JP3753389B2 - Signal readout processing method for solid-state image sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal readout processing method of a solid-state image sensor, and particularly, a solid-state image pickup capable of following a change in dark fixed pattern noise due to a temperature change or the like and always stably suppressing dark fixed pattern noise. The present invention relates to a signal readout processing method of an image sensor.
[0002]
[Prior art]
Conventionally, an internal amplification type photoelectric conversion element represented by, for example, SIT (Static Induction Transistor), AMI (Amplified MOS Imager), CMD (Charge Modulation Device), which has a photoelectric conversion function and a stored charge amplification, readout and reset function. An apparatus that reproduces an image using a solid-state imaging device used as a unit pixel is known. In such an image reproducing device, in order to cancel fixed pattern noise (hereinafter abbreviated as FPN) inherent to the solid-state imaging device, it is stored in a storage means such as a frame memory for storing the FPN for each pixel. The FPN corresponding to each pixel is subtracted from the image information corresponding to each pixel of the solid-state imaging device.
[0003]
FIG. 7 shows a block diagram of a conventional FPN suppressing means disclosed in, for example, Japanese Patent Application Laid-Open No. 64-39171 used in an image reproducing apparatus using such an internal amplification type photoelectric conversion element. .
[0004]
In FIG. 7, an image signal output from the solid-state image element 31 is amplified by an amplifier 32 and converted into a digital signal by an A / D converter 33. A dark signal (FPN signal) output from the solid-state image element 31 in a state where the incident light is blocked is stored in the FPN memory 35 including a frame memory by connecting the changeover switch 34 to the b side. After the dark-time FPN storage operation is completed, the changeover switch 34 is switched to the a side to release the cutoff. As a result, the light signal generated by the photo-generated charges output from the solid-state imaging device 31 is A / D converted by the A / D converter 33, and is repeated with the FPN signal stored in the FPN memory 35 in the subtractor 36. Subtraction processing is performed to obtain an image signal in which FPN is suppressed. This image signal is D / A converted by the D / A converter 37 and output as a video signal. The FPN memory 35 normally stores an averaged dark signal of one frame or several frames.
[0005]
Here, at the time of dark FPN storage, instead of shielding the solid-state image sensor, the dark-time FPN signal is obtained by reading the signal from the solid-state image sensor immediately after resetting the accumulated photogenerated charge or while resetting. It can also be.
[0006]
By the way, the conventional FPN suppressing means shown in FIG. 7 stores the dark FPN signal in the FPN memory 35 in advance, and subtracts the dark FPN signal from the image signal corresponding to the photogenerated charge. Since the signal is output, there is a problem that when the FPN in the dark changes due to a temperature change or the like, the change cannot be followed and a stable FPN suppression effect cannot always be obtained.
[0007]
As a countermeasure against the temperature change, there is known a method of capturing a dark-time FPN signal by intermittently shielding a solid-state image sensor during imaging. By this method, for example, in order to store a dark signal for one frame in the FPN memory during continuous imaging operation, an output as shown in FIG. 8A is required from the solid-state imaging device, and time td In this case, a dark signal in which no photo-generated charges are accumulated is output from the solid-state imaging device. If the output of this solid-state imaging device is directly used as video output, as shown in FIG. 8B, a video output is not obtained at time td, and a screen on which nothing is displayed on the monitor at time td. It becomes a broken state. As shown in FIG. 8C, even if this screen break is repeatedly output and interpolated from the immediately preceding imaging screen, the motion becomes unnatural for a moving image, which is a serious problem.
[0008]
In order to solve the above problems, the applicant of the present application is directed to a signal reading processing method of an XY address type solid-state imaging device in which an internal amplification type photoelectric conversion device is a unit pixel and the unit pixels are arranged in a matrix. After reading a light-time signal based on the photogenerated charge of each pixel in a specific row in the scanning period, immediately after resetting or resetting the photogenerated charge of each pixel in the specific row, in the dark state without the photogenerated charge A first step of reading a signal and storing a dark signal of each pixel of the specific row in an external memory; and changing the specific row for each vertical scanning period or for each of a plurality of vertical scanning periods, The first step of storing the dark signal of each pixel in the external memory is sequentially executed for each specific row, and the dark signal of each pixel of all effective rows is stored in the external memory in a plurality of vertical scanning periods. And, for each of the plurality of vertical scanning periods for storing the dark signal of each pixel in all effective rows in the external memory, refreshing the dark signal of each pixel in all effective rows stored in the external memory, or A third step of adding and storing the dark signal stored in the previous storage step and the newly read dark signal at a predetermined ratio, and the dark signal of each row of pixels stored in the external memory; And a signal readout processing method of a solid-state imaging device including a fourth step of subtracting from the bright signal of the pixels in each corresponding row at the same timing (see Japanese Patent Laid-Open No. 7-15666).
