JP2010130194A - A/d conversion apparatus and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that specific noise is generated by interference of a period for A/D conversion of an analog signal and periodical noise in a conventional art. <P>SOLUTION: An A/D conversion apparatus 101 has: an A/D converter 102 that converts an analog electrical signal into a digital signal at a predetermined timing; and a timing generator 103 that changes the timing period of the A/D converter irregularly. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an A / D converter that converts an analog signal into a digital signal, and an imaging apparatus using the A / D converter.

  A general digital camera has a CCD image sensor or a CMOS image sensor. These image sensors receive subject light with a two-dimensionally arranged photoelectric conversion unit and output an analog electric signal corresponding to the received light quantity. Then, the photoelectrically converted analog electrical signal is sequentially converted into a digital signal for each pixel (A / D conversion), and the digital signal for one screen is output as image data to a display or a memory.

However, since a general A / D conversion apparatus has a constant A / D conversion timing cycle, A / D conversion is performed when there is periodic noise due to a power supply unit or a clock circuit used in the same apparatus. The beat period (interference noise) may occur due to interference between the timing period and the noise period. The beat noise appears as a fixed pattern stripe noise in the photographed image, and the image quality is significantly impaired. Therefore, a technique for phase-synchronizing a plurality of clocks has been studied (see, for example, Patent Document 1).
JP 2006-157720 A

  However, if a complex circuit that synchronizes the phases of multiple clocks is required, or if periodic noise is power supply noise, disturbance noise, etc., the circuit board is separate or a complex noise source. In many cases, it is difficult to achieve phase synchronization completely. Even when analog audio signals and other analog signals are A / D converted as well as image signals as described above, the noise period included in the analog signal to be A / D converted and the timing period for A / D conversion A similar problem arises in the condition of interference.

  An object of the present invention is to provide an A / D conversion device and an imaging device that can make fixed pattern noise inconspicuous when an analog signal including periodic noise is A / D converted.

  An A / D converter according to the present invention includes an A / D converter that converts an analog electrical signal into a digital signal at a predetermined timing, and a timing generator that irregularly changes the timing period of the A / D converter. It is characterized by having.

  An imaging apparatus according to the present invention includes a plurality of photoelectric conversion units that convert subject light incident via a photographing optical system into analog electrical signals, and analog outputs that are sequentially output from the plurality of photoelectric conversion units at a predetermined cycle. An A / D converter that converts an electrical signal into a digital signal at a predetermined timing, a timing generator that irregularly changes the timing period of the A / D converter, and a digital signal output by the A / D converter And an image output unit that outputs the image data.

  Preferably, a timing cycle output from the timing generator is shorter than a cycle in which the plurality of photoelectric converters sequentially output analog electric signals, and the A / D converter performs A / D conversion. It is characterized by including time.

  Preferably, the plurality of photoelectric conversion units constitute an imaging device arranged in a two-dimensional matrix.

  Preferably, the image pickup device is configured by a CMOS image pickup device that reads all at once for each row, and the A / D converter is arranged for each column of the image pickup device.

  Preferably, the image pickup device is configured by a CCD type image pickup device that horizontally transfers and outputs one pixel at a time for each row, and the A / D converter is provided at a position that is horizontally transferred and output from the image pickup device. It is arranged.

  The A / D conversion device and the imaging device according to the present invention can make fixed pattern noise inconspicuous when A / D converting an analog signal including periodic noise.

  Hereinafter, embodiments relating to an A / D conversion device and an imaging device according to the present invention will be described. First, FIG. 1 is a block diagram of an A / D conversion apparatus 101 according to this embodiment.

  In FIG. 1, an A / D converter 101 receives an analog electrical signal and converts it into a digital signal, and generates timing for giving A / D conversion timing to the A / D converter 102. Part (TG) 103. The A / D converter 102 converts the input analog signal into a digital signal having a quantization bit number of 12 bits (4096 gradations), for example. Here, the analog signal input to the A / D conversion unit 102 is, for example, an analog image signal output from a photoelectric conversion unit configured by a photodiode or the like, an analog audio signal output from a microphone, or an acceleration sensor. And analog signals output by sensors such as temperature sensors.

