JP2006093815A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image free from dark current unevenness by arranging the FD storage time when electronic shutter operation is realized by a CMOS sensor. <P>SOLUTION: In order to arrange the FD storage time in electronic shutter operation, reset only for PD is provided and an FD is reset according to read out by shifting the timing from reset timing of the FD thus equalizing the storage time of the FD between upper and lower parts of a screen. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus and system using a solid-state imaging device, and an imaging apparatus according to a configuration and a driving method of a solid-state imaging device for realizing an accurate and high-speed shutter operation and a high-quality image.

  An electronic shutter operation using an image pickup device employing a conventional XY address type scanning method will be described.

  First, a scan for removing unnecessary charges accumulated in a pixel for each pixel or line, that is, a reset scan is executed, and then a signal charge is read for each pixel or line after a predetermined time has elapsed. It is known that it can be realized by doing. Such an electronic shutter is hereinafter referred to as a rolling electronic shutter.

  The structure and driving method of a conventional image sensor will be described with reference to FIGS. 1 and 3, and the rolling electronic shutter operation will be described.

  FIG. 1 shows the configuration of an image sensor that employs an XY address type scanning method. Reference numeral 101 denotes a unit pixel. Reference numeral 102 denotes a photodiode (hereinafter referred to as PD) that converts light into electric charge. Reference numeral 103 denotes a transfer switch that transfers charges generated in the PD by the transfer pulse φTX to an FD described later. Reference numeral 104 denotes a region for temporarily storing electric charges (hereinafter referred to as FD), and reference numeral 105 denotes an amplification MOS amplifier that functions as a source follower. Reference numeral 106 denotes a selection switch that selects a pixel by a selection pulse φSEL, and reference numeral 107 denotes a reset switch that removes charges accumulated in the FD by a reset pulse φRES. The FD 104, the amplification MOS amplifier 105, and a constant current source 109 described later constitute a floating diffusion amplifier, and the signal charge of the pixel selected by the selection switch 106 is converted into a voltage and output to the readout circuit 113 via the signal output line 108. The Reference numeral 109 denotes a constant current source serving as a load for the amplification MOS amplifier 105.

  Reference numeral 110 denotes a selection switch that selects an output signal from the readout circuit 113 and is driven by the horizontal scanning circuit 114. Reference numeral 112 denotes a vertical scanning circuit for selecting the switches 103, 106, and 107.

  The nth scanning line selected by the vertical scanning circuit 112 in each of φTX, φRES, and φSEL is defined as φTXn, φRESn, and φSELn.

  FIG. 3 shows a driving pulse and an operation sequence in the rolling electronic shutter operation. In FIG. 3, description is made with respect to n + 3 lines from n lines selected by the vertical scanning circuit 112.

  In the rolling electronic shutter operation, at time n31 to time t32, first, pulses are applied to φRESn and φTXn to turn on transfer switch 103 and reset switch 107, and are stored in PD102 and FD104 on the nth line. A reset operation for removing charges is performed. At time t32, the transfer switch 103 is turned off, and an accumulation operation for accumulating the photocharge generated in the PD is started.

  Next, at time t <b> 34, a pulse is applied to φTXn to turn on the transfer switch 103, and a transfer operation for transferring the photocharge accumulated in the PD 102 to the FD 104 is performed. Note that the reset switch 107 needs to be turned off prior to the transfer operation, and in this figure, the reset switch 107 is turned off simultaneously with the transfer switch 103 at time t32. Here, the accumulation time is from time t32 to time t35. After the transfer operation for the nth line is completed, a pulse is applied to φSELn and the selection switch 106 is turned on, whereby the charge held in the FD 104 is converted into a voltage and output to the reading circuit 113. The signals temporarily held by the readout circuit 113 are sequentially output from the time t36 by the horizontal scanning circuit 112. The time from the start of transfer at time t34 to the end of reading at time t37 is T3read, and the time from time t31 to time t33 is T3wait. Similarly, in other lines, the time from the start of transfer to the end of reading is T3read, and the time from the start of resetting of one line to the start of resetting of the next line is T3wait.

  From the upper sequence of FIG. 3, the rolling electronic shutter has a problem that the accumulation time is shifted by the time required for scanning the screen at the top and bottom of the screen. This is because the time T3wait from the reset and transfer scan of a line to the reset and transfer scan of the next line must be set to a time longer than T3read. This is because if the T3wait time is shorter than the T3read time, the information of the pixel for which the reading operation has not been completed enters the reading circuit and the information of the next line is lost. Therefore, if the readout scanning of the signal output cannot be performed at high speed, this deviation becomes large especially when the number of pixels is large.

