JP2010063156A - Solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device which performs a good operation for acquiring a noise measuring signal even when a driving mode is switched. <P>SOLUTION: In the solid-state imaging device which has a valid pixel part where valid pixels including a photoelectric converter for converting incident light into charge are matrix-arranged, an invalid pixel part where at least one row of invalid pixel part including no photoelectric converter is arranged, and an invalid pixel row selecting part to select a pixel of the invalid pixel part in units of rows, includes two or more driving modes, and outputs an image signal based on the valid pixel part and the noise measuring signal based on the invalid pixel part, the invalid pixel row selecting part selects the pixel of the invalid pixel part until the image signal is output just after the driving mode is changed, and outputs the noise measuring signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device used for a video camera or the like.

  Noise superimposed on pixel signals of solid-state imaging devices used in video cameras, etc., is generated as random noise generated randomly in time and space, and as fixed patterns such as vertical stripes and horizontal stripes at the same location on the output screen. It can be roughly divided into fixed pattern noise. Random noise appears as uneven noise when passing through ground glass over the entire screen, causes light shot noise, thermal noise, and the like, and easily changes depending on the environmental temperature. On the other hand, the fixed pattern noise is often caused by an imbalance in electrical characteristics such as a circuit constituting a pixel of a solid-state imaging device and a readout circuit. In particular, when different fixed pattern noise occurs for each pixel column, it appears as vertical stripes on the output screen and is easily noticeable.

  In order to remove such fixed pattern noise components that differ for each pixel column, the following techniques are known. First, a signal (hereinafter referred to as a noise measurement signal) from a dummy line to which no pixel capable of photoelectric conversion is connected is output, and a fixed pattern noise component is detected and held from the noise measurement signal. Next, when a pixel signal at the time of imaging (hereinafter referred to as an effective pixel signal) is output, the detected fixed pattern noise component is subtracted from the effective pixel signal to cancel the noise component.

  Further, a technique for detecting a fixed pattern noise component that reflects the variation in the row direction of the reading transistor without being affected by dark current is known (see, for example, Patent Document 1). Patent Document 1 uses a non-effective pixel composed of an amplifying transistor and a reset transistor, omitting a photodiode, as a dummy line, and cancels a fixed pattern noise component with high accuracy.

In the technique described in Patent Document 1, the number of dummy lines that output a noise measurement signal is set to M square rows or more, and the noise measurement signal is averaged for each pixel column, thereby being superimposed on the noise measurement signal. The random noise component is suppressed to 1 / M times or less of the total noise component. If the random noise component is ¼ or less of the total noise component, the random noise cannot be recognized on the display screen. Further, by averaging the noise measurement signals of a plurality of frames, the same effect can be obtained with a dummy line having a smaller number of rows.
A solid-state imaging device having a plurality of drive modes is known.

JP 2005-176061 A

  Incidentally, in Patent Document 1, it is not clarified at what timing the noise measurement signal is acquired when the drive mode is switched.

  Further, due to the recent demand for noise reduction in solid-state imaging devices, it is required to average more noise measurement signals, and the above-mentioned M is 4, that is, noise measurement from 16 dummy lines. The signal may not be enough.

  An object of the present invention is to provide a solid-state imaging device that performs a suitable operation for acquiring a noise measurement signal even when the drive mode is switched.

  The solid-state imaging device according to the present invention has an effective pixel unit in which effective pixels including a photoelectric conversion unit that converts incident light into electric charges are arranged in a matrix, and an ineffective in which at least one row of ineffective pixels not including the photoelectric conversion unit is arranged. A non-effective pixel row selection unit that selects a pixel of the non-effective pixel unit for each row, and a first signal based on the effective pixel unit and a second signal based on the non-effective pixel unit A solid-state imaging device that outputs a signal, and further includes an input unit that receives a third signal for switching a driving mode of the solid-state imaging device from the outside, and the ineffective pixel row selection unit includes the driving mode In a period from immediately after the switching terminal receives the third signal to when the first signal is output, the pixels in the ineffective pixel portion are selected and the second signal is continuously output. And

  According to the present invention, it is possible to provide a solid-state imaging device that performs a suitable operation of acquiring a second signal such as a noise measurement signal even when the drive mode is switched.