[0009]
In the signal readout processing method configured in this way, the dark signal stored in the external memory is refreshed or averaged every short time every plural vertical scanning periods, so that the dark FPN changes due to temperature change or the like. Even in this case, it is possible to obtain a stable dark-time FPN suppression effect that sufficiently follows the change. In addition, the period during which the dark signal is read during the imaging is only one to several line periods during one vertical scanning period, and the continuity of imaging is not impaired, and there is no problem with moving images. It can be made to correspond.
[0010]
Next, the conventional example will be described with reference to FIG. In FIG. 9, the solid-state imaging device 1 includes a light receiving unit 101 using an internal amplification type photoelectric conversion element as a pixel and arranging the pixel in a matrix. In this example, CMD is used as the internal amplification type photoelectric conversion element. The light receiving unit 101 has a configuration of 3 rows × L columns in order to simplify the description. The vertical scanning circuit 102 sends a scanning signal for selecting a readout row. The horizontal scanning circuit 103 sequentially amplifies the output signal of the L CMD pixels in the row in the readout state, and the output signal amplified by the amplifier 2 is A / D converted by the A / D converter 3 and 1H The signals are supplied to the delay line 4, the input terminal b of the changeover switch 5, and the FPN memory 8, respectively. The change-over switch 5 receives the control signal G input from the control signal input terminal, the output signal of the 1H delay line 4 supplied to the input terminal a, the output signal of the A / D converter 3 supplied to the input terminal b, and the input Any one of the GND supplied to the terminal c, that is, the digital 00... 0 signal is selectively output. The subtracter 6 subtracts the output of the FPN memory 8 from the signal selected by the changeover switch 5. The output signal of the subtracter 6 is D / A converted by the D / A converter 7 to output a video signal.
[0011]
The operation of the signal readout processing apparatus configured as described above will be described with reference to timing charts showing signal waveforms of the respective parts in FIGS.
[0012]
In the solid-state imaging device 1, the CMD pixels in the selected row to be read by driving the vertical scanning circuit 102 are set in a reading state, and the signals of the CMD pixels in the reading state are sequentially read out by the horizontal scanning circuit 103. The readout state of the CMD pixel in the row selected by the vertical scanning circuit 102 is made possible by setting the common gate line potential of the CMD pixel in the selected row to the readout potential VRD. At this time, the common gate line potential of the non-selected rows is set to the storage potential VST. In addition, after reading a signal based on the photogenerated charge accumulated in each pixel for one row, the common gate line potential is set to the reset potential VRST in the horizontal blanking period in order to reset the stored charge. When CMD is used as a pixel, excessive storage charge is swept out by setting the gate potential to an overflow potential VOF higher than the storage potential VST in the horizontal blanking period for blooming control. Oh Overflow operation is also performed.
[0013]
In FIG. 10, common gate line potential waveforms of the first to third rows of the solid-state imaging device 1 are indicated by A, B, and C, respectively. As can be seen from the gate line potential waveforms A, B, and C, in this example, in the first frame, the light signal in the state where the photogenerated charges in the first row are accumulated is read in the period of t = 0 to 1. Then, after the accumulated charge is reset at the time t = 1, the gate line potential is controlled so that the signal of the pixel in the first row is read again in the period t = 1 to 2. This corresponds to reading out a dark signal in a state where photogenerated charges are not accumulated in a period of t = 1 to 2.
[0014]
The internal amplification type photoelectric conversion element generates FPN due to variations in characteristics of transistors that amplify the accumulated charge, but reading of the dark signal is dark FPN when the dark current is zero (hereinafter used in this sense). Is read out. Dark current has recently been kept very small and can be ignored under normal solid-state imaging device usage conditions, so dark FPN means that it is caused by variations in transistor characteristics. To do. The dark-time FPN exists at a certain level regardless of the amount of light, and is weighted in an offset manner to the light-time signal corresponding to the photogenerated charge read out first.
