JP7091044B2 - Image sensor and image sensor - Google Patents

Description

The present invention relates to an image pickup device and an image pickup apparatus.

In recent years, image pickup devices using image pickup elements such as CMOS sensors have become more multifunctional, and not only the generation of captured images such as still images and moving images, but also, for example, in Patent Document 1, the signal obtained from the image pickup element is described. An image pickup device having a configuration capable of focal detection by a pupil division method is disclosed. In the configuration described in Patent Document 1, the amount of data increases, the read time becomes long, the frame rate decreases, and the power consumption increases. Further, in Patent Document 2, for the purpose of power saving of the analog-to-digital conversion circuit (squid or ADC circuit) in the image sensor, the operating state and the standby state are described according to the calculation result of the calculation unit for each pixel block. The switching control is disclosed.

Japanese Unexamined Patent Publication No. 2001-124984 Japanese Unexamined Patent Publication No. 2016-184843

However, each pixel in Patent Document 2 is premised on the conventional configuration for acquiring a captured image, and how the pixel block is configured has not been clarified. Further, it is not clear how to configure the pixel blocks and control each of them in the case of a pixel configuration capable of acquiring focus detection other than generating an captured image as in Patent Document 1, and rather, the power consumption is reduced. There is also a concern that it will increase.

An object of the present invention is to provide an image pickup device and an image pickup device capable of realizing power saving of the image pickup device while suppressing a decrease in the frame rate due to an increase in the amount of data.

The image pickup element according to the present invention processes a first substrate having a pixel array in which a plurality of pixel blocks formed by a plurality of pixels for performing photoelectric conversion are arranged in a matrix, and a signal based on the photoelectric conversion. An image pickup element in which a second substrate having a circuit array in which a plurality of signal processing units are arranged in a matrix is laminated , and the signal processing unit and a corresponding pixel block are connected by a plurality of signal lines . Each of the plurality of signal processing units includes an addition circuit that adds the signals input from the plurality of signal lines during synchronization, and a conversion circuit that converts the signal added by the addition circuit into analog and digital. When each of the plurality of signal processing units adds the signal by the addition circuit, the conversion circuit is provided with a control unit that performs a power saving operation on the conversion circuit while the conversion circuit is not performing the analog-digital conversion operation. It is a feature.

According to the present invention, it is possible to provide an image pickup device and an image pickup device that can realize power saving of the image pickup device while suppressing a decrease in the frame rate due to an increase in the amount of data.

It is a block diagram which shows the schematic structure of the image pickup apparatus according to 1st Embodiment of this invention. It is a block diagram which shows the schematic structure of the image pickup device according to 1st Embodiment of this invention. It is a top view which shows an example of the pixel arrangement of the image pickup element in the image pickup apparatus by 1st Embodiment of this invention. It is a schematic diagram which shows the relationship between the light flux emitted from the exit pupil of an image pickup optical system, and a unit pixel. It is a graph which shows the example of the image signal waveform obtained from the two sub-pixels of an image pickup device. It is a schematic diagram which shows an example of the structure of the image pickup element in the image pickup apparatus by 1st Embodiment of this invention. It is a figure which shows an example of the circuit structure of the unit pixel of the image pickup element in the image pickup apparatus by 1st Embodiment of this invention. It is a figure which shows an example of the structure of the row common readout circuit of the image pickup element in the image pickup apparatus by 1st Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus by 1st Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus by 1st Embodiment of this invention. It is a figure which shows an example of the structure of the row common readout circuit of the image pickup element in the image pickup apparatus according to 2nd Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus by the 2nd Embodiment of this invention. This is an example of a pixel block according to the second embodiment of the present invention. It is a figure which shows an example of the structure of the row common readout circuit of the image pickup element in the image pickup apparatus according to 3rd Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus according to 3rd Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus according to 4th Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus according to 4th Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus according to 4th Embodiment of this invention. It is a schematic diagram which shows an example of the structure of the image pickup element in the image pickup apparatus according to 5th Embodiment of this invention. It is a schematic diagram which shows an example of the wiring of the image pickup element in the image pickup apparatus according to 5th Embodiment of this invention. It is a figure which shows an example of the structure of the row common readout circuit of the image pickup element in the image pickup apparatus according to 5th Embodiment of this invention. It is a timing chart which shows the reading operation of the image pickup element in the image pickup apparatus according to the 6th Embodiment of this invention. This is an example of a pixel block according to the seventh embodiment of the present invention. It is a schematic diagram which shows an example of the structure of the image pickup element in the image pickup apparatus according to 7th Embodiment of this invention. It is a block diagram of the correction parameter by 7th Embodiment of this invention. It is an internal block diagram of the ADC circuit by 8th Embodiment of this invention. It is a timing chart which shows the operation of the ADC circuit by 8th Embodiment of this invention.

(First Embodiment)
The image pickup device and the image pickup apparatus according to the first embodiment of the present invention will be described with reference to each figure. At that time, those having the same function in all the figures are given the same number, and the explanation of the repetition is omitted.

First, a schematic configuration of the image pickup apparatus 100 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 1, the image pickup apparatus 100 in the present embodiment includes a first lens group 101, an aperture 102, a second lens group 103, a third lens group 104, an optical low-pass filter 105, and an image pickup element 106. There is. Further, the image pickup apparatus 100 includes an aperture actuator 117, a focus actuator 118, an aperture drive circuit 115, and a focus drive circuit 116. Further, the image pickup device 106 includes a signal processing unit 107. The image pickup apparatus 100 further includes a DFE (Digital Front End) 108 and a DSP (Digital Signal Processor) 109. Further, the image pickup apparatus 100 includes a display unit 111, a RAM 112, a timing generation circuit (TG) 113, a CPU 114, a ROM 119, and a recording medium 110.

The first lens group 101, the aperture 102, the second lens group 103, the third lens group 104, and the optical low-pass filter 105 are arranged along the optical axis in this order from the subject side, thereby forming an imaging optical system. It is composed. The image pickup optical system corresponds to an optical system for forming an optical image of a subject. The first lens group 101 is a lens group arranged at the frontmost portion (subject side) of the image pickup optical system, and is held so as to be able to move forward and backward along the optical axis direction. The diaphragm 102 has a function of adjusting the amount of light at the time of imaging by adjusting the aperture diameter thereof. The second lens group 103 moves forward and backward along the optical axis direction integrally with the aperture 102, and realizes a variable magnification operation (zoom function) in conjunction with the advance / backward operation of the first lens group 101. The third lens group 104 has a function of adjusting the focus by advancing and retreating along the optical axis direction. The optical low-pass filter 105 is an optical element for reducing false color and moire in a captured image.

Although the present embodiment shows an example in which a lens device having an image pickup optical system is integrally configured with the main body of the image pickup device 100, the embodiment of the present invention is not limited to this. The present invention can also be applied to an image pickup system composed of an image pickup device main body and a lens device (imaging optical system) detachably attached to the image pickup device main body.

The diaphragm actuator 117 is provided with a mechanism for changing the opening diameter of the diaphragm 102. The aperture drive circuit 115 is a drive circuit for controlling the aperture diameter of the aperture 102 by the aperture actuator 117 to adjust the amount of image pickup light and to control the exposure time at the time of still image imaging. The focus actuator 118 is provided with a mechanism for moving the third lens group 104 forward and backward along the optical axis direction. The focus drive circuit 116 is a drive circuit for adjusting the focus position by driving the focus actuator 118.

The image sensor 106 is a two-dimensional CMOS image sensor arranged on the image plane of the image pickup optical system. As shown in FIG. 2, the image pickup device 106 of the present embodiment is a laminated image sensor having a laminated structure, unlike a normal image sensor. More specifically, the first substrate 10 including the pixel unit 11 that performs photoelectric conversion with respect to the incident light, and the second substrate 20 including the signal processing unit 21 that processes the signal from the pixel unit 11 and peripheral circuits and the like. It has a laminated structure in which and is laminated. A plurality of signal processing units 21 including the pixel unit 11 are periodically arranged in the row direction and the column direction in each substrate. In this embodiment, the structure is such that two substrates are laminated, but more substrates may be laminated. For example, the image pickup device 106 can be provided with a new function by stacking a substrate having a memory such as a DRAM or a substrate including a different signal processing circuit. The peripheral circuit included in the second substrate in the present embodiment includes a power supply circuit, a timing generation circuit, a register, an output amplifier, and the like.

The image pickup device 106 converts the subject image (optical image) imaged by the image pickup optical system into an electric signal by photoelectric conversion. In this specification, the image sensor 106 may be referred to as an image pickup unit. The TG 113 is for supplying a drive signal for driving the image pickup device 106 and the like at a predetermined timing to the image pickup device 106 and the like. The drive signal includes a clock signal and a synchronization signal for operating the image pickup device 106, and further includes various setting parameters for mode change for selecting the drive of the image pickup device 106 and the like. The TG 113 may be provided inside the image pickup device 106 as an internal TG, or may be configured to generate a drive signal based on a synchronization signal supplied from the outside. Further, as a mode for selecting the drive of the image pickup device 106, at least a still image mode, a moving image mode, and a live view mode are provided.

The signal processing unit 107 is provided in the image pickup device 106, and includes an ADC circuit that converts at least an analog image signal output from the pixel unit into a digital image signal.

The DFE 108 has a function of executing a predetermined arithmetic process on the digital image signal output from the image pickup device 106. The DSP 109 has a function of performing correction processing, development processing, and the like on the digital image signal output from the DFE 108. The DSP 109 also has a function of performing AF (autofocus) calculation for calculating the amount of defocus from an image signal (digital image signal). Further, the DFE108 and the DSP109 include a reconfigurable circuit such as an FPGA circuit. By adopting various circuit configurations by setting from the outside, complicated correction operation and the like can be realized with a small amount of circuit resources.

The display unit 111 has a function of displaying captured images, various menu screens, and the like. A liquid crystal display (LCD), an organic EL display (OLED), or the like is used for the display unit 111. The RAM 112 is a random access memory for temporarily storing captured image data and the like. The ROM 119 is a read-only memory that stores various correction data, a program for executing a predetermined process, and the like. The recording medium 110 is for recording the data of the captured image. The recording medium 110 may be removable, such as a memory card using a non-volatile semiconductor memory such as an SD memory card. The RAM 112, ROM 119, and recording medium 110 are connected to the DSP 109.