  The timing generation unit 102 gives A / D conversion timing to the A / D conversion unit 102. In this embodiment, the timing for A / D conversion is changed randomly (irregularly) instead of a fixed period. Here, the relationship among the analog signal, the timing signal, and the digital signal will be described with reference to FIG. In FIG. 2, an analog signal input to the A / D conversion unit 102 is converted into a digital signal at each timing of timing signals s <b> 1 to s <b> 7 output from the timing generation unit 103. Here, the digital signal is converted into a digital value with a predetermined number of quantization bits, for example, a digital value with a quantization bit number of 12 bits (4096 gradations), at each timing of the timing signals s1 to s7. Digital data. Note that the A / D conversion timing is precisely the timing at which an analog signal is sampled and held, and the timing at which an analog signal is sampled and held randomly changes.

  In FIG. 2, the intervals (cycles) t1 to t7 between the timing signals s1 to s7 output by the timing generator 103 are not constant. For example, the interval t1 between the timing signals s1 and s2 is shorter than the interval t2 between the timing signals s2 and s3, but longer than the interval t3 between the timing signals s3 and s4. That is, the period of the timing signal output from the timing generator 103 changes randomly. At this time, the interval between the output digital signals also changes according to the intervals t1 to t7 between the timing signals s1 to s7, but the digital value does not change during each interval between the intervals t1 to t7. It is also possible to output to the outside in line with the digital signal.

  Here, a method of generating a randomly changing timing signal can be realized, for example, by providing an M-sequence code circuit that generates a pseudo-random signal in a logic circuit that generates a timing pulse. Further, the generation by software can be realized by controlling the output of the timing signal using the random number generated by the random number generation process. Alternatively, an analog circuit using white noise unique to the diode may be used. In the present embodiment, any method other than the above may be used as long as the period of the timing signal generated by the timing generator 103 can be irregularly changed.

  Next, the difference between the case where the timing period of the timing generator 103 is a fixed period and the case where it is a random period will be described with reference to FIG. 3A shows a case where the timing cycle is a fixed cycle, and FIG. 3B shows a case where the timing cycle is a random cycle. Further, in FIG. 3A and FIG. 3B, only an analog noise component that changes periodically is drawn without drawing an image signal and an audio signal input to the A / D converter 102 for easy understanding. It is exaggerated. In the figure, the period in which the analog noise component changes is depicted as a period slightly shorter than the timing period at which the A / D converter 102 performs A / D conversion, but it may be shifted to a longer period. In any case, there is a problem when there is a difference between the fixed period of the timing signal and the period of the noise component.

  In FIG. 3A, an analog noise signal input to the A / D converter 102 is a digital signal at timings s11 to s17 output from the timing generator 103 at a fixed interval (fixed period) tc1. Is converted to However, the difference between the cycle tc1 of the timing signals s11 to s17 and the noise cycle tnc1 appears as beat noise (interference noise). For example, the level of the analog signal sampled and held by the timing signal S11 in FIG. 3A is substantially the same as the level of the analog signal sampled and held by the timing signal S14 three times later. Similarly, the level of the analog signal sampled and held by the timing signal S12 is almost the same as the level of the analog signal sampled and held by the timing signal S15 three times later, and the analog signal sampled and held by the timing signal S13 The level and the level of the analog signal sampled and held by the timing signal S16 after the third level are substantially the same. Further, the level of the analog signal sampled and held by the timing signal S14 and the level of the analog signal sampled and held by the third timing signal S17 are almost the same, so that the timing signal S11, the timing signal S14, and the timing signal S17 The level of the analog signal sampled and held at each timing is substantially the same.

  In this manner, beat noise that repeats a periodic value occurs every three timing signals, and the digital signal output at each timing of the timing signals s11 to s17 is also the noise period and the A / D conversion timing period. Inherent noise that changes with the beat period due to the difference between the two appears. Beat noise is displayed on the image as vertical, horizontal, or diagonal stripe noise in the case of an image, and is output as a beat sound in the case of audio. In the case of an analog signal such as a sensor, the sensor may malfunction or the accuracy of the sensor may be deteriorated. As described above, when A / D conversion is performed on an analog signal at a fixed timing cycle, various problems occur due to the influence of periodic noise due to power supply, disturbance, and the like.

