JP2017069887A - Imaging apparatus and imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus and system for obtaining satisfactory image quality by an imaging device in which a floating diffusion is shared among a plurality of pixels, regardless of an imaging mode.SOLUTION: The imaging apparatus has a shared pixel structure in which a transfer switch for transferring a photoelectric conversion element is connected to one floating diffusion and a reset switch for resetting the floating diffusion and the photoelectric conversion element is shared among a plurality of pixels at least in a vertical direction. In read scanning of the photoelectric conversion element, there is a period for resetting the floating diffusion during reading control of each line of the shared pixel structure and in accordance with the reset period, reset cancellation of the floating diffusion is controlled a fixed time before the reading control of pixels in a leading line of the shared pixel structure. The imaging apparatus comprises imaging mode selection means and in accordance with an imaging mode selected thereby, it is switched whether to perform full line floating diffusion reset cancellation scanning.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a solid-state imaging device represented by a CMOS image sensor and a camera system.

  In recent years, the development of CMOS type solid-state imaging devices has been remarkable. A pixel of the CMOS type solid-state imaging device includes a photodiode, a floating diffusion (hereinafter referred to as FD) that converts the charge transferred by the transfer switch into a voltage signal, an amplification amplifier, and a reset switch that resets the FD. The increase in the number of pixels and the reduction in pixels of CMOS type solid-state imaging devices are progressing year by year. In order to cope with this tendency, a technique is known in which each of a plurality of photodiodes has a transfer switch, and the transferred charges are transferred to one FD region (Patent Document 1). According to this method, the number of source follower amplifiers and reset switches per pixel can be reduced, and a large photodiode area can be secured.

  A method for transferring charges of a plurality of photodiodes described in Patent Document 1 to a common FD region will be described. When two photodiodes share one FD region, the FD is first maintained in the reset state by continuing the reset switch to be in the HIGH state. At the time when the signal of the first photodiode is read, after the reset switch becomes LOW, the transfer switch connected to the first photodiode becomes HIGH and the signal charge is transferred to the FD. After that, the FD is reset when the reset switch becomes HIGH again. Thereafter, the signal charge is transferred to the FD by setting the transfer switch connected to the second photodiode to HIGH. By sequentially performing the above operations, signals of all pixels are read out.

Japanese Patent Laid-Open No. 9-46596

  In the technique of Patent Document 1, it takes a long time to settle the FD reset before the charge transfer operation from the first photodiode to the FD. On the other hand, there is a charge transfer operation from the first photodiode to the FD before the charge transfer from the second photodiode to the FD. Therefore, the time taken for the settling time of the FD reset period is short. There is a possibility that a potential difference is caused by the difference in the settling time. This difference becomes a difference in image output and may reduce image quality.

  An object of the present invention is to provide an imaging apparatus capable of obtaining a good image quality by aligning potentials in all imaging modes.

In order to achieve the above object, an imaging apparatus according to the present invention includes:
A plurality of pixels are arranged two-dimensionally, a photoelectric conversion element that converts light into electric charge in each pixel, a transfer switch for transferring electric charge from the photoelectric conversion element, and a transfer switch at least in the plurality of pixels in the vertical direction Is connected to one floating diffusion, and a shared pixel structure sharing a reset switch for resetting the floating diffusion and the photoelectric conversion unit of each pixel, and reading for performing control for transferring charges from the photoelectric conversion element In the readout scanning of the photoelectric conversion element having the shared pixel structure by the scanning control unit and the readout scanning control unit, there is a period in which the floating floating diffusion is reset during readout control of each row of the shared pixel structure, and the reset period In response, reading out pixels in the first row of the shared pixel structure According to a shooting mode selected by the shooting mode selection unit, including an imaging device having a floating diffusion reset release scanning control unit that controls reset release of the floating diffusion a predetermined time before the control, and a shooting mode selection unit In this case, whether or not to perform the all-row floating diffusion reset cancel scanning is switched.