The CPU 114 is a control device that controls the entire image pickup apparatus 100, and controls each component in an integrated manner. At the same time, various setting parameters and the like are set for each component. Further, the CPU includes 114, a cache memory capable of electrically writing / erasing data, and the like, and executes a program recorded in the cache memory. The memory is used as a program storage area executed by the CPU, a work area during program execution, a data storage area, and the like. The CPU 114 also analyzes the signal output from the image pickup device 106 and performs image processing. The analysis result is output as image information. The image information is an image analysis result, and includes not only the brightness and color of the subject, but also the presence / absence and features of an object (including the human body), the position / velocity / acceleration of the object, the detection result of a specific subject, and the like. Further, the CPU 114 controls the focus drive circuit 116 based on the AF calculation result output from the DSP 109, and adjusts the focal position of the imaging optical system by the focus actuator 118.

Next, an example of the pixel arrangement of the image pickup device 106 in the image pickup apparatus 100 according to the present embodiment will be described with reference to FIG. The pixel arrangement shown in FIG. 3 corresponds to the arrangement of the pixel portions 11 included in the first substrate 10.

As shown in FIG. 3, for example, the image pickup element 106 has a pixel region PA (pixel array) in which a plurality of pixel portions 11 (unit pixels) are arranged in a two-dimensional array along the row direction and the column direction. There is. The pixel region PA is not particularly limited, but may include, for example, a pixel array of pixel portions 11 having 4000 rows × 8000 columns. Note that FIG. 3 shows an extracted pixel array of 6 rows × 8 columns.

Each pixel unit 11 includes two photodiodes (hereinafter referred to as “PD”) 401a and 401b, one microlens (not shown), and a color filter (not shown). PD401a and PD401b are photoelectric conversion units of two sub-pixels a and sub-pixel b configured in the pixel unit 11, respectively. One microlens is provided for each pixel unit 11, and the incident light is focused on two photoelectric conversion units of the same pixel unit 11.

The symbols a and b shown in the pixel portion 11 of FIG. 2 represent the sub-pixels a and b whose pupils are divided into left and right. The output signal a (A signal) output from the sub-pixel a and the output signal b (B signal) output from the sub-pixel b are focus detection signals used for focus detection. Further, the signal (A + B signal) obtained by adding the A signal and the B signal is used for image generation (generation of captured image). Further, the reference numerals R, G, and B represent the colors (spectral characteristics) of the color filter, where R is a red filter, G is a green filter, and B is a blue filter. Color filters of the same color are assigned to the two PD401a and 401b constituting one pixel unit 11. Note that FIG. 2 shows an example in which the color filters are arranged by a so-called Bayer arrangement, but the arrangement of the color filters is not limited to this. Further, the division direction of the pupil is not limited to the left and right, and may be up and down, or may be divided into two or more.

Next, the relationship between the luminous flux emitted from the exit pupil of the image pickup optical system (imaging lens) and the pixel portion 11 of the image pickup element 106 will be described with reference to FIG. The pixel unit 11 includes PD401a, 401b, a color filter 201 arranged on PD401a, 401b, and a microlens 202. It is assumed that the luminous flux that has passed through the exit pupil 203 of the image pickup optical system (imaging lens) is incident on the pixel unit 11 around the optical axis 204 of the image pickup optical system. Focusing on the luminous flux passing through the pupil regions (partial regions) 205 and 206 of the exit pupil 203 of the imaging optical system (imaging lens), the luminous flux passing through the pupil region 205 is transmitted through the microlens 202. Then, the light is received by the PD401a of the sub-pixel a. On the other hand, the luminous flux that has passed through the pupil region 206 is received by the PD401b of the sub-pixel b via the microlens 202.

In this way, the sub-pixels a and b each receive light that has passed through different regions (regions different from each other) of the exit pupil 203 of the image pickup lens. Therefore, by comparing the A signal, which is the output signal of the sub-pixel a, and the B signal, which is the output signal of the sub-pixel b, the focus detection of the phase difference method becomes possible.

Next, the image signal waveforms obtained from the sub-pixels a and b of the image pickup device 106 will be described with reference to FIG. FIG. 5A is a graph showing an example of an image signal waveform obtained from the sub-pixels a and b when the state is out of focus (out of focus). FIG. 5B is a graph showing an example of an image signal waveform obtained from the sub-pixels a and b in the in-focus state (substantially in-focus state). In FIGS. 5A and 5B, the vertical axis indicates the signal output, and the horizontal axis indicates the position (pixel horizontal position).

When out of focus (out of focus), the image signal waveforms (A signal, B signal) obtained from the sub-pixels a and b do not match each other, as shown in FIG. 5 (a). , It will be in a state of large deviation. As the out-of-focus state approaches the in-focus state, the deviation of the image signal waveforms of the sub-pixels a and b becomes smaller as shown in FIG. 5 (b). Then, in the focused state, these image signal waveforms overlap each other. In this way, the amount of focus shift (defocus amount) can be detected by detecting the shift (shift amount) of the image signal waveforms obtained from the sub-pixels a and b, and by using this information, The focus of the imaging optical system can be adjusted.

Next, a configuration example of the image pickup device 106 in the image pickup apparatus 100 according to the present embodiment will be specifically described.

As shown in FIG. 2, the image pickup device 106 has a laminated structure in which a first substrate 10 including a pixel unit 11 and a second substrate 20 including a signal processing unit 21 are laminated. FIG. 6 is a diagram showing the arrangement of the pixel unit 11 and the positional relationship of the signal processing unit 21 on a plane. The square shown in white indicates one pixel portion 11 provided on the first substrate 10, and the attached characters indicate the color of the color filter provided on each pixel portion 11. Further, a rectangle arranged on the back surface of the pixel unit 11 and shown in gray indicates one signal processing unit 21 provided on the second substrate 20.

As shown in FIG. 6, a plurality of pixel units 11 and signal processing units 21 are periodically arranged in the row direction and the column direction in each substrate to form a pixel array and a circuit array. The area of the pixel unit 11 on the first substrate 10 is smaller than the area of the signal processing unit 21 on the second substrate 20. Therefore, a predetermined number of pixel units 11 shown by dotted lines are designated as pixel blocks 12, and one signal processing unit 21 is arranged corresponding to each pixel block 12. In the present embodiment, the pixel portion 11 having 4 rows × 12 columns is used as one pixel block 12, but this is an example and a different number of pixels or arrangement may be used as the pixel block 12. Further, the signal processing unit 21 corresponding to each pixel block 12 does not necessarily have to correspond in position (for example, located directly below the pixel unit 11). The pixel unit 11 and the signal processing unit 21 may be arranged apart from each other.

As shown in FIG. 7, each of the pixel units 11 has PD401a, 401b, transfer transistors 402a, 402b, reset transistor 405, amplification transistor 404, and selection transistor 406. The anode of the PD401a is connected to the ground voltage line and the cathode of the PD401a is connected to the source of the transfer transistor 402a. The anode of the PD401b is connected to the ground voltage line and the cathode of the PD401b is connected to the source of the transfer transistor 402b. The drain of the transfer transistor 402a and the drain of the transfer transistor 402b are connected to the source of the reset transistor 405 and the gate of the amplification transistor 404. The drain of the transfer transistors 402a and 402b, the source of the reset transistor 405, and the connection node of the gate of the amplification transistor 404 form a floating diffusion unit (hereinafter referred to as “FD unit”) 403. The drain of the reset transistor 405 and the drain of the amplification transistor 404 are connected to the power supply voltage line (voltage Vdd). The source of the amplification transistor 404 is connected to the drain of the selection transistor 406.

The PD401a and 401b of the sub-pixels a and b photoelectrically convert the incident optical signal (optical image) and accumulate an electric charge according to the exposure amount. The transfer transistors 402a and 402b transfer the electric charge stored in the PD 401a and 401b to the FD unit 403 according to the high level signals PTXA and PTXB. The FD unit 403 converts the electric charge transferred from the PD 401a and 401b into a voltage corresponding to the amount of the electric charge by the parasitic capacitance, and applies the electric charge to the gate of the amplification transistor 404. The reset transistor 405 is a switch circuit for resetting the FD unit 403, and resets the FD unit 403 in response to the high level signal PRESS. When resetting the charges of PD401a and 401b, the signal PRESS and the signals PTXA and PTXB are set to the high level at the same time, and the transfer transistors 402a and 402b and the reset transistor 405 are turned on. Then, the PD401a and 401b are reset via the FD unit 403. The selection transistor 406 outputs a pixel signal converted into a voltage by the amplification transistor 404 to the output node vout of the pixel unit 11 (pixel) according to the high level signal PSEL.

In each row of the pixel array of the first substrate 10, drive signal lines (not shown) are arranged so as to extend in the row direction. The drive signal line is connected to a vertical scanning circuit provided on the first substrate 10 or the second substrate 20. A predetermined drive signal for driving the pixel readout circuit of the pixel unit 11 is output from the vertical scanning circuit to the drive signal line at a predetermined timing. Specifically, each drive signal line is a plurality of (for example, four) signal lines for supplying the above-mentioned signal PTXA, signal PTXB, signal PRESS, and signal PSEL to a plurality of pixel units 11 arranged in the row direction. including. Each signal line forms a signal line common to a plurality of pixel units 11 belonging to the same line.

A reading circuit for reading a signal from each pixel unit 11 in the image pickup device 106 will be described with reference to FIG. FIG. 8 shows an equivalent circuit relating to the readout circuit of the image sensor 106. FIG. 8 shows only the pixel portions 11 arranged in the odd-numbered rows among the pixel portions 11 shown in FIG. The first substrate 10 has four signal lines 803a for each row of the pixel portions 11. The signal line 803a is connected to the 803b having the current source 802 in the second substrate 20 via the connecting portion 801. The signal output from each pixel unit 11 is read from the first substrate 10 to the second substrate 20 via the signal line 803a and the signal line 803b. In the following, when the signal line 803a and the signal line 803b are described without distinction, they are simply referred to as the signal line 803. Further, each row of the pixel unit 11 has four signal lines 803, and each signal line is represented by col_xN (x: column number of the pixel unit 11, N: A to D). Specifically, the pixel portion 11 in the first row is connected to col_xA. Similarly, the pixel portions 11 on the 2nd to 4th rows are sequentially connected to the signal lines col_xB to col_xD. The signal line 803 is arranged in the other rows in the same manner as the pixel portion 11 in the first row. In the present embodiment, the configuration is such that each row of the pixel unit 11 has four signal lines 803, but the present invention is not limited to this. It is preferable to provide more signal lines 803 in order to read at higher speed. However, the number of signal lines is preferably a multiple of 2 or a multiple of 4. Further, although only one pixel block 12 is shown in FIG. 8, a plurality of pixel blocks are arranged in a matrix in the pixel array. That is, the signal line 803 is shared with the pixel portion 11 of the other pixel block.

