JP2009005015A - Imaging apparatus, imaging system, and method for driving imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus and an imaging system capable of improving a temporal correlation between a signal for a storage operation for a long period and the signal for the storage operation in a short period. <P>SOLUTION: The imaging apparatus has a pixel array arraying a plurality of pixels containing photoelectric conversion sections respectively in the line direction and the row direction and a line selecting section selecting and driving pixels in either line in the pixel array. The imaging apparatus further has a reading section reading and successively outputting the signals for the pixels in each row from the pixels in the line selected by the line selecting section for one-line period for selecting one line by the line selecting section. The reading section conducts a first reading operation reading the signal stored for a first storage period from a period before the one-line period is started to the intermediate period of the one-line period from the pixels and a second reading operation reading the signal stored for a second storage period shorter than the first storage period and the one-line period from the pixels for the one-line period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging device, an imaging system, and a driving method of the imaging device.

  In an imaging device having a pixel array in which pixels including a photoelectric conversion unit are arranged in a row direction and a column direction, the photoelectric conversion unit performs an accumulation operation of signal charges.

In the imaging apparatus disclosed in Patent Document 1, the photoelectric conversion unit performs a long-period accumulation operation in the first half of one field period (one frame period), and the photoelectric conversion unit performs a short-period accumulation operation in the second half of one field period. Do. Thus, in a captured image signal of one field period, if a signal for accumulation operation for a short period is used for a high luminance part and a signal for accumulation operation for a long period is used for a low luminance part, the dynamic range of the signal is increased. Can be enlarged.
JP 07-095481 A

  In the imaging apparatus disclosed in Patent Document 1, the timing at which each photoelectric conversion unit completes the accumulation operation for a long period and the timing at which each photoelectric conversion unit completes the accumulation operation for a short period are at least 1/2 field period. Just shift. Thereby, in the captured image signal, there is a possibility that the temporal correlation between the signal for the accumulation operation for a long period and the signal for the accumulation operation for a short period may be low.

  An object of the present invention is to provide an imaging apparatus and an imaging system capable of improving the temporal correlation between a long-period accumulation operation signal and a short-period accumulation operation signal.

  An imaging apparatus according to a first aspect of the present invention includes a pixel array in which a plurality of pixels each including a photoelectric conversion unit are arrayed in a row direction and a column direction, a row selection unit that selects a row in the pixel array, and the row In one line period from selection of one row to selection of the next row, the signals of the pixels in each column are read out from the pixels in the row selected by the row selection unit and sequentially output. A first readout operation for reading out signals accumulated in a first accumulation period from the start of the one line period to the middle of the one line period from a pixel; A second readout operation for reading out signals accumulated in the second accumulation period shorter than the first accumulation period and shorter than the one line period from the pixels is performed in the one line period.

  An imaging system according to a second aspect of the present invention processes the imaging device according to the first aspect of the present invention, an optical system that forms an image on the imaging surface of the imaging device, and a signal output from the imaging device. And a signal processing unit for generating image data.

  An imaging apparatus driving method according to a third aspect of the present invention includes a pixel array in which a plurality of pixels each including a photoelectric conversion unit are arrayed in a row direction and a column direction, and a row selection unit that selects a row in the pixel array. In a one-line period from the selection of one row by the row selection unit to the selection of the next row, the signals of the pixels in each column are read out from the pixels in the row selected by the row selection unit. And a readout unit that sequentially outputs the signals, wherein the readout unit outputs the signal accumulated in the first accumulation period from the start of the one line period to the middle of the one line period. A first reading step of performing a first reading operation for reading from a pixel in a part of the one line period; and a second step in which the reading unit is shorter than the first accumulation period and shorter than the one line period. Accumulation of The second read operation for reading the stored signal period from a pixel, characterized in that a second reading step of performing in another part of the period of the one line period.

  According to the present invention, it is possible to improve the temporal correlation between a long period accumulation operation signal and a short period accumulation operation signal.

  The problem of the present invention will be described using the imaging device 1.

  First, the configuration of the imaging apparatus 1 will be described with reference to FIG. FIG. 1 is a circuit configuration diagram of an imaging apparatus 1 used for explaining the problem of the present invention.

  The imaging device 1 includes a pixel array PA, a row selection unit 40, a reading unit 20, and an output unit 30.