  According to the imaging apparatus according to the present invention, it is possible to obtain a good image quality in which the difference between the first photodiode output and the second photodiode output is small with an imaging element sharing the FD with a plurality of pixels regardless of the mode. Can do. Further, since the drive for aligning the potential of the FD can be realized only in the read operation mode, the circuit can be simplified.

1 is a block diagram of an imaging apparatus according to Embodiment 1 of the present invention. Schematic of the image sensor 1400 according to the first embodiment of the present invention. 1 is an equivalent circuit diagram of a pixel 205 in Embodiment 1 of the present invention. Conventional read timing chart State transition diagram and row scanning diagram at the time of still image acquisition in Embodiment 1 of the present invention Timing chart of preliminary reset release scanning at the time of still image acquisition in Embodiment 1 of the present invention State transition diagram and row scanning diagram at the time of moving image acquisition in Embodiment 1 of the present invention Timing chart of preliminary reset release scanning at moving image acquisition in embodiment 1 of the present invention The flowchart in Example 1 of this invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of an imaging apparatus according to an embodiment of the present invention.

  Reference numeral 100 denotes an image processing apparatus, 200 denotes a recording medium such as a memory card or a hard disk, and 300 denotes a lens unit.

  Next, details of the block will be described.

  First, the inside of the image processing apparatus 100 will be described. A shutter 12 controls the amount of light entering the image sensor 1400, and an image sensor 1400 converts an optical image into an electrical signal. The image sensor 1400 includes a timing generator 1401 that drives the image sensor. An A / D converter 1402 for converting an analog signal into a digital signal is also incorporated.

  130 is a mirror, and 131 is a pentaprism. Reference numeral 104 denotes an optical viewfinder. When 130 is in the light beam, the incident light that has passed through the lens is imaged, and the composition of the still image taken by the user can be confirmed.

  Reference numeral 1700 denotes a digital front end that performs signal processing on a digital signal output from the image sensor 1400.

  A liquid crystal monitor 1200 can display a live view (LV) image or a captured still image.

  Reference numeral 50 denotes a system control circuit (hereinafter referred to as CPU) that controls the entire imaging apparatus 100 including image processing.

  Reference numeral 61 denotes a shutter switch. The shutter switch 61 has two stages. When the user presses lightly to the first step, it is called half-press, and when the user presses deeply to the second step, it is called full press. When the CPU 50 is half-pressed, automatic focusing is performed, and the shutter speed and aperture value are set by the automatic exposure mechanism in a state before photographing. When fully pressed, the shutter 12 operates and the photographing operation is performed.

  Reference numeral 62 denotes an LV start / stop switch, which continuously performs a moving image recording operation when instructed to start by the user.

  63 is an ISO sensitivity setting switch, and the CPU 50 sets the sensitivity of the imaging apparatus 100 with respect to the amount of light according to a user instruction.

  Reference numeral 64 denotes a power switch, and the CPU 50 switches between power-on and power-off of the imaging apparatus 100 in accordance with a user instruction. In addition, the power-on and power-off settings of various accessory devices such as the lens unit 300 and the recording medium 200 connected to the imaging device 100 can be switched.

  Reference numeral 70 denotes a volatile memory (hereinafter referred to as RAM) for temporarily recording image data. It also has a function as a work memory of the CPU 50.

  Reference numeral 71 denotes a nonvolatile memory (ROM) that stores a program used when the CPU 50 operates.

  An image processing unit 72 performs processing such as still image correction / compression.

  Reference numeral 73 denotes a shooting mode control unit that controls the shooting mode.

  An operation mode control unit 74 controls the operation mode of the image sensor.

  A power control unit 80 includes a battery detection circuit, a DC-DC converter, a switch circuit that switches a block to be energized, and the like. Further, the presence / absence of a battery, the type of battery, the remaining battery level are detected, the DC-DC converter is controlled based on the detection result and the instruction of the system control circuit 50, and the necessary voltage is recorded for a necessary period. Supply to each part including

  Reference numerals 82 and 84 denote connectors, and 86 denotes a power supply unit including a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a Li battery, an AC adapter, or the like.