[0015]
Next, in the same way, the dark signal of the second row is read out in the second frame, the dark signal of the third row is read out in the third frame, and the dark signal of the first row is read out again in the fourth frame. . Normally, there is a vertical blanking period between each frame, but in FIG. 10, 5 lines of each frame correspond to the vertical blanking period. A signal waveform E and signal waveforms F to L described below when an image of a subject with uniform brightness read by applying such a gate line potential output from the vertical scanning circuit 102 is as follows: Although it is a digital signal, the waveform is shown as an analog signal for easy understanding.
[0016]
As can be seen from the output signal waveforms D and E, in the first frame, the first row dark signal 1F is read after the first row light signal 1S, and the signals are solid in the order of 1S, 1F, 2S, and 3S. A signal is read from the image sensor 1. The bright signals in the first to third rows are represented by 1S, 2S, and 3S, and the dark signals are represented by 1F, 2F, and 3F. Similarly, in the second frame, the order is 1S, 2S, 2F, and 3S, in the third frame, the order is 1S, 2S, 3S, and 3F, and in the fourth frame, the signal readout order is the same as that of the first frame again.
[0017]
An output signal obtained by delaying the output signal E by one line by the 1H delay line 4 is indicated by F in FIG. 10, and a light signal and a dark signal in each row are indicated by a dash.
[0018]
The changeover switch 5 selects and outputs the output signals to the input terminals a, b, and c according to the control pressures Va, Vb, and Vc of the control signal G, respectively, and gives the control signal waveform indicated by G in FIG. Thus, as shown by the signal waveform H, a continuous bright signal without a dark signal is obtained from the output terminal of the changeover switch 5.
[0019]
On the other hand, the FPN memory 8 performs the write operation when the control signal J applied to the memory write control signal input terminal is at the H level, but the control signal H level is applied only during the period when the dark signal is output from the solid-state imaging device 1. The dark signal is written and stored. That is, the dark signal 1F in the first row is written in the first frame, and the dark signals 2F and 3F in the second and third frames are written in the second and third frames, respectively. 2. The dark signal writing and storing operation for all valid rows is completed in the period of the second and third frames. Then, the dark signal is continuously read from the FPN memory 8 at the same timing as the output signal H of the changeover switch 5, and the dark signal read from the FPN memory 8 is displayed. 11 M. The subtracter 6 subtracts the dark signal M from the FPN memory 9 from the output signal H of the changeover switch 5 to obtain a video signal N in which the dark FPN is controlled.
[0020]
In the conventional example shown in FIG. 9, the dark-time FPN stored in the FPN memory 8 is refreshed every three frames. However, considering a normal solid-state imaging device having the number of rows corresponding to the NTSC system, the dark-time FPN is Since one line is written in one field and the dark signal storage of all lines is completed in 525 fields, the dark signal refresh cycle is 525 fields, which is 1/60 (seconds) × 525≈9 seconds. This refresh cycle is sufficiently shorter than the ambient temperature change time, and can completely follow the change in the dark FPN with respect to the ambient temperature change. Also, the signal stored in the FPN memory is not completely refreshed every 9 seconds, and the stored signal and the newly read signal are added at an appropriate ratio using a general noise reduction method. In addition, highly accurate FPN subtraction is possible by a method of re-storing while suppressing random noise.
[0021]
Since it takes 9 seconds to capture the dark-time FPN of all rows, it takes 9 seconds after the power is turned on to output an image signal in which the dark-time FPN is suppressed. This time is usually within the allowable range for the start-up time of the device. For example, when the power is turned on, the overflow potential VOF is made equal to the reset potential VRST, and the reset operation is performed every horizontal blanking. Using a method of storing the dark FPNs of all rows in the FPN memory in at least one frame period (1/30 second) by continuously writing the dark signals into the FPN memory in a signal output state. As a result, it is possible to shorten the startup time.
[0022]
In the conventional example, since one row of dark signal is read in one frame period, the continuity of reading of the bright signal is interrupted by the one row reading period. However, in a general solid-state imaging device corresponding to the NTSC system with 525 scanning lines, the readout period of one row is about 64 μsec. Even if the continuity of readout between rows is impaired during this period, visually, Not detected and no problem. That is, there is no problem in taking a moving image.
