JP6688854B2 - Imaging device - Google Patents

Description

  The present technology relates to an image pickup apparatus, and particularly to an image pickup apparatus capable of suppressing reduction in image quality.

  In recent years, image pickup devices such as video cameras and digital still cameras have used image sensors (image pickup devices) such as CCDs (Charge Coupled Devices) and CMOSs (Complementary Metal Oxide Semiconductors) as image pickup devices for picking up images.

  In such an image pickup device, kTC noise, which is reset noise generated due to thermal fluctuation of electric charges, is generated in a portion converting electric charges into voltage. Then, the method of suppressing kTC noise was considered (for example, refer patent document 1).

JP, 2013-30820, A

  However, with the method described in Patent Document 1, it is difficult to sufficiently suppress the kTC noise, and the kTC noise that cannot be completely removed adversely affects the RN noise of the image sensor, resulting in a captured image obtained by the image sensor. There was a risk of reducing the image quality.

  In particular, when the pixel structure of the image sensor is a structure that cannot be completely depleted, the kTC noise is large, and it is more difficult to sufficiently suppress the kTC noise, and the image quality of the captured image obtained by the image sensor is improved. There was a risk of further reduction.

  The present technology has been proposed in view of such a situation, and an object thereof is to suppress reduction in image quality.

One aspect of the present technology is to compare a unit pixel including a first photoelectric conversion unit provided in a semiconductor substrate and a second photoelectric conversion unit provided on the semiconductor substrate with a unit pixel connected to the unit pixel. Unit, a DAC (Digital Analog Converter) connected to the comparator, and a clamp control unit connected to the comparator , the clamp control unit is a color separated in the unit vertical direction in the substrate vertical direction. Separately, at each timing of the shutter operation for resetting the floating diffusion provided in the unit pixel and the read operation for reading out the charges obtained by photoelectric conversion from the floating diffusion, the clamp amount adjustment value is independently set, Based on the set adjustment value of the clamp amount, clamp control is performed at each timing for each color, and the reference signal from the DAC is output. An imaging device for clamping.

  According to the present technology, a signal can be processed. In particular, it is possible to suppress a reduction in image quality.

It is a figure showing the main examples of composition of an image sensor. It is a figure which shows the main structural examples of a unit pixel. It is a figure which shows the example of a pixel arrangement. It is a figure which shows the example of a pixel structure. 9 is a timing chart illustrating an example of a pixel reading state. It is a flow chart explaining an example of a flow of read-out control processing. 9 is a timing chart illustrating an example of a driving state when reading pixels. It is a figure which shows the detailed structural example of an image sensor. It is a flow chart explaining an example of a flow of read-out control processing. 9 is a timing chart illustrating an example of a driving state when reading pixels. It is a figure showing a part of main composition example of a CMOS image sensor. It is a figure which shows the main structural examples of an imaging device.

Hereinafter, modes for carrying out the present disclosure (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. First Embodiment (Signal Processing Device / Imaging Element / Imaging Device)
2. Second embodiment (imaging device)
3. Third embodiment (imaging device)
4. Fourth embodiment (imaging device)
5. Fifth embodiment (imaging device)

<1. First Embodiment>
<KTC noise>

  In recent years, in image pickup apparatuses such as video cameras and digital still cameras, CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) image sensors (image pickup elements) have been used as image pickup elements for picking up images. Further, a single plate method is used as a method of such an image pickup device.

  In the single plate method, an image pickup device in which different color filters are arranged for each pixel (generally, an RGB Bayer array is widely used) is used. For example, in the case of the Bayer array using the primary color filters, red and blue light does not pass through the color filters in the pixels under the green color filter, so that there is a problem that the light cannot be used efficiently. Further, there is a problem that false color is generated because a process (demosaic process) that complements the insufficient color information from the peripheral pixels to generate a color image is required.

  In order to solve these problems, an image sensor that performs color separation in the substrate vertical direction (depth direction) is expected. The pixel structure of the image pickup device that performs color separation in the substrate vertical direction (depth direction) includes a pixel structure that performs color separation in the substrate vertical direction using the silicon depth direction, and a substrate vertical direction that uses a photoelectric conversion film. A pixel structure that performs color separation, a pixel structure that performs color separation in the substrate vertical direction using both the depth direction of silicon and the photoelectric conversion film, and the like are known.

  An image pickup apparatus using an image pickup element that performs color separation in the substrate vertical direction (depth direction) can hold color information of a plurality of colors (normally three RGB colors) per pixel. Compared with the single plate method, this is expected to improve the pixel characteristics because light can be used efficiently and to avoid false colors because demosaicing is not required.

  However, in the pixel structure in which the photoelectric conversion film is used to perform color separation in the direction perpendicular to the substrate, it is necessary to connect the photoelectric conversion film and the floating diffusion (FD) with a metal. Therefore, there arises a problem that complete depletion cannot be achieved. As a result, there is a possibility that the kTC noise is large and the kTC noise cannot be removed.

  In the method described in Patent Document 1, a large kTC noise can be suppressed to a small kTC noise, but it is difficult to sufficiently suppress the kTC noise, and the kTC noise that cannot be removed is RN of the image sensor. There is a risk that the noise is adversely affected and the image quality of the captured image obtained by the image sensor is reduced.

<Countermeasure against kTC noise>
Therefore, in the signal processing device, as a shutter operation of photoelectrically converting incident light and resetting a floating diffusion of a unit pixel which is not completely depleted, a first read-out signal from the unit pixel in a high state of a reset signal of the unit pixel is used. Signal, a second signal read from the unit pixel when the reset signal of the unit pixel is in a low state as a shutter operation, and resetting the unit pixel as a read operation in which charges obtained by photoelectric conversion from the floating diffusion of the unit pixel are read The third signal read out from the unit pixel when the signal is low (Low) and the fourth signal read out from the unit pixel when the reset signal of the unit pixel is high in the read operation are respectively A The A / D converter that performs A / D conversion and the A / D converter Correlation signal using the first digital data obtained by A / D conversion of the signal of No. 2 and the second digital data obtained by A / D conversion of the second signal by the A / D conversion unit. Double sampling is performed to generate the first output signal, and the third digital data obtained by A / D converting the third signal by the A / D conversion unit and the fourth digital data by the A / D conversion unit. Correlated double sampling is performed using the fourth digital data obtained by A / D conversion of the signal to generate the second output signal, and the first output signal and the second output signal are used. And a correlated double sampling processing unit that performs correlated double sampling to generate a third output signal.

  In other words, the first signal read out from the unit pixel when the reset signal of the unit pixel is high (A / D) is used as the shutter operation for photoelectrically converting incident light and resetting the floating diffusion of the unit pixel that is not completely depleted. The second signal obtained by converting and performing A / D conversion of the second signal read from the unit pixel in the state where the reset signal of the unit pixel is low as a shutter operation is obtained. Floating diffusion of the unit pixel by performing correlated double sampling using the first digital data and the second digital data obtained by A / D converting the second signal to generate the first output signal. As a read operation for reading out the charges obtained by photoelectric conversion from the unit pixel, the reset signal of the unit pixel is read out from the unit pixel in a low state. The signal of 3 is A / D converted, and the fourth signal read from the unit pixel is A / D converted in the read operation when the reset signal of the unit pixel is high (High), and the third signal is A / D converted. Correlated double sampling is performed using the third digital data obtained by conversion and the fourth digital data obtained by A / D conversion of the fourth signal to generate a second output signal. Then, correlated double sampling is performed using the first output signal and the second output signal to generate the third output signal.