  Therefore, in the case of the A / D conversion device 101 according to the present embodiment, the timing generation unit 103 makes the A / D conversion timing cycle given to the A / D conversion unit 102 random, so that it is specific to the output digital signal. No beat noise. For example, as shown in FIG. 3B, timing signals s1 to s7 of a random period output from the timing generator 103 are given to the A / D converter 102, and intervals t1 to t7 between the timing signals s1 to s7 are Change irregularly. As a result, there is no periodicity in the level of the analog signal sampled and held at each timing of the timing signals s1 to s7, and no inherent beat noise appears in the digital signal output from the A / D converter 102.

  As described above, the A / D conversion apparatus 101 according to this embodiment does not generate beat noise inherent in the output digital signal even when A / D converting an analog signal including periodic noise, and generates periodic noise. It can be inconspicuous.

(Application examples to imaging devices)
Next, an embodiment of the imaging device 201 will be described as an application example of the A / D conversion device 101 described above. Here, as an example of the imaging apparatus 201, a case of a camera such as a digital camera or a video camera will be described. However, an imaging apparatus having a line sensor for one line or several lines such as a scanner or a FAX may be used. I do not care.

  FIG. 4 is a block diagram illustrating a configuration of the imaging apparatus 201. In FIG. 4, the same reference numerals as those in FIG. The imaging apparatus 201 includes a lens 202, an imaging element 203, an A / D conversion unit 204, a timing generation unit (TG) 205, an image buffer 206, a system bus 207, a control unit 208, and an image processing unit 209. And a display circuit 210, a liquid crystal monitor 211, a memory card IF 212, a memory card 212a, a memory 213, and an operation panel 214. The A / D conversion unit 204 and TG 205 correspond to the A / D conversion unit 102 and TG 103 in FIG. 1, and the A / D conversion device 101 in FIG. 1 corresponds to a part surrounded by a dotted line 250 in FIG. .

  In FIG. 4, the subject light incident from the lens 202 is imaged on the light receiving surface of the image sensor 203. Here, the image pickup device 203 is a CCD type image pickup device including a plurality of photoelectric conversion units (photodiodes) and readout circuits arranged in a two-dimensional matrix in the row direction and the column direction. The subject light imaged on the light receiving surface of the image sensor 203 is converted into an analog electrical signal by the photoelectric converter, and is output to the A / D converter 204 in accordance with the readout signal output from the TG 205 to the image sensor 203. The

  Here, the configuration of the image sensor 203 will be described with reference to FIG. FIG. 5 is a diagram showing a configuration example of the CCD type image sensor 203. In FIG. 5, the same reference numerals as those in FIG. 4 denote the same components. The imaging element 203 illustrated in FIG. 5 includes 154 pixels of 11 rows from row a to row k and 14 columns from column 1 to column 14. The electric charge accumulated in the photodiode of each pixel according to the amount of incident light is read out to the horizontal transfer circuit 301 by the bucket relay method in the column direction according to the readout signal in units of rows output from the TG 205. Further, the charge for one row read to the horizontal transfer circuit 301 in accordance with the pixel-unit readout signal output from the TG 205 is an A / D conversion unit outside the image sensor 203 by the bucket relay method for each pixel. 204 is output as an analog electric signal. The A / D converter 204 is supplied with an analog power supply AVcc and a reference voltage Vref for A / D conversion, and is grounded (GND). The digital signal output from the A / D conversion unit 204 is temporarily stored in the image buffer 206 as shown in FIG.

  Next, the operation when reading signals from 154 pixels of the image sensor 203 shown in FIG. 5 will be described in detail with reference to FIG. FIG. 6A shows the case where the timing signal has a fixed period, and FIG. 6B shows the case where the timing signal has a random period. Similarly to FIG. 3, the analog image signal is drawn with only the analog noise component that periodically changes. Although the case of a general analog signal has been described with reference to FIG. 3, the case of reading an analog image signal from the image sensor 203 will be described with reference to FIG. 6.