  In the pixel array PA, a plurality of pixels P11, P21, ..., Pmn, ... are arranged in the row direction and the column direction. Each pixel P11 includes a photoelectric conversion unit 2, a transfer unit 6, a charge-voltage conversion unit 7, an amplification unit 4, a reset unit 5, and a selection unit 3. The photoelectric conversion unit 2 performs an accumulation operation for accumulating light as a charge signal. The photoelectric conversion unit 2 is, for example, a photodiode. The transfer unit 6 transfers the signal accumulated by the photoelectric conversion unit 2 to the charge-voltage conversion unit 7 during a period in which the signal Tx1 supplied from the row selection unit 40 is active. At this time, the pixel P11 is reset. That is, the photoelectric conversion unit 2 is reset. The transfer unit 6 is, for example, a transfer MOS transistor to which a signal Tx1 is supplied to its gate. The charge-voltage converter 7 converts the charge as the transferred signal into a voltage. The charge-voltage converter 7 is, for example, a floating diffusion (FD). The reset unit 5 resets the charge-voltage conversion unit 7 during a period in which the signal Reset1 supplied from the row selection unit 40 is active. Here, resetting the pixel P11 means resetting the photoelectric conversion unit 2, and is different from resetting the charge-voltage conversion unit 7.

  The amplifying unit 4 amplifies the voltage as a signal supplied from the charge / voltage converting unit 7 and outputs the amplified voltage to the column signal line RL. The amplifying unit 4 is, for example, an amplifying MOS transistor in which the voltage supplied from the charge-voltage converting unit 7 is input to its gate, and operates as a source follower together with the constant current source CI connected via the column signal line RL. . The selection unit 3 transmits the output signal of the amplification unit 4 to the column signal line RL during a period in which the signal Select1 supplied from the row selection unit 40 is active. The selection unit 3 is, for example, a selection MOS transistor that receives the signal Select1 at its gate.

  The row selection unit 40 includes a vertical scanning circuit 41. The vertical scanning circuit 41 drives the pixels P11,... By supplying signals Tx1, Reset1, Select1, etc. to the pixels P11,. For example, the vertical scanning circuit 41 supplies Select 1 to the selection unit 3 to select and drive the pixels P 11,. That is, the row selection unit 40 selects and drives pixels in any row in the pixel array PA.

  The readout unit 20 includes readout circuits 20a, 20b,... And a horizontal scanning circuit 25. Each readout circuit 20a,... Is provided for each column signal line RL corresponding to each column of the pixel array PA. The readout unit 20 performs a first readout operation in which a signal accumulated in the first accumulation period from the start of one line period to the middle of the one line period is read from the pixels during a part of the one line period. . The readout unit 20 performs a second readout operation in which a signal accumulated in the second accumulation period shorter than the first accumulation period and shorter than one line period is read from the pixel in another part of the one line period. Do. The one line period is a period from when the row selection unit 40 selects one row until the next row is selected.

  The read circuit 20a includes a switch 21a, a holding unit 23a, and a switch 22a. The switch 21a accumulates the output signal of the amplifying unit 4 transmitted by the column signal line RL in the holding unit 23a while the supplied signal Tr is active. The holding unit 23a holds the accumulated signal for a predetermined period. The switch 22a outputs the signal held by the holding unit 23a to the horizontal output line 31 by capacitive division while the signal HSR1 supplied from the horizontal scanning circuit 25 is active. Here, the horizontal scanning circuit 25 sequentially outputs the signals of the pixels in each column by sequentially activating the signals HSR1, HSR2,. That is, the reading unit 20 selects the row selected by the row selection unit 40 in one line period (see LT1 in FIG. 2) from when the row selection unit 40 selects one row until the next row is selected. The signals of the pixels in each column are read out from these pixels and sequentially output. The other readout circuits 20b,... Are the same as the readout circuit 20a.

  The output unit 30 is connected to the horizontal output line 31, performs impedance conversion or the like based on the signal output to the horizontal output line 31, generates an image signal, and outputs the image signal to the subsequent stage.

  Next, a schematic operation of the imaging apparatus 1 will be described with reference to FIGS. FIG. 2 is a conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 1. FIG. 3 is a timing waveform diagram showing the operation of each pixel of the imaging apparatus 1.

  In FIG. 2, the vertical axis indicates the position in the vertical direction of each pixel P11 in the pixel array PA. The horizontal axis shows the timing. In FIG. 3, the vertical axis indicates the signal name, and the horizontal axis indicates the timing.

  As shown in FIG. 2, in a one-line period LT1 for the row selection unit 40 to select a row of pixels P11, a read operation is performed on the pixels P11 and the like of each column in the row selected in the period A. The pixel P11 and the like are reset. In the period B, the scanning unit 20 performs horizontal scanning, and signals such as pixels P11 in each column are sequentially output. In the following, the description will be focused on the pixel P11, but the same applies to other pixels.