  By doing so, kTC noise included in the pixel signal can be sufficiently suppressed. Therefore, the signal processing device can suppress the reduction in the image quality of the image of the image data.

  Note that this signal processing device further includes a storage unit that stores the first to fourth digital data obtained in the A / D conversion unit, and the correlated double sampling processing unit reads from the storage unit. Correlated double sampling may be performed using the first digital data and the second digital data, or the third digital data and the fourth digital data. By doing so, the signal processing device can cope with the timing intervals of the shutter operation and the read operation, and can perform the correlated double sampling at more arbitrary timing.

  The storage unit further stores the first output signal generated by the correlated double sampling processing unit, and the correlated double sampling processing unit reads out the generated second output signal from the storage unit. Correlated double sampling may be performed using the first output signal. By doing so, the signal processing device can perform correlated double sampling at more arbitrary timing.

  In the image sensor, a unit pixel that photoelectrically converts incident light and is not completely depleted and a shutter operation that resets the floating diffusion of the unit pixel are read out from the unit pixel in a high state as a reset signal of the unit pixel. The first signal is the shutter operation, the second signal is read from the unit pixel when the reset signal of the unit pixel is in a low state, and the read operation is a unit of the read operation in which charges obtained by photoelectric conversion from the floating diffusion of the unit pixel are read. The third signal read from the unit pixel when the reset signal of the pixel is low (Low) and the fourth signal read from the unit pixel when the reset signal of the unit pixel is high (High) in the read operation , A / D conversion section for A / D conversion and A / D conversion section respectively The first digital data obtained by A / D conversion of the first signal and the second digital data obtained by A / D conversion of the second signal by the A / D conversion unit are used. Correlated double sampling is performed to generate the first output signal, and the third digital data obtained by A / D converting the third signal by the A / D conversion unit and the A / D conversion unit Correlated double sampling is performed using the fourth digital data obtained by A / D conversion of the fourth signal to generate the second output signal, and the first output signal and the second output signal May be used to perform correlated double sampling to generate a third output signal.

  By doing so, kTC noise included in the pixel signal can be sufficiently suppressed. Therefore, the image sensor can suppress the reduction in the image quality of the image of the image data.

  Further, in the unit pixel, a photoelectric conversion unit that photoelectrically converts incident light and a floating diffusion may be connected by metal. In such a case, it is more difficult to sufficiently reduce the kTC noise, but even in this case, by applying the present technology, the kTC noise included in the pixel signal can be sufficiently suppressed.

  Further, the unit pixel may have a pixel structure that performs color separation in the substrate vertical direction. At that time, green may be color-separated by using an organic photoelectric conversion film, and red and blue may be color-separated according to the depth of silicon, or green, red, and blue may be silicon-respectively. You may make it color-separate according to the depth of.

  The image pickup apparatus includes an image pickup unit that picks up an image of a subject and an image processing unit that processes the image data obtained by the image pickup by the image pickup unit. The image pickup unit photoelectrically converts incident light and is not completely depleted. The unit pixel and the first signal read from the unit pixel when the reset signal of the unit pixel is in a high state as a shutter operation for resetting the floating diffusion of the unit pixel, and the reset signal of the unit pixel is low (Low) as a shutter operation. ) State, the second signal read from the unit pixel, and the read operation of reading the electric charge obtained by photoelectric conversion from the floating diffusion of the unit pixel, the reset signal of the unit pixel is read from the unit pixel in the low state as a read operation. Third signal and reset of unit pixel as read operation When the fourth signal read from the unit pixel in the high state of the signal is A / D converted by the A / D converter, and the first signal is A / D converted by the A / D converter. Correlated double sampling is performed using the obtained first digital data and the second digital data obtained by A / D converting the second signal by the A / D conversion unit, and then the first output A signal is generated, and the third digital data obtained by A / D converting the third signal by the A / D converter and the fourth digital signal obtained by A / D converting by the A / D converter are obtained. Correlated double sampling is performed using the obtained fourth digital data to generate a second output signal, and correlated double sampling is performed using the first output signal and the second output signal, and a third output is performed. May be provided.

  By doing so, kTC noise included in the pixel signal can be sufficiently suppressed. Therefore, the imaging device can suppress the reduction in the image quality of the image of the image data.

<2. Second Embodiment>
<Imaging device>
FIG. 1 is a diagram illustrating a main configuration example of an image sensor to which the present technology is applied. The image sensor 100 shown in FIG. 1 is, for example, an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The image sensor 100 captures an image of a subject, performs photoelectric conversion, etc. It is an element that outputs as data (captured image data) to the outside.

  As illustrated in FIG. 1, the image sensor 100 includes a pixel region 111, an A / D conversion unit 112, a CDS (Correlated Double Sampling) processing unit 113, a storage unit 114, and a data output unit 115.

  The pixel region 111 is a region in which pixels that receive light from the outside, photoelectrically convert it, and output it as an electrical signal are provided. In the pixel region 111, a plurality of unit pixels including photoelectric conversion elements and the like are arranged in a predetermined pattern such as a matrix (array). The number of unit pixels (that is, the number of pixels) arranged in the pixel region 111 and the arrangement pattern are arbitrary. For example, when the unit pixels are arranged in a matrix, the number of rows and the number of columns are also arbitrary. The configuration of the unit pixel will be described later. The electric signal read from the unit pixel in the pixel region 111 is supplied to the A / D conversion unit 112.

  The A / D conversion unit 112 performs A / D conversion on the signal (analog signal) read from the unit pixel in the pixel region 111. The A / D conversion unit 112 has a plurality of ADCs (Analog Digital Converters) (ADC112-1 to ADC112-N (N is an arbitrary natural number)).

  Different unit pixels in the pixel region 111 are assigned to the ADCs 112-1 to 112-N, respectively. For example, when the unit pixels are arranged in a matrix in the pixel region 111, the unit pixels in different columns may be assigned to the ADCs 112-1 to 112-N. Further, unit pixels of different partial areas may be assigned to each of the ADCs 112-1 to 112-N.

  Each of the ADCs 112-1 to 112-N performs A / D conversion on the analog signal supplied from the unit pixel assigned to itself. For example, when N columns of unit pixels are arranged in the pixel region 111 and ADC 112-1 to ADC 112-N are assigned to different column unit pixels, the ADC 112-1 to ADC 112-N By A / D converting the signals supplied from the unit pixels of, the A / D conversion unit 112 can A / D convert the signals supplied from all the unit pixels of the pixel region 111 (that is, It is possible to A / D convert the signal for one picture).

  The A / D conversion unit 112 (ADC112-1 to ADC112-N) sequentially supplies the digital data corresponding to each unit pixel obtained by the A / D conversion to the CDS processing unit 113.

  A CDS (Correlated Double Sampling) processing unit 113 performs correlated double sampling (also referred to as CDS (Correlated Double Sampling)) using the supplied digital data. By using the storage unit 114, the CDS processing unit 113 performs correlated double sampling (CDS) using a plurality of digital data supplied at mutually different timings. For example, the CDS processing unit 113 stores the supplied digital data in the storage unit 114, reads the digital data from the storage unit 114 at a predetermined timing, and performs correlated double sampling (CDS). Further, for example, the CDS processing unit 113 stores the processing result (output signal) of correlated double sampling (CDS) in the storage unit 114, and reads the processing result (output signal) from the storage unit 114 at a predetermined timing. , It is also possible to obtain the new processing result (output signal) by performing correlated double sampling (CDS) again.