  Reference numeral 90 denotes an interface with a recording medium such as a memory card or hard disk, and reference numeral 92 denotes a connector for connecting to a recording medium such as a memory card or hard disk.

  Reference numeral 200 denotes a recording medium such as a memory card or a hard disk. The recording medium 200 includes a recording unit 201 composed of a semiconductor memory, a magnetic disk, and the like, and an interface 202 with the imaging apparatus 100.

  Reference numeral 300 denotes a lens unit, 310 denotes a photographing lens, 312 denotes an aperture, and 316 and 106 denote lens mounts for connecting the lenses. Reference numeral 320 denotes a lens control unit, and reference numeral 322 denotes a connector that electrically connects the lens unit 300 to the imaging apparatus 100. The lens control unit 320 receives a signal from the imaging apparatus 100 via the connectors 322 and 122 and the interface 120. The position of the imaging lens 310 on the optical axis is changed by the signal to control the focus. Similarly, the lens control unit 320 receives a signal from the image processing apparatus 100 and controls the size of the aperture of the diaphragm 312.

  FIG. 2 is a simplified configuration diagram of the image sensor 1400.

  Pixels 205 are two-dimensionally arranged on the image sensor 1400. Arranged in a matrix, the vertical arrangement is called a “column” and the horizontal arrangement is called a “row”. Reference numeral 208 denotes a pixel group in which all columns and rows are collected. Reference numeral 204 denotes a vertical scanning circuit, which outputs a signal necessary for row selection for reading a selected row and readout of electric charge in each row to the circuit of each pixel. In the vertical scanning circuit 204, a reading scanning circuit 209 and a preliminary reset cancellation scanning circuit 210 for performing an operation to be described later are incorporated.

  The signal output to the vertical output line 310 is output to the horizontal scanning circuit 203 via the column circuit 207 connected to each vertical output line. The horizontal scanning circuit 203 sequentially outputs the signal output for one row in the horizontal direction. The column circuit includes a column gain and a column analog / digital conversion circuit.

  FIG. 3 is an equivalent circuit diagram of the pixel 205.

  205_1, 205_2, and 205_3 are unit pixels, and the unit pixel 205_1 includes a photodiode 311A_1 and a photodiode 311B_1. In addition, the pixel includes a unit pixel 205_2 photodiode 311A_2 and a photodiode 311B_2. The unit pixel 205_3 includes a photodiode 311A_3 and a photodiode 311B_3.

  The charges generated and accumulated in the photodiodes 311A_1 and 311B_1 are transferred to the FD 307_1 by controlling the transfer control signal 301_1, the transfer switch 305A_1, the transfer control signal 302_1, and the transfer switch 305B_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal. A row selection control signal 304_1 controls a row selection switch 309_1 to connect the output of the source follower amplifier to the vertical output line 310.

  In the case of resetting unnecessary charges accumulated in the FD 307_1, the reset switch 306_1 is controlled by a reset control signal 303_1. Further, when resetting the photodiodes 311A_1 and 311B_1, together with the reset switch 306_1, the transfer control signal 301_1 is controlled to control the transfer switch 305A_1, the transfer control signal 302_1 is controlled to control the transfer switch 305B_1, and the reset is executed. To do.

  The unit pixels 205_1 and 205_2 share an FD. Charges generated and accumulated in the photodiodes 311A_2 and 311B_2 of 205_2 are transferred to the FD 307_1 by controlling the transfer control signal 301_2 and the transfer switch 305A_2 by controlling the transfer control signal 302_2 and controlling the transfer switch 305B_2. The signal output from the FD 307_1 to the vertical line is the same as that of the pixel 203_1.

  When resetting the photodiodes 311A_2 and 311B_2, together with the reset switch 306_1, the transfer control signal 301_2 is controlled to control the transfer switch 305A_2, the transfer control signal 302_2 is controlled to control the transfer switch 305B_2, and the reset is executed. .