  Specifically, as shown in FIG. 3, in the period A of the one line period LT1, the active signal Select1 is supplied from the row selection unit 40 to the selection unit 3 of the pixel P11.

  At this time, in the first half of the period A, the active signal Reset1 is supplied from the row selection unit 40 to the reset unit 5 of the pixel P11. Thereby, the reset unit 5 resets the charge-voltage conversion unit 7, and the potential of the charge-voltage conversion unit 7 becomes the potential of the reset state. After the signal Reset1 becomes inactive, the active signal Tx1 is supplied from the row selection unit 40 to the transfer unit 6 of the pixel P11. Thereby, the transfer unit 6 transfers the signal accumulated in the pixel P11 (photoelectric conversion unit 2) to the charge-voltage conversion unit 7, and resets the pixel P11 (photoelectric conversion unit 2). Here, the transferred signal is a signal accumulated in the accumulation operation of the pixel P11 (photoelectric conversion unit 2) in the long period ST1 (see FIG. 4). After the signal Tx1 becomes inactive, the active signal Tr is supplied to the switch 21a of the reading unit 20. Thereby, the reading unit 20 reads and holds the signal accumulated in the pixel P11 (photoelectric conversion unit 2) from the pixel P11 (photoelectric conversion unit 2) via the amplification unit 4, the selection unit 3, and the column signal line RL. It accumulates in the part 23a.

  In the period B of one line period LT1, the signal Select1 supplied from the row selection unit 40 to the selection unit 3 of the pixel P11 becomes non-active.

  At this time, the signals HSR1, HSR2,... Of each column supplied from the horizontal scanning circuit 25 of the reading unit 20 to the switches 22a,. Thereby, the signals of the pixels P11 and the like of each column held in the holding unit 23a are sequentially output to the horizontal output line 31. At the same time, the potential of the horizontal output line 31 changes like the waveform “output” shown in the lower part of FIG. 2 every time the pixel P11 or the like of each column is output. The waveform shown in the lower part of FIG. 2 conceptually shows the potential of the horizontal output line 31 every time the pixel P11 and the like in each column is output. In practice, there are sawtooth teeth corresponding to the number of columns. It will be in line.

  Further, after the one line period LT1, a one line period LT2 for the row selection unit 40 to select a row of the pixels P21 is provided. In the one line period LT2, the same operation as that in the one line period LT1 is performed.

  In this way, in the imaging device 1, signal reading from pixels, pixel resetting, and horizontal scanning are performed for each row.

  Next, a short period accumulation operation and a long period accumulation operation of each pixel in the imaging apparatus 1 will be described with reference to FIG. 4 is the same as FIG. 2 in that it is a conceptual diagram showing an operation sequence of each pixel of the imaging device 1, but differs from FIG. 2 in that an accumulation operation for a short period is further shown. In the following, the description will be focused on the pixel P11, but the same applies to other pixels. The technique shown in FIG. 4 is called a rolling electronic shutter.

  In the period R shown in FIG. 4, the active signal Reset1 is supplied from the row selection unit 40 to the reset unit 5 of the pixel P11, and the active signal Tx1 is supplied from the row selection unit 40 to the transfer unit 6 of the pixel P11. As a result, the pixel P11 (photoelectric conversion unit 2) is reset and the charge-voltage conversion unit 7 is reset. Then, at the timing when the signal Tx1 changes from active to non-active, the pixel P11 (photoelectric conversion unit 2) starts the accumulation operation in the short period ST2. That is, the accumulation operation period ST2 starts at a timing when the signal Tx1 changes from active to non-active.

  The operation in the period A of the 1-line period LT1a is basically the same as the operation in the period A of the 1-line period LT1 shown in FIG. 3, but the accumulation is performed in the accumulation operation in the short period ST2 of the pixel P11 (photoelectric conversion unit 2). The difference is that the processed signal is transferred to the charge-voltage converter 7. Here, the accumulation operation period ST2 ends at a timing when the signal Tx1 changes from non-active to active. Then, at the timing when the signal Tx1 changes from active to non-active, the pixel P11 (photoelectric conversion unit 2) starts the accumulation operation in the long period ST1. That is, the accumulation operation period ST1 starts at a timing when the signal Tx1 changes from active to non-active.

  Furthermore, the above-described one line period LT1 starts at the timing when one frame period has elapsed from one line period LT1a. The accumulation operation period ST1 ends when the signal Tx1 changes from non-active to active.