  The CDS processing unit 113 supplies the processing result of the correlated double sampling (CDS) thus obtained to the data output unit 115 as an output signal.

  The storage unit 114 has an arbitrary storage medium such as a hard disk or a semiconductor memory such as a flash memory, a RAM (Random Access Memory), or an SSD (Solid State Drive), and stores data supplied from the CDS processing unit 113. Remember. In addition, the storage unit 114 supplies the stored data to the CDS processing unit 113 based on the request from the CDS processing unit 113.

  The data output unit 115 has an external terminal and the like, and outputs the output signal supplied from the CDS processing unit 113 to the outside of the image sensor 100. At that time, the data output unit 115 may output the output signal after encoding the output signal by a predetermined encoding method.

  The image sensor 100 also includes a sensor control unit 121, a vertical scanning unit 122, and a horizontal scanning unit 123.

  The sensor control unit 121 controls the operation of each unit in the image sensor 100, such as the vertical scanning unit 122, the horizontal scanning unit 123, and the CDS processing unit 113.

  The vertical scanning unit 122 controls the operation of each unit pixel in the pixel region 111 based on the control of the sensor control unit 121. For example, the vertical scanning unit 122 controls reading of a signal from each unit pixel (for example, a pixel signal corresponding to charges accumulated by photoelectrically converting incident light in each unit pixel).

  The horizontal scanning unit 123 controls the operation of the ADCs 112-1 to 112-N (A / D conversion, data transfer after conversion, etc.) based on the control of the sensor control unit 121.

  That is, by the control of the vertical scanning unit 122 and the horizontal scanning unit 123 controlled by the sensor control unit 121, a signal is read from each unit pixel of the pixel region 111 and A / D converted.

  The CDS processing unit 113 operates at a timing based on the control of the sensor control unit 121, so that the digital signal corresponding to the signal read from each unit pixel is sequentially supplied from the A / D conversion unit 112 as described above. Correlated double sampling is performed on the data.

<Unit pixel configuration>
FIG. 2 is a diagram showing a main configuration example of a unit pixel formed in the pixel region 111 of FIG. As shown in FIG. 2, the unit pixel 130 includes a photodiode (PD) 131, a floating diffusion (FD), a reset transistor 132, an amplification transistor 133, and a select transistor 134.

  The photodiode (PD) 131 receives light that has entered the unit pixel 130, photoelectrically converts the received light into photocharges (here, photoelectrons) having a charge amount corresponding to the light amount, and accumulates the photocharges. To do. The anode electrode of the photodiode (PD) 131 is connected to the ground (GND) of the pixel area, and the cathode electrode is connected to the floating diffusion (FD).

  The reset transistor 132 resets the potential of the floating diffusion (FD). The reset transistor 132 has a drain electrode connected to the power supply potential (VDD) and a source electrode connected to the floating diffusion (FD). A reset pulse (RST) is applied to the gate electrode of the reset transistor 132 from the vertical scanning unit 122 (FIG. 1) via a reset line (not shown).

  The amplification transistor (AMP) 133 amplifies a potential change of the floating diffusion (FD) and outputs it as an electric signal (analog signal). The amplification transistor 133 has a gate electrode connected to the floating diffusion (FD), a drain electrode connected to the power supply potential (VDD), and a source electrode connected to the drain electrode of the select transistor 134.

  The select transistor 134 controls the output of the electric signal supplied from the amplification transistor 133 to the vertical signal line (VSL). The drain electrode of the select transistor 134 is connected to the source electrode of the amplification transistor 133, and the source electrode is connected to the vertical signal line (VSL). A selection pulse (SEL) is applied to the gate electrode of the select transistor 134 from the vertical scanning unit 122 (FIG. 1) via a selection line (not shown).

<Pixel array>
In the pixel region 111, the unit pixels 130 having the configuration shown in FIG. 2 are arranged in a matrix (array) as in the example shown in FIG.

<Pixel structure>
Further, as shown in FIG. 4, the unit pixel 130 (photodiode 131) has a so-called vertical spectral structure capable of color separation in the substrate vertical direction (depth direction). In the structure of the example of FIG. 4, the unit pixel 130 (photodiode 131) color-separates green using an organic photoelectric conversion film, and red and blue are color-separated according to the depth of silicon. You may In addition, the unit pixel 130 (photodiode 131) may color-separate green, red, and blue, respectively, according to the depth of silicon.

<Complete depletion>
Further, as shown in FIG. 2, the photodiode 131 (the organic photoelectric conversion film thereof) having the above structure is connected to the floating diffusion (FD) by a metal, and therefore is not completely depleted. Therefore, as a result, the kTC noise is large, and it is difficult to sufficiently reduce the kTC noise by the conventional method.

<Read>
FIG. 5 is a timing chart for explaining an example of how signals are read from the unit pixel 130 as described above.

  As shown in FIG. 5, in the image sensor 100, reading is performed from each unit pixel in the shutter operation and the read operation. The shutter operation is an operation of resetting the floating diffusion (FD), and the read operation is an operation of reading out electric charges obtained by photoelectric conversion from the floating diffusion (FD). As shown in FIG. 5, in each unit pixel 130, the shutter operation and the read operation are alternately performed. In other words, a signal corresponding to the charges photoelectrically converted and accumulated after resetting the floating diffusion by the shutter operation is read by the read operation.

<Read control processing>
In the image sensor 100 that reads out a signal from the unit pixel 130 having the above-described configuration in the above-described procedure, the sensor control unit 121 executes the read-out control processing as described below to control each unit, and each unit. A signal is read from the pixel. An example of the flow of the read control process will be described with reference to the flowchart in FIG. Description will be made with reference to FIG. 7 as necessary.

  When the read control process is started, in step S101, the sensor control unit 121 controls the vertical scanning unit 122 to set the reset signal to H (High) as the shutter operation, and controls the unit pixel 130. Then, in that state, AZ (Auto Zero: matching the ramp wave and VSL reference) operation is performed. That is, in step S101, the vertical scanning unit 122 sets the reset signal to H for the unit pixel 130 of the shutter row that is the row of the shutter operation target. Further, each unit of the unit pixel 130 in the shutter row performs the AZ operation and reads out the signal when the reset signal is in the H state.

  In step S102, the sensor control unit 121 controls the A / D conversion unit 112 via the horizontal scanning unit 123 to perform A / D conversion on the signals read from the unit pixels in each column by the process of step S101. That is, in step S102, the A / D conversion unit 112 performs A / D conversion on the signals read from the unit pixels in each column.

  As a result, the A / D conversion result of the "A / D1 (represented by circled numbers in FIG. 7)" portion in FIG. 7 is obtained.

  In step S103, the sensor control unit 121 controls the storage unit 114 via the CDS processing unit 113 to store the digital data of the A / D conversion result obtained by the process of step S102. That is, in step S103, the storage unit 114 stores the supplied digital data (A / D conversion result obtained by the process of step S102).