1 is a block diagram illustrating a configuration example of a solid-state imaging device according to a first embodiment of the present invention. 1 is a block diagram illustrating a configuration example of an imaging system according to a first embodiment of the present invention. 3 is a timing chart illustrating a method for driving the solid-state imaging device according to the first embodiment of the present invention. It is a timing chart which shows the drive method of the solid-state imaging device concerning the 2nd Embodiment of this invention. 10 is a timing chart illustrating a method for driving a solid-state imaging device according to a third embodiment of the present invention. It is a block diagram which shows the structural example of the solid-state imaging device concerning the 4th Embodiment of this invention. It is a timing chart which shows the drive method of the solid-state imaging device concerning the 4th Embodiment of this invention. It is a timing chart which shows the drive method of the solid-state imaging device in a prior art.

Preferred embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 shows a configuration example of a solid-state imaging device, and FIG. 2 shows a configuration example of an imaging system regarding a method for driving a solid-state imaging device according to the first embodiment of the present invention. FIG. 3 shows a timing chart according to the driving method of the solid-state imaging device according to the present embodiment.

  The solid-state imaging device 1 shown in FIG. 1 includes a pixel unit 2, a vertical drive unit 4, a line memory unit 31, a horizontal scanning unit 32, an amplifier 33, a vertical driving unit 4, a line memory 31, and a horizontal scanning unit 32. Are provided with a timing generation unit 5 and a communication unit 6. The pixel unit 2 is composed of a plurality of pixels arranged two-dimensionally. The timing generation unit is a drive mode selection unit that drives the solid-state imaging device in two or more drive modes, and generates a vertical synchronization signal, a horizontal synchronization signal, and the like. The line memory unit 31 stores pixel signals read from each of a plurality of pixels in one row selected based on a control signal from the vertical driving unit 4. The horizontal scanning unit 32 sequentially transfers the pixel signals stored in the line memory unit 31. The amplifier 33 amplifies the read pixel signal. The pixel unit 2 includes an effective pixel unit 21 including an effective pixel 211 having a photodiode that converts incident light into electric charge, and an ineffective pixel unit 22 including an ineffective pixel 221 from which the photodiode is omitted. Composed. The ineffective pixel unit 22 may be composed of a plurality of rows or a single row. In FIG. 1, the vertical drive unit 4 includes an electronic shutter scanning unit 41, a readout row scanning unit 42, and an ineffective pixel row selection unit 43. However, the electronic shutter scanning and readout row scanning are common scanning units. It may be configured. Further, the non-effective pixel row selection unit 43 may be configured by a scanning unit common to the readout row scanning.

  In addition, the solid-state imaging device 1 includes a terminal (input unit) (not shown) that receives a signal for switching a driving mode, which is a third signal, from the outside. Upon receiving the third signal, for example, the timing generation unit 5 changes the timing for driving the vertical driving unit 4 and the horizontal scanning unit 32, or changes the gain of the amplifier.

  The operation of the solid-state imaging device 1 will be described. When light enters each of the effective pixels 211, the photodiodes of the effective pixels 211 accumulate charges generated by photoelectric conversion. First, an electronic shutter operation is performed prior to the reading operation. After the charge accumulated in the photodiodes of the pixels 211 in one row selected by the electronic shutter scanning unit 41 is reset to the reset potential, charge accumulation is started again. Next, after the accumulation time corresponding to the amount of light has elapsed, the charges accumulated in the pixels 211 in the row selected again by the readout row scanning unit 42 are read out and stored in the line memory unit 31. Next, the horizontal scanning unit 32 sequentially selects the pixel signals read to the line memory unit 31 based on the horizontal transfer pulse from the timing generation unit 5, and outputs them to the amplifier 33. The amplifier 33 amplifies and outputs the input pixel signal.