  Also, there is a MOS type image pickup device that performs a reset operation and a transfer operation collectively as described in Patent Document 1. A sequence of each line in such an operation is shown in FIG. In FIG. 4, the reset operation of all lines is performed simultaneously from time t41 to time t42. The transfer operation from time t43 to time t44 is also performed at the same time. Such an electronic shutter is hereinafter referred to as a batch electronic shutter. When the collective electronic shutter is performed, the accumulation time is from t42 to t44 for all lines, and an electronic shutter in which the accumulation time does not deviate up and down the screen is obtained.

  In addition, in order to perform the reset operation and the transfer operation at high speed, there is a MOS type image pickup device that performs the sequence shown in FIG. 5 in which the reset operation and the transfer operation are speeded up. This sequence will be described with reference to FIGS. First, by applying a pulse to φRESn and φTXn from time t51 to t52, switches 107 and 103 are turned on, and a reset operation is performed to reset PD102 and FD104 on the nth line. From time t52, an accumulation operation in which photoelectric charges are generated in the PD on the n-th line starts, and the reset operation up to the final line is completed at t53.

  From time t54 to t55, a pulse is applied to φTXn to turn on the switch 103, and a transfer operation for transferring the photocharge accumulated in the PD 102 to the FD 104 is performed. The accumulation time from the time t52 to the time t54 is the nth line accumulation time. The transfer operation from the (N + 1) th line is sequentially performed at time after t55, and transfer of all lines is completed at time t57. Here, after the transfer operation for the Nth line is completed, a pulse is applied to φSELn at time t56 and the switch 106 is turned on, whereby the charge held at 104 is converted into a voltage by 105 and read out to the reading circuit 113. The signals temporarily held in the reading circuit 113 are sequentially output from the time 15 by the horizontal scanning circuit 112. Reading of the (n + 1) th line is performed after time t58.

With the sequence shown in FIG. 5, the time from the start of scanning of one line to the start of scanning of the next line can be determined without depending on the readout time, so that image distortion due to the rolling electronic shutter can be reduced. Such an electronic shutter is called a rolling transfer electronic shutter.
JP 2003-17677 A JP-A-10-155100

  However, in the collective electronic shutter and the rolling transfer electronic shutter, the accumulation time of the accumulation unit is the time between the pixel reset time and the readout time, and therefore the accumulation time of the accumulation unit differs between the top and bottom of the screen. For this reason, the amount of dark current generated in proportion to the time in the storage unit differs between the upper and lower portions of the screen, leading to a reduction in image quality.

  Therefore, an object of the present invention is to provide an electronic shutter that does not cause a difference in dark current amount at the top and bottom of the screen due to a difference in accumulation time even when a batch electronic shutter and a rolling transfer electronic shutter are performed.

  In order to solve the above problems, the imaging apparatus of the present invention is configured as (1) or (2).

  (1) An image sensor having a light receiving unit that generates and accumulates photocharges according to the amount of received light, a storage unit that temporarily stores the photocharges of the light receiving unit, and a first scan that initializes signals of the storage unit Means, second scanning means for performing charge accumulation start scanning of the light receiving section, third scanning means for performing accumulation end scanning of the image pickup device by transferring photocharges of the light receiving section to the storage section, In the imaging apparatus having the fourth scanning unit for reading out the signal of the storage unit, the storage unit is initialized by the first scanning unit, and the row or column is sequentially stored by the second scanning unit. The imaging is characterized in that reading is sequentially performed by the fourth scanning unit from the row or column for which transfer has been completed by the scanning unit, and the time from the initialization of the signal in the accumulation unit to the readout is the same for the row or column. apparatus.

  In the imaging apparatus of (1), the second scanning unit performs the FD accumulation time defined by the initialization of the storage unit performed by the first scanning unit and the readout performed by the fourth scanning unit. When the PD accumulation time defined by the start of charge accumulation in the light receiving unit and the end of accumulation performed by the third scanning unit is short, scanning starts from the first scanning unit, and when short, the scanning starts from the second scanning unit. It is characterized by doing.

  In the imaging apparatus of (1), scanning is always started from the first scanning unit regardless of the FD accumulation time and the PD accumulation time.