  In step S104, the sensor control unit 121 controls the vertical scanning unit 122 to set the reset signal to L (Low) as the shutter operation, controls the unit pixel 130, and reads the signal in that state. To perform. That is, in step S104, the vertical scanning unit 122 switches the reset signal to L for the unit pixel 130 in the shutter row. Further, each unit of the unit pixel 130 of the shutter row reads out a signal when the reset signal is in the L state.

  In step S105, the sensor control unit 121 controls the A / D conversion unit 112 via the horizontal scanning unit 123, and performs A / D conversion on the signals read from the unit pixels in each column by the processing of step S104. That is, in step S105, the A / D conversion unit 112 performs A / D conversion on the signals read from the unit pixels in each column.

  As a result, the A / D conversion result of the portion "A / D2 (represented by circled numbers in FIG. 7)" in FIG. 7 is obtained.

  In step S106, the sensor control unit 121 controls the storage unit 114 via the CDS processing unit 113 to store the digital data of the A / D conversion result obtained by the process of step S105. That is, in step S106, the storage unit 114 stores the supplied digital data (the A / D conversion result obtained by the process of step S105).

  In step S107, the sensor control unit 121 controls the CDS processing unit 113 to read the digital data of the A / D conversion result stored in the storage unit 114 in steps S103 and S106, and uses them to release the shutter. Perform correlated double sampling (CDS) on the rows. That is, in step S107, the CDS processing unit 113 reads the digital data of the A / D conversion result stored in the storage unit 114 in steps S103 and S106 and uses them to perform the correlated double sampling ( CDS). By this processing, the A / D conversion result (first output signal) corresponding to kTC noise is obtained.

  In step S108, the sensor control unit 121 controls the storage unit 114 via the CDS processing unit 113 to obtain the CDS result obtained by the process of step S107 (that is, the A / D conversion result corresponding to kTC noise (first Output signal))) is stored. That is, in step S108, the storage unit 114 stores the supplied CDS result (the A / D conversion result (first output signal) corresponding to kTC noise obtained by the process of step S107).

  Next, in step S109, as the read operation, the sensor control unit 121 controls the vertical scanning unit 122 to set the reset signal to L, controls the unit pixel 130, and causes the AZ operation in that state. That is, in step S109, the vertical scanning unit 122 sets the reset signal to L for the unit pixel 130 of the read row that is the row for the read operation. Further, each part of the unit pixel 130 in the read row performs the AZ operation in the state where the reset signal is L, and reads the signal.

  In step S110, the sensor control unit 121 controls the A / D conversion unit 112 via the horizontal scanning unit 123 to perform A / D conversion on the signals read from the unit pixels in each column by the process of step S109. That is, in step S110, the A / D conversion unit 112 performs A / D conversion on the signals read from the unit pixels in each column.

  As a result, the A / D conversion result of the "A / D3 (represented by circled numbers in FIG. 7)" portion in FIG. 7 is obtained.

  In step S111, the sensor control unit 121 controls the storage unit 114 via the CDS processing unit 113 to store the digital data of the A / D conversion result obtained by the process of step S110. That is, in step S111, the storage unit 114 stores the supplied digital data (A / D conversion result obtained by the process of step S110).

  In step S112, as the read operation, the sensor control unit 121 controls the vertical scanning unit 122 to set the reset signal to H, controls the unit pixel 130, and causes the signal to be read in that state. That is, in step S112, the vertical scanning unit 122 switches the reset signal to H for the unit pixels 130 in the read row. Further, each unit of the unit pixel 130 in the read row reads out a signal when the reset signal is in the H state.

  In step S113, the sensor control unit 121 controls the A / D conversion unit 112 via the horizontal scanning unit 123, and performs A / D conversion on the signals read from the unit pixels in each column by the process of step S112. That is, in step S113, the A / D conversion unit 112 performs A / D conversion on the signals read from the unit pixels in each column.

  As a result, the A / D conversion result of the portion "A / D4 (represented by circled numbers in FIG. 7)" in FIG. 7 is obtained.

  In step S114, the sensor control unit 121 controls the storage unit 114 via the CDS processing unit 113 to store the digital data of the A / D conversion result obtained by the process of step S113. That is, in step S114, the storage unit 114 stores the supplied digital data (A / D conversion result obtained by the process of step S113).

  In step S115, the sensor control unit 121 controls the CDS processing unit 113 to read the digital data of the A / D conversion result stored in the storage unit 114 in step S111 and step S114, and read the digital data using the digital data. Perform correlated double sampling (CDS) on the rows. That is, in step S115, the CDS processing unit 113 reads the digital data of the A / D conversion result stored in the storage unit 114 in steps S111 and S114, and uses them to perform the correlated double sampling ( CDS). By this processing, the A / D conversion result (second output signal) corresponding to the amount of charge photoelectrically converted according to the kTC noise and the predetermined accumulation time is obtained.

  In step S116, the sensor control unit 121 controls the storage unit 114 via the CDS processing unit 113, and the CDS result stored in the storage unit 114 in step S108 (that is, the A / D conversion result corresponding to kTC noise ( The first output signal)) is read out, and the CDS result obtained by the process of step S115 (that is, A / D conversion corresponding to the amount of charge photoelectrically converted according to the kTC noise and a predetermined accumulation time) The result (second output signal)) is used to perform correlated double sampling (CDS). That is, in step S116, the CDS processing unit 113 reads the first output signal from the storage unit 114 and performs correlated double sampling (CDS) using the first output signal and the second output signal. For example, the CDS processing unit 113 subtracts the first output signal from the second output signal. By this processing, the A / D conversion result (third output signal) corresponding to the amount of charge photoelectrically converted according to the predetermined accumulation time, in which kTC noise is sufficiently suppressed, is obtained.

  In step S117, the sensor control unit 121 controls the CDS control unit 113, supplies the third output signal obtained in step S116 to the data output unit 115, and outputs the third output signal to the outside of the image sensor 100. That is, in step S117, the data output unit 115 outputs the third output signal supplied from the CDS processing unit 113 to the outside.

  When the process of step S117 ends, the read control process ends.

  By performing the processing as described above, the image pickup device 100 (CDS processing unit 113) can perform A / D conversion corresponding to the amount of charge photoelectrically converted according to a predetermined accumulation time in which kTC noise is sufficiently suppressed. The result (third output signal) can be output to the outside as captured image data. Therefore, the image sensor 100 can suppress the reduction in the image quality of the captured image due to kTC noise or the like.

  Although the configuration of the unit pixels, the arrangement of the unit pixels, the pixel structure, and the like have been described above with reference to FIGS. 2 to 4 and the like, the present technology has an arbitrary configuration and structure, and an arbitrary configuration. It can be applied to a signal processing device that processes a signal read from unit pixels arranged in a pattern. That is, the present technology can be applied to an image sensor having unit pixels arranged in an arbitrary pattern and having an arbitrary configuration or structure. Therefore, the configuration of the unit pixel to which the present technology is applied, the arrangement of the unit pixels, the pixel structure, and the like are not limited to the above-described examples (examples of FIGS. 2 to 4).

  However, as described above, in the case of a unit pixel that cannot be completely depleted, it is more difficult to sufficiently suppress kTC noise. However, even in this case, by applying the present technology, the kTC noise included in the pixel signal can be sufficiently suppressed. Therefore, in this case, by applying the present technology, the imaging element can suppress the reduction in the image quality of the image of the image data, and can obtain a greater effect.