  Here, the length of the accumulation operation period ST1 is substantially equal to the length of one frame period. On the other hand, the length of the accumulation operation period ST2 is shorter than the length of the accumulation operation period ST1. Therefore, in FIG. 4, the accumulation operation in the long period ST1 is expressed as “long accumulation”, and the accumulation operation in the short period ST2 is expressed as “short accumulation”. In FIG. 4, the potential of the horizontal output line 31 changes like a waveform “output” shown in the lower part of FIG. 4 every time the pixel P <b> 11 of each column is output. That is, FIG. 4 shows that the signal level of the accumulation operation for a short period is low and the signal level of the accumulation operation for a long period is high.

  As illustrated in FIG. 4, the timing at which each photoelectric conversion unit 2 completes the accumulation operation for a long period is shifted from the timing at which each photoelectric conversion unit 2 completes the accumulation operation for a short period by approximately one frame period. Thereby, in the captured image signal, there is a possibility that the temporal correlation between the signal for the accumulation operation for a long period and the signal for the accumulation operation for a short period may be low. Accordingly, the signal for the accumulation operation for a long period and the signal for the accumulation operation for a short period are combined using an image processing unit 97a and the like using a frame memory 87a as shown in FIG. Is performed for each frame. As a result, there is a possibility that the load that the imaging apparatus 1 exerts on the subsequent image processing unit 97a and the like becomes large.

  In addition, there is a method in which high brightness is systematically detected by the image processing unit 97a and the like, and an electronic shutter operation is performed. Considering to prevent stroboscopic images, it must be slow.

  Furthermore, when an irregular line selection operation such as line feed is performed during the electronic shutter operation, there is a concern that the accumulation time may be inconsistent and the image may be distorted.

  Such a problem similarly occurs even in the imaging apparatus 100 (see FIG. 6) in which the reading unit 120 further includes the column amplifier 126a.

  On the other hand, even when the technique disclosed in Patent Document 1 is used, the timing at which each photoelectric conversion unit completes the charge accumulation operation for a long period and the timing at which the charge accumulation operation for a short period is completed are ½ field period. Just shift. As a result, in the captured image signal, there is a possibility that the temporal correlation between the long-period charge accumulation operation signal and the short-period charge accumulation operation signal is low. That is, even if the technique disclosed in Patent Document 1 is used, the same problem as described above occurs.

  Next, the imaging apparatus 200 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 7 is a circuit configuration diagram of the imaging apparatus 200 according to the first embodiment of the present invention. Below, it demonstrates centering on a different part from the imaging device 1 used for description of the subject of this invention, and abbreviate | omits description about the same part.

  The imaging apparatus 200 is different from the imaging apparatus 1 (see FIG. 1) in that it includes a row selection unit 240 and a reading unit 220. The row selection unit 240 is different from the row selection unit 40 (see FIG. 1) in that it includes a vertical scanning circuit 241. The readout unit 220 is different from the readout unit 20 (see FIG. 1) in that it includes readout circuits 220a, 220b,... And a vertical scanning circuit 225. The read circuit 220a includes a switch 221a.

  As shown in FIG. 8, the one-line period LT201 for the row selection unit 240 to select the row of the pixel P11 is the first period A1, the second period B1, the third period A2, and the fourth period. It differs from the one line period LT1 (see FIG. 2) in that it includes B2. Here, the second period B1 is a period following the first period A1. The third period A2 is a period following the second period B1. The fourth period B2 is a period following the third period A2. FIG. 8 is a conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 200.

  In the first period A1 of the one line period LT201, the reading unit 220 performs a first reading operation. The first readout operation is an operation of reading out the signal accumulated in the first accumulation period ST201 from the pixel P11 or the like before the start of the one line period LT201 to the middle of the one line period LT201. That is, by performing the first readout operation, the pixel P11 and the like in the row selected by the row selection unit 240 are reset, the first accumulation period ST201 is completed, and the first readout operation is completed. Thus, the second accumulation period ST202 starts.

  In the second period B1 of the one-line period LT201, the reading unit 220 sequentially outputs the pixel signals of each column read by the first reading operation.

  In the third period A2 of the one line period LT201, the reading unit 220 performs a second reading operation. The second reading operation is an operation of reading out signals accumulated in the second accumulation period ST202 shorter than the first accumulation period ST201 and shorter than the one line period LT201 from the pixels. The second accumulation period ST202 is included in the first period A1, the second period B1, and the third period A2. That is, by performing the second readout operation, the pixels P11 and the like in the row selected by the row selection unit 240 are reset, and the second accumulation period ST202 is completed.

  In the fourth period B2 of the one-line period LT201, the reading unit 220 sequentially outputs the pixel signals of each column read by the second reading operation.