  The unit pixel 205_3 has the same configuration as the unit pixel 205_1 and is controlled in the same manner as the reading and reset operations of the unit pixel 205_1. The unit pixel 205_4 (not shown) has the same configuration as the unit pixel 205_2, and is controlled in the same manner as the reading and reset operations of the unit pixel 205_2.

  FIG. 4 is a timing chart of conventional reading. This timing chart is a reference timing chart that is not used in the present invention.

  The period before the timing T400 is a state before reading, and the reset control signal 303_1 is HIGH and the FD 307_1 is reset.

  At timing T400, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_1 to HIGH.

  At timing T401, the reset control signal 303_1 is set to LOW so that the FD 307_1 is in a reset release state.

  At timing T402, the transfer control signals 301_1 and 302_1 of the unit pixel 205_1 are set to HIGH, and the charges of the photodiodes 311A_1 and 311B_1 are sent to the FD 307_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal.

  At timing T403, the transfer control signals 301_1 and 302_1 are set to LOW.

  At a timing T404, the reset control signal 303_1 is set to HIGH to reset the FD307_1.

  At timing T405, the row selection control signal 304_1 is set to LOW.

  As a result, reading of the first row sharing pixels is completed.

  At timing T406, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_1 to HIGH.

  At timing T407, the reset control signal 303_1 is set to LOW so that the FD 307_1 is in a reset release state.

  At timing T408, the transfer control signals 301_2 and 302_2 of the unit pixel 205_2 are set to HIGH, and the charges of the photodiodes 311A_2 and 311B_2 are sent to the FD 307_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal.

  At timing T409, the transfer control signals 301_2 and 302_2 are set to LOW.

  At timing T410, the reset control signal 303_1 is set to HIGH to reset the FD 307_1.

  At timing T411, the row selection control signal 304_1 is set to LOW.

  This completes the readout of the second row sharing the pixels. Hereinafter, the read operation can be realized by repeating every two rows as described above.

  At timing T412, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_3 to HIGH.

  At timing T413, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T414, the transfer control signals 301_3 and 302_3 of the unit pixel 205_3 are set to HIGH, and the charges of the photodiodes 311A_3 and 311B_3 are sent to the FD 307_3. The source follower amplifier 308_3 amplifies a voltage signal based on the electric charge accumulated in the FD 307_3 and outputs it as a pixel signal.

  At timing T415, the transfer control signals 301_3 and 302_3 are set to LOW.

  At timing T416, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At a timing T417, the row selection control signal 304_3 is set to LOW.

  At timing T418, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_3 to HIGH.

  At timing T419, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T420, the transfer control signals 301_4 and 302_4 of the unit pixel 205_4 are set to HIGH, and the charges of the photodiodes 311A_4 and 311B_4 are sent to the FD 307_3. The source follower amplifier 308_3 amplifies a voltage signal based on the electric charge accumulated in the FD 307_3 and outputs it as a pixel signal.

  At timing T421, the transfer control signals 301_4 and 302_4 are set to LOW.

  At timing T422, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At a timing T423, the row selection control signal 304_3 is set to LOW.

  In FIG. 4, the reset time until the unit pixel 205_3 is read out is long from before the timing T400 to T413. On the other hand, the reset time before reading out the unit pixel 205_4 is from T416 to T419, which is shorter than before reading out the unit pixel 205_3. Therefore, there is a difference in the FD307_1 potential of the pixel when sending 205_1 and 205_2 with respect to the settling time of the FD reset period. This difference becomes a difference in image output, and there is a problem that the image quality may be lowered. In the following description, an operation for solving the above problem will be described.

  FIG. 5 is a state transition diagram and a row scanning diagram when a still image is captured by the imaging apparatus 100.

  At the time of still image shooting, the CPU 50 controls the shooting mode control unit to drive a sequence for still images. First, the CPU 50 controls the image sensor via the operation mode control unit. Prior to timing T510, the image sensor 1400 is activated, and is set to the accumulation mode after resetting all rows. While the shutter 12 is open during the accumulation mode, electric charge is generated in the photodiode 311 according to the amount of light. At timing T511, the CPU 50 puts the image sensor 1400 into the reading mode. At timing T511, the CPU 50 starts the reading scan by controlling the reading scanning control unit 209 from L1. Further, at timing T511, the CPU 50 controls the preliminary reset cancellation scanning circuit 210 to scan the preliminary reset cancellation operation from the third row L3. In other words, when driving a still image, the CPU 50 controls the vertical scanning circuit 204 of the image sensor 1400 to provide two rows, L1 and L2, which perform reading scanning but not preliminary reset cancellation scanning.