  (2) An image sensor having a light receiving unit that generates and accumulates photocharges according to the amount of received light and a storage unit that temporarily stores the photocharges of the light receiving unit, and a first scan that initializes signals of the storage unit Means, second initialization means for starting the charge accumulation of the light receiving section, third transfer means for ending the accumulation of the image sensor by transferring the photocharge of the light receiving section to the storage section, and the accumulation In the imaging apparatus having the fourth scanning means for reading out the signal of the part, the storage unit is initialized by the first scanning means, the accumulation is started by the second initialization means, and the transfer is performed by the third transfer means And the fourth scanning means performs reading after the transfer is completed, and the time from the initialization of the signal in the storage section to the reading is the same for each row or column.

  In the imaging apparatus of (2), the second initialization unit with respect to the FD accumulation time defined by the initialization of the storage unit performed by the first scanning unit and the readout performed by the fourth scanning unit. When the PD accumulation time defined by the charge accumulation start of the light receiving unit and the accumulation end performed by the third transfer unit is short, scanning starts from the first scanning unit, and when the PD accumulation time is short, from the second initialization unit. An imaging apparatus characterized by starting operation.

  (2) In the imaging apparatus, the scanning is always started from the first scanning means regardless of the FD accumulation time and the PD accumulation time.

  Even during electronic shutter operation, high image quality with no dark current unevenness is obtained.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 6 shows an image sensor. Reference numeral 601 denotes a unit pixel, which is shown in FIG. Reference numeral 701 denotes a photodiode (hereinafter referred to as PD) that converts light into electric charge. Reference numeral 703 denotes an accumulation region (hereinafter referred to as FD) for temporarily accumulating charges, and reference numeral 702 denotes a transfer switch for transferring charges generated in the PD to the FD by a transfer pulse φTX. A reset switch 704 resets the PD by a reset pulse φRESP. Reference numeral 705 denotes a load capacity. Reference numeral 706 denotes an amplification MOS amplifier that functions as a source follower. Reference numeral 707 denotes a reset switch that resets the FD by a reset pulse φRESF. Reference numeral 708 denotes a selection switch that selects a pixel by a selection pulse φSEL, and a signal of the selected pixel is transferred to the readout circuit 603 through a signal output line 602. The reading circuit 603 has a function of holding the transferred pixel signal. Reference numeral 604 denotes a load current source. Reference numeral 605 denotes a selection switch for selecting an output signal held by the readout circuit, which is sequentially selected by the horizontal scanning circuit 606. Reference numeral 607 denotes a vertical scanning circuit for selecting the switches 702, 704, 707, and 708. The pixel signal selected by the horizontal scanning circuit 607 is amplified by the output amplifier 608 and output. In each of φTX, φRESP, φRESF, and φSEL, the nth scan line is set to φTXn, φRESPn, φRESFn, and φSELn. Here, for the sake of simplicity, an image sensor in which the unit pixel is composed of 4 × 4 rows is shown, but the number of pixels is not limited to 4 × 4.

  FIG. 8 shows a driving method and an operation sequence in the first embodiment of the present invention.

  By applying a pulse to φRESFn from time t801 to t802, the switch 707 is turned on, and the FD reset operation for resetting the FD703 is performed. The FD reset operation for the nth line starts from time t801, and the FD reset operation up to the last line is completed at t809. By applying a pulse to φRESPn from time t803 to t804, a PD reset operation is performed to turn on the switch 704 and reset the PD701. From time t804, an accumulation operation in which photoelectric charges are generated in the PD on the n-th line starts, and at time t805, the PD reset operation up to the final line is completed.

  From time t806 to t807, a pulse is applied to φTXn to turn on the switch 702, and a transfer operation for transferring the photocharge accumulated in the PD 701 to the FD 703 is performed. From the time t804 to the time t806 is the accumulation time of the nth line. The transfer operation from the (N + 1) th line is sequentially performed at time after t807, and transfer of all lines is completed at time t810.

  Here, after the transfer operation for the Nth line is completed, a pulse is applied to φSELn and the switch 708 is turned on, whereby the charge held in the FD 703 is converted into a voltage by 706 and 604 and read to the reading circuit 603. The signals temporarily held in the reading circuit 603 are sequentially output by the horizontal scanning circuit 606 from time t808. Reading of the (n + 1) th line is performed after time t811. The time from time t802 to t808 is the FD accumulation time.