  Specifically, as illustrated in FIG. 9, the operation of the imaging device 200 is different from the operation of the imaging device 1 (see FIG. 3) in the following points. FIG. 9 is a timing waveform diagram showing the operation of each pixel of the imaging apparatus 200.

  The operation in the first period A1 of the one-line period LT201 is basically the same as the operation in the period A of the one-line period LT1 (see FIG. 3), but a short accumulation is performed at the timing when the signal Tx1 changes from active to non-active. The difference is that the period ST202 starts. Note that the long accumulation period ST201 ends at the timing when the signal Tx1 becomes active from the non-active state is the same as the operation in the period A of the one-line period LT1. Further, the point that the length of the first accumulation period (long accumulation period) ST201 is substantially equal to one frame period is the same as that of the long accumulation period ST1 (see FIG. 3).

  The operation in the second period B1 in the one-line period LT201 is basically the same as the operation in the period B in the one-line period LT1 (see FIG. 3), but the pixel P11 (photoelectric conversion unit 2) is in the short period ST202. It differs in that the accumulation operation is performed. Note that in the period B of the one-line period LT1, neither the accumulation operation in the long period ST1 nor the accumulation operation in the short period ST2 is performed in the pixel P11 (photoelectric conversion unit 2) (see FIG. 4).

  The operation in the third period A2 of the one-line period LT201 is basically the same as the operation in the period A of the one-line period LT1a (see FIG. 4), but a long accumulation is performed at the timing when the signal Tx1 changes from active to non-active. The difference is that the period ST201 does not start. Further, the second accumulation period (short accumulation period) ST202 is shorter than one frame period in that the second accumulation period (short accumulation period) ST202 is different from the short accumulation period ST2 (see FIG. 3). Note that the short accumulation period ST202 ends at the timing when the signal Tx1 becomes active from non-active is the same as the operation in the period A of the one-line period LT1a.

  The operation in the fourth period B2 in the one-line period LT201 is basically the same as the operation in the period B in the one-line period LT1a (see FIG. 4), but the pixel P11 (photoelectric conversion unit 2) is in the long period ST202. The difference is that the accumulation operation is not performed. Note that in the period B of the one-line period LT1a, the pixel P11 (photoelectric conversion unit 2) performs the accumulation operation in the long period ST1 (see FIG. 4).

As described above, the timing at which each photoelectric conversion unit 2 completes the accumulation operation in the long period ST201 and the timing at which each photoelectric conversion unit 2 completes the accumulation operation in the short period ST202 are shorter than one line period (1 It shifts by about half of the line period). For example, in the case of the VGA size (640 × 480) imaging apparatus 200, the storage time ratio is ST202 / ST201 = 1/960 Equation 1
It becomes. The difference between the timing at which the first accumulation period ST201 is completed and the timing at which the second accumulation period ST202 is completed is: 1 horizontal scanning period = about half of one line period.
It becomes.

  Thereby, in the captured image signal, it is possible to improve the temporal correlation between the signal for the accumulation operation for a long period and the signal for the accumulation operation for a short period. Therefore, the signal for the accumulation operation for the long period and the signal for the accumulation operation for the short period are combined using the line memory 87b as shown in FIG. 10 (configuration diagram showing a part of the imaging system), etc. Is performed for each line. As a result, it is possible to reduce the load that the imaging apparatus 200 exerts on the subsequent image processing unit 97b and the like.

  In addition, since the temporal correlation between the signal for the accumulation operation for a long period and the signal for the accumulation operation for a short period can be improved, high-speed imaging is possible.

  Furthermore, as expressed by Equation 1, the ratio between the second accumulation period and the first accumulation period can be made very small, so that the dynamic range of the signal can be easily expanded.

  Next, an example of an imaging system to which the imaging apparatus of the present invention is applied is shown in FIG.

  As shown in FIG. 11, the imaging system 90 mainly includes an optical system, an imaging device 200, and a signal processing unit. The optical system mainly includes a shutter 91, a photographing lens 92, and a diaphragm 93. The signal processing unit mainly includes an imaging signal processing circuit 95, an A / D converter 96, an image signal processing unit 97, a memory unit 87, an external I / F unit 89, a timing generation unit 98, an overall control / calculation unit 99, and a recording. A medium 88 and a recording medium control I / F unit 94 are provided. The signal processing unit may not include the recording medium 88.

  The shutter 91 is provided in front of the photographic lens 92 on the optical path and controls exposure.

  The taking lens 92 refracts the incident light and forms an image of the subject on the pixel array PA (imaging surface) of the imaging device 200.

  The diaphragm 93 is provided between the photographing lens 92 and the imaging device 200 on the optical path, and adjusts the amount of light guided to the imaging device 200 after passing through the photographing lens 92.