Each signal line 803 is connected to a signal processing unit 21 provided on the second substrate 20. As shown in FIG. 6, the image pickup device 106 of the present embodiment is provided with one signal processing unit 21 for the pixel block 12 including the plurality of pixel units 11. Therefore, a plurality of signal lines 803 are connected to the signal processing unit 21. The signal processing unit 21 has a multiplexer circuit 804 (hereinafter referred to as an MPX circuit), and a plurality of signal lines 803 are connected to the input of the MPX circuit 804. Further, the signal processing unit 21 has an ADC circuit 805, and the ADC circuit 805 is connected to the output of the MPX circuit 804. By providing the MPX circuit 804 between the plurality of signal lines 803 and the ADC circuit 805, the signal processing unit 21 can process a plurality of signals in a single ADC circuit 805 in a time-division manner at high speed. As will be described in detail later in another embodiment, in this embodiment, the ADC circuit 805 employs a sequential comparison type AD conversion format. By using this method, it is possible to realize high speed and low power consumption of the ADC circuit 805. Further, in the present embodiment, the MPX circuit 804 corresponds to a selection unit for selecting a signal line to be connected to the ADC circuit 805 from a plurality of signal lines 803.

In the present embodiment, the signal processing unit 21 has two MPX circuits 804a and 804b, and the ADC circuits 805a and 805b correspond to each of them. The MPX circuit 804a is configured to be able to receive signals from col_xA and col_xC connected to a pixel having an R color filter. Further, the MPX circuit 804b is configured to be able to receive signals from col_xB and col_xD connected to a pixel having a G color filter. Then, the output of the MPX circuit 804a is connected to the ADC circuit 805a, and the output of the MPX circuit 804b is connected to the ADC circuit 805b. Each ADC circuit 805 can operate the ADC function independently. Although the signal processing unit 21 of the present embodiment has two MPX circuits and an ADC circuit, the present invention is not limited to this, and the signal processing unit 21 may have only one or three or more. ..

Further, although the signal line 803 and the MPX circuit 804 are directly connected to each other, a sample hold circuit (not shown) may be provided between them so that the signal read from the pixel unit 11 can be temporarily held.

Further, the ADC circuit 805 of the present embodiment can perform power saving operation (standby operation) collectively or individually. In order to control the power saving operation, the PSAVE control unit 806 is provided on the second substrate 20. Each ADC circuit 805 starts or ends the power saving operation according to the control signal from the PSAVE control unit 806. As an example of the power saving operation, there is an operation of stopping the supply of the power supply or the clock supplied to the ADC circuit 805. The PSAVE control unit 806 may be provided in the signal processing unit 21 or may be provided in a region unit such as a row unit or a column unit.

Although only the pixel portions 11 provided in the odd-numbered rows are shown in FIG. 8, it is assumed that the pixel portions 11 arranged in the even-numbered rows also have the same circuit configuration.

FIG. 9 is a diagram showing a normal readout operation of the image pickup device 106. In the operation of FIG. 9, the signals read from the pixel unit 11 are sequentially read without being added. This normal readout operation is mainly used when acquiring a high-definition still image. FIG. 9 describes a case where the focus detection signal is not output and only the image pickup signal is output. That is, the pixel unit 11 does not output the first signal based on the PD signal of only a part of the plurality of PDs, but outputs only the second signal based on the signals of the plurality of PDs.

The signal PRESS in FIG. 9 shows a signal supplied from the vertical scanning circuit to the gate of the reset transistor 405 via a control line (not shown). Similarly, the signal PSEL indicates a signal supplied from the vertical scanning circuit to the gate of the selection transistor 406 of the pixel unit 11 on the Nth line via the control line. As for the signal PSEL, the row position of the output pixel unit 11 is shown at the end. That is, the signal PSEL (1) indicates that it is the signal PSEL output to the pixel unit 11 on the first line. The signal PTXA indicates a signal supplied from the vertical scanning circuit to the gate of the transfer transistor 402a via the control line. The signal PTXB indicates a signal supplied from the vertical scanning circuit to the gate of the transfer transistor 402b via the control line. Although the signal PSEL has been described as a signal corresponding to each line, a configuration capable of supplying a plurality of signal PSEL to each line may be used. With this configuration, it is possible to periodically select which pixel signal is to be output even in the column direction.

The signal PSAVE in FIG. 9 shows a signal supplied from the PSAVE control unit 806 to each ADC circuit 805. By inputting a signal corresponding to the High level to the ADC circuit 805, the input ADC circuit 805 starts the power saving operation. Further, normal operation is performed by inputting a signal corresponding to the Low level to the ADC circuit 805. In the present embodiment, the signal PSAVE will be described as a single signal for the sake of brevity, but the present invention is not limited to this. For example, by configuring the signal PSAVE to be individually supplied for each region in the pixel array or for each ADC circuit 805, it is possible to control the power saving operation for each region.

FIG. 9 shows the operations related to the MPX circuit 804a and the ADC circuit 805a. In the MPX circuit 804a and the ADC circuit 805a, as shown in FIG. 8, in the first row and the third row including the color filter of R in the arrangement of the pixel block 12, the odd number among the 1st to 12th columns. The signal of the pixel unit 11 located in the row is input. Therefore, FIG. 9 shows the operations related to the operation of the pixel unit 11 located in the odd-numbered columns of the 1st to 12th columns in the first row and the third row.

Further, in FIG. 9, which column is selected as the column for outputting the signal to the ADC circuit 805a by the MPX circuit 804a is indicated by the name Col_xN of the signal line. The notation of this xN will be described. x indicates the column number of the pixel unit 11. Further, N indicates any one of the four signal lines 803 arranged corresponding to the pixel portion 11 in one row.

At time t1, the vertical scanning circuit sets the signal PRESS output to the pixel units 11 on the first and third rows to the High level. As a result, the reset transistor 405 of the pixel unit 11 in the first row is turned on. Therefore, the FD unit 403 is reset to the potential corresponding to the power supply voltage Vdd. Further, at time t1, the vertical scanning circuit sets the signal PSEL (1) to the High level. As a result, the selection transistor 406 of the pixel unit 11 in the first row is turned on. Therefore, the current supplied by the current source 802 shown in FIG. 8 is supplied to the amplification transistor 404 via the selection transistor 406 of the pixel unit 11 in the first row. As a result, a source follower circuit is formed by the power supply voltage Vdd, the amplification transistor 404, and the current source 802. That is, the amplification transistor 404 performs a source follower operation that outputs a signal corresponding to the potential of the FD unit 403 to the signal line 803 via the selection transistor 406. In the present embodiment, the period after the time t1 corresponds to the read period for the N signal.

At time t2, the vertical scanning circuit sets the signal PRESS output to the pixel unit 11 on the first row to the Low level. As a result, the reset transistor 405 of the pixel unit 11 in the first row is turned off. Therefore, the reset of the FD unit 403 is released. The amplification transistor 404 outputs a signal based on the potential of the FD unit 403 whose reset has been released to the corresponding signal line 803 shown in FIG. This signal is referred to as an N signal (noise signal). As a result, an N signal is output from the pixel unit 11 to the signal line 803 in each row. As a result, the N signal corresponding to the pixel unit 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period.

After the time t2, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the N signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the first row, which is output from the MPX circuit 804a, into a digital signal. After that, the N signal output to the signal line 803a corresponding to the pixel unit 11 in the first row of the odd-numbered columns of the 1st to 12th columns is sequentially AD-converted into a digital signal. Since each N signal has already been input to the MPX circuit 804a, high-speed AD conversion can be performed simply by switching the output of the MPX circuit 804a. In the present embodiment, the period after the time t2 corresponds to the AD conversion period for N signals.

At time t3, the vertical scanning circuit sets the signal PRESS input to the pixel unit 11 on the third row to the Low level. As a result, the reset transistor 405 of the pixel portion 11 on the third row is turned off. Therefore, the reset of the FD unit 403 is released. The amplification transistor 404 outputs an N signal, which is a signal based on the potential of the FD unit 403 whose reset has been released, to the signal line 803 shown in FIG. As a result, the N signal is output from the pixel unit 11 in the third row to the signal line 803 in each column. As a result, the N signal corresponding to the pixel unit 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period.

After the time t3, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the N signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the third row, which is output from the MPX circuit 804a, into a digital signal. After that, the N signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. Since each N signal has already been input to the MPX circuit 804a, high-speed AD conversion can be performed simply by switching the output of the MPX circuit 804a. In the present embodiment, the period after the time t3 corresponds to the AD conversion period for N signals.

Further, at time t3, the vertical scanning circuit sets the signals PTXA and PTXB output to the pixel unit 11 on the first row to the High level. As a result, the electric charge (electrons in this embodiment) accumulated in the PD 401a and 401b is transferred to the FD unit 403 via the transfer transistors 402a and 402b. In the FD unit 403, the electric charges of PD401a and 401b are added. As a result, the FD unit 403 has a potential corresponding to the sum of the charges of the PD 401a and 401b. Temporarily, the signal output by the amplification transistor 404 based on the potential of the FD unit 403 due to the charge of only PD401a is defined as the A signal. Further, tentatively, the signal output by the amplification transistor 404 based on the potential of the FD unit 403 due to the charge of only PD401b is defined as the B signal. According to this notation, the signal output by the amplification transistor 404 based on the potential of the FD unit 403 corresponding to the added charge of each of the PD401a and 401b can be regarded as the A + B signal obtained by adding the A signal and the B signal. .. The A + B signal of the pixel unit 11 in the first row is output to the signal line 803 in each column. As a result, the A + B signal corresponding to the pixel portion 11 in the odd-numbered columns of the 1st to 12th columns is input to the MPX circuit 804a during the same period. The A + B signal is a second signal based on the signals generated by the plurality of PDs. The second signal can be used as a signal for imaging. In the present embodiment, the period after the time t3 corresponds to the read period for the A + B signal.