[0023]
[Problems to be solved by the invention]
As described above, FPN cancellation capable of capturing moving images is possible, but in the conventional example, a signal read immediately after resetting the photogenerated charge in the horizontal blanking period is used as a dark signal (when applied to CMD, SIT, and AMI). Therefore, the following problems occur.
[0024]
In other words, even during the dark signal readout period, the photogenerated charge is accumulated until the next reset operation, so that the dark signal contains a slight amount of photogenerated charge, unlike the case where the dark signal is read out in a light-shielded state. It will end up. In the above-described conventional example, the number of pixels in three rows is set for simplification, but considering the general number of pixels, the number of pixels corresponding to the NTSC system is 525 rows, and the number of pixels in the row from which the light signal is read is 525 rows. The accumulation operation is performed for the time to be scanned. On the other hand, the pixels in the row from which the dark signal is read immediately after the resetting are accumulated during one horizontal scanning period until the resetting is performed in the next horizontal blanking period. The accumulation time is 1/525 compared to the signal at the time of light, and can be ignored for a normal subject, but when the subject has high brightness, it becomes a level that cannot be ignored when the subject is high in luminance, and is stored in the FPN memory as an error component of FPN. Even if the high-luminance object disappears, the stored data remains until the next refresh, and this error component is subtracted from the bright signal, causing a false signal.
[0025]
This problem will be described with reference to FIGS. A high-luminance subject enters the screen in the second frame period, and the position on the screen is the th period of two lines. A high luminance signal is added to 2S of the imager outputs D and E, but a high luminance signal component is also included in 2F to be read next. This 2F is written into the FPN memory as an FPN memory write signal and read out as an FPN memory read signal M, and is subtracted from the changeover switch output H to generate a subtracter output N. As a result, a false signal nH is generated in the two-row signal after the third frame of the subtracter output N. This continues until 2F is refreshed.
[0026]
SUMMARY OF THE INVENTION An object of the present invention is to provide a signal readout processing method for a solid-state imaging device that can cope with moving image imaging capable of suppressing FPN with high accuracy even when there is a high-luminance subject.
[0027]
[Means for Solving the Problems]
In order to solve the above-described problem, the signal readout processing method of the solid-state imaging device according to the present invention is:
Signal readout of a solid-state imaging device that reads out and processes a signal obtained by scanning photogenerated charges generated in response to incident light on unit photoelectric conversion elements arranged in a matrix in the horizontal and vertical directions as a video signal In the processing method,
Each position immediately after resetting the photogenerated charge of each pixel in the horizontal blanking period of the specific row by changing the position in the vertical direction of the specific row as a dark signal extraction target for each predetermined vertical scanning period The dark signal of each pixel in all the effective rows obtained by repeating the operation of reading out the dark signal of the pixel for every specific row that changes sequentially is stored in the memory, and stored in the memory for each predetermined vertical scanning period. Update the dark signal of each pixel in all the valid rows The bright signal level of the bright signal read immediately before reading out the dark signal has exceeded a predetermined threshold level. The process is performed for other than the specific pixels, and the dark signal of the pixels in each row read from the memory is subtracted from the bright signals of the pixels in each corresponding row.
[0028]
Said The specific pixel is a pixel in which the bright signal level of the bright signal read immediately before reading out the dark signal exceeds a predetermined threshold level. Toss Can. Also In the update of the memory content of the memory, the content read from the memory can be stored as it is for the specific pixel. Further, the predetermined level can be changed with respect to pixels in a horizontal direction, and the specific row is a single row, and a plurality of consecutive rows Toss Can.
[0029]
In the signal readout processing system configured as described above, an image in which the photogenerated charge included in the dark signal generated by the high-luminance subject exceeds a predetermined level is used. Naturally Since the dark signal data in the external memory does not change, FPN suppression corresponding to moving image capturing can be performed with high accuracy without generating a false signal.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration block diagram showing a first embodiment of the present invention. The parts corresponding to those of the conventional example shown in FIG. Compared to FIG. 9, a level detector 9, an AND circuit 10, and an input terminal P to which a high luminance determination threshold voltage Vref is supplied are added. Here, whether or not the signal component due to the photogenerated charge in the dark signal exceeds a predetermined level is determined from the previous light signal. Since the temporal correlation between the immediately preceding light signal and dark signal is very strong, if the bright signal has a high-intensity part, light-generated charges from the high-intensity part are generated in that part of the dark signal. It is because it is thought that there is.