  In the case of the image sensor 203, as described with reference to FIG. 5, since A / D conversion is performed for each pixel, the relationship between the period of conversion to a digital signal for each pixel and the noise period becomes a problem. In general, in a digital camera or the like, in order to speed up the processing at the time of shooting, the time until the image signal for one screen shot is read from the image sensor 203 and stored as image data in the image buffer 206 is determined at the time of design. The time for reading from the image sensor 203 in units of pixels is limited. For example, it is determined as 500 nsec per pixel. Therefore, the sample and hold timing for A / D conversion must be within this time. However, the process of converting the analog signal once sampled and held into a digital signal can be performed together later, but the sample and hold timing must be performed within the time when the analog pixel signal is read out. There is. For example, in FIGS. 6A and 6B, an interval (period) tp1 indicates this pixel period, and each timing signal for A / D conversion is an interval between the pixels a1 to a7. One is always required within tp1. In the case of FIG. 6A, since the timing signal is a fixed cycle, the timing cycle tc1 and the pixel interval tp1 are drawn at the same interval. Note that the sample-holding timings s11 to s17 and the pixel change point are not necessarily matched as shown in FIG.

  In the case of FIG. 6A, as in the case of FIG. 3A, the period tc1 of the timing signals s1 to s7 interferes with the noise period tnc1, and beat noise with a beat period of every three pixels is generated. Such beat noise appears as striped noise in the captured image, as shown in FIG. In FIG. 7A, pixels a1 to a7 correspond to pixels a1 to a7 in FIG. In addition, although the noise position is drawn so as to be shifted by one pixel for each row, for example, when noise appears at the same position for each row, the noise becomes a vertical stripe pattern that periodically changes in units of columns. In any case, the same pattern appears periodically, so it is noticeable. Further, FIG. 7A shows an example of displaying an image in the case of only periodic noise, and is drawn with emphasis so that black and white are clear, but the actual noise level is about 4096 gradations of about 10 gradations. .

  On the other hand, in the case of the imaging apparatus 201 according to the present embodiment, as shown in FIG. 6B, the A / D provided to the A / D converter 204 by the timing generator 205 is the same as in the case of FIG. Since the timing cycle of D conversion is randomly changed, a periodic pattern does not appear in the output digital signal. For example, as shown in FIG. 6B, timing signals s1 to s7 of a random period output from the timing generator 205 are given to the A / D converter 204, and intervals t1 to t7 between the timing signals s1 to s7 are Change irregularly. As a result, there is no periodicity in the level of the analog image signal sampled and held at each timing of the timing signals s1 to s7, and no beat appears in the digital image signal output from the A / D converter 204. For example, as shown in FIG. 7B, periodic noise is dispersed in the captured image so that it is not noticeable. In FIG. 7B, the pixels a1 to a7 correspond to the pixels a1 to a7 in FIG. FIG. 7B shows an example of image display in the case of only periodic noise, as in FIG. 7A, and is drawn with emphasis so that black and white are clear.

  As described above, the imaging apparatus 201 according to the present embodiment has a periodic pattern that does not appear in the output digital image signal even when the analog image signal including the periodic noise is A / D converted. Can be eliminated.

  In FIG. 6B, the timing signal interval t1 to t7 changes irregularly and becomes shorter or longer, but the timing signal interval t1 to t7 is one pixel when reading from the image sensor 203. When the hit reading time is fixed, it is necessary to make it smaller than twice the reading time (including the time for A / D converting the sampled and held analog signal and outputting the digital signal). Therefore, the timing generation unit 205 in FIG. 4 randomly generates timing signals within this range. Alternatively, when an image signal is read out from the image sensor 203 by randomly changing the readout time per pixel itself, the total time for reading the image signal for one screen from the image sensor 203 is an image for one screen from the image sensor 203. The design time for reading the signal may be set.

  Further, although the CCD type image pickup device 203 shown in FIG. 4 has the A / D conversion unit 204 provided outside, the A / D conversion unit 204 may be provided inside the image pickup device 203.

  Next, an example of a CMOS image sensor will be described. FIG. 8 is a diagram showing a configuration of a CMOS type image sensor 303. In FIG. 8, 14 A / D converters 304 (1) to 304 (14) are in the A / D converter 204 in FIG. 5, TG 305 is in TG 205 in FIG. 5, and image buffer 306 is in the image buffer in FIG. 206 respectively. 5 is different from the CCD-type image pickup device 203 in that A / D converters 304 (1) to 304 (14) are provided for each column, and analog signals read to each column in units of rows are simultaneously converted to A. / D conversion.