<3. Third Embodiment>
By the way, in the read control processing (FIGS. 6 and 7) in the above-described second embodiment, in order to extract the kTC noise by performing correlated double sampling (CDS) on the voltage fluctuation due to the feed through (FT). It is necessary to read out the change in feedthrough at the time of reading. Therefore, the voltage of the Reset phase (R phase) is higher than that of the Data phase (D phase) by the amount of feedthrough, and when the conventional A / D converter is used, the reference signal (ramp wave) of the ramp waveform is In some cases, the signal (VSL) read from the unit pixel 130 deviates from the signal, and the phenomenon that normal A / D conversion cannot be performed may occur.

  In order to avoid this phenomenon, A / D converters are prepared for each of green, red, and blue colors, or a clamp circuit is mounted in two systems of a pixel of an organic photoelectric conversion film and a pixel of a photodiode. However, if such a configuration is adopted, the circuit scale increases and the control becomes complicated. Therefore, there is a demand for an A / D converter capable of avoiding the influence of voltage fluctuation due to feedthrough while suppressing an increase in circuit scale and complication of control.

  In order to satisfy such a requirement, the detailed description is omitted in the above description, but in the read control processing (FIGS. 6 and 7) in the second embodiment, the circuit scale is increased. By suppressing the influence of the voltage fluctuation due to the feedthrough while suppressing the complication of the control, the signal read from the unit pixel 130 via the vertical signal line (VSL) and the ramp waveform in the A / D conversion unit 112. The A / D conversion performed by comparing with the reference signal (ramp wave) of is performed normally.

  Therefore, as the third embodiment, more detailed contents of the read control processing (FIGS. 6 and 7) in the second embodiment will be described below.

<Imaging device>
FIG. 8 is a diagram showing a main configuration example of an image sensor to which the present technology is applied. The image pickup device 100 shown in FIG. 8 is a CMOS image sensor or the like, and portions corresponding to those of the image pickup device 100 shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be appropriately omitted. . That is, in the image sensor 100 shown in FIG. 8, a more detailed configuration of the pixel region 111 and the A / D conversion unit 112 is shown.

  In the pixel area 111, unit pixels 130 (M, N) are arranged in an M × N matrix (M and N are arbitrary natural numbers). In the pixel region 111, row control lines 141-1 to 141-M are formed for each row in a matrix of pixel arrangement along the pixel arrangement direction of the pixel row (left-right direction in the drawing), and columns are arranged. Vertical signal lines (VSL) 142-1 to 142-N are formed for each of them in the pixel array direction (vertical direction in the drawing).

  The A / D conversion unit 112 performs A / D conversion on the analog signal read from the unit pixels 130 arranged in a matrix in the pixel region 111. The A / D converter 112 includes ADCs 112-1 to 112-N (N is an arbitrary natural number) and a DAC (Digital Analog Converter) 151 for generating a ramp waveform reference signal (ramp wave (RAMP)). A clamp controller 152 and an adder 153 are provided.

  The DAC 151 generates a ramp wave under the control of the sensor control unit 121 and supplies it to the adder 153 as an output signal. The clamp control unit 152 generates an output signal for DC level control based on the control of the sensor control unit 121, and supplies the output signal to the adder 153. The adder 153 adds the output signal from the DAC 151 and the output signal from the clamp control unit 152, and supplies it to the ADC 112-1 to ADC 112-N as a reference signal (ramp wave (RAMP)) having a ramp waveform.

  In the ADC 112-1, the voltage level of the analog signal (pixel signal) read from the unit pixel 130 in the first column via the VSL 142-1 by the comparator 161-1 and the reference signal from the adder 153 (predetermined It is compared to the voltage level of a ramp wave (RAMP) that rises or falls with a slope. At this time, in the counter 162-1, the counter latch is operating. Then, in the ADC 112-1, the reference signal from the adder 153 and the counter value in the counter 162-1 change in a one-to-one correspondence so that the analog signal (pixels) input via the VSL 142-1 is changed. Signal) to digital data.

  That is, the ADC 112-1 converts a change in the voltage level of the reference signal into a change in time, and counts the time in a certain cycle (clock) to convert it into a digital value. Here, when the analog signal (pixel signal) input via the VSL 142-1 and the reference signal from the adder 153 intersect, the output of the comparator 161-1 is inverted and the input clock of the counter 162-1 is input. To complete the A / D conversion.

  Similar to the ADC 112-1, the ADCs 112-2 to 112-N add the analog signals (pixel signals) input via the VSLs 142-2 to 142-N by the comparators 161-2 to 161-N and the addition. The reference signal from the device 153 is compared, and the counters 162-2 to 162-N perform a counter latch operation, thereby performing A / D conversion.

  Here, the clamp control unit 152 generates an output signal for DC level control based on the clamp signal (CLPEN) from the sensor control unit 121 and supplies it to the adder 153. That is, the clamp control unit 152 controls the DC level in a state where the reset signal of the unit pixel 130 is high as a shutter operation and in a state where the reset signal of the unit pixel 130 is high as a read operation. Generate an output signal. Then, in the adder 153, the output signal from the DAC 151 and the output signal from the clamp control unit 152 are added, and a reference signal (ramp wave (RAMP)) having a ramp waveform is obtained.

  The reference signal of the ramp waveform has an expanded dynamic range as compared with the case where it is not clamped. Therefore, when the reset signal is in a high state, that is, at the timing of the R phase (Reset phase) in which the influence of the voltage fluctuation due to the feedthrough occurs, the reference signal is controlled to be clamped, and the dynamic range of the reference signal is controlled. Is enlarged, the analog signal (pixel signal) read from the unit pixel 130 via the VSL 142 can be prevented from deviating from the reference signal, and the A / D conversion can be normally performed.

  The clamp control unit 152 is provided with a register that can set an adjustment value (clamp code) of the clamp amount. The sensor control unit 121 supplies a clamp signal (CLPEN) to the clamp control unit 152, and the register is independently supplied to the register for each of green, red, and blue colors at each timing of the shutter row and the read row. An adjustment value for the clamp amount can be set. The clamp control unit 152 can perform the clamp control for each timing of each color based on the adjustment value of the clamp amount set in the register and clamp the reference signal. As a result, accurate read control processing can be performed without adding a new circuit such as preparing an A / D converter for each color or mounting two systems of clamp circuits.

<Read control processing>
In the image sensor 100 (FIG. 8) having the above-described configuration, when reading a signal from the unit pixel 130, the sensor control unit 121 executes a read control process as described below to control each unit and each unit pixel. The signal is read from 130. Next, an example of the flow of read control processing will be described with reference to the flowchart in FIG. Description will be made with reference to FIG. 10 as necessary.

  When the read control process is started, in steps S201 to S204, as in steps S101 to S103 in FIG. 6, as the shutter operation, the vertical scanning unit 122 is controlled to set the reset signal to H (High). Each unit of the unit pixels 130 of the set shutter row performs the AZ operation in the state where the reset signal is H, and reads the signal. Then, the A / D conversion unit 112 performs A / D conversion of the signal read from the unit pixel 130 of each column by the process of step S201, but the reset signal is in a high state, that is, the feed signal. Since the timing of the R phase is caused by the voltage variation due to the through, the clamp control unit 152 performs the clamp control (S202), and the output signal from the DAC 151 is clamped.