  FIG. 6 is a read timing chart when the preliminary reset cancellation scan is performed in still image shooting.

  A period between timings T511 and T600 is a state before reading, and the reset control signal 303_1 is HIGH and the FD 307_1 is reset.

  At timing T600, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_1 to HIGH.

  At timing T601, the reset control signal 303_1 is set to LOW so that the FD 307_1 is in a reset release state. Further, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T602, the transfer control signals 301_1 and 302_1 of the unit pixel 205_1 are set to HIGH, and the charges of the photodiodes 311A_1 and 311B_1 are sent to the FD 307_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal.

  At timing T603, the transfer control signals 301_1 and 302_1 are set to LOW.

  At timing T604, the reset control signal 303_1 is set to HIGH to reset the FD 307_1. Further, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T605, the row selection control signal 304_1 is set to LOW.

  As a result, reading of the first row sharing pixels is completed.

  At timing T606, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_1 to HIGH.

  At timing T607, the reset control signal 303_1 is set to LOW so that the FD 307_1 is in a reset release state. Further, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T608, the transfer control signals 301_2 and 302_2 of the unit pixel 205_2 are set to HIGH, and the charges of the photodiodes 311A_2 and 311B_2 are sent to the FD 307_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal.

At timing T609, the transfer control signals 301_2 and 302_2 are set to LOW.
At timing T610, the reset control signal 303_1 is set to HIGH to reset the FD 307_1. Further, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T611, the row selection control signal 304_1 is set to LOW.

  As a result, the readout of the second row sharing the pixels and the FD reset release operation of the next row to be read out are completed. Hereinafter, the read operation can be realized by repeating every two rows as described above.

  At timing T612, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_3 to HIGH.

  At timing T613, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T614, the transfer control signals 301_3 and 302_3 of the unit pixel 205_3 are set to HIGH, and the charges of the photodiodes 311A_3 and 311B_3 are sent to the FD 307_3. The source follower amplifier 308_3 amplifies a voltage signal based on the electric charge accumulated in the FD 307_3 and outputs it as a pixel signal.

  At timing T615, the transfer control signals 301_3 and 302_3 are set to LOW.

  At timing T616, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T617, the row selection control signal 304_3 is set to LOW.

  At timing T618, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_3 to HIGH.

  At timing T619, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T620, transfer control signals 301_4 and 302_4 of the unit pixel 205_4 are set to HIGH, and the charges of the photodiodes 311A_4 and 311B_4 are sent to the FD 307_3. The source follower amplifier 308_3 amplifies a voltage signal based on the electric charge accumulated in the FD 307_3 and outputs it as a pixel signal.

  At timing T621, the transfer control signals 301_4 and 302_4 are set to LOW.

  At timing T622, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T623, the row selection control signal 304_3 is set to LOW.

  Note that the reset control signal 303_3 is set to LOW at timing T601, but this is performed in accordance with the reading scan. Therefore, if the reset release operation at the timing T607 is realized, the reset control signal 303_3 may be set to HIGH during the period from the timing T601 to T604, and the FD 307_3 may be reset.

  Comparing the timing charts of FIG. 4 and FIG. 6, in FIG. 4, the reset time before reading out the unit pixel 205_3 is long from before the timing T400 to T413. On the other hand, the reset time before reading out the unit pixel 205_4 is from T416 to T419, which is shorter than before reading out the unit pixel 205_3. On the other hand, in FIG. 6, the reset before reading the unit pixel 205_3 is a period from T610 to T613, and the reset before reading the unit pixel 205_4 is a period from T616 to T619, both of which are the same period. Preliminary reset cancellation scanning is performed for each row to reset the reset switch 306_3 once before the start of reading. As a result, the readout rows prior to L503 can have the same state at the time of reset cancellation of the FDs of the pixel Nth row and the N + 1th row sharing the FD.