  According to the sequence shown in FIG. 8, since the FD accumulation time is the same for each row, there is no difference in the amount of dark current at the top and bottom of the screen due to the difference in the accumulation time, and a uniform image is obtained at the top and bottom. The FD reset start time and the PD reset start time are interchanged depending on the FD accumulation time and the PD accumulation time. Further, the FD reset time can be selected in a range in which the end of the FD reset satisfies the time before the transfer time when the charge of the PD is transferred to the FD in all lines.

  Based on FIG. 2, an embodiment in the case where the above-described driving method of the imaging element is applied to a digital camera which is an imaging apparatus will be described in detail.

  In FIG. 2, reference numeral 201 denotes a lens unit that forms an optical image of a subject on the image sensor 205, and zoom control, focus control, aperture control, and the like are performed by the lens driving device 202. Reference numeral 203 denotes a shutter means having a shutter curtain corresponding to the rear curtain of a focal plane type shutter used in a so-called single-lens reflex camera, and is controlled by a shutter driving means 204. Reference numeral 205 denotes an image pickup device for capturing an object imaged by the lens unit 201 as an image signal. Reference numeral 206 denotes an A / D conversion that performs amplification of an image signal output from the solid-state image pickup device 205 or analog-digital conversion. This is an imaging signal processing circuit that performs various corrections on the image data after D conversion and compresses the data. Reference numeral 207 denotes a solid-state imaging device 205, a timing generation circuit that is a driving unit that outputs various timing signals to the imaging signal processing circuit 206, 209 a control circuit that controls various operations and the entire imaging apparatus, and 208 temporarily stores image data. Memory for storing, 210 an interface for recording or reading on a recording medium, 211 a removable recording medium such as a semiconductor memory for recording or reading image data, and 212 communicating with an external computer or the like Interface.

  Next, the operation of the digital camera at the time of shooting in the above configuration will be described.

  When the main power supply is turned on, the power supply for the control system is turned on, and further, the power supply for the imaging system circuit such as the imaging signal processing circuit 206 is turned on.

  Then, when a release button (not shown) is pressed, in order to control the exposure amount, the control circuit 209 performs photometry with the photometry device 213 to determine the brightness, and the lens driving device determines the aperture of the optical system according to the result. To control.

  Next, based on the signal output from the distance measuring device 214, a high frequency component is extracted and the distance to the subject is calculated by the control circuit 209. Thereafter, the lens driving device 202 drives the lens unit to determine whether or not it is in focus. When it is determined that the lens unit is not in focus, the lens unit is driven again to perform distance measurement.

  Then, after the in-focus state is confirmed, the photographing operation starts.

  A sequence of photographing operations will be described with reference to FIGS. When the PD accumulation time is shorter than the reading time, the FD is first reset as shown in FIG. When the FD reset scanning is started, the FD reset operation is sequentially performed in the line direction of the image sensor. After the start of the FD reset scanning, the PD reset scanning is started. When PD reset scanning is started, PD reset operation is sequentially performed in the line direction of the image sensor. Charge transfer scanning is started after a certain accumulation time TPD after the PD reset is started. When the charge transfer scanning is performed, the charge transfer operation is sequentially performed in the line direction of the image sensor. The FD reset scanning start time is defined such that the FD reset end time is before the charge transfer scanning end time. The FD accumulation time is TFD.

  The readout scanning is started after the start of the charge transfer scanning. In order to prevent the image sensor from being exposed during the readout operation, the mechanical shutter is scanned after the start of the charge transfer operation. This mechanical shutter is not provided to define the accumulation time, but because the accumulation time is defined by the image sensor, a so-called front curtain and rear curtain two-blade type of a conventional single-lens reflex camera type may be used. However, a single-blade type with only the trailing curtain may be used. In the single blade type, the thickness of the shutter unit can be reduced as compared with the conventional two-blade type focal plane shutter, which is advantageous in terms of space.

  Further, since the scanning time of the mechanical shutter varies when the image pickup device is scanned, this difference can be further reduced by making the scanning time of the mechanical shutter and the charge transfer time of the image pickup device substantially the same. . When the reading operation is finished, the photographing operation is finished.