  As a result, as shown by the dotted line A in FIG. 10, the dynamic range of the reference signal from the adder 153 is expanded, and the signal read from the unit pixel 130 in each column deviates from the reference signal of the ramp waveform. Without it, A / D conversion can be performed normally (S203). As a result, the A / D conversion result of the portion "A / D1 (represented by circled numbers in FIG. 10)" in FIG. 10 is obtained. Then, the digital data of the A / D conversion result obtained by the process of step S203 is stored in the storage unit 114 (S204).

  In steps S205 to S207, as in steps S104 to S106 in FIG. 6, as the shutter operation, the vertical scanning unit 122 is controlled to set the reset signal to L (Low), and the unit pixel of the shutter row is set. Each unit of 130 reads out a signal when the reset signal is L. Then, the A / D conversion unit 112 performs A / D conversion on the signal read from the unit pixel 130 of each column by the process of step S205.

  As a result, the A / D conversion result of the "A / D2 (represented by circled numbers in FIG. 10)" portion in FIG. 10 is obtained. Then, the digital data of the A / D conversion result obtained by the process of step S206 is stored in the storage unit 114 (S207).

  In steps S208 and S209, as in steps S107 and 108 in FIG. 6, the CDS processing unit 113 reads the digital data of the A / D conversion result stored in the storage unit 114 in steps S204 and S207, and reads them. Is used to perform correlated double sampling (CDS) for shutter rows. By this processing, kTC noise and the A / D conversion result (first output signal) corresponding to the feedthrough voltage are obtained. Then, the CDS result obtained by the process of step S208 is stored in the storage unit 114 (S209).

  Next, in steps S210 to S212, as in steps S109 to S111 of FIG. 6, as the read operation, the vertical scanning unit 122 is controlled to set the reset signal to L, and each unit of the unit pixel 130 of the read row is read. However, when the reset signal is L, the AZ operation is performed and the signal is read. Then, the A / D conversion unit 112 performs A / D conversion on the signal read from the unit pixel 130 in each column by the process of step S210.

  As a result, the A / D conversion result of the portion "A / D3 (represented by circled numbers in FIG. 10)" in FIG. 10 is obtained. Then, the digital data of the A / D conversion result obtained by the process of step S211 is stored in the storage unit 114 (S212).

  In steps S213 to S216, as in steps S112 to S114 of FIG. 6, as the read operation, the vertical scanning unit 122 is controlled to set the reset signal to H, and each unit of the unit pixel 130 in the read row is reset. The signal is read in the state where the signal is H. Then, the A / D conversion unit 112 performs A / D conversion of the signal read from the unit pixel 130 of each column by the process of step S213, but the reset signal is in a high state, that is, the feed signal. Since the timing of the R phase is affected by the voltage fluctuation due to the through, the clamp control unit 152 performs the clamp control (S214), and the output signal from the DAC 151 is clamped.

  As a result, as shown by the dotted line B in FIG. 10, the dynamic range of the reference signal from the adder 153 is expanded, and the signal read from the unit pixel 130 in each column deviates from the reference signal of the ramp waveform. Without it, A / D conversion can be performed normally (S215). As a result, the A / D conversion result of the portion "A / D4 (represented by circled numbers in FIG. 10)" in FIG. 10 is obtained. Then, the digital data of the A / D conversion result obtained by the process of step S215 is stored in the storage unit 114 (S216).

  In step S217, as in step S115 of FIG. 6, the CDS processing unit 113 reads the digital data of the A / D conversion result stored in the storage unit 114 in steps S212 and S216, and reads it using the digital data. Perform correlated double sampling (CDS) on the rows. By this processing, the kTC noise, the feedthrough voltage, and the A / D conversion result (second output signal) corresponding to the amount of charge photoelectrically converted according to the predetermined accumulation time are obtained.

  In steps S218 and 219, as in steps S116 and 117 in FIG. 6, the CDS processing unit 113 stores the CDS result stored in the storage unit 114 in step S209 (that is, A / A corresponding to kTC noise and feedthrough voltage). The D conversion result (first output signal) is read from the storage unit 114, and the CDS result and the CDS result (that is, kTC noise, the feedthrough voltage, and the predetermined accumulation time) obtained by the process of step S217 are read. Correlated double sampling (CDS) is performed using the A / D conversion result (second output signal) corresponding to the amount of charges photoelectrically converted accordingly.

  For example, the CDS processing unit 113 subtracts the first output signal from the second output signal. By this processing, the A / D conversion result (third output signal) corresponding to the amount of charge photoelectrically converted according to the predetermined accumulation time, in which kTC noise is sufficiently suppressed, is obtained. The third output signal obtained in step S218 is supplied to the data output unit 115 and output to the outside of the image sensor 100 (S219).

  When the process of step S219 ends, the read control process of FIG. 9 ends.

  By performing the processing as described above, the image pickup device 100 (CDS processing unit 113) can perform A / D conversion corresponding to the amount of charge photoelectrically converted according to a predetermined accumulation time in which kTC noise is sufficiently suppressed. The result (third output signal) can be output to the outside as captured image data. Therefore, the image sensor 100 can suppress the reduction in the image quality of the captured image due to kTC noise or the like.

  Further, the reset signal of the unit pixel 130 is in a high state as a shutter operation, and the reset signal of the unit pixel 130 is in a high state as a read operation, that is, the influence of voltage fluctuation due to feedthrough occurs. At the phase timing, the reference signal of the ramp waveform (ramp wave (RAMP)) is controlled to be clamped so that the dynamic range of the reference signal is expanded (amplitude is expanded). The analog signal (pixel signal) read from the VSL 142 through the VSL 142 can be prevented from deviating from the reference signal of the ramp waveform, and the A / D conversion can be normally performed.

  In the read control process (FIGS. 9 and 10) according to the third embodiment, of the green, red, and blue that are color-separated in the unit pixel 130 having the vertical spectral structure, the green is the organic photoelectric. The read control processing of the green pixel in the case of performing color separation using the conversion film is illustrated.

  However, as described above, the clamp control unit 152 controls the timings of the shutter row and the read row (for example, “A in FIG. 10” for each color of green, red, and blue (for example, green in FIG. 10)). At the timing of / D1 ”and“ A / D3 ”), the clamp control unit 152 has a register capable of independently setting the adjustment value of the clamp amount. Therefore, the clamp control unit 152 adjusts the clamp amount set in the register. Based on the value, clamp control can be performed at each timing for each color to clamp the reference signal.

  As a result, for example, clamp control can be performed for each color at an arbitrary timing without preparing A / D converters for each of green, red, and blue colors and mounting a clamp circuit. Further, for example, clamp control can be performed on pixels having different characteristics without mounting a clamp circuit on the two systems of the pixel of the organic photoelectric conversion film and the pixel of the photodiode.

  As described above, the clamp control unit 152 is provided with the register capable of setting the adjustment value of the clamp amount, so that the A / D converter for each color is prepared and the clamp circuit is mounted, or the organic photoelectric conversion film Since it is not necessary to mount the clamp circuit on the two systems of the pixel and the pixel of the photodiode, it is possible to suppress an increase in the circuit scale and avoid the complication of the control.

<4. Fourth Embodiment>
<Imaging device>
The image sensor to which the present technology is applied may have a plurality of semiconductor substrates that are superposed on each other.