[0031]
The operation of the embodiment shown in FIG. 1 will be described with reference to the timing charts of FIGS. The level detector 9 compares the output of 1HDL4 and the threshold voltage Vref for high brightness determination by the comparator 91, and generates a pulse if the voltage is larger than the Vref voltage. This pulse is inverted by the inverter 92 and a high brightness detection pulse K is output. The FPN memory 8 is controlled by the AND output of the high luminance detection pulse K and the FPN memory write control pulse J, that is, the composite FPN memory write control signal L from the AND circuit 10. In the pixel portion where the photogenerated charge by the high luminance portion exceeds a predetermined level, the composite FPN memory write control signal L becomes L level, and the rewriting operation (data update) to the memory is not performed, and the data in the FPN memory Does not change. As a result, the FPN memory write signal and the read signal do not include photogenerated charges due to the high luminance part, and no false signal is generated at the subtracter output N.
[0032]
Next, as another embodiment of the present invention, a second embodiment having a different level detection method will be described with reference to FIG. 4, parts similar to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In this example, the read dark signal and the output signal level of the FPN memory are compared, and it is determined whether the signal component due to the photogenerated charge in the dark signal exceeds a predetermined level (Vref). This is because the portion where the photogenerated charges are present in the dark signal is larger than the output level of the FPN memory.
[0033]
In the level detector 11, the FPN memory read signal M is subtracted from 2F of the imager output E by the subtractor 111, and the difference is compared with the threshold voltage Vref for high brightness determination by the comparator 112. As a result of comparison, if the difference is larger than the Vref voltage, a pulse is generated. This pulse is inverted by the inverter 113 and the high-intensity detection pulse K is output. The AND output of the high brightness detection pulse K and the FPN memory write control pulse J, that is, the composite FPN memory write control signal L is output from the AND circuit 10 to control the FPN memory. In the pixel portion where the photogenerated charge by the high luminance portion exceeds a predetermined level, the composite FPN memory write control signal L becomes L level and the rewriting operation to the memory is not performed, and the data in the FPN memory does not change. As a result, the FPN memory write signal and the read signal do not include photogenerated charges due to the high luminance part, and no false signal is generated at the subtracter output N.
[0034]
In the above example, the memory writing operation is stopped using the high luminance detection pulse K to prevent the data in the FPN memory of the pixel portion from changing the photogenerated charge by the high luminance portion exceeding a predetermined level. On the other hand, in FIG. 5 showing the third embodiment, the memory writing operation is not stopped, and the pixel portion where the photogenerated charge by the high luminance portion exceeds a predetermined level is read from the FPN memory 8. By writing the signal again into the FPN memory, the data in the FPN memory 8 is prevented from changing. In FIG. 5 as well, the same parts as those in FIGS. 1 and 4 are denoted by the same reference numerals. The imager output E is supplied to the terminal a of the switch circuit 12, and the FPN memory read signal M is supplied to the terminal b of the switch circuit 12. The switch circuit 12 uses the high brightness detection pulse K output from the level detector 9 as a switch switching control voltage, and outputs a signal input to the a side when the switch switching control voltage is at the H level and to the b side when the switch switching control voltage is at the L level. Switching control is performed as follows. In the pixel portion where the photogenerated charge by the high luminance portion exceeds a predetermined level, the high luminance detection pulse K becomes L level, so that the FPN memory read signal M is written again in the FPN memory 8 and the data does not change. As a result, the FPN memory write signal and the read signal do not include photogenerated charges due to the high luminance part, and no false signal is generated at the subtracter output N.