  By sequentially performing reset row selection of the electronic shutter scanning unit 41 and readout row selection of the readout row scanning unit 42 at the same timing, the accumulation time of each row of the pixel unit 2 is controlled to be constant. Then, electronic shutter scanning, readout scanning, and horizontal scanning are repeated, and readout of pixel signals for one screen is completed.

  The pixel addition in the vertical direction in the effective pixel unit 21 is performed as follows. After the row selected by the readout row scanning unit 42 is read out and stored in the line memory unit 31, the readout row scanning unit 42 further selects the addition target row, reads out the pixel signal of the addition target row to the line memory unit 31, and the line memory The unit 31 performs signal addition. The added pixel signals are sequentially selected by the horizontal scanning unit 32, amplified by the amplifier 33, and then output.

  On the other hand, the non-valid pixel row selection unit 43 selects the row of the non-valid pixel 221 at the same timing as the electronic shutter scanning during the period when the readout row scanning unit 42 does not select the row of the valid pixel unit 21 and The pixel signal is stored in the line memory unit 31. The ineffective pixel signals read to the line memory unit 31 are sequentially selected by the horizontal scanning unit 32, amplified by the amplifier 33, and then output as a noise measurement signal.

  Next, a configuration example of the imaging system illustrated in FIG. 2 will be described. Reference numeral 7 denotes an AD (analog-digital) converter, which converts an image signal that is a first signal that is an analog signal output from the solid-state imaging device 1 into a digital signal by performing known analog signal processing. A signal processing unit 8 subtracts a fixed pattern noise component of the image signal converted into a digital signal by the AD converter 7 and cancels it. A fixed pattern noise component detection unit 82 includes a line memory 821 and an averaging unit 822, which averages the noise measurement signals that are the second signals of the plurality of rows that are input, and suppresses random noise components. The pattern noise component is stored in the line memory 821. An arithmetic unit 81 subtracts the fixed pattern noise component stored in the line memory 821 from the image signal of the effective pixel unit 21. Further, 9 is a CPU and 10 is a switch unit. The switch unit 10 includes a switch operated to set an imaging condition and a switch operated to start an imaging preparation operation and an imaging operation. Reference numeral 11 denotes a video display unit such as an EVF (Electronic View Finder), which performs display using the display image data generated by the signal processing unit 8. An image recording unit 12 records the recording image data generated by the signal processing unit 8 in an internal memory of the camera body or a recording medium detachable from the camera body.

  Next, a driving method of the solid-state imaging device according to the present embodiment will be described using the timing chart shown in FIG. FIG. 3A shows a driving mode of the solid-state imaging device 1. Here, the driving mode represents a driving method of the solid-state imaging device 1, and this driving mode differs depending on the presence / absence of pixel addition, the number of pixels to be added when pixel addition is performed, and the like. 3B shows a synchronization signal input to the timing generator 5, and FIG. 3C corresponds to the synchronization signal shown in FIG. 3B in the drive mode shown in FIG. The operation of the vertical drive unit 4 of the solid-state imaging device 1 is shown. FIG. 3D shows a state in which the pixel unit 2 is scanned for each row in the vertical direction corresponding to the operation of the vertical driving unit 4 shown in FIG. Scanning corresponding to the readout row is composed of a horizontal blanking period and a horizontal transfer period. The horizontal blanking period indicates a period in which pixel signals are read out from the pixels in the row selected by the readout row scanning unit 42 or the ineffective pixel row selection unit 43 to the line memory 31. The horizontal transfer period indicates a period for reading from the line memory 31 by the horizontal scanning unit 32. When the drive mode is the vertical three-pixel addition mode, the horizontal blanking period for reading the first row to the line memory 31, the horizontal blanking period for reading the second row to the line memory 31, and the third row to the line memory 31 are read. The horizontal blanking period and the horizontal transfer period are repeated. In the horizontal transfer period, signals of the three pixels added on the line memory 31 are sequentially read out. The scanning corresponding to the electronic shutter row indicates the timing at which the photodiodes in the rows sequentially selected by the electronic shutter scanning unit 41 are reset. FIG. 3E shows a signal output from the solid-state imaging device 1, and shows signals output corresponding to the readout row scanning and horizontal scanning shown in FIG. After the effective pixel row scanning is completed, the non-effective pixel row continues to be selected and the non-effective pixel signal, that is, the noise measurement signal is output until the vertical synchronization signal VD of the next frame is input to the timing generation unit 5. The Here, a period from when the vertical synchronization signal VD is input to the timing generation unit 5 until the next vertical synchronization signal VD is input is referred to as one frame period. Therefore, it can be said that only the signals from the pixels in the ineffective pixel row are output in the frame period immediately after the drive mode is changed. Further, the noise measurement signal in the frame period immediately after the drive mode is changed is output according to the horizontal synchronization signal HD in the changed drive mode. That is, the number of rows of noise measurement signals output in the frame period immediately after the drive mode is changed is equal to the number of effective pixel rows read (output) during one frame period in the changed drive mode.