  FIG. 11 is a diagram showing a main configuration example of an example of an image sensor to which the present technology is applied. The image sensor 300 shown in FIG. 11 is an element that, like the image sensor 100, images a subject and obtains digital data of a captured image. As shown in FIG. 11, the image sensor 300 has two semiconductor substrates (layered chips (pixel chip 301 and circuit chip 302)) that are superimposed on each other. The number of semiconductor substrates (layered chips) (the number of layers) may be plural, and may be, for example, three or more.

  In the pixel chip 301, a pixel region 311 in which a plurality of unit pixels including photoelectric conversion elements that photoelectrically convert incident light are arranged is formed. Further, in the circuit chip 302, a peripheral circuit area 312 in which a peripheral circuit for processing the pixel signal read from the pixel area 311 is formed is formed.

  The circuit configuration of the image sensor 300 is the same as that of the image sensor 100 (FIGS. 1 and 8). That is, the pixel area 311 is an area similar to the pixel area 111, and a plurality of unit pixels 130 (FIG. 2) are formed similarly to the pixel area 111. In the peripheral circuit area 312, the A / D conversion unit 112, the CDS processing unit 113, the storage unit 114, the data output unit 115, the sensor control unit 121, the vertical scanning unit 122, the horizontal scanning unit 123, and the like are provided as peripheral circuits. Is formed.

  As described above, the pixel chip 301 and the circuit chip 302 are overlapped with each other to form a multi-layer structure (laminated structure). Each of the pixels in the pixel area 311 formed in the pixel chip 301 and the peripheral circuit in the peripheral circuit area 312 formed in the circuit chip 302 includes through vias (VIA) 313 and via areas (VIA) 314. VIA) and the like are electrically connected to each other.

  Like this image sensor 300, peripheral circuits such as the A / D conversion unit 112 and the CDS processing unit 113 to which the present technology is applied may be formed on a chip different from the pixel region 311 (pixel region 111). . That is, as long as it is possible to form a configuration substantially similar to the configuration of the image pickup device 100 described with reference to FIG. 1, they may be formed in any way. Not all the configurations need to be integrally formed. That is, for example, some or all of the peripheral circuits such as the A / D conversion unit 112 and the CDS processing unit 113 may be formed as an LSI different from (the unit pixel 130 of) the pixel region 111. Further, the peripheral circuits may be formed dispersedly in a plurality of LSIs.

<5. Fifth Embodiment>
<Imaging device>
Note that the present technology can be applied to other than the image sensor. For example, the present technology may be applied to a device (an electronic device or the like) having an image pickup device, such as an image pickup device. FIG. 12 is a block diagram illustrating a main configuration example of an imaging device as an example of an electronic device to which the present technology is applied. The imaging device 600 illustrated in FIG. 12 is a device that images a subject and outputs an image of the subject as an electric signal.

  As illustrated in FIG. 12, the imaging device 600 includes an optical unit 611, a CMOS sensor 612, an operation unit 614, a control unit 615, an image processing unit 616, a display unit 617, a codec processing unit 618, and a recording unit 619.

  The optical unit 611 includes a lens that adjusts the focus to a subject and collects light from a focused position, a diaphragm that adjusts the exposure, and a shutter that controls the timing of imaging. The optical unit 611 transmits the light (incident light) from the subject and supplies it to the CMOS sensor 612.

  The CMOS sensor 612 photoelectrically converts incident light to A / D-convert a signal for each pixel (pixel signal), performs signal processing such as CDS, and supplies the processed image data to the image processing unit 616.

  The operation unit 614 includes, for example, a jog dial (trademark), a key, a button, a touch panel, or the like, receives an operation input by the user, and supplies a signal corresponding to the operation input to the control unit 615.

  The control unit 615, based on the signal corresponding to the user's operation input input by the operation unit 614, the optical unit 611, the CMOS sensor 612, the image processing unit 616, the display unit 617, the codec processing unit 618, and the recording unit 619. Is controlled to cause each unit to perform processing related to imaging.

  The image processing unit 616 performs image processing on the captured image data obtained by the CMOS sensor 612. More specifically, the image processing unit 616 applies, for example, color mixture correction, black level correction, white balance adjustment, matrix processing, gamma correction, and YC conversion to the captured image data supplied from the CMOS sensor 612. Various image processing of. The image processing unit 616 supplies the captured image data subjected to the image processing to the display unit 617 and the codec processing unit 618.

  The display unit 617 is configured as, for example, a liquid crystal display or the like, and displays the image of the subject based on the captured image data supplied from the image processing unit 616.

  The codec processing unit 618 subjects the captured image data supplied from the image processing unit 616 to encoding processing of a predetermined method, and supplies the obtained encoded data to the recording unit 619.

  The recording unit 619 records the encoded data from the codec processing unit 618. The encoded data recorded in the recording unit 619 is read by the image processing unit 616 and decoded as necessary. The captured image data obtained by the decoding process is supplied to the display unit 617, and the captured image corresponding to the captured image data is displayed.

  The present technology described above is applied as the CMOS sensor 612 of the above-described imaging device 600. That is, as the CMOS sensor 612, the image sensor of the above-described embodiment is used. As a result, the CMOS sensor 612 can suppress deterioration in image quality. Therefore, the imaging device 600 can obtain a high-quality image by imaging the subject.

  The image pickup apparatus to which the present technology is applied is not limited to the above-described configuration and may have another configuration. For example, not only a digital still camera or a video camera, but also an information processing apparatus having an imaging function such as a mobile phone, a smart phone, a tablet device, a personal computer, or the like may be used. Further, it may be a camera module mounted on another information processing device for use (or mounted as an embedded device).

  Further, in the above, the configuration described as one device (or processing unit) may be divided and configured as a plurality of devices (or processing units). Conversely, the configurations described above as a plurality of devices (or processing units) may be integrated into one device (or processing unit). Further, it is of course possible to add a configuration other than the above to the configuration of each device (or each processing unit). Furthermore, if the configuration and operation of the entire system are substantially the same, part of the configuration of a certain device (or processing unit) may be included in the configuration of another device (or another processing unit). .

  Although the preferred embodiments of the present disclosure have been described above in detail with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field of the present disclosure can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood that the above also naturally belongs to the technical scope of the present disclosure.