  When the PD accumulation time is longer than the FD accumulation time, the PD is first reset as shown in FIG. When PD reset scanning is started, PD reset operation is sequentially performed in the line direction of the image sensor. After the PD reset scanning is started, the FD reset scanning is started. When the FD reset scanning is started, the FD reset operation is sequentially performed in the line direction of the image sensor. Charge transfer scanning is started after a certain accumulation time TPD after the PD reset is started. When the charge transfer scanning is performed, the charge transfer operation is sequentially performed in the line direction of the image sensor. The FD reset scanning start time is defined such that the FD reset end time is before the charge transfer scanning end time. The FD accumulation time is TFD. The readout scanning is started after the start of the charge transfer scanning. In order to prevent the image sensor from being exposed during the readout operation, the mechanical shutter is scanned after the start of the charge transfer operation. As described above, the mechanical shutter does not define the accumulation time. When the reading operation is finished, the photographing operation is finished.

  Next, when always starting from the reset of the FD regardless of the PD accumulation time and the FD accumulation time, the FD is first reset as shown in FIG. When the FD reset scanning is started, the FD reset operation is sequentially performed in the line direction of the image sensor. After the start of the FD reset scanning, the PD reset scanning is started. When PD reset scanning is started, PD reset operation is sequentially performed in the line direction of the image sensor. Charge transfer scanning is started after a certain accumulation time TPD after the PD reset is started. When the charge transfer scanning is performed, the charge transfer operation is sequentially performed in the line direction of the image sensor. The FD reset scanning start time is defined such that the FD reset scanning end time is before the PD reset scanning end time.

  That is, the time TPF from the start of the FD reset scan to the start of the PD reset scan is constant. The FD accumulation time is TFD. The readout scanning is started after the start of the charge transfer scanning. In order to prevent the image sensor from being exposed during the readout operation, the mechanical shutter is scanned after the start of the charge transfer operation. As described above, the mechanical shutter does not define the accumulation time. When the reading operation is finished, the photographing operation is finished.

  When the photographing operation is completed, the image signal output from the solid-state imaging element 205 is subjected to processing such as amplification and A / D conversion by the imaging signal processing circuit 206 and is written to the memory by the control circuit 209.

  Thereafter, the data stored in the memory 208 is recorded on a removable recording medium 211 such as a semiconductor memory through the recording medium control I / F unit 210 under the control of the control circuit 209.

  Further, the image may be processed by directly inputting to a computer or the like through the external I / F unit 213.

  Embodiment 2 of the present invention will be described below with reference to the drawings.

  FIG. 6 shows an image sensor. Reference numeral 601 denotes a unit pixel, which is shown in FIG. Reference numeral 701 denotes a photodiode (hereinafter referred to as PD) that converts light into electric charge. Reference numeral 703 denotes an accumulation region (hereinafter referred to as FD) for temporarily accumulating charges, and reference numeral 702 denotes a transfer switch for transferring charges generated in the PD to the FD by a transfer pulse φTX. A reset switch 704 resets the PD by a reset pulse φRESP. Reference numeral 705 denotes a load capacity. Reference numeral 706 denotes an amplification MOS amplifier that functions as a source follower. Reference numeral 707 denotes a reset switch that resets the FD by a reset pulse φRESF. Reference numeral 708 denotes a selection switch that selects a pixel by a selection pulse φSEL, and a signal of the selected pixel is transferred to the readout circuit 603 through a signal output line 602. The reading circuit 603 has a function of holding the transferred pixel signal. Reference numeral 604 denotes a load current source. Reference numeral 605 denotes a selection switch for selecting an output signal held by the readout circuit, which is sequentially selected by the horizontal scanning circuit 606. Reference numeral 607 denotes a vertical scanning circuit for selecting the switches 702, 704, 707, and 708. The pixel signal selected by the horizontal scanning circuit 607 is amplified by the output amplifier 608 and output. In each of φTX, φRESP, φRESF, and φSEL, the nth scan line is set to φTXn, φRESPn, φRESFn, and φSELn. Here, for the sake of simplicity, an image sensor in which the unit pixel is composed of 4 × 4 rows is shown, but the number of pixels is not limited to 4 × 4.

  FIG. 9 shows a driving method and an operation sequence in the second embodiment of the present invention.

  By applying a pulse to φRESFn from time t901 to t902, an FD reset operation for turning on the switch 707 and resetting the FD703 is performed. The FD reset operation for the nth line starts from time t901, and the FD reset operation up to the last line is completed by t905. By applying a pulse to φRESP in all rows from time t903 to t904, a switch 704 is turned on, and a PD reset operation for resetting the PD 701 at once is performed. From time t904, an accumulation operation in which photoelectric charges are generated in the PDs of all the pixels starts.