After the time t4, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the A + B signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the first row, which is output from the MPX circuit 804a, into a digital signal. After that, the A + B signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. Since each A + B signal has already been input to the MPX circuit 804a, high-speed AD conversion can be performed simply by switching the output of the MPX circuit 804a. In the present embodiment, the period after the time t4 corresponds to the AD conversion period for the A + B signal.

At time t4, the vertical scanning circuit sets the signals PTXA and PTXB output to the pixel unit 11 on the third row to the High level. As a result, the A + B signal of the pixel unit 11 in the third row is output to the signal line 803 in each column. As a result, the A + B signal corresponding to the pixel portion 11 in the odd-numbered columns of the 1st to 12th columns is input to the MPX circuit 804a during the same period. In the present embodiment, the period after the time t4 corresponds to the read period for the A + B signal.

After the time t5, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the A + B signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the third row, which is output from the MPX circuit 804a, into a digital signal. After that, the A + B signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. Since each A + B signal has already been input to the MPX circuit 804a, high-speed AD conversion can be performed simply by switching the output of the MPX circuit 804a. In the present embodiment, the period after the time t5 corresponds to the AD conversion period for the A + B signal.

Then, these operations are also performed in parallel for the second and fourth rows provided with the G color filter. Further, the same procedure is performed for the pixel portions 11 located in the even-numbered rows. By executing in parallel and sequentially for each pixel block 12, it is possible to acquire an image signal for one screen. Further, when it is desired to acquire the A signal or the B signal, either the signal PTXA or the signal PTXB may not be controlled at the timing of reading the A + B signal. Further, as will be described in detail in another embodiment, it is preferable that the reading order is after reading the N signal and before reading the A + B signal.

Here, one of the characteristic effects in this embodiment will be described.

In the operation shown in FIG. 9, a plurality of operations are performed in parallel as follows.
(1) Parallel operation of AD conversion of the N signal corresponding to the pixel portion 11 of the first row and reading of the N signal corresponding to the pixel portion 11 of the third row (2) Corresponding to the pixel portion 11 of the third row Parallel operation of AD conversion of the N signal to be performed and reading of the A + B signal corresponding to the pixel unit 11 of the first line (3) AD conversion of the A + B signal corresponding to the pixel unit 11 of the first line and the third line. Parallel operation with reading out the A + B signal corresponding to the pixel unit 11.

By this parallel operation, the waiting period from the end of one AD conversion by the ADC 805a to the next AD conversion can be shortened. As a result, the period required for AD conversion of the signals output by all the pixel units 11 can be shortened. Therefore, it is possible to advance the increase in the frame rate in the entire image pickup apparatus 100.

Note that FIG. 9 shows an example in which the read period for each N signal and the read period for the A + B signal are controlled at the same time by the connection line 803 connected to the same MPX circuit 804, but this operation is limited. do not have. An important feature is that the readout operation is started for another signal line 803 that can be connected to the ADC circuit 805 at the same time as the AD conversion of each signal by the ADC conversion circuit 805. That is, it is preferable to appropriately change the read timing for each signal line 803, the read timing, and the AD conversion timing according to the image pickup conditions (ISO sensitivity and frame rate) and the characteristics of the image pickup element 106. For example, the AD conversion of each signal is sequentially performed in each AD conversion period after the time t2 and the time t4, but the timing of the AD conversion corresponding to the first column and the other columns is different. The end of the read period does not have to be uniform, and may be completed by the timing of AD conversion. Therefore, in FIG. 9, the end of the read period of each column is collectively performed at time t2 and time t4, but each column may be shifted backward according to the timing of AD conversion. More specifically, the end timing of the read period of the third column with respect to the first column is set immediately before the end of the AD conversion of the first column. Then, the end timing of the read period of the other columns can be similarly shifted before the end of the immediately preceding AD conversion. By operating at such timing, AD conversion can be performed immediately after reading the signal, and an extra time until the start of AD conversion can be shortened.

Further, although the end of the read period has been described above, the same applies to the start. In particular, when the end timing of the read period changes, it is preferable to change the start timing of the read period accordingly so that the lengths of the read periods of each column are substantially the same. Further, in FIG. 9, for example, at time t1 and time t3, the read period is uniformly started, but the signal MPX (Col_xN) corresponding to the period for performing AD conversion of each column is moved forward until the time when the signal MPX (Col_xN) falls. Is possible. That is, it is not necessary to wait for the end of the AD conversion of all the columns, and it is possible to start reading the next signal at the timing when the AD conversion period for each column ends. This makes it possible to further improve the frame rate. Then, the load on the current source 802 can be reduced by shifting the read period for the plurality of signal lines 803 without making them uniform. That is, in order to individually execute the read operation for the corresponding pixel unit 11 at different timings, the signal PRESS, the signal PTXA, the signal PTXB, etc. require a plurality of wires for each line, and the control is complicated. However, on the other hand, the effect of reducing the peak current consumption supplied to the image sensor 106 can be obtained, and the power consumption can be reduced as a whole. It is preferable to shift each signal line 803 to an appropriate timing, but if the circuit becomes too complicated, the timing may be shifted by using a predetermined number of signal lines 803 as one unit.

Next, the characteristic readout operation of the image pickup device 106 in the image pickup apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 10 is a diagram showing an additive / readout operation of the image pickup device 106. In the operation of FIG. 10, the signals read from the pixel unit 11 are sequentially read while being added before the AD conversion. This addition / reading operation is mainly used when acquiring a moving image. In FIG. 10, a case where only the signal for imaging is output without outputting the signal for focus detection will be described. The signal line displayed in FIG. 10 is the same as that in FIG. Further, the description of the operation common to the normal read operation will be omitted.

At time t2, the vertical scanning circuit sets the signal PRESS output to the pixel unit 11 on the first row to the Low level. As a result, an N signal is output from the pixel unit 11 to the signal line 803 in each row. As a result, the N signal corresponding to the pixel unit 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period.

After the time t2, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113. In the addition / reading operation, unlike the normal reading operation, a plurality of signal lines 803 are simultaneously connected to the ADC circuit 805a. By this operation, the output of the MPX circuit 804a is substantially equivalent to the signal obtained by adding and averaging the signals output to the signal lines 803 connected at the same time. As a result, signal addition can be performed between the signal lines 803. In the present embodiment, the corresponding signal line 803 is simultaneously connected to the ADC circuit 805a in order to add two adjacent rows of the same color as in the first row and the third row. As a result, the required number of AD conversions is half that of the normal read operation. Then, as a whole, the AD conversion can be completed in half the time of the normal read operation. In this embodiment, the signal line 803 and the MPX circuit 804 correspond to an addition circuit for adding signals from the pixel unit 11.

Further, the signal PSAVE output to each ADC circuit 805 is set to the High level at the timing when the AD conversion is completed after the time t2. As a result, the ADC circuit 805 is switched to the power saving operation. Then, by setting the Low level at time t3, the power saving operation is ended and AD conversion to the next signal becomes possible.

Further, in FIG. 10, the signal PSAVE signal is set to the High level at the timing when the AD conversion of each row or each pixel block is completed and corresponds to the horizontal blanking period. This enables further power saving. Since each ADC circuit 805 operates independently, it is not always necessary to collectively execute the power saving operation for the entire image sensor 106. It is preferable to appropriately execute the power saving operation according to the operation of each ADC circuit 805.

By performing signal addition using the MPX circuit 804 provided in front of the ADC circuit 805 in this way, it is possible to shorten the time related to AD conversion. Then, by operating the ADC circuit 805 with power saving operation in a shortened time, it is possible to realize power saving of the entire image pickup device 106 while maintaining the frame rate. In the present embodiment, the number of signal additions is set to two columns, but three or more columns may be added. By increasing the number of additions, the AD conversion time can be further shortened, and further power saving can be achieved. Furthermore, the frame rate can be improved.

Further, when a sample hold circuit is provided between the signal line 803 and the MPX circuit 804, it is not necessary to simultaneously connect a plurality of signal lines 803 to the MPX circuit 804 when adding signals. For example, signal addition can be realized by further providing a switch circuit or the like for connecting capacitances (capacitors or the like) holding signals in the sample hold circuit. Further, the addition / reading operation may be performed by combining the signal addition method of connecting the capacitances and the addition method of simultaneously connecting a plurality of signal lines 803 to the MPX circuit 804.

Although the operation of adding signals of the same color is shown in the present embodiment, signals of different colors may be added. It can be used as a signal for AF or exposure calculation other than the generation of an image signal.

Further, although only the read timing is described in each timing chart, the reset operation of each PD 401 in the pixel unit 11 is performed before the read timing. In order to make the entire screen have the same storage period, the scanning timing for each pixel portion 11 in the reset operation is also performed in combination with the reading timing described in the present embodiment.

(Second embodiment)
In the first embodiment, an example is shown in which a plurality of signal lines 803 connected to the MPX circuit 804 are simultaneously connected to the ADC circuit 805 to realize signal addition in the column direction. In this embodiment, a connection example of the signal line 803 and the MPX circuit 804, which is different from the first embodiment, is shown, and an operation of performing signal addition also in the row direction is shown.

A reading circuit for reading a signal from each pixel portion 11 in the image pickup device 106 in the present embodiment will be described with reference to FIG. 11. FIG. 11 corresponds to FIG. 8 in the first embodiment, and shows an equivalent circuit relating to the readout circuit of the image pickup device 106. The same components as those in FIG. 8 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 11, the signal output from each pixel unit 11 is read out via the signal line 803. It has four signal lines 803 for each row of the pixel unit 11. Each signal line is represented by col_xN (x: column number of pixel unit 11, N: A to D). The signal line 803 is arranged in the other rows in the same manner as the pixel portion 11 in the first row. The difference from the circuit in the first embodiment in FIG. 11 is the connection form between the signal line 803 and the MPX circuit 804. Specifically, in the present embodiment, the configuration is such that each row of the pixel unit 11 has four signal lines 803, but the present invention is not limited to this. It is preferable to provide more signal lines 803 in order to read at higher speed. However, the number of signal lines is preferably a multiple of 2 or 4, or a multiple of the number of signals to be added.