Note that the present technology may also be configured as below.
(1) A first signal read from the unit pixel when the reset signal of the unit pixel is in a high state as a shutter operation for photoelectrically converting incident light and resetting a floating diffusion of the unit pixel that is not completely depleted, As the shutter operation, as a read operation for reading a second signal read from the unit pixel in a state where the reset signal of the unit pixel is low, and a charge obtained by photoelectric conversion from the floating diffusion of the unit pixel A third signal read from the unit pixel when the reset signal of the unit pixel is low, and from the unit pixel when the reset signal of the unit pixel is high as the read operation. A / D conversion of the read fourth signal And A / D conversion unit that,
First digital data obtained by A / D conversion of the first signal by the A / D conversion unit, and obtained by A / D conversion of the second signal by the A / D conversion unit Correlated double sampling is performed using the second digital data to generate a first output signal, and the third signal obtained by A / D converting the third signal by the A / D conversion unit. Correlated digital double sampling is performed using the digital data of 4 and the fourth digital data obtained by A / D converting the fourth signal by the A / D converter to generate a second output signal. And a correlated double sampling processing unit that performs correlated double sampling using the first output signal and the second output signal to generate a third output signal.
(2) A storage unit that stores the first digital data to the fourth digital data obtained by the A / D conversion unit is further included.
The correlated double sampling processing unit uses the correlated double sampling using the first digital data and the second digital data or the third digital data and the fourth digital data read from the storage unit. Sampling The signal processing device according to (1).
(3) The storage unit further stores the first output signal generated by the correlated double sampling processing unit,
The correlated double sampling processing unit performs correlated double sampling using the generated second output signal and the first output signal read from the storage unit. (1) or (2) Signal processing equipment.
(4)
In the state where the reset signal of the unit pixel is high as the shutter operation, and in the state where the reset signal of the unit pixel is high as the read operation, the unit in the A / D converter is A clamp controller is further provided for clamping the reference signal so that the A / D conversion performed by comparing the signal read from the pixel with the reference signal of the ramp waveform is normally performed (1) to (3) The signal processing device according to any one of 1.
(5) As a shutter operation for photoelectrically converting incident light and resetting a floating diffusion of a unit pixel that is not completely depleted, a first signal read from the unit pixel when the reset signal of the unit pixel is high (High) is used. A / D conversion,
As the shutter operation, the second signal read from the unit pixel is A / D converted in a state where the reset signal of the unit pixel is low (Low),
Correlated double sampling using first digital data obtained by A / D conversion of the first signal and second digital data obtained by A / D conversion of the second signal To generate a first output signal,
As a read operation for reading charges obtained by photoelectric conversion from the floating diffusion of the unit pixel, A / D conversion is performed on the third signal read from the unit pixel when the reset signal of the unit pixel is low. ,
As the read operation, A / D conversion is performed on the fourth signal read from the unit pixel when the reset signal of the unit pixel is in a high state.
Correlated double sampling using third digital data obtained by A / D conversion of the third signal and fourth digital data obtained by A / D conversion of the fourth signal To generate a second output signal,
A signal processing method, wherein correlated double sampling is performed using the first output signal and the second output signal to generate a third output signal.
(6) A unit pixel that photoelectrically converts incident light and is not completely depleted,
As a shutter operation for resetting the floating diffusion of the unit pixel, a first signal read from the unit pixel when the reset signal of the unit pixel is high, and as the shutter operation, the reset signal of the unit pixel is low. In the (Low) state, the reset signal of the unit pixel is in a Low state as a read operation for reading the second signal read from the unit pixel and the charge obtained by photoelectric conversion from the floating diffusion of the unit pixel. In the A / D conversion, the third signal read from the unit pixel and the fourth signal read from the unit pixel when the reset signal of the unit pixel is in a high state as the read operation are performed. A / D converter that
First digital data obtained by A / D conversion of the first signal by the A / D conversion unit, and obtained by A / D conversion of the second signal by the A / D conversion unit Correlated double sampling is performed using the second digital data to generate a first output signal, and the third signal obtained by A / D converting the third signal by the A / D conversion unit. Correlated digital double sampling is performed using the digital data of 4 and the fourth digital data obtained by A / D converting the fourth signal by the A / D converter to generate a second output signal. And a correlated double sampling processing unit that performs correlated double sampling using the first output signal and the second output signal to generate a third output signal.
(7) In the unit pixel, a photoelectric conversion unit that photoelectrically converts the incident light and the floating diffusion are connected by a metal. (6), (8) to (10) .
(8) The image sensor according to any one of (6), (7), (9), and (10), in which the unit pixel has a pixel structure that performs color separation in a substrate vertical direction.
(9) In the unit pixel, green is color-separated using an organic photoelectric conversion film, and red and blue are color-separated according to the depth of silicon. (6) to (8), (10) An image sensor according to item 1.
(10) The image sensor according to any one of (6) to (9), wherein the unit pixel separates green, red, and blue from each other according to the depth of silicon.
(11) An imaging unit that images a subject,
An image processing unit that performs image processing on the image data obtained by the image pickup by the image pickup unit,
The imaging unit is
A unit pixel that photoelectrically converts incident light and is not completely depleted,
As a shutter operation for resetting the floating diffusion of the unit pixel, a first signal read from the unit pixel when the reset signal of the unit pixel is high, and as the shutter operation, the reset signal of the unit pixel is low. In the (Low) state, the reset signal of the unit pixel is in a Low state as a read operation for reading the second signal read from the unit pixel and the charge obtained by photoelectric conversion from the floating diffusion of the unit pixel. In the A / D conversion, the third signal read from the unit pixel and the fourth signal read from the unit pixel when the reset signal of the unit pixel is in a high state as the read operation are performed. A / D converter that
First digital data obtained by A / D conversion of the first signal by the A / D conversion unit, and obtained by A / D conversion of the second signal by the A / D conversion unit Correlated double sampling is performed using the second digital data to generate a first output signal, and the third signal obtained by A / D converting the third signal by the A / D conversion unit. Correlated digital double sampling is performed using the digital data of 4 and the fourth digital data obtained by A / D converting the fourth signal by the A / D converter to generate a second output signal. And a correlated double sampling processing unit that performs correlated double sampling using the first output signal and the second output signal to generate a third output signal.

  100 image sensor, 111 pixel area, 112 A / D conversion section, 113 CDS processing section, 114 storage section, 115 data output section, 121 sensor control section, 122 vertical scanning section, 123 horizontal scanning section, 130 unit pixel, 131 photo Diode, 132 reset transistor, 133 amplification transistor, 134 select transistor, 141 row control line, 142 vertical signal line (VSL), 151 DAC, 152 clamp control unit, 153 adder, 161 comparator, 162 counter, 300 image sensor, 301 pixel chip, 302 circuit chip, 311 pixel area, 312 peripheral circuit area, 313 and 314 via area, 600 imaging device, 612 CMOS sensor, 616 image processing unit

Claims (8)

A unit pixel having a first photoelectric conversion unit provided in the semiconductor substrate and a second photoelectric conversion unit provided on the semiconductor substrate;
A comparator connected to the unit pixel,
A DAC (Digital Analog Converter) connected to the comparator,
A clamp controller connected to the comparator ,
The clamp control unit,
At each timing of a shutter operation for resetting a floating diffusion provided in the unit pixel and a read operation for reading out charges obtained by photoelectric conversion from the floating diffusion for each color separated in the substrate vertical direction in the unit pixel. , Set the clamp amount adjustment value independently,
Clamp control is performed for each timing of each color based on the set adjustment value of the clamp amount, and the reference signal from the DAC is clamped.
Imaging device. The imaging device according to claim 1, wherein the second photoelectric conversion unit includes a first electrode, a second electrode, and an organic photoelectric conversion film. The first electrode, the imaging apparatus according to claim 2 connected in the floating diffusion and the metal. The imaging device according to claim 3, wherein the floating diffusion is connected to a gate of an amplification transistor. The imaging device according to claim 4, wherein the amplification transistor is connected to a selection transistor. The imaging device according to claim 5, wherein the selection transistor is connected to the comparator. The imaging device according to claim 1, wherein a third photoelectric conversion unit is provided in the semiconductor substrate. The first photoelectric conversion unit color-separates red,
The second photoelectric conversion unit color-separates green,
The imaging device according to claim 7, wherein the third photoelectric conversion unit color-separates blue.

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