  From time t905 to t906, a pulse is applied to φTX to turn on the switch 702, and a transfer operation is performed in which the photocharges accumulated in the PD 701 are collectively transferred to the FD 703. The PD accumulation time is from time t904 to time t905. After time t906, a pulse is applied to φSELn and the switch 708 is turned on, whereby the electric charge held in 703 is converted into a voltage by 706 and 604 and read out to the reading circuit 603. The signals temporarily held by the reading circuit 603 are sequentially output from the horizontal scanning circuit 606 from time t907. Reading of the (n + 1) th line is performed after time t908, and the reading operation ends at time t909. The time from time t901 to t906 is the FD accumulation time.

  With the sequence shown in FIG. 9, since the FD accumulation time is the same for each row, there is no difference in the amount of dark current at the top and bottom of the screen due to the difference in the accumulation time, and a uniform image is obtained at the top and bottom. The FD reset start time and the PD reset start time are interchanged depending on the FD accumulation time and the PD accumulation time. Further, the FD reset time can be selected in a range in which the end of the FD reset satisfies the time before the transfer time when the charge of the PD is transferred to the FD in all lines.

  Based on FIG. 2, an embodiment in the case where the above-described driving method of the imaging element is applied to a digital camera which is an imaging apparatus will be described in detail.

  In FIG. 2, reference numeral 201 denotes a lens unit that forms an optical image of a subject on the image sensor 205, and zoom control, focus control, aperture control, and the like are performed by the lens driving device 202. Reference numeral 203 denotes a shutter means having a shutter curtain corresponding to the rear curtain of a focal plane type shutter used in a so-called single-lens reflex camera, and is controlled by a shutter driving device 204. Reference numeral 205 denotes an image pickup device for capturing an object imaged by the lens unit 201 as an image signal. Reference numeral 206 denotes an A / D conversion that performs amplification of an image signal output from the solid-state image pickup device 205 or analog-digital conversion. This is an imaging signal processing circuit that performs various corrections on the image data after D conversion and compresses the data. Reference numeral 207 denotes a solid-state imaging device 205, a timing generation circuit that is a driving unit that outputs various timing signals to the imaging signal processing circuit 206, 209 a control circuit that controls various operations and the entire imaging apparatus, and 208 temporarily stores image data. Memory for storing, 210 an interface for recording or reading on a recording medium, 211 a removable recording medium such as a semiconductor memory for recording or reading image data, and 212 communicating with an external computer or the like Interface.

  Next, the operation of the digital camera at the time of shooting in the above configuration will be described.

  When the main power supply is turned on, the power supply for the control system is turned on, and further, the power supply for the imaging system circuit such as the imaging signal processing circuit 206 is turned on.

  Then, when a release button (not shown) is pressed, in order to control the exposure amount, the control circuit 209 performs photometry with the photometry device 213 to determine the brightness, and the lens driving device determines the aperture of the optical system according to the result. To control.

  Next, based on the signal output from the distance measuring device 214, a high frequency component is extracted and the distance to the subject is calculated by the control circuit 209. Thereafter, the lens driving device 202 drives the lens unit to determine whether or not it is in focus. When it is determined that the lens unit is not in focus, the lens unit is driven again to perform distance measurement.

  Then, after the in-focus state is confirmed, the photographing operation starts.

  A sequence of photographing operations will be described with reference to FIGS. When the PD accumulation time is shorter than the FD accumulation time, first, as shown in FIG. 13, FD reset scanning is performed. When the FD reset scanning is started, the FD reset operation is sequentially performed in the line direction of the image sensor. After the FD reset scan starts, PD reset is performed. After the PD reset, the charge transfer operation is performed after a certain accumulation time TPD. The FD reset scanning start time is defined such that the FD reset end time is before the charge transfer operation time. The FD accumulation time is TFD. When the reading operation is finished, the photographing operation is finished.

  When the PD accumulation time is longer than the FD accumulation time, a PD reset is first performed as shown in FIG. After PD reset, FD reset scanning is performed. When the FD reset scanning is started, the FD reset operation is sequentially performed in the line direction of the image sensor. After the PD reset, the charge transfer operation is performed after a certain accumulation time TPD. The FD reset scanning start time is defined such that the FD reset end time is before the charge transfer operation time. The FD accumulation time is TFD. When the reading operation is finished, the photographing operation is finished.