  Here, when it is necessary to change the driving mode of the solid-state imaging device by a switch operation or the like at time T0, the CPU 9 immediately communicates with the solid-state imaging device 1 and changes the driving mode of the solid-state imaging device 1. For example, the mode is changed from the three-pixel addition readout drive mode (pixel addition mode) to the all-pixel readout drive mode (all-pixel readout mode). In the all-pixel readout drive mode, pixel addition is not performed. When the vertical synchronization signal VD is input to the timing generation unit 5 at time T1, the solid-state imaging device 1 starts operation in the changed drive mode (here, all-pixel readout drive mode). At this time, the solid-state imaging device 1 selects an ineffective pixel row by the ineffective pixel row selection unit 43 of the vertical driving unit 4 and starts outputting an ineffective pixel signal, that is, a noise measurement signal. At time T3, until the next vertical synchronization signal VD is input to the timing generation unit 5, the non-effective pixel row selection unit 43 repeats the selection of the non-effective pixel row and outputs a noise measurement signal equal to or greater than the number of rows in one frame. Output. At time T2, the electronic shutter scanning unit 41 starts electronic shutter scanning for the first frame. Next, at time T3, when the vertical synchronization signal VD is input to the timing generation unit 5, the solid-state imaging device 1 starts scanning effective pixel rows by the readout row scanning unit 42 of the vertical driving unit 4, and 1 frame Output of the imaging signal of the eye is started. From time T2 to time T3 is the accumulation time for the effective pixels in the first frame. Then, from time T5 when the scanning of the effective pixel row is completed, the solid-state imaging device 1 selects the ineffective pixel row by the ineffective pixel row selection unit 43 of the vertical driving unit 4, and outputs the ineffective pixel signal, that is, the noise measurement signal. To start. Then, at time T6, until the next vertical synchronization signal VD is input to the timing generation unit 5, the non-effective pixel row selection unit 43 repeats selection of the non-effective pixel row a plurality of times and outputs a noise measurement signal. At time T4, the electronic shutter scanning unit 41 starts electronic shutter scanning for the second frame. Thereafter, by repeating the driving of the solid-state imaging device from T3 to T6, an imaging signal as a moving image is obtained.

  In FIG. 3D, the driving method in which one non-effective pixel row is repeatedly read is described. However, when the non-effective pixel portion 22 is composed of a plurality of rows, the row read by the non-effective pixel portion 22 is described. These scans may be repeated.

  In addition, if the number of dummy lines (rows of ineffective pixel portions) for acquiring noise measurement signals is about 1/10 or less of the total number of readout rows (rows of effective pixel portions), random noise components can be sufficiently obtained. Can be reduced. An operation may be performed in which dummy lines (rows of ineffective pixel portions) of about 100 rows or less are provided and scanning of the ineffective pixel portions 22 is repeated. The number of dummy lines is preferably 100 or less. Accordingly, it is possible to average the variation due to the characteristic difference between the dummy lines while suppressing an increase in the area of the solid-state imaging device due to the provision of the dummy lines. Furthermore, the region where the dummy line is arranged is not limited to the region shown in FIG. 1 and may be provided above the read row. The same applies to other embodiments described later.