In FIG. 11, the MPX circuit 804 and the ADC circuit 805 are provided with an R color filter, and the signals of the pixel portions 11 located in the odd columns of the 1st to 12th columns in the first and third rows are transmitted. Entered. Further, the signals of the pixel units 11 located in the odd-numbered columns of the 1st to 12th columns in the second and fourth rows provided with the G color filter are input. In FIG. 11, only the odd-numbered columns necessary for explanation are shown, and the other odd-numbered columns and even-numbered columns are omitted for simplification.

FIG. 12 is a diagram showing an additive / readout operation of the image pickup device 106 in the second embodiment. In the operation of FIG. 12, the signals read from the pixel unit 11 are sequentially read while being added before the AD conversion. This addition / reading operation is mainly used when acquiring a moving image. FIG. 12 describes a case where the focus detection signal is not output and only the image pickup signal is output. The signal line displayed in FIG. 12 is the same as that in FIG. 10, and only the signal input to the MPX circuit 804 is different. Further, the description of the operation common to the operation shown in the first embodiment will be omitted.

At time t2, the vertical scanning circuit sets the signal PRESS to be output to the pixel unit 11 of the first row and the signal PRESS to be output to the pixel unit 11 of the third row to the Low level. As a result, an N signal is output from the pixel unit 11 to the signal line 803 in each row. As a result, the N signals corresponding to the pixel portions 11 in the odd-numbered columns in the first and third rows of the 1st to 12th columns are input to the MPX circuit 804.

After time t2, the MPX circuit 804 sequentially connects the signal lines 803 corresponding to the pixel portions 11 in the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805 by the signal MPX supplied from the TG 113. In the addition / reading operation of the present embodiment, a plurality of signal lines 803 are simultaneously connected to the ADC circuit 805. Specifically, Col_xA corresponding to the pixel unit 11 in the first row and Col_xC corresponding to the pixel unit 11 in the third row are simultaneously connected. By this operation, in the output of the MPX circuit 804, the signals output to the signal lines 803 connected at the same time are added and averaged, and signal addition in the row direction can be realized. In the present embodiment, it is necessary to connect the corresponding signal line 803 to the ADC circuit 805 at the same time in order to add two adjacent lines having the same color as the first line and the third line. As a result, a signal corresponding to two rows of AD conversion can be obtained by one AD conversion, and the AD conversion can be completed in half the time of the normal read operation.

Further, the signal PSAVE output to each ADC circuit 805 is set to the High level at the timing when the AD conversion is completed after the time t2. As a result, the ADC circuit 805 is switched to the power saving operation. Then, by setting the Low level immediately before the time t3, the power saving operation is ended and AD conversion to the next signal becomes possible.

In this embodiment, the operation of performing only the addition in the row direction is exemplified, but by combining the addition / reading operation in the column direction as shown in the first embodiment, the addition in both the row direction and the column direction is performed. Can be realized at the same time.

By making it possible to connect to the MPX circuit 804 provided in front of the ADC circuit 805 from the pixel unit 11 corresponding to the column or row to be added, both the normal read operation and the additional read operation can be realized. .. Further, by operating the ADC circuit 805 with power saving during the time when the AD conversion time is shortened, it is possible to realize power saving of the entire image sensor 106 while maintaining the frame rate. In the present embodiment, the number of signal additions is two lines, but three or more lines may be added. Further, it may be combined with the addition in the column direction, and in that case, the addition number in the column direction and the addition number in the row direction do not necessarily have to be the same.

Further, although FIG. 6 shows an example in which one signal processing unit 21 is arranged for a pixel block 12 including a predetermined number of pixel units 11, the pixel units 11 included in the pixel block 12 are not necessarily adjacent to each other. You don't have to. For example, when the color center of gravity (sampling cycle) after adding pixels of the same color is taken into consideration, the block consisting of the pixel portion 11 shown by the solid line in FIG. 13 is designated as the pixel block 12, and the signal line from each pixel portion 11 is used. The 803 may be connected to one MPX circuit 804. By adopting the pixel block shown in FIG. 13, when the signals for three pixels are added in the column direction, the color centers of gravity after the addition can be aligned in the column direction. Further, by arranging the same arrangement in the vertical direction, it is possible to align the color center of gravity in the vertical direction as well.

(Third embodiment)
In the first embodiment and the second embodiment, the control of performing signal addition in the MPX circuit 804 to shorten the AD conversion time and operating the ADC circuit 805 in a power saving operation during that time has been described. In the present embodiment, the point that the signal addition is performed in the MPX circuit 804 is common, and the control of the power saving operation for the ADC circuit 805 that is not used in the addition / reading operation will be described.

A reading circuit for reading a signal from each pixel portion 11 in the image pickup device 106 in the present embodiment will be described with reference to FIG. FIG. 14 corresponds to FIG. 8 in the first embodiment, and shows an equivalent circuit relating to a readout circuit of the image pickup device 106. The same components as those in FIG. 8 are designated by the same reference numerals.

In FIG. 14, the signal output from each pixel unit 11 is read out via the signal line 803. It has four signal lines 803 for each row of the pixel unit 11. Each signal line is represented by col_xN (x: column number of pixel unit 11, N: A to D). The signal line 803 is arranged in the other rows in the same manner as the pixel portion 11 in the first row. The difference between the circuits in the first embodiment and the second embodiment in FIG. 14 is the MPX circuit 1404 and the PSAVE control unit 1406, which are added to the configuration of the signal processing unit 21.

In FIG. 14, the MPX circuit 804a is input with the signal of the pixel unit 11 provided with the color filter of R and located in the odd-numbered columns of the 1st to 12th columns in the first and third rows. Further, the MPX circuit 804b is provided with a G color filter, and the signals of the pixel units 11 located in the odd-numbered columns of the 1st to 12th columns in the second and fourth rows are input. Then, the output of the MPX circuit 804a and the output of the MPX circuit 804b are input to the MPX circuit 1404. The output of the MPX circuit 1404 is controlled based on the signal MPX2 which is a control signal, and operates to switch whether the output of the MPX circuit 804a or the output of the MPX circuit 804b is output to the ADC circuit 805a. Specifically, when the signal MPX2 is at the Low level, the output of the MPX circuit 804a is output, and when the signal is at the High level, the output of the MPX circuit 804b is output. By this operation, the output of the MPX circuit 804a and the output of the MPX circuit 804b can be AD-converted by one of the ADC circuits 805a.

Further, the output of the MPX circuit 804b is input to the ADC circuit 805b, and the output of the MPX circuit 804b is AD-converted. However, when the output of the MPX circuit 804a and the output of the MPX circuit 804b are AD-converted by one of the ADC circuits 805a as described above, it is not necessary to operate the ADC circuit 805b.

Further, the ADC circuit 805 of the present embodiment can individually perform a power saving operation. In order to control the power saving operation, the PSAVE control unit 1406 is provided on the second substrate 20. The ADC circuit 805a and the ADC circuit 805b start or end the power saving operation, respectively, according to the individual control signals (PSAVE1 and PSAVE2) from the PSAVE control unit 1406. Therefore, when the AD conversion operation is performed only by the ADC circuit 805a, it is possible to perform the power saving operation by using the signal PSAVE2 only for the ADC circuit 805b.

FIG. 15 is a diagram showing an additive / readout operation of the image pickup device 106 in the third embodiment. In the operation of FIG. 15, the signals read from the pixel unit 11 are sequentially read while being added before the AD conversion. This addition / reading operation is mainly used when acquiring a moving image. FIG. 15 describes a case where the focus detection signal is not output and only the image pickup signal is output. As for the signal line displayed in FIG. 15, the signal MPX2 for controlling the MPX circuit 1404, the signal PSAVE1 from the PSAVE control unit 1406, and the signal PSAVE2 are added to FIG. 10 and the like. Further, the description of the operation common to the operations shown in the first embodiment and the second embodiment will be omitted.

At time t2, the vertical scanning circuit sets the signal PRESS output to the pixel units 11 on the first and second rows to the Low level. As a result, an N signal is output from the pixel unit 11 to the signal line 803 in each row. As a result, the N signals corresponding to the pixel portions 11 in the odd-numbered columns in the first and second rows of the 1st to 12th columns are input to the MPX circuit 804a and the MPX circuit 804b.

After the time t2, the MPX circuit 804 sequentially connects the signal line 803 corresponding to the pixel portion 11 in the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX and the signal MPX2 supplied from the TG 113. In the addition / reading operation of the present embodiment, a plurality of signal lines 803 are simultaneously connected to the ADC circuit 805a. Specifically, Col_1A corresponding to the pixel portion 11 in the first row and Col_3A corresponding to the pixel portion 11 in the third column in the first row are simultaneously connected to the MPX circuit 804a. By this operation, the output of the MPX circuit 804a becomes a signal obtained by adding and averaging the signals output to the signal lines 803 connected at the same time, and signal addition can be realized in the column direction. Then, at the same timing, the signal MPX2 is controlled to the Low level, and the output of the MPX circuit 804a is input to the ADC circuit 805a as the output of the MPX circuit 1404.

Further, at the timing when the AD conversion of the first column and the third column is completed after the time t2, it corresponds to the Col_1B corresponding to the pixel portion 11 of the first column and the pixel portion 11 of the third column in the second row. Col_3B is simultaneously connected to the MPX circuit 804b. By this operation, the output of the MPX circuit 804b becomes a signal obtained by adding and averaging the signals output to the signal lines 803 connected at the same time, and signal addition can be realized in the column direction. Then, at the same timing, the signal MPX2 is controlled to the High level, and the output of the MPX circuit 804b is input to the ADC circuit 805a as the output of the MPX circuit 1404.

Then, by repeating the above operation and performing the addition / reading operation, it is possible to complete the AD conversion operation for two lines in the time for one line in the normal reading operation. That is, two ADC circuits 805, which are normally required in the read operation, are sufficient for one ADC circuit 805 to read the entire pixel block 12. Therefore, for the ADC circuit 805b that is no longer needed, the signal PSAVE2 can be controlled to a high level, and the power saving operation can always be performed during the addition / reading operation, and the power consumption can be greatly reduced.

In this embodiment as well, as in the second embodiment, the signal PSAVE is set to the High level when the AD conversion operation in the ADC circuit 805a is completed, so that further power saving can be achieved.