  The imaging device 200 converts the image of the subject formed on the pixel array PA into an image signal. The imaging device 200 reads the image signal from the pixel array PA and outputs it.

  The imaging signal processing circuit 95 is connected to the imaging device 200 and processes an image signal output from the imaging device 200.

  The A / D converter 96 is connected to the imaging signal processing circuit 95 and converts the processed image signal (analog signal) output from the imaging signal processing circuit 95 into a digital signal.

  The image signal processing unit 97 is connected to the A / D converter 96, and performs various kinds of arithmetic processing such as correction on the image signal (digital signal) output from the A / D converter 96 to generate image data. To do. The image data is supplied to the memory unit 87, the external I / F unit 89, the overall control / calculation unit 99, the recording medium control I / F unit 94, and the like. The image signal processing unit 97 includes the above-described image processing unit 97b.

  The memory unit 87 is connected to the image signal processing unit 97 and stores the image data output from the image signal processing unit 97. The memory unit 87 includes the line memory 87b described above.

  The external I / F unit 89 is connected to the image signal processing unit 97. Thus, the image data output from the image signal processing unit 97 is transferred to an external device (such as a personal computer) via the external I / F unit 89.

  The timing generation unit 98 is connected to the imaging device 200, the imaging signal processing circuit 95, the A / D converter 96, and the image signal processing unit 97. Thereby, a timing signal is supplied to the imaging device 200, the imaging signal processing circuit 95, the A / D converter 96, and the image signal processing unit 97. The imaging device 200, the imaging signal processing circuit 95, the A / D converter 96, and the image signal processing unit 97 operate in synchronization with the timing signal.

  The overall control / arithmetic unit 99 is connected to the timing generation unit 98, the image signal processing unit 97, and the recording medium control I / F unit 94, and the timing generation unit 98, the image signal processing unit 97, and the recording medium control I / F. The unit 94 is controlled as a whole.

  The recording medium 88 is detachably connected to the recording medium control I / F unit 94. As a result, the image data output from the image signal processing unit 97 is recorded on the recording medium 88 via the recording medium control I / F unit 94.

  With the above configuration, if a good image signal is obtained in the imaging apparatus 200, a good image (image data) can be obtained.

  Next, an imaging apparatus 300 according to the second embodiment will be described with reference to FIG. FIG. 12 is a circuit configuration diagram of the imaging apparatus 300 according to the second embodiment. Below, it demonstrates centering on a different point from 1st Embodiment, and abbreviate | omits description about the same point.

  The imaging apparatus 300 is different from the first embodiment in that it includes a row selection unit 340, a readout unit 320, and an output unit 330. The row selection unit 340 is different from the row selection unit 240 (see FIG. 7) in that it includes a vertical scanning circuit 341. The readout unit 320 is different from the readout unit 220 (see FIG. 7) in that it includes readout circuits 320a, 320b,... And a vertical scanning circuit 225. The readout circuit 320a includes a switch 327a, a first holding unit 323a, a second holding unit 324a, a switch 328a, and AND gates 329a1 and 329a2. The output unit 330 is different from the output unit 30 (see FIG. 7) in that it includes a first output unit 330a and a second output unit 330b.

  As shown in FIG. 13, the one-line period LT301 for the row selection unit 340 to select the row of the pixel P11 includes a first period A1, a fifth period A3, and a sixth period B3. This is different from the one-line period LT201 (see FIG. 8). Here, the fifth period A3 is a period following the first period A1. The sixth period B3 is a period following the fifth period A3. FIG. 13 is a conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 300.

  In the fifth period A3 of the one line period LT301, the reading unit 320 performs the second reading operation. The second readout operation is an operation of reading out signals accumulated in the second accumulation period ST302 shorter than the first accumulation period ST301 and shorter than the one line period LT301 from the pixels. The second accumulation period ST302 is included in the first period A1 and the fifth period A3. That is, by performing the second reading operation, the pixel P11 and the like in the row selected by the row selection unit 340 are reset, and the second accumulation period ST302 is completed.

  In the sixth period B3 of the one-line period LT301, the reading unit 320 reads the pixel signal of each column read by the first reading operation and the pixel signal of each column read by the second reading operation. The signals are sequentially output.

  Specifically, as shown in FIG. 14, the operation of the imaging apparatus 300 differs from the operation of the imaging apparatus 200 (see FIG. 9) in the following points. FIG. 14 is a timing waveform diagram illustrating the operation of each pixel of the imaging apparatus 300.