  In the present embodiment, the change in the drive mode is the difference in whether or not addition is performed, but the operation performed in each period indicated by the HD and VD intervals in FIG. 3 can also be switched by changing the drive mode. is there. For example, in FIG. 3, before the time T0, a horizontal blanking period for three rows and a horizontal transfer period for one row are provided in the interval of the horizontal synchronization signal HD. On the other hand, after the time T1 when the drive mode is switched, the interval of the horizontal synchronization signal HD is narrowed, and the horizontal blanking period and the horizontal transfer period are provided for only one row each. As the operation performed during the HD period is changed, the operation performed during the VD period is also changed. In addition to the all-pixel readout mode for reading out signals from all the pixels in the effective pixel portion, the mode is switched to a thinning-out readout mode for selecting signals to be read out at a low density, a cutout readout mode for reading out signals from only a part of the area, This also changes the drive mode.

  In addition, it is possible to change the characteristics of each column, such as changing the gain of the amplifier in a solid-state imaging device having a variable gain amplifier (column amplification unit) provided corresponding to the column of the pixel unit. include.

  The noise measurement signal output from the solid-state imaging device 1 is input to the fixed pattern noise component detection unit 82 of the signal processing unit 8. The averaging means 822 averages the input invalid pixel rows for each pixel column, and detects a fixed pattern noise component in which the line dam noise component is suppressed. The fixed pattern noise is stored in the line memory 821. The computing unit 81 subtracts the fixed pattern noise stored in the line memory 821 from the image signal of the effective pixel unit 21 to remove the fixed pattern noise.

  As described above, Patent Document 1 describes that detection of a fixed pattern noise component may be performed in a plurality of frames. FIG. 8 shows a timing chart in which this operation is performed when the drive mode is switched, and the differences from the present embodiment of the present invention will be described.

  In order to obtain a noise measurement signal before time T106, which is the image signal output start timing of the first frame after the drive mode is switched, scanning of ineffective pixel rows is performed over a plurality of frames from time T101 to T102. Then, the effective pixel row readout scan is started from time T103, but since the electronic shutter scan has not been performed before time T103, the pixel accumulation time of the image signal output from time T103 is not controlled. For this reason, the brightness of the obtained image differs depending on the row, and the brightness differs compared to the image of other frames. For this reason, the image signal output from time T103 cannot be used.

  Furthermore, as described above, random noise components may not be sufficient in the noise measurement signals for 16 rows. When the operation shown in FIG. 8 is performed in such a case, electronic shutter scanning is performed after the acquisition of the noise measurement signal. For this reason, in a solid-state imaging device that requires high noise reduction, the time lag from when the drive mode is switched to when the first usable image signal is output becomes significant.

  According to the first embodiment of the present invention, random noise is sufficiently obtained without depending on the number of rows of the ineffective pixel unit 22 before outputting the image signal of the first frame after changing the drive mode of the solid-state imaging device 1. It is possible to output noise measurement signals with the number of rows that can be averaged. By averaging this noise measurement signal in the fixed pattern noise component detection unit 82 of the signal processing unit 8, a fixed pattern noise component in which the random noise component is sufficiently suppressed can be detected. Then, the signal processing unit 8 can satisfactorily cancel the fixed pattern noise component from the image signal of the first frame. If the configuration is such that the number of rows of the non-effective pixel portion 22 is reduced and the noise measurement signal is repeatedly read therefrom, an increase in the area of the solid-state imaging device can be reduced, which does not cause an increase in cost. Further, since the noise measurement signal is output during the electronic shutter scanning period of the first frame, the readout frame for outputting the noise measurement signal at times T100 to T103 shown in FIG. There is no time lag until the eye image signal is output.

  Furthermore, if the output of the ineffective pixel row after the change of the drive mode is started from the time T2 in FIG. 3, the time until the output of the image signal of the first frame can be shortened.

(Second Embodiment)
Next, a second embodiment to which the present invention can be applied will be described with a focus on differences from the first embodiment.