By providing a plurality of MPX circuits in the signal processing unit 21 in this way, it is possible to obtain an ADC circuit that does not need to be operated in the addition / reading operation. Then, by operating the ADC circuit with power saving, it is possible to realize power saving of the entire image pickup device 106 while maintaining the frame rate. In the present embodiment, the number of signal additions is set to two columns, but three or more columns may be added. Further, it may be combined with the addition in the row direction, and in that case, the addition number in the column direction and the addition number in the row direction do not necessarily have to be the same.

In the present embodiment, the AD conversion time is shortened by adding the signals of the plurality of signal lines 803, but it is also possible to shorten the AD conversion time by combining the thinning operation. For example, in the embodiment, the signal lines 803 of the third, seventh, and eleventh columns are not connected, and only the signal lines 803 of the signals of the first, fifth, and ninth columns are shown in FIG. It is also possible to read at each timing.

Further, in the case of thinning out reading, the MPX circuit 1404 can be omitted by devising the connection between the signal line 803 and the MPX circuit 804. As an example, the signal line 803 from the pixel unit 11 to be thinned out (for example, the pixel unit 11 in the third row, the seventh row, and the eleventh row) is connected to the MPX circuit 804b. Then, the signal line 803 from the pixel unit 11 to be read (for example, the pixel unit 11 in the first row, the fifth row, and the ninth row) is connected to the MPX circuit 804a. By making such a connection, it is possible to obtain the same effect as that of the third embodiment by saving power in the MPX circuit 804b and the ADC circuit 805b during the thinning-out reading operation.

In the first to third embodiments, signals are read from the pixel unit 11 (for example, the first column) located at the end of the pixel block 12, but the order of signal reading is not limited to this. For example, it may be read in the reverse order or every other read.

(Fourth Embodiment)
In the first to third embodiments, an example is shown in which the power saving operation of the ADC circuit 805 is controlled at the timing when the AD conversion operation is not performed during the read period while the signal addition or the like is performed in the MPX circuit 804. .. However, in the operation of the image pickup apparatus 100 using the image pickup element 106, there are other timings at which the power saving operation can be set for the ADC circuit 805.

FIG. 16 shows the timing when one image is captured by the image pickup apparatus 100. The signal VD is a vertical synchronization signal and is supplied from the TG 113 to the image pickup device 106. Further, the signal VD is also supplied to other components such as DFE108 and DSP109, and plays a role of synchronizing the operation timing of the entire image pickup apparatus 100. The period of the signal VD corresponds to the frame rate for acquiring the moving image, and is 1/120 seconds in the present embodiment. The internal HD is a horizontal synchronization signal, which is an internal signal generated by a circuit in the image sensor 106 in synchronization with the signal VD supplied from the TG 113. The timing of the operation of the image pickup device 106 is defined by the internal HD, and for example, the reset operation and the read operation of the pixel unit 11 are controlled. The image sensor 106 outputs a signal from the pixel unit 11 corresponding to a predetermined number of lines during the 1HD period. In this embodiment, the time (reading period) required for the image sensor 106 to output an image signal for one frame is 1/180 second.

As shown in FIG. 16, if the readout period required to acquire one image is 1/180 second, the surplus time is the blanking period because it is sufficiently fast for the frame rate. During the blanking period, signal reading and AD conversion operations are not performed. Therefore, power saving operation is possible during this period. As shown in FIG. 16, power saving operation can be achieved by setting the signal PSAVE to the High level during the blanking period.

In addition, the frame rate needs to be constant in order to acquire a smooth moving image. When the frame rate is not variable and is constant, the blanking period depends on the amount of signal read from the image sensor 106. For example, as shown in FIG. 17, it is assumed that a still image is acquired while a moving image at a predetermined frame rate (for example, 60 fps) is being imaged. Assuming that the number of pixels required for a moving image is 8 million pixels, the number of pixels used for a still image is quadrupled to 32 million pixels. Then, the blanking period at the time of still image imaging is inevitably shorter than that of moving image imaging. In such a case, as shown in FIG. 17, it is preferable to execute the power saving operation only during the blanking period at the time of capturing the moving image and not to perform the operation at the time of capturing the still image. Since the still image is captured in a single shot for the moving image to be continuously captured, it is possible to save the power of the image sensor 106 as a whole without performing the power saving operation when capturing the still image. Is.

Further, as in the blanking period, there is an accumulation period as a period during which the signal reading and the AD conversion operation are not performed. As shown in FIG. 18A, the image pickup device 106 is exposed for a predetermined storage period after resetting the pixel unit 11, and then the signal is read out in the read-out period. The storage period is determined by the user himself or automatically based on the brightness of the subject, and the period is defined by the signal VD or the internal HD. The image sensor 106 of the present embodiment can be set to save power even during the storage period.

As shown in FIG. 18B, when the storage period is short (for example, about 1/1000 second), the period during which the power saving operation can be set is short, and the power saving operation is considered in consideration of the influence of the recovery from the power saving operation. Control not to set the operation. As an example, when a storage period of 1/8 second to 1 second or more is set, it is preferable to set a power saving operation during the storage period.

(Fifth Embodiment)
In the fourth embodiment, the timing for executing the power saving operation of the ADC circuit 805 in the image pickup operation in the image pickup apparatus 100 in which the image pickup element 106 is used has been described. In the present embodiment, the operation of dividing the region in the circuit array of the image pickup element 106 to execute the power saving operation will be described in detail.

FIG. 19 shows a circuit array formed on the second substrate 20 of the image pickup device 106. Each element of the circuit array represents a signal processing unit 21, and as a whole, n pieces in the horizontal direction and m in the vertical direction. A number of signal processing units 21 are arranged. FIG. 19 (a) shows a normal image pickup state, and in order to acquire an image using the entire screen, all the circuit arrays are used to read out the signal. Therefore, all signal processing units 21 are set to normal operation. On the other hand, FIG. 19B shows a clip imaging state (imaging using only horizontal i to k columns and vertical h to j rows), and an image is acquired using only from the center of the screen. , Do not use peripheral circuit arrays. Therefore, the signal processing unit 21 in the peripheral portion is set to power saving operation during the clip imaging state.

A circuit configuration for executing a power saving operation for each region in the present embodiment will be described with reference to FIGS. 20 and 21. FIG. 20 is a diagram showing a wiring layout of the supply line of the signal PSAVE. The signal PSAVE of the present embodiment is supplied to each signal processing unit 21 by PSAVE_H (n) (n: column number) for horizontal control and PSAVE_V (m) (m: row number) for vertical control. PSAVE_H (n) and PSAVE_V (m) are connected by a driver circuit (not shown) and controlled by a timing signal or the like from the TG 113.

A reading circuit for reading a signal from each pixel portion 11 in the image pickup device 106 will be described with reference to FIG. 21. FIG. 21 shows an equivalent circuit relating to the readout circuit of the image pickup device 106 in the fifth embodiment. FIG. 21 corresponds to FIG. 8 in the first embodiment. The same components as those in FIG. 8 are designated by the same reference numerals.

In FIG. 21, the signal output from each pixel unit 11 is read out via the signal line 803. It has four signal lines 803 for each row of the pixel unit 11. The difference from the circuit in the first embodiment in FIG. 21 is the PSAVE control unit 2106. PSAVE_H (n) and PSAVE_V (m) described with reference to FIG. 20 are input to the PSAVE control unit 2106. Then, the PSAVE control unit 2106 includes an AND circuit, and controls the ADC circuit 805 for power saving operation when a high level signal is supplied from either PSAVE_H (n) or PSAVE_V (m). By using PSAVE_H (n) and PSAVE_V (m) in this way, it is possible to control the power saving operation for any signal processing unit 21 in the circuit array. It is preferable to provide a latch circuit (not shown) in the signal processing unit 21 in order to enable easier control of power saving operation in an arbitrary region in the circuit array. This is a high level from both PSAVE_H (n) and PSAVE_V (m), and it is possible to store in the latch that the power saving operation is controlled, and to hold the state until the latch is reset. This eliminates the need to constantly supply the High level to PSAVE_H (n) and PSAVE_V (m) corresponding to the signal processing unit 21 to be controlled for power saving operation, and enables region selection with a higher degree of freedom. As an example, it is possible to control the power saving operation in a plurality of areas in the pixel array. When controlling the power saving operation with a higher degree of freedom, it can be dealt with by increasing the number of wirings of PSAVE_H (n) or PSAVE_V (m).

(Sixth Embodiment)
FIG. 22 is a diagram showing a signal readout operation for focus detection in addition to the normal readout operation of the image sensor 106. In the operation of FIG. 22, the signals read from the pixel unit 11 are sequentially read without being added. In FIG. 22, a case where a focus detection signal and an image pickup signal are output will be described. That is, the pixel unit 11 outputs the first signal based on the PD signal of only a part of the plurality of PDs, and further outputs the second signal based on the signals of the plurality of PDs. The signal line displayed in FIG. 22 is the same as that in FIG. Further, the description of the operation common to the operation shown in the first embodiment will be omitted.

At time t3, the vertical scanning circuit sets only the signal PTXA output to the pixel unit 11 on the first row as the high level. As a result, the electric charge accumulated in the PD 401a is transferred to the FD unit 403 via the transfer transistor 402a. As a result, the FD unit 403 has a potential corresponding to PD401a. Then, the amplification transistor 404 outputs the A signal based on the potential of the FD unit 403 due to the charge of only PD401a. The A signal of the pixel unit 11 in the first row is output to the signal line 803 in each column. As a result, the A signal corresponding to the pixel unit 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period. In the present embodiment, the period after the time t3 corresponds to the read period for the A signal.

After the time t4, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the A signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the first row, which is output from the MPX circuit 804a, into a digital signal. After that, the A signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. Since each A signal has already been input to the MPX circuit 804a, high-speed AD conversion can be performed simply by switching the output of the MPX circuit 804a. In the present embodiment, the period after the time t4 corresponds to the AD conversion period for the A signal.

At time t4, the vertical scanning circuit sets only the signal PTXA output to the pixel unit 11 on the third row as the high level. As a result, the electric charge accumulated in the PD 401a is transferred to the FD unit 403 via the transfer transistor 402a. As a result, the FD unit 403 has a potential corresponding to PD401a. Then, the amplification transistor 404 outputs the A signal based on the potential of the FD unit 403 due to the charge of only PD401a. The A signal of the pixel unit 11 in the third row is output to the signal line 803 in each column. As a result, the A signal corresponding to the pixel unit 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period. In the present embodiment, the period after the time t4 corresponds to the read period for the A signal.