[0035]
In the above description, the accumulation operation of photogenerated charges is performed for one horizontal scanning time even in the dark signal readout period immediately after reset, but the accumulation period actually differs depending on the position of the pixel in the same line. Pixels read immediately after reset have an accumulation time of 0 and the accumulation time of the last pixel in the line is one horizontal scanning time. That is, the photogenerated charges accumulated in the dark signal readout period differ depending on the position of the high luminance portion on the screen. The pixel read immediately after reset has a level of 0, and the accumulated photogenerated charge of the last pixel in the line is maximized. In the first embodiment, the high-luminance pixel is determined from the bright signal immediately before the dark signal is read. However, the high-luminance determination threshold voltage Vref is changed according to the position on the screen for the above reason. It is effective to make it. This is shown in FIG. The Vref voltage P is changed to be large at the beginning of the horizontal scanning period and small at the end. That is, as the end of the horizontal scanning period, the threshold voltage of the high luminance part is decreased to make it easy to output the high luminance detection pulse K. As a result, it is possible to generate the optimum high-intensity detection pulse K in consideration of the difference in accumulation time. Incidentally, in the second embodiment, there is no problem even if the Vref voltage Q is constant because the photogenerated charge level included in the dark signal is directly detected.
[0036]
In each of the embodiments described above, the case where the dark signal is read out by one row per frame has been described. However, the dark signal is read out continuously by several rows per frame or at intervals. It doesn't matter. For example, when a solid-state image sensor having N rows of light-receiving units continuously reads out two rows per frame, signals are read from the solid-state image sensor as follows.
1S, 1F, 2S, 2F, 3S, 4S, 5S ... NS in the first frame
1S, 2S, 3S, 3F, 4S, 4F, 5S ... NS in the second frame
In addition, when reading two rows per frame with an interval of two rows, signals are read as follows.
1S, 1F, 2S, 3S, 4S, 4F, 5S ... NS in the first frame
1S, 2S, 2F, 3S, 4S, 5S, 5F ... NS in the second frame
[0037]
The arrangement and effect of each claim of the present invention are summarized as follows.
[0038]
(1) A solid-state image sensor that reads and processes a signal obtained by scanning photogenerated charges generated in response to incident light to unit solid-state image sensors arranged in a matrix in the horizontal and vertical directions as a video signal. In the signal readout processing method of
The vertical specific rows are changed every predetermined vertical scanning period, and the dark signal of each pixel obtained immediately after resetting the photogenerated charge of each pixel in the horizontal blanking period of the specific row is obtained. The dark signal of each pixel in the effective row is stored in the memory, and the update of the dark signal of each pixel in all the effective rows stored in the memory is performed in correspondence with each pixel for each predetermined vertical scanning period. Corresponding to the dark signal of the pixels in each row read from the memory without performing for the specific pixel determined that the signal component level due to the photogenerated charge contained in the obtained dark signal exceeds a predetermined level A signal readout processing method for a solid-state imaging device that performs subtraction processing from the light signal of the pixels in each row.
[0039]
According to the configuration of (1) above, dark-time FPN data can be taken in with high accuracy even when there is a high-luminance subject.
[0040]
(2) The storage in the memory and the update of the storage contents are intermittently performed with a plurality of predetermined vertical scanning periods in which only the light signal is read out. (1) The signal readout processing method of the solid-state imaging device described in 1.
[0041]
According to the configuration of (2) above, the dark-time FPN data can be taken in with high accuracy even when there is a high-luminance subject as in (1).
[0042]
(3) The specific pixel is a pixel in which a bright signal level of a bright signal read immediately before reading out the dark signal exceeds a predetermined threshold level. (1) or (2) The signal readout processing method of the solid-state imaging device described in 1.
[0043]
According to the configuration of (3) above, since the high-intensity part of the bright signal is used, level detection is facilitated.
[0044]
(4) The specific pixel is a pixel whose difference exceeds a predetermined level by comparing the dark signal read from the solid-state image sensor and the corresponding dark signal level stored in the external memory. (1) or (2) The signal readout processing method of the solid-state imaging device described in 1.
[0045]
According to the configuration of (4) above, since a dark signal is directly used for detection, highly accurate level detection is possible.
[0046]
(5) Updating the memory content of the memory is a process of storing the content read from the memory as it is for the specific pixel. (1) The signal readout processing method of the solid-state imaging device described in 1.
[0047]
According to the configuration of (5) above, the dark-time FPN data can be taken in with high accuracy even when there is a high-luminance subject as in (1).
[0048]
(6) The predetermined level is changed with respect to the pixels in the horizontal direction. (1)-(3) Any of Crab A signal readout processing method of the solid-state imaging device described.