  The solid-state imaging device 1 of the present embodiment designates a pixel that outputs a pixel signal, outputs a picture in which pixels of the effective pixel unit 21 are uniformly thinned, and an image obtained by cutting out a part of the effective pixel unit 21 A partial pixel readout mode (screen cut-out drive mode) having a function of outputting. In the partial pixel readout mode, vertical row thinning, horizontal pixel thinning, and screen cutout are possible, and pixel addition is not performed.

  A method for driving the solid-state imaging device according to the present embodiment will be described with reference to a timing chart shown in FIG. When the drive mode of the solid-state imaging device needs to be changed by a switch operation or the like at time T10, the CPU 9 communicates with the solid-state imaging device 1 and changes the driving mode of the solid-state imaging device 1. For example, the pixel addition mode (3-pixel addition readout drive mode) is changed to the partial pixel readout mode (screen cutout drive mode). When the vertical synchronization signal VD is input to the timing generation unit 5 at time T11, the solid-state imaging device 1 starts operation in the screen cutout drive mode. At this time, the solid-state imaging device 1 selects the ineffective pixel row a plurality of times by the ineffective pixel row selection unit 43 of the vertical driving unit 4 and reads out the ineffective pixel signal to the line memory unit 31. Next, the horizontal scanning unit 32 sequentially selects the start of reading from pixel signals of ineffective pixels connected to the designated column, and outputs an ineffective pixel signal, that is, a noise measurement signal. At time T13, this operation is repeated until the next vertical synchronization signal VD is input to the timing generation unit 5, and noise measurement signals having a number of rows of one frame or more are output. At time T12, the electronic shutter scanning unit 41 starts electronic shutter scanning for the first frame according to the cutout position of the screen. After time T13, readout scanning and electronic shutter scanning corresponding to the cutout position of the screen are repeated to obtain an imaging signal as a moving image.

  Here, a period from when the vertical synchronization signal VD is input to the timing generation unit 5 until the next vertical synchronization signal VD is input is referred to as one frame period. Therefore, it can be said that only signals from pixels in the ineffective pixel row are output in the frame period immediately after the drive mode is changed. Further, the noise measurement signal in the frame period immediately after the drive mode is changed is output according to the horizontal synchronization signal HD in the changed drive mode. That is, the number of rows of noise measurement signals output in the frame period immediately after the drive mode is changed is equal to the number of effective pixel rows read (output) during one frame period in the changed drive mode.

  According to the second embodiment of the present invention, before outputting the image signal of the first frame after changing the drive mode of the solid-state imaging device 1, the noise measurement signal corresponding to the cutout position of the screen or the pixel thinning is randomly selected. It is possible to output the number of rows that can sufficiently average noise. Therefore, it is possible to satisfactorily cancel the fixed pattern noise component from the image signal of the first frame after the drive mode is changed. Moreover, both the change of the drive mode of FIG. 3 and the change of the drive mode of FIG. 4 can be performed.

(Third embodiment)
Next, a third embodiment to which the present invention can be applied will be described focusing on differences from the first embodiment.

  FIG. 5 shows a timing chart according to the driving method of the solid-state imaging device according to the present embodiment. FIG. 5F shows the waveform of the power supply voltage supplied to the solid-state imaging device 1. When the power supply voltage is stabilized at time T20, the CPU 9 communicates with the solid-state imaging device 1 to perform initial setting of the solid-state imaging device 1. When the initial setting of the solid-state imaging device 1 is completed and the vertical synchronization signal VD is input to the timing generation unit 5 at time T21, the solid-state imaging device 1 starts operating in the initially set drive mode. At this time, the solid-state imaging device 1 selects an ineffective pixel row by the ineffective pixel row selection unit 43 of the vertical driving unit 4 and starts outputting an ineffective pixel signal, that is, a noise measurement signal. Until the vertical synchronization signal VD at time T23 is input to the timing generation unit 5, the non-effective pixel row selection unit 43 repeats selection of the non-effective pixel row a plurality of times and outputs a noise measurement signal equal to or greater than the number of rows in one frame. To do. At time T22, the electronic shutter scanning unit 41 starts electronic shutter scanning for the first frame. After time T23, readout scanning and electronic shutter scanning are repeated to obtain an imaging signal as a moving image.