  Next, FIG. 7 is a state transition diagram and a row scanning diagram when a moving image is captured by the imaging apparatus 100. At the time of moving image shooting, the CPU 50 controls the read mode control unit to drive a sequence for a still image. First, the CPU 50 starts up the image sensor 1400 and starts a continuous reading operation. At T700, frame n-1 is read. In T701, a preliminary reset release scan is started before reading the read frame n. Thereafter, reading of the reading frame n is started at T702.

  FIG. 8 is a timing chart for reading when preliminary reset cancellation scanning is performed in moving image shooting.

  The period before the timing T800 is a state before reading, and the reset control signal 303_1 is HIGH and the FD 307_1 is reset.

At timing T800, the CPU 50 controls the TG 1401 in the image sensor 1400, sets the reset control signal 303_1 to LOW, and sets the FD 307_1 to the reset release state.
At timing T801, the reset control signal 303_1 is set to HIGH, and the FD 307_1 is reset.

  At timing T802, the reset control signal 303_1 is set to LOW, and the FD 307_1 is set to the reset release state.

  At a timing T803, the reset control signal 303_1 is set to HIGH to reset the FD 307_1.

  As a result, the FD reset release operation for the first row to be read is completed.

  At timing T701, the image sensor 1400 is put into an operation mode in which readout scanning starts for the nth frame.

  At timing T804, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_1 to HIGH.

  At timing T805, the reset control signal 303_1 is set to LOW so that the FD 307_1 is in a reset release state. Further, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T806, the transfer control signals 301_1 and 302_1 of the unit pixel 205_1 are set to HIGH, and the charges of the photodiodes 311A_1 and 311B_1 are sent to the FD 307_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal.

  At timing T807, the transfer control signals 301_1 and 302_1 are set to LOW.

  At timing T808, the reset control signal 303_1 is set to HIGH and the FD 307_1 is reset. Further, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T809, the row selection control signal 304_1 is set to LOW.

  As a result, reading of the first row sharing pixels is completed.

  At timing T810, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_1 to HIGH.

  At timing T811, the reset control signal 303_1 is set to LOW so that the FD 307_1 is in a reset release state. Further, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T812, the transfer control signals 301_2 and 302_2 of the unit pixel 205_2 are set to HIGH, and the charges of the photodiodes 311A_2 and 311B_2 are sent to the FD 307_1. The source follower amplifier 308_1 amplifies a voltage signal based on the electric charge accumulated in the FD 307_1 and outputs it as a pixel signal.

  At timing T813, the transfer control signals 301_2 and 302_2 are set to LOW.

  At timing T814, the reset control signal 303_1 is set to HIGH to reset the FD 307_1. Further, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T815, the row selection control signal 304_1 is set to LOW.

  As a result, the readout of the second row sharing the pixels and the FD reset release operation of the next row to be read out are completed. Hereinafter, the read operation can be realized by repeating every two rows as described above.

  At timing T816, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_3 to HIGH.

  At timing T817, the reset control signal 303_3 is set to LOW, and the FD 307_3 is set to the reset release state.

  At timing T818, the transfer control signals 301_3 and 302_3 of the unit pixel 205_3 are set to HIGH, and the charges of the photodiodes 311A_3 and 311B_3 are sent to the FD 307_3. The source follower amplifier 308_3 amplifies a voltage signal based on the electric charge accumulated in the FD 307_3 and outputs it as a pixel signal.

At timing T819, the transfer control signals 301_3 and 302_3 are set to LOW.
At timing T820, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At timing T821, the row selection control signal 304_3 is set to LOW.

  At timing T822, the CPU 50 controls the TG 1401 in the image sensor 1400 to set the row selection control signal 304_3 to HIGH.

  At timing T823, the reset control signal 303_3 is set to LOW so that the FD 307_3 is in a reset release state.