After the time t5, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the A signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the third row, which is output from the MPX circuit 804a, into a digital signal. After that, the A signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. In the present embodiment, the period after the time t5 corresponds to the AD conversion period for the A signal.

Further, at time t5, the vertical scanning circuit sets the signals PTXA and PTXB output to the pixel unit 11 on the first row to the High level. As a result, the electric charge (electrons in this embodiment) accumulated in the PD 401a and 401b is transferred to the FD unit 403 via the transfer transistors 402a and 402b. In the FD unit 403, the electric charges of PD401a and 401b are added. As a result, the FD unit 403 has a potential corresponding to the charge obtained by adding the charges of PD401a and 401b at time t5 in addition to the charges of PD401a transferred at time t3. The A + B signal of the pixel unit 11 in the first row is output to the signal line 803 in each column. As a result, the A + B signal corresponding to the pixel portion 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period. In the present embodiment, the period after the time t5 corresponds to the read period for the A + B signal.

After the time t6, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the A + B signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the first row, which is output from the MPX circuit 804a, into a digital signal. After that, the A + B signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. In the present embodiment, the period after the time t6 corresponds to the AD conversion period for the A + B signal.

Further, at time t6, the vertical scanning circuit sets the signals PTXA and PTXB output to the pixel unit 11 on the third row to the High level. As a result, the electric charge (electrons in this embodiment) accumulated in the PD 401a and 401b is transferred to the FD unit 403 via the transfer transistors 402a and 402b. In the FD unit 403, the electric charges of PD401a and 401b are added. As a result, the FD unit 403 has a potential corresponding to the charge obtained by adding the charges of PD401a and 401b at time t6 in addition to the charges of PD401a transferred at time t4. The A + B signal of the pixel unit 11 in the third row is output to the signal line 803 in each column. As a result, the A + B signal corresponding to the pixel portion 11 in the odd-numbered rows of the 1st to 12th rows is input to the MPX circuit 804a during the same period. In the present embodiment, the period after the time t6 corresponds to the read period for the A + B signal.

After the time t7, the MPX circuit 804a sequentially connects the signal line 803 corresponding to the pixel portion 11 of the odd-numbered rows of the 1st to 12th rows to the ADC circuit 805a by the signal MPX supplied from the TG 113.

The ADC circuit 805a AD-converts the A + B signal of the signal line 803 in the first column corresponding to the pixel unit 11 in the third row, which is output from the MPX circuit 804a, into a digital signal. After that, the A + B signal output to the signal line 803 corresponding to the pixel portion 11 of the odd-numbered columns in the 1st to 12th columns is sequentially AD-converted into a digital signal. In the present embodiment, the period after the time t7 corresponds to the AD conversion period for the A + B signal.

In this way, by reading the A signal before reading the A + B signal, it is possible to read both the focus detection signal and the image signal. The B signal used for focus detection is calculated by reading out the A signal and the A + B signal and then subtracting both of them.

(7th Embodiment)
Although the configuration inside the image sensor 106 has been exemplified in the first to third embodiments, a plurality of circuits are arranged in parallel in order to read a signal from the pixel unit 11 at high speed, and the circuits are read simultaneously in each circuit. The operation will be performed. On the other hand, the image sensor used in an image pickup device represented by a single-lens reflex camera has a diagonal length of several centimeters. Therefore, in-plane variations such as the reference voltage level inside the image sensor cannot be ignored. In addition, due to manufacturing variations and asymmetry of circuit wiring length, output variations may occur for each circuit arranged in parallel. In this embodiment, a method for correcting the variation will be described. The readout circuit of the image pickup device 106 will be described on the premise of the readout circuit of the first embodiment shown in FIG. Examples of corrections include offset correction and gain correction. As the correction parameter, a value stored in ROM 119 or the like in advance may be used, or a value generated in real time immediately before or immediately after reading the signal may be used.

FIG. 23 shows one signal processing unit 21 and the corresponding pixel block 12. As shown in FIG. 8, the pixel block 12 has the first and third rows in which the pixel portion 11 having the R color filter is arranged, and the second row in which the pixel portion 11 having the G color filter is arranged. The fourth line is read via different MPX circuits 804 and ADC circuits 805. Therefore, it is desirable to use different correction values for the first and third lines shown by P in FIG. 23 and the second and fourth lines shown by Q. This is because it is considered that common circuit variations occur in a periodic circuit, and by using the same correction value periodically, the number of parameters used for correction can be reduced, thereby reducing the processing load. And power consumption can be achieved.

FIG. 24 shows the pixel array on the first substrate 10 and the corresponding correction parameters. As shown in FIG. 24A, the pixel array includes n pixel blocks 12 in the horizontal direction and m pixel blocks 12 in the vertical direction. The image pickup device 106 of the present embodiment is a pixel block 12 adjacent to each other in the vertical direction, and has a configuration in which the MPX circuit and the ADC circuit are shared. In this configuration, it is preferable that two pixel blocks 12 having a common circuit are used as one unit and have corresponding correction parameters. FIG. 24B shows the correction parameters corresponding to each unit. One rectangle represents one correction parameter, and each correction parameter includes the correction parameters indicated by P and Q for each row as described with reference to FIG. 23.

Note that FIG. 23 shows an example in which different correction parameters are provided for each row, but the present invention is not limited to this. As shown in FIG. 8, a plurality of (four in FIG. 8) signal lines 803 are provided in one row. Therefore, it is also effective to provide a correction parameter corresponding to each signal line 803. FIG. 25 shows the correction parameters corresponding to the four signal lines as A to D. As described with reference to FIG. 24, even a unit having a common ADC circuit has different parameters in the vertical direction as shown in FIG. 25 as having correction parameters.

As described above, an example in which the correction parameters are provided according to the circuit cycle constituting the image sensor 106 has been shown, but the correction parameters may be stored in a functional format instead of being stored for each pixel block. Further, when the periodicity of the circuit changes due to the addition / reading operation or the like, it is preferable to switch the correction parameter according to the operation mode. In addition, it may be changed according to the imaging conditions such as ISO sensitivity and exposure time. note that. In the present embodiment, an example of making corrections by providing correction parameters according to the circuit cycle is shown, but a plurality of corrections may be made individually for each circuit cycle.

(8th Embodiment)
FIG. 26 is an equivalent circuit diagram of the ADC circuit 805 of the image pickup device 106. The ADC circuit 805 has an input terminal IN and an output terminal OUT, converts an analog signal Sin (output of the MPX circuit 804) input from the input terminal IN into a digital signal Sout, and outputs the analog signal S out from the output terminal OUT. This analog signal Sin can be one or both of the N signal and the A + B signal (S signal) described in the first embodiment. The ADC circuit 805 converts the output of the MPX circuit 804 into a digital signal Sout with a resolution of 5 bits.

The ADC circuit 805 further includes a generation circuit 810 that generates a comparison signal used for comparison with the analog signal Sin. The generation circuit 810 has a plurality of capacitive elements cp0 to cp4 having a binary weight capacitance value, and a plurality of switches sw0 to sw4 connected to the capacitive elements cp0 to cp4. The plurality of switches sw0 to sw4 constitute a switch circuit for selecting one or more of the capacitive elements cp0 to cp4. The binary weight is a set of weights (capacity values) forming a geometric progression with a common ratio of 2. In the example of FIG. 26, the capacitive elements cp0 to cp4 have capacitance values of 1C, 2C, 4C, 8C, and 16C in order. One electrode of the capacitive elements cp0 to cp4 is connected to the supply terminal SPL of the generation circuit 810, and the other electrode is connected to the switches sw0 to sw4, respectively. One end of each of the switches sw0 to sw4 is connected to the capacitive elements cp0 to cp4, and the other end toggles between the terminal A and the terminal B. The ground potential GND is supplied to the terminal A, and the reference voltage VRF is supplied to the terminal B. The reference voltage VRF is a constant voltage supplied from the outside of the ADC 805, and is a value larger than the ground potential GND. When the switch sw0 toggles to the terminal A, the ground potential GND is supplied to the capacitive element cp0, and when the switch sw0 toggles to the terminal B, the reference voltage VRF is supplied to the capacitive element cp0. The same applies to the other switches sw1 to sw4. By switching the switches sw0 to sw4, the combined capacitance value of the capacitive element connected between the supply terminal SPL and the reference voltage VRF changes, and as a result, the value of the comparison signal Vcmp output from the supply terminal SPL changes. do.

Further, a lamp signal Vrmp from the outside of the ADC circuit 805 is supplied to the supply terminal SPL of the generation circuit 810 via the capacitive element cp5. The capacitive element cp5 is a capacitive element for adjusting the magnitude of the lamp signal Vrmp, and has a capacitive value of 1C. That is, the capacitance value of the capacitance element cp5 is equal to the minimum capacitance value of the capacitance element groups cp0 to cp4 having the capacitance value of the binary weight. When the value of the lamp signal Vrmp changes, the value of the comparison signal Vcmp output from the supply terminal SPL also changes.

By combining the set of capacitive elements connected between the supply terminal SPL and the reference voltage VRF and the value of the lamp signal Vrmp, the comparison signal Vcmp can take any value above the ground potential GND and below the reference voltage VRF. sell.

The ADC circuit 805 further comprises a comparator 815. The comparator 815 compares the value of the analog signal Sin with the value of the comparison signal Vcmp, and outputs a signal corresponding to the comparison result. An analog signal Sin is supplied to the non-inverting terminal of the comparator 815 via the capacitive element cp6, and a comparison signal Vcmp is supplied to the inverting terminal of the comparator 815 from the supply terminal SPL of the generation circuit 810. As a result, the High level is output when the value of the analog signal Sin is equal to or greater than the value of the comparison signal Vcmp, and the Low level is output when the value of the analog signal Sin is less than the value of the comparison signal Vcmp. In this example, the High level is output when the value of the analog signal Sin and the value of the comparison signal Vcmp are equal, but the Low level may be output. The capacitive element cp6 adjusts the value of the analog signal Sin within a range that can be compared with the comparison signal Vcmp. In the present embodiment, for the sake of simplicity, the value of the analog signal Sin is equal to or higher than the ground potential GND and equal to or lower than the reference voltage VRF, and a signal having the same magnitude as that of the analog signal Sin is supplied to the non-inverting terminal of the comparator 815. Handle the case where it is done.