  Here, a period from when the vertical synchronization signal VD is input to the timing generation unit 5 until the next vertical synchronization signal VD is input is referred to as one frame period. Therefore, it can be said that only signals from pixels in the ineffective pixel row are output in the frame period immediately after the drive mode is changed. Further, the noise measurement signal in the frame period immediately after the drive mode is changed is output according to the horizontal synchronization signal HD in the changed drive mode. That is, the number of rows of noise measurement signals output in the frame period immediately after the drive mode is changed is equal to the number of effective pixel rows read (output) during one frame period in the changed drive mode.

  According to the third embodiment of the present invention, the noise measurement signal outputs the number of rows that can sufficiently average the random noise before outputting the image signal of the first frame immediately after the power-on of the solid-state imaging device 1. Is possible. Therefore, it is possible to satisfactorily cancel the fixed pattern noise component from the image signal of the first frame immediately after the power is turned on.

(Fourth embodiment)
Next, a fourth embodiment to which the present invention can be applied will be described focusing on differences from the first embodiment.

  FIG. 6 shows a configuration example of the solid-state imaging device according to the present embodiment. The vertical drive unit 4 of the solid-state imaging device 1 according to the present embodiment includes an effective pixel row scanning unit 44. The effective pixel row scanning unit 44 performs electronic shutter scanning and readout row scanning at the same time, and cannot control each scanning independently.

  FIG. 7 shows a timing chart according to the driving method of the solid-state imaging device according to the present embodiment. First, electronic shutter scanning is started at time T30 of the frame in the three-pixel addition reading drive mode. Next, the drive mode is switched at time T31 when the vertical synchronization signal VD is input to the timing generator 5. In FIG. 7, after the time T31, the mode is switched to the all-pixel readout drive mode. That is, at time T31, the scanning timing of the vertical driving unit 4 is switched, and the timing of electronic shutter scanning started from time T30 is switched before all the effective pixel rows are scanned.

  When the effective pixel row is scanned at time T31, as shown in FIG. 7, the accumulation time does not become constant in each row, so that it cannot be used as an image.

  Therefore, the ineffective pixel row is continuously selected a plurality of times from time T31, and the ineffective pixel signal, that is, the noise measurement signal is output.

  Also, from time T32, electronic shutter scanning for the first frame after switching the drive mode is started. When the vertical synchronization signal VD is input to the timing generation unit 5 at time T33, the effective pixel row readout scan is started, and the image signal of the first frame is obtained.

  Here, a period from when the vertical synchronization signal VD is input to the timing generation unit 5 until the next vertical synchronization signal VD is input is referred to as one frame period. Therefore, it can be said that only signals from pixels in the ineffective pixel row are output in the frame period immediately after the drive mode is changed. Further, the noise measurement signal in the frame period immediately after the drive mode is changed is output according to the horizontal synchronization signal HD in the changed drive mode. That is, the number of rows of noise measurement signals output in the frame period immediately after the drive mode is changed is equal to the number of effective pixel rows read (output) during one frame period in the changed drive mode.

  According to the fourth embodiment of the present invention, instead of outputting an unusable image signal, a noise measurement signal is output for the number of rows of one frame, so that a fixed pattern noise is derived from the image signal of the next frame. It becomes possible to cancel the components satisfactorily. Further, since there is no vertical drive unit dedicated for electronic shutter scanning, the chip size of the solid-state imaging device can be reduced, and the cost can be further reduced.

  According to the driving method of the solid-state imaging device according to the first to fourth embodiments, the dummy line is detected immediately after the driving mode of the solid-state imaging device is changed or immediately after the start of imaging, while the electronic shutter is driven corresponding to the first readout frame. Output noise measurement signal multiple times. This makes it possible to obtain noise measurement signals with the number of rows that can sufficiently average random noise before reading out the first frame, sufficiently suppressing random noise components, and accurately removing fixed pattern noise from the first frame. Is possible. In addition, since it is not necessary to increase the number of dummy lines, the area of the solid-state imaging device does not increase and the cost is not increased. Further, since the noise measurement signal is output while the electronic shutter is being driven, no time lag occurs until the effective pixel signal is output.

