals from the output unit and the second pixels that connect the supply unit and the storage unit is constant. Image sensor to change.
9. In the imaging device according to any one of claims 1 to 8,
   The imaging unit is an imaging device that causes a signal used for image generation to be output from the output unit of the first pixel and does not output a signal used for image generation from the output unit of the second pixel.
10. In the imaging device according to any one of claims 1 to 9,
    The control unit is an image sensor that connects the supply unit and the storage unit to the switching unit of the second pixel when the control unit outputs signals simultaneously from the output units of the plurality of first pixels.
11. In the image sensor according to any one of claims 1 to 10,
    The control unit connects the supply unit and the storage unit to the switching unit of the first pixel before outputting a signal from the output unit of the first pixel, and the supply unit and the storage unit An image sensor that changes the number of the second pixels to which the supply unit and the storage unit are connected based on the number of the first pixels to which the pixel is connected.
12. The imaging device according to claim 11,
    The control unit is an image pickup device that changes the number of the first pixels that connect the supply unit and the storage unit when the number of the first pixels to which the supply unit and the storage unit are connected changes.
13. The imaging device according to claim 11 or 12,
    The image pickup device that changes the number of the second pixels so that the total number of the first pixels and the second pixels that connect the supply unit and the storage unit is constant.
14. The imaging device according to any one of claims 1 to 13,
    The control unit causes the output unit of some of the pixels to output a signal used for image generation, and causes the output unit of the plurality of pixels to output a signal used for image generation. Perform the second control,
    The first pixel is a pixel that outputs a signal used for image generation from the output unit in the first control,
    In the first control, the second pixel is a pixel that does not output a signal used for image generation from the output unit.
15. In the imaging device according to any one of claims 1 to 14,
    The control unit performs third control for simultaneously outputting signals from the output units of the plurality of first pixels, and fourth control for sequentially outputting signals from the output units of the plurality of first pixels,
    In the third control, the control unit connects the supply unit and the storage unit to the switching unit of the second pixel.
16. The image sensor according to any one of claims 1 to 15,
    The first pixel and the second pixel are image sensors in a region where light enters from the outside.
17. The imaging device according to any one of claims 1 to 16,
    The image pickup device, wherein the switching unit is a discharge unit that discharges the charge accumulated in the accumulation unit to the supply unit.
18. The image sensor according to any one of claims 1 to 17,
    A generating unit that generates image data based on a signal output from the output unit;
    An imaging apparatus comprising:

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