  At timing T824, the transfer control signals 301_4 and 302_4 of the unit pixel 205_4 are set to HIGH, and the charges of the photodiodes 311A_4 and 311B_4 are sent to the FD 307_3. The source follower amplifier 308_3 amplifies a voltage signal based on the electric charge accumulated in the FD 307_3 and outputs it as a pixel signal.

  At timing T825, the transfer control signals 301_4 and 302_4 are set to LOW.

  At timing T826, the reset control signal 303_3 is set to HIGH to reset the FD 307_3.

  At a timing T827, the row selection control signal 304_3 is set to LOW.

  Comparing the timing charts of FIG. 6 and FIG. 8, in FIG. 6, the FD 307_1 can also perform the preliminary reset release scanning in the same manner as the FD 307_3.

  FIG. 9 shows a flowchart of the first embodiment.

  After the activation, the CPU 50 determines whether still image shooting or moving image shooting operation is performed (s900), and the CPU 50 controls the reading scanning circuit 209 and the preliminary reset cancellation scanning circuit 210 to set during still image shooting. A line is set (s901). Thereafter, the CPU 50 controls the TG 1401 to perform setting for performing the preliminary reset release scanning simultaneously with the readout scanning (s902), and performs the still image readout (s903). At the time of moving image shooting, setting is made to start the preliminary reset release scanning for moving images two lines before (s904), and reading for moving images is performed (s905). It is determined whether or not the shooting is finished (s906). If the image is shot again, the process returns to the determination of still image shooting or moving image shooting operation.

  As described above, in this embodiment, in order to realize the preliminary reset release scanning, two lines are provided in the still image shooting, which perform reading scanning but not preliminary reset cancellation scanning. In moving image shooting, the preliminary reset cancellation scan is started from the period one frame before the readout scan. By switching the operation method between still image shooting and moving image shooting in this way, an appropriate output can be obtained with an image sensor in which a plurality of photodiodes are connected to the FD regardless of the shooting mode. Further, since the preliminary reset cancellation scanning can be realized only during the reading scanning, the preliminary reset cancellation scanning circuit can be simplified.

100 imaging device, 204 vertical scanning circuit, 205 pixel unit,
307 Floating diffusion, 1400 First image sensor

Claims (6)

A plurality of pixels are arranged two-dimensionally,
A photoelectric conversion element that converts light into electric charge for each pixel;
A transfer switch for transferring charge from the photoelectric conversion element;
A shared pixel structure in which a transfer switch is connected to one floating diffusion at least in the plurality of pixels in the vertical direction and shares a reset switch for resetting the floating diffusion and the photoelectric conversion unit of each pixel;
A read scanning control unit that performs control of transferring charges from the photoelectric conversion element;
In readout scanning of a photoelectric conversion element having a shared pixel structure by a readout scanning control unit, there is a period in which the floating floating diffusion is reset during readout control of each row of the shared pixel structure, and the shared pixel is set according to the reset period. An imaging element having a floating diffusion reset release scanning control unit for controlling reset release of the floating diffusion a predetermined time before the readout control of the pixels in the first row of the structure, and an imaging mode selection unit,
An imaging apparatus that switches whether or not to perform all-row floating diffusion reset cancellation scanning according to the imaging mode selected by the imaging mode selection means. The photographing mode selection means has a first photographing mode having a row in which at least some of the rows do not perform floating diffusion reset cancel scanning, and a photographing mode 2 in which all rows of floating diffusion reset cancel scanning are performed. The imaging device according to claim 1. The imaging apparatus according to claim 2, wherein the shooting mode 1 is a still image shooting mode. The imaging apparatus according to claim 2, wherein the shooting mode 2 is a moving image shooting mode. The imaging apparatus according to claim 2, wherein some of the rows that are not subjected to the floating diffusion reset cancellation scan are rows that share the first pixel of claim 1 that performs the scan. The imaging apparatus according to claim 1, wherein the fixed time is the same as a period during which the floating floating diffusion is reset during readout control of each row of the pixel structure.