  The operation in the first period A1 in the one-line period LT301 is basically the same as the operation in the first period A1 in the one-line period LT201 (see FIG. 9), but the pixels in each column are subjected to the first readout operation. This is different in that the signal read from is held by the first holding unit 323a.

  The operation in the fifth period A3 in the one-line period LT301 is basically the same as the operation in the third period A2 in the one-line period LT201 (see FIG. 9), but the pixels in each column are subjected to the second readout operation. This is different in that the signal read from the second holding unit 324a holds the signal. The second accumulation period ST302 is different from the second accumulation period ST202 (see FIG. 3) in that the length is shorter than half of one frame period.

  The operation in the sixth period B3 in the one-line period LT301 is basically the same as the operation in the fourth period B2 in the one-line period LT201 (see FIG. 9), but the pixels in each column are subjected to the first readout operation. It is different in that the signal read from is output.

  That is, the AND gate 329a1 calculates a logical product of the signal Storage-Normal and HSR1 and supplies the logical product to the switch 22a. The AND gate 329a2 calculates a logical product of the signal Storage-Short and the HSR1 and supplies the logical product to the switch 328a. As a result, the horizontal scanning circuit 325 sequentially activates the switch 22a and the switch 328a in each column. Thereby, the pixel signals of each column read from the first holding unit 323a and the second holding unit 324a are sequentially output to the horizontal output lines 331a and 331b, respectively. The first output unit 330a generates a first image signal based on the signal output from the first holding unit 323a, and outputs the first image signal. In parallel, the second output unit 330b generates a second image signal based on the signal output from the second holding unit 324a, and outputs the second image signal.

  Thus, the signal read from the pixels in each column by the first read operation and the signal read from the pixels in each column by the second read operation can be output simultaneously. Accordingly, the difference between the timing at which each photoelectric conversion unit 2 completes the accumulation operation in the long period ST201 and the timing at which each photoelectric conversion unit 2 completes the accumulation operation in the short period ST202 is less than half of the one-line period LT301. Can be shortened. Therefore, in the captured image signal, it is possible to easily improve the temporal correlation between the long-period accumulation operation signal and the short-period accumulation operation signal.

  In addition, since the number of times the horizontal scanning circuit 325 performs horizontal scanning of the reading circuit 320a and the like can be reduced, the one-line period LT301 can be shortened. Thereby, high-speed imaging becomes possible.

  Next, an imaging apparatus 400 according to the third embodiment will be described with reference to FIG. FIG. 15 is a circuit configuration diagram of an imaging apparatus 400 according to the third embodiment. Below, it demonstrates centering on a different point from 1st Embodiment, and abbreviate | omits description about the same point.

  The imaging device 400 is different from the first embodiment in that it includes a reading unit 420 and an output unit 430. The reading unit 420 is different from the reading unit 220 (see FIG. 7) in that it includes A / D conversion units 420a, 420b,. The A / D conversion unit 420a and the like are, for example, analog-digital converters. The output unit 430 is different from the output unit 30 (see FIG. 7) in that it is a circuit for processing a digital signal. The output unit 430 is a circuit for processing an analog signal.

  In the first period A1 and the third period A2 (see FIG. 9), the A / D converter 420a performs the first read operation and the second read operation in accordance with the trigger signal Trigger. The A / D conversion unit 420a performs A / D conversion and holds the signals of the pixels in each column.

  Further, in the second period B1 and the fourth period B2 (see FIG. 9), the A / D conversion unit 420a transmits the pixel signals of each column read by the first reading operation to the bus line 431. Output in parallel. Thereby, the length of the second period B1 and the fourth period B2 can be shortened.

The circuit block diagram of the imaging device 1 used for description of the subject of this invention. FIG. 3 is a conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 1. FIG. 4 is a timing waveform diagram showing the operation of each pixel of the imaging apparatus 1. Conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 1 The block diagram which shows a part of imaging system. FIG. 6 is another circuit configuration diagram of the imaging apparatus 1 used for explaining the problem of the present invention. 1 is a circuit configuration diagram of an imaging apparatus 200 according to a first embodiment of the present invention. FIG. 3 is a conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 200. FIG. 6 is a timing waveform diagram showing the operation of each pixel of the imaging apparatus 200. The block diagram which shows a part of imaging system. The figure which shows an example of the imaging system to which the imaging device of this invention is applied. The circuit block diagram of the imaging device 200 which concerns on 2nd Embodiment of this invention. FIG. 3 is a conceptual diagram showing an operation sequence of each pixel of the imaging apparatus 300. FIG. 6 is a timing waveform diagram showing the operation of each pixel of the imaging apparatus 300. The circuit block diagram of the imaging device 200 which concerns on 3rd Embodiment of this invention.