  In FIG. 8, the image sensor 303 includes 224 pixels of 16 rows from row a to row p and 14 columns from column 1 to column 14. The electric charge accumulated in the photodiode of each pixel according to the amount of incident light is converted into an analog electric signal, and read out in units of rows to the vertical readout line provided for each column according to the address selection signal output from the TG 305. It is. The analog electric signals read out to the vertical signal lines of each column are respectively input to 14 A / D conversion units 304 (1) to 304 (14) provided for each column. The A / D converters 304 (1) to 304 (14) perform A / D conversion simultaneously according to the timing signal output from the TG 305. The digital signal converted by the A / D converters 304 (1) to 304 (14) is temporarily stored in the image buffer 306. Note that digital signals may be transferred from the 14 A / D converters 304 to the image buffer 306 in parallel, and the A / D converters 304 (1) to 304 (14) and the image buffer 306 may be transferred. A buffer for holding a digital signal may be provided between them, and the pixels may be transferred to the image buffer 306 pixel by pixel.

  Next, the operation when signals are read from 224 pixels of the image sensor 303 shown in FIG. 8 will be described in detail with reference to FIG. 9A shows a case where the timing signal has a fixed period, and FIG. 9B shows a case where the timing signal has a random period. Similarly to FIG. 3, the analog image signal is drawn with only the analog noise component that periodically changes. Here, as in the case of the image sensor 203 in FIG. 6, a description will be given specifically for the case of reading an analog image signal.

  In the case of the imaging device 303, as described with reference to FIG. 8, A / D conversion is performed by 14 A / D conversion units 304 for each row, and therefore, a cycle of conversion to a digital signal for each row and a noise cycle The relationship becomes a problem. In the case of FIG. 6A of the CCD-type imaging device 203 described above, the timing when A / D conversion is performed on the timing signals s11 to s17 with the fixed period tc1 in units of pixels for the pixels a1 to a7 is shown. In the case of FIG. 9A of the image sensor 303, the timing when A / D conversion is performed on the timing signals s21 to s27 in the fixed period tc2 from the a row to the g row in units of rows is shown. Note that the period tcn2 of the periodic noise of the analog signal is also drawn with a period slightly shorter than the period tc2 when A / D conversion is performed in units of rows. Therefore, the cases of FIGS. 6A and 6B and FIGS. 9A and 9B are drawn based on the period of the pixel unit or the period of the row unit. It differs depending on whether it is drawn on.

  In the case of FIG. 9A, the A / D conversion cycle tc2 and the noise cycle tnc2 of the row unit interfere with each other to generate beat noise of the beat cycle every three rows. As shown in FIG. 10A, such beat noise appears as a noise with a horizontal stripe pattern that differs from line to line in a captured image. Note that lines a to g in FIG. 10A are the same as lines a to g in FIG. 9A. FIG. 10A shows a display example of an image of only periodic noise, and is drawn with emphasis so that black and white is clear.

  On the other hand, in the case of the image sensor 303, as shown in FIG. 9B, as in the case of FIG. 3B, the A / D conversion given to the 14 A / D converters 304 by the timing generator 305. Since the timing period is randomly changed, a periodic pattern does not appear in the output digital signal. For example, as shown in FIG. 9B, timing signals s31 to s37 of a random period output from the timing generator 305 are given to the A / D converter 304, and intervals t31 to t37 between the timing signals s31 to s37 are Change irregularly. As a result, there is no periodicity in the level of the analog image signal sampled and held at each timing of the timing signals s31 to s37, and a beat also appears in the digital image signals output from the 14 A / D converters 304. Absent. For example, as shown in FIG. 10B, the captured image is not noticeable because periodic noise is dispersed in units of rows and the periodicity is lost. Note that line a to line g in FIG. 10B correspond to line a to line g in FIG. FIG. 10B shows a display example of an image containing only periodic noise, as in FIG. 10A, and is drawn with emphasis so that the black and white are clear.

  As described above, even in an image pickup apparatus using the CMOS image pickup element 303, a periodic pattern due to periodic noise does not appear in the A / D converted digital image signal, and the periodic noise can be made inconspicuous.

  Similarly to the case of FIG. 6B, in FIG. 9B, the timing signal intervals t31 to t37 vary irregularly and become shorter or longer, but the timing signal intervals t31 to t37. If the readout time per row when reading from the image sensor 303 is fixed, twice the readout time (including the time for A / D converting the sampled and held analog signal and outputting the digital signal) ) It needs to be smaller. Therefore, the timing generator 305 in FIG. 8 randomly generates timing signals within this range. Alternatively, when the image signal is read from the image sensor 303 with the read time per row changed randomly, the total time for reading the image signal for one screen from the image sensor 303 is one image from the image sensor 303. It may be within a range that satisfies the design time for reading the signal.