In the example of FIG. 26, the analog signal Sin is supplied to the non-inverting terminal of the comparator 815, and the comparison signal Vcmp is supplied to the inverting terminal of the comparator 815. If it can be determined, other configurations can be taken. For example, the difference between the analog signal Sin and the comparison signal Vcmp may be supplied to the non-inverting terminal of the comparator 815, and the ground potential GND may be supplied to the inverting terminal of the comparator 815.

The ADC circuit 805 further includes switches sw5 and sw6. When these switches sw5 and sw6 are in a conductive state, the ground potential GND is supplied to the non-inverting terminal and the inverting terminal of the comparator 815, and the comparator 815 is reset.

The ADC circuit 805 further includes a control circuit 820. The comparison result is supplied to the control circuit 820 from the comparator 815, and the control circuit 820 generates a digital signal Sout based on the comparison result and outputs it from the output terminal OUT. The control circuit 820 also transmits a control signal to each switch sw0 to sw6 to switch the state.

In FIG. 27, sw0 to sw6 indicate the values of the control signals supplied from the control circuit 820 to the switches sw0 to sw6. The switches sw0 to sw4 toggle to the terminal B when the supplied control signal is at the High level, and toggle to the terminal A when the control signal is at the Low level. The switches sw5 and sw6 are in a conductive state when the supplied control signal is at the High level, and are in the non-conducting state when the control signal is at the Low level. The analog signal Sin and the comparison signal Vcmp are shown on the lower side of FIG. 27. In FIG. 27, the case where the value of the analog signal Sin corresponds to 00110 in binary is treated as an example.

Subsequently, the AD conversion operation of the ADC circuit 805 will be described in chronological order. During the preparation period, the control circuit 820 sets the control signals supplied to the switches sw0 to sw4 to the Low level, and sets the control signals supplied to the switches sw5 and sw6 to the High level. As a result, the non-inverting terminal and the inverting terminal of the comparator 815 are reset to the ground potential GND, and the value of the comparison signal Vcmp becomes equal to the ground potential GND. After that, the control circuit 820 sets the control signal supplied to the switches sw5 and sw6 to the Low level. In the subsequent operation, the analog signal Sin continues to be supplied to the non-inverting terminal of the comparator 815.

Next, when the sequential comparison period starts, the control circuit 820 changes the control signal supplied to the switch sw4 to the High level. As a result, the switch sw4 toggles to the terminal B, and the reference voltage VRF is applied to the supply terminal SPL of the generation circuit 810 via the capacitor cp4 having the largest capacitance value in the binary weight. As a result, the comparison signal Vcmp increases by VRF / 2, and the value of the comparison signal Vcmp becomes equal to VRF / 2. The control circuit 820 determines that the value of the analog signal Sin is smaller than the value of the comparison signal Vcmp (VRF / 2) based on the comparison result from the comparator 815, and sets the control signal supplied to the switch sw4 to the Low level. Return to. As a result, the value of the comparison signal Vcmp returns to the ground potential GND. This comparison result means that the MSB (the 5th bit when the LSB is the 1st bit) of the value of the digital signal Sout is 0.

Next, the control circuit 820 changes the control signal supplied to the switch sw3 to the High level. As a result, the reference voltage VRF is applied to the supply terminal SPL of the generation circuit 810 via the capacitor cp3 having the second largest capacitance value in the binary weight. As a result, the comparison signal Vcmp is increased by VRF / 4, and the value of the comparison signal Vcmp becomes equal to VRF / 4. The control circuit 820 determines that the value of the analog signal Sin is smaller than the value of the comparison signal Vcmp (VRF / 4) based on the comparison result from the comparator 815, and sets the control signal supplied to the switch sw3 to the Low level. Return to. As a result, the value of the comparison signal Vcmp returns to the ground potential GND. This comparison result means that the fourth bit of the value of the digital signal Sout is 0.

Next, the control circuit 820 changes the control signal supplied to the switch sw2 to the High level. As a result, the reference voltage VRF is applied to the supply terminal SPL of the generation circuit 810 via the capacitor cp2 having the third largest capacitance value in the binary weight. As a result, the comparison signal Vcmp increases by VRF / 8, and the value of the comparison signal Vcmp becomes equal to VRF / 8. The control circuit 820 determines that the value of the analog signal Sin is larger than the value of the comparison signal Vcmp (VRF / 8) based on the comparison result from the comparator 815, and sets the control signal supplied to the switch sw2 to the High level. Leave it as it is. Thereby, the value of the comparison signal Vcmp is maintained at VRF / 8. This comparison result means that the third bit of the value of the digital signal Sout is 1.

Next, the control circuit 820 changes the control signal supplied to the switch sw1 to the High level. As a result, the reference voltage VRF is applied to the supply terminal SPL of the generation circuit 810 via the capacitor cp1 having the fourth largest capacitance value in the binary weight and the capacitor cp2. As a result, the comparison signal Vcmp increases by VRF / 16, and the value of the comparison signal Vcmp becomes equal to VRF * 3/16. In addition, "*" used in this specification means multiplication. The control circuit 820 determines that the value of the analog signal Sin is larger than the value of the comparison signal Vcmp (VRF * 3/16) based on the comparison result from the comparator 815, and determines that the control signal supplied to the switch sw1 is used. Leave at High level. As a result, the value of the comparison signal Vcmp is maintained at VRF * 3/16. This comparison result means that the second bit of the value of the digital signal Sout is 1.

Finally, the control circuit 820 changes the control signal supplied to the switch sw0 to the High level. As a result, the reference voltage VRF is applied to the supply terminal SPL of the generation circuit 810 via the capacitors cp0 having the fifth largest capacitance value in the binary weight and cp1 and cp2. As a result, the comparison signal Vcmp increases by VRF / 32, and the value of the comparison signal Vcmp becomes equal to VRF * 7/32. The control circuit 820 determines that the value of the analog signal Sin is smaller than the value of the comparison signal Vcmp (VRF * 7/32) based on the comparison result from the comparator 815, and determines that the control signal supplied to the switch sw0 is used. Return to Low level. As a result, the value of the comparison signal Vcmp returns to VRF * 3/16. This comparison result means that the first bit of the value of the digital signal Sout is 0.

By the above sequential comparison, the control circuit 820 determines that the digital signal Sout corresponding to the analog signal is 00110.

In this way, the ADC circuit 805 can perform AD conversion to generate a digital signal corresponding to the input analog signal.

An example of using a successive approximation type ADC circuit as another AD conversion format has been described. The ADC circuit 805 is not limited to this successive approximation type ADC circuit. For example, as another ADC circuit, various ADC circuits such as a lamp signal comparison type, a delta sigma type, a pipeline type, and a flash type can be used.

(9th embodiment)
The image pickup device 106 and the image pickup apparatus 100 described in each embodiment can be applied to various applications. For example, the image sensor 106 can be used for sensing light such as infrared light, ultraviolet light, and X-rays in addition to visible light. The image pickup device 100 is typified by a digital camera, but can also be applied to a camera-equipped mobile phone such as a smartphone, a surveillance camera, a game device, and the like. Further, it can be applied to an endoscope, a medical device for imaging blood vessels, a beauty device for observing the skin and scalp, and a video camera for capturing sports and action videos. It can also be applied to traffic purpose cameras such as traffic monitoring and drive recorders, academic cameras such as astronomical observation and sample observation, home appliances with cameras, machine vision, and the like. In particular, as machine vision, it is not limited to robots in factories, etc., but can also be used in agriculture and fisheries.

Further, the configuration of the image pickup apparatus shown in the above embodiment is an example, and the image pickup apparatus to which the present invention can be applied is not limited to the configuration shown in FIG. Further, the circuit configuration of each part of the image pickup apparatus is not limited to the configuration shown in each figure.

The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

It should be noted that the above embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features.

10 1st board 11 Pixel part 12 Pixel block 20 2nd board 21 Signal processing unit 100 Image sensor 106 Image sensor 803 Signal line 804 MPX circuit 805 ADC circuit 806 PSAVE control unit

Claims (7)

A first substrate having a pixel array in which a plurality of pixel blocks formed by a plurality of pixels for performing photoelectric conversion are arranged in a matrix, and a plurality of signal processing units for processing a signal based on the photoelectric conversion are arranged in a matrix. An image pickup device in which a second substrate having a circuit array arranged in the above is laminated , and the signal processing unit and the corresponding pixel block are connected by a plurality of signal lines .
Each of the plurality of signal processing units includes an adder circuit for adding the signals input from the plurality of signal lines during synchronization, and a conversion circuit for analog-digital conversion of the signal added by the adder circuit .
Each of the plurality of signal processing units includes a control unit that performs a power saving operation on the conversion circuit while the conversion circuit is not performing the analog-to-digital conversion operation when the signal is added by the addition circuit. An image pickup element characterized by. The image pickup device according to claim 1, further comprising a plurality of photoelectric conversion units for each pixel. The image pickup device according to claim 1 or 2 , wherein the addition circuit includes a selection unit for selecting which signal line is to be connected to the conversion circuit from the plurality of signal lines. The image pickup device according to claim 3 , wherein the addition circuit adds the signals by selecting two or more signal lines by the selection unit. The image pickup device according to claim 3 or 4 , wherein the addition circuit includes a sample hold circuit provided between the plurality of signal lines and the selection unit . The pixel array contains a plurality of pixels having color filters of different colors.
The addition circuit is any of claims 1 to 5 , wherein the addition circuit adds signals corresponding to pixels included in the pixel block and having color filters of the same color adjacent to each other in the row direction or the column direction. The image pickup device according to item 1. The image sensor according to any one of claims 1 to 6 and the image sensor.
An acquisition means for acquiring a digital signal output from the conversion circuit from the image sensor, and
A driving means for controlling the driving of the image sensor and
Equipped with
The drive means has at least a first drive mode for acquiring a digital signal based on a signal added by the adder circuit by the acquisition means, and a digital signal based on a non-addition signal regardless of the adder circuit. An image pickup device comprising driving the image pickup element in any of the second drive modes for acquiring the image by the acquisition means.

Images