Explanation of symbols

1, 100, 200, 300, 400 Imaging device 2 Photoelectric conversion unit 30, 330, 430 Output unit 40, 240, 340 Row selection unit 20, 120, 220, 320, 420 Reading unit 90 Imaging system 323a, etc. First holding unit 324a etc. 2nd holding | maintenance part 330a 1st output part 330b 2nd output part P11 etc. Pixel PA Pixel arrangement

Claims (11)

A pixel array in which a plurality of pixels each including a photoelectric conversion unit are arranged in a row direction and a column direction;
A row selection unit for selecting a row in the pixel array;
In one line period from the selection of one row by the row selection unit to the selection of the next row, the pixel signal of each column is read out from the pixels of the row selected by the row selection unit. A readout unit for sequentially outputting;
With
The readout unit includes a first readout operation for reading out signals accumulated in a first accumulation period from a pixel before the start of the one line period to a middle of the one line period from a pixel, and a shorter period than the first accumulation period. An image pickup apparatus that performs a second readout operation for reading out signals accumulated in a second accumulation period shorter than the one line period from pixels in the one line period. The one line period is
A first period during which the first read operation is performed;
A second period in which the signals of the pixels in each column read out by the first readout operation are sequentially output after the first period;
A period following the second period, wherein the second read operation is performed; and
A period following the third period, a fourth period in which the signals of the pixels in each column read out by the second readout operation are sequentially output;
The imaging apparatus according to claim 1, comprising: The imaging apparatus according to claim 2, wherein the second accumulation period is included in the first period, the second period, and the third period. In the first period, by performing the first readout operation, the pixels in the row selected by the row selection unit are reset, and the first accumulation period is completed, so that the first readout is performed. When the operation is completed, the second accumulation period begins,
In the third period, by performing the second reading operation, pixels in a row selected by the row selection unit are reset, and the second accumulation period is completed. Item 4. The imaging device according to Item 2 or 3. The one line period is
A first period during which the first read operation is performed;
A period following the first period, wherein the second read operation is performed;
It is a period following the fifth period, and the pixel signal of each column read by the first readout operation and the pixel signal of each column read by the second readout operation are , Respectively, a sixth period output sequentially,
The imaging apparatus according to claim 1, comprising: The imaging apparatus according to claim 5, wherein the second accumulation period is included in the first period and the fifth period. In the first period, by performing the first readout operation, the pixels in the row selected by the row selection unit are reset, and the first accumulation period is completed, so that the first readout is performed. When the operation is completed, the second accumulation period begins,
In the fifth period, by performing the second reading operation, pixels in a row selected by the row selection unit are reset, and the second accumulation period is completed. Item 7. The imaging device according to Item 5 or 6. An image signal is generated based on the signal output from the reading unit, and an output unit that outputs the image signal is further provided.
The reading unit
A first holding unit that holds signals read from pixels in each column by the first reading operation in the first period;
A second holding unit that holds signals read from pixels in each column by the second reading operation in the fifth period;
Including
The output unit is
A first output unit that generates a first image signal based on a signal output from the first holding unit and outputs the first image signal in the sixth period;
A second output unit that generates a second image signal based on the signal output from the second holding unit and outputs the second image signal in the sixth period;
The imaging apparatus according to any one of claims 5 to 7, further comprising: A plurality of column signal lines respectively connecting the pixels arranged in the column direction in the pixel arrangement and the readout unit;
9. The imaging according to claim 1, wherein the readout unit includes an A / D conversion unit that performs A / D conversion on a signal transmitted by each of the plurality of column signal lines. 10. apparatus. The imaging device according to any one of claims 1 to 9,
An optical system for forming an image on the imaging surface of the imaging device;
A signal processing unit that processes the signal output from the imaging device to generate image data;
An imaging system comprising: A pixel array in which a plurality of pixels each including a photoelectric conversion unit are arrayed in a row direction and a column direction, a row selection unit that selects a row in the pixel array, and the row selection unit selects one row and then the next In the driving method of the imaging apparatus, the readout unit reads out the signals of the pixels in each column from the pixels in the row selected by the row selection unit and sequentially outputs them in one line period until the row is selected. There,
A first readout operation in which the readout unit reads out signals accumulated in a first accumulation period from the pixel before the start of the one line period to the middle of the one line period from a pixel, as a part of the one line period. A first reading step performed in a period;
A second readout operation in which the readout unit reads out signals accumulated in the second accumulation period shorter than the first accumulation period and shorter than the one line period from the pixel is performed in another part of the one line period. A second reading step performed during the period of
An image pickup apparatus driving method comprising:

Images