[0049]
According to the configuration of (6) above, the level detection of (4) can be performed more accurately.
[0050]
(7) The specific line is a single line. (1)-(5) Any of Crab A signal readout processing method of the solid-state imaging device described.
[0051]
According to the configuration of (7) above, continuity during moving image capturing is improved.
[0052]
(8) The specific line is a plurality of continuous lines. (1)-(5) Any of Crab A signal readout method of the solid-state imaging device described.
[0053]
With configuration (8) above, the refresh cycle of the FPN memory is shortened, and the responsiveness to temperature changes and the like is improved.
[0054]
(9) The specific line is a plurality of lines at intervals. (1)-(5) Any of Crab A signal readout processing method of the solid-state imaging device described.
[0055]
According to the configuration of (9) above, the refresh cycle of the FPN memory is shortened as in (8), and the responsiveness to temperature changes and the like is improved.
[0056]
【The invention's effect】
As described above in detail, according to the signal readout processing method of the solid-state imaging device of the present invention, FPN suppression that can cope with high-accuracy video imaging without generation of false signals even when there is a high-luminance subject is realized. it can.
[Brief description of the drawings]
FIG. 1 is a configuration block diagram showing a first embodiment of a signal readout processing method of a solid-state imaging device according to the present invention.
FIG. 2 is a timing chart for explaining the operation of the configuration shown in FIG. 1;
FIG. 3 is a timing chart for explaining the operation of the configuration shown in FIG. 1;
FIG. 4 is a configuration block diagram showing a second embodiment of a signal readout processing method of a solid-state imaging device according to the present invention.
FIG. 5 is a configuration block diagram showing a third embodiment of the signal readout processing method of the solid-state imaging device according to the present invention.
FIG. 6 is a configuration block diagram showing a fourth embodiment of the signal readout processing method of the solid-state imaging device according to the present invention.
FIG. 7 is a block diagram of conventional FPN suppression means.
8 is a diagram for explaining the operation of the configuration shown in FIG. 7; FIG.
FIG. 9 is a block diagram showing another example of conventional FPN suppression means.
FIG. 10 is a timing chart showing signal waveforms of respective parts for explaining the operation of the conventional FPN suppressing means.
FIG. 11 is a timing chart showing signal waveforms of respective parts for explaining the operation of the conventional FPN suppressing means.
[Explanation of symbols]
1,31 Solid-state image sensor
2,32 amplifier
3,33 A / D converter
4 1H delay line
5,34 selector switch
6,111,36 subtractor
7,37 D / A converter
8,35 FPN memory
9,11 level detector
10 AND circuit
12 Switch circuit
101 Light receiver
102 Vertical scanning circuit
103 Horizontal scanning circuit
112 comparator
113 Inverter

Claims (5)

Signal readout of a solid-state imaging device that reads out and processes a signal obtained by scanning photogenerated charges generated in response to incident light on unit photoelectric conversion elements arranged in a matrix in the horizontal and vertical directions as a video signal In the processing method,
Each position immediately after resetting the photogenerated charge of each pixel in the horizontal blanking period of the specific row by changing the position in the vertical direction of the specific row as a dark signal extraction target for each predetermined vertical scanning period The dark signal of each pixel in all the effective rows obtained by repeating the operation of reading out the dark signal of the pixel for every specific row that changes sequentially is stored in the memory, and stored in the memory for each predetermined vertical scanning period. The update of the dark signal of each pixel in all the valid rows is performed for the pixels other than the specific pixel in which the bright signal level of the bright signal read immediately before reading the dark signal exceeds a predetermined threshold level , A signal readout processing method for a solid-state imaging device, wherein a dark signal of pixels in each row read from a memory is subtracted from a bright signal of pixels in each corresponding row. The note updating of the contents of Li, the for a specific pixel, signal readout processing system for a solid state image pickup device according to claim 1 is a process of directly storing the contents read out from the memory. 2. The signal readout processing method for a solid-state imaging device according to claim 1 , wherein the predetermined level is changed with respect to a pixel in a horizontal direction . 2. The signal readout processing method for a solid-state imaging device according to claim 1 , wherein the specific row is a single row . 2. The signal readout system for a solid-state imaging device according to claim 1, wherein the specific row is a plurality of continuous rows .

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