  Further, the CMOS type image pickup device 303 shown in FIG. 8 is provided with the A / D conversion unit 304 for each column inside, but even if it is a CMOS type image pickup device, the CCD type image pickup device shown in FIG. An A / D conversion unit may be provided outside as in 203. In this case, 14 A / D converters may be provided outside, and a circuit that holds an analog signal for each column in a capacitor or the like and outputs it to the outside in units of pixels is provided inside the CMOS type image pickup device. In this case, it is only necessary to provide one A / D conversion unit 204 outside as in the CCD type image pickup device 203 shown in FIG. In the above embodiment, A / D conversion has been described in units of pixels and rows. However, even when A / D conversion is performed in units of columns, the timing of A / D conversion can be changed to random, as shown in FIG. Contrary to the case of the above, it is possible to suppress a phenomenon in which beat noise having a vertical stripe pattern appears in the column direction. Further, the same applies when A / D conversion is performed at a fixed period, such as A / D conversion in units of several pixels.

  As described above, as described in each embodiment, the A / D conversion apparatus and the imaging apparatus according to the present invention make fixed pattern noise inconspicuous when A / D converting an analog signal including periodic noise. can do.

1 is a block diagram of an A / D conversion device 101 according to the present embodiment. It is explanatory drawing which shows the timing of A / D conversion of the A / D conversion apparatus 101 which concerns on this embodiment. It is explanatory drawing which shows the difference between a fixed period and a random period. It is a block diagram of the imaging device 201 concerning this embodiment. 2 is a block diagram illustrating a configuration of a CCD type image sensor 203. FIG. It is explanatory drawing which shows the difference of the fixed period and random period of the image pick-up element 203. FIG. It is explanatory drawing which shows the example of an image of the fixed period and random period of the image pick-up element 203. FIG. 3 is a block diagram showing a configuration of a CMOS type image sensor 303. FIG. It is explanatory drawing which shows the difference of the fixed period and random period of the image pick-up element 303. FIG. It is explanatory drawing which shows the example of an image of the fixed period and random period of the image pick-up element 303. FIG.

Explanation of symbols

101 ... A / D converter 102 ... A / D converter 103 ... timing generator (TG)
DESCRIPTION OF SYMBOLS 201 ... Imaging device 202 ... Lens 203 ... Imaging element 204 ... A / D conversion part 205 ... Timing generation part (TG)
206 ... Image buffer 207 ... System bus 208 ... Control unit 209 ... Image processing unit 210 ... Display circuit 211 ... Liquid crystal monitor 212 ... Memory card IF 212a ... Memory card 213 ... Memory 214 ... Operation panel 303 ... Image sensor 304 (1) to 304 (14) ... A / D converter 305 ... Timing generator (TG)
306: Image buffer

Claims (6)

An A / D converter that converts an analog electrical signal into a digital signal at a predetermined timing;
A timing generation unit that irregularly changes a timing period of the A / D conversion unit. A plurality of photoelectric conversion units that convert subject light incident through the photographing optical system into analog electrical signals;
An A / D converter that converts analog electrical signals that are sequentially output from the plurality of photoelectric converters into a digital signal at a predetermined timing; and
A timing generator for irregularly changing the timing cycle of the A / D converter;
An image output device comprising: an image output unit configured to output a digital signal output from the A / D conversion unit as image data. The imaging device according to claim 2,
The timing cycle output by the timing generation unit is shorter than the cycle in which the plurality of photoelectric conversion units sequentially output analog electrical signals, and includes a time for the A / D conversion unit to perform A / D conversion. An imaging device that is characterized. In the imaging device according to claim 2 or 3,
The plurality of photoelectric conversion units constitute an imaging device arranged in a two-dimensional matrix. The imaging apparatus according to claim 4,
The image pickup device is composed of a CMOS type image pickup device that reads all at once for each row,
The A / D conversion unit is arranged for each column of the imaging elements. The imaging apparatus according to claim 4,
The image sensor is composed of a CCD type image sensor that horizontally transfers and outputs one pixel per row,
One A / D conversion unit is arranged at a position to be horizontally transferred and output from the imaging element.

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