  The solid-state imaging devices according to the first to fourth embodiments do not include the effective pixel unit 21 including the effective pixels 211 including the photoelectric conversion units arranged in a two-dimensional matrix and the photoelectric conversion units arranged in at least one row. A non-effective pixel portion 22 having effective pixels 221. The photoelectric conversion unit is, for example, a photodiode. In FIG. 3 and the like, the ineffective pixel row selection unit 43 selects and outputs the signal of the ineffective pixel 221 in the same row a plurality of times immediately after changing the drive mode.

  In FIG. 3 and the like, the electronic shutter operation unit 41 resets the photoelectric conversion unit of the effective pixel 211 in a period in which the non-effective pixel row selection unit 43 selects the signal of the non-effective pixel in the same row a plurality of times. .

  In FIG. 3 and the like, the readout row scanning unit 42 selects and outputs the signal of the effective pixel 211 in units of rows after the electronic shutter operation unit 41 is reset.

  In FIG. 3, the drive modes include a pixel addition mode (3-pixel addition read drive mode) and an all-pixel read mode (all-pixel read drive mode).

  In the pixel addition mode, the line memory unit 31 adds and stores the signals of the plurality of effective pixels 211 selected by the readout row scanning unit 42. Further, the line memory unit 31 stores the signals of the plurality of effective pixels 211 selected by the readout row scanning unit 42 without adding them in the all-pixel readout mode. The invalid pixel row selection unit 43 selects and outputs the signal of the invalid pixel 221 in the same row a plurality of times immediately after changing from the pixel addition mode to the all pixel readout mode.

  In FIG. 4, the drive modes include a partial pixel readout mode (screen cutout drive mode) and a pixel addition mode (3-pixel addition readout drive mode).

  The readout row scanning unit 42 selects signals of effective pixels 211 in some rows in the partial pixel readout mode, and selects signals of effective pixels 211 in all rows in the pixel addition mode. In the pixel addition mode, the line memory unit 31 adds and stores the signals of the plurality of effective pixels 211 selected by the readout row scanning unit 42. In the partial pixel readout mode, the line memory unit 31 stores the signals of the plurality of effective pixels 211 selected by the readout row scanning unit 42 without adding them. The invalid pixel row selection unit 43 selects and outputs the signal of the invalid pixel 221 in the same row a plurality of times immediately after changing from the pixel addition mode to the partial pixel readout mode.

  In FIG. 5, after the power is turned on, the ineffective pixel row selection unit 43 selects the signal of the ineffective pixel 221 in the same row a plurality of times during the period before the first effective frame (first frame). Output.

  By selecting the ineffective pixel signal a plurality of times, the number of rows of ineffective pixels can be reduced, and the area can be reduced. In addition, a time lag until the first frame is output can be prevented.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Solid-state imaging device 2 Pixel part 4 Vertical drive part 5 Timing generation part 6 Communication part 7 AD converter 8 Signal processing part 9 CPU
DESCRIPTION OF SYMBOLS 21 Effective pixel part 22 Ineffective pixel part 31 Line memory part 32 Horizontal scanning part 33 Amplifier 41 Electronic shutter scanning part 42 Reading line scanning part 43 Ineffective pixel line selection part 82 Fixed pattern noise component detection part

Claims (1)

An effective pixel portion in which effective pixels including a photoelectric conversion portion that converts incident light into charges are arranged in a matrix;
An ineffective pixel portion in which at least one row of ineffective pixels not including the photoelectric conversion portion is disposed;
An ineffective pixel row selection unit that selects pixels of the ineffective pixel unit for each row;
A solid-state imaging device that outputs a first signal based on the effective pixel portion and a second signal based on the non-effective pixel portion,
Furthermore, it has an input unit for receiving a third signal for switching the drive mode of the solid-state imaging device from the outside,
The ineffective pixel row selection unit selects a pixel in the ineffective pixel unit during a period from immediately after the drive mode switching terminal receives the third signal to when the first signal is output. A solid-state imaging device characterized by continuing to output the second signal.

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