  Next, when it always starts from resetting the FD without depending on the PD accumulation time and the FD accumulation time, the FD reset scanning is first performed as shown in FIG. When the FD reset scanning is started, the FD reset operation is sequentially performed in the line direction of the image sensor. After the FD reset scan starts, PD reset is performed. After the PD reset, the charge transfer operation is performed after a certain accumulation time TPD. The FD reset scanning start time is defined such that the FD reset end time is before the PD reset operation time. That is, the time TPF from the start of the FD reset scanning to the PD reset is constant. The FD accumulation time is TFD. When the reading operation is finished, the photographing operation is finished.

  When the photographing operation is completed, the image signal output from the solid-state imaging element 205 is subjected to processing such as amplification and A / D conversion by the imaging signal processing circuit 206 and is written to the memory by the control circuit 209.

  Thereafter, the data stored in the memory 208 is recorded on a removable recording medium 211 such as a semiconductor memory through the recording medium control I / F unit 210 under the control of the control circuit 209.

  Further, the image may be processed by directly inputting to a computer or the like through the external I / F unit 213.

The figure showing the composition of the image sensor used for the conventional imaging device 1 is a block diagram of an imaging apparatus according to Embodiments 1 and 2 of the present invention. Timing chart of conventional driving method Timing chart of conventional driving method Timing chart of conventional driving method The figure which shows the image pick-up element used for the imaging device of Embodiment 1, 2 of this invention. The figure which shows the unit pixel of the image pick-up element used for the imaging device of Embodiment 1 and 2 of this invention. Timing chart of driving method of embodiment 1 of the present invention Timing chart of driving method of embodiment 2 of the present invention Timing chart of photographing operation according to Embodiment 1 of the present invention Timing chart of photographing operation according to Embodiment 1 of the present invention Timing chart of photographing operation according to Embodiment 1 of the present invention Timing chart of photographing operation according to embodiment 2 of the present invention Timing chart of photographing operation according to embodiment 2 of the present invention Timing chart of photographing operation according to embodiment 2 of the present invention

Explanation of symbols

101 Unit pixel 102 Photodiode 103 Transfer switch 104 Storage region 105 Amplification MOS amplifier 106 Selection switch 107 Reset switch 108 Signal output line 109 Constant current source 110 Horizontal selection switch 111 Output amplifier 112 Vertical scanning circuit 113 Reading circuit 114 Horizontal scanning circuit 201 Lens Unit 202 Lens driving device 203 Shutter 204 Shutter driving device 205 Imaging element 206 Imaging signal processing circuit 207 Timing generation unit 208 Memory unit 209 Overall control / calculation unit (control circuit)
210 Recording medium control I / F unit 211 Recording medium 212 External I / F unit 213 Photometric device 214 Distance measuring device 601 Unit pixel 602 Signal output line 603 Read circuit 604 Load current source 605 Horizontal selection switch 606 Horizontal scanning circuit 607 Vertical scanning circuit 608 Output amplifier 701 Photodiode 702 Transfer switch 703 Storage area 704 PD reset switch 705 Load capacitor 706 Amplification MOS amplifier 707 FD reset switch 708 Vertical selection switch

Claims (6)

An imaging device having a light receiving portion that generates and accumulates photocharge according to the amount of received light, and a storage portion that temporarily stores the photocharge of the light receiving portion, and a first scanning unit that initializes a signal of the storage portion; A second scanning unit that performs a charge accumulation start scan of the light receiving unit, a third scanning unit that performs a storage end scan of the imaging device by transferring photocharges of the light receiving unit to the storage unit, and the storage unit In the imaging apparatus having the fourth scanning means for reading the signal of
The storage unit is initialized by the first scanning unit, the storage of the rows or the columns is sequentially started by the second scanning unit, and the fourth scanning unit is sequentially started from the row or the column which has been transferred by the third scanning unit. The imaging apparatus is characterized in that the time from the initialization of the signal in the storage unit to the readout is the same in rows or columns.   2. The imaging device according to claim 1, wherein the second scanning unit corresponds to an FD accumulation time defined by initialization of the storage unit performed by the first scanning unit and readout performed by the fourth scanning unit. Scanning is started from the first scanning means when the PD accumulation time defined by the charge accumulation start of the light receiving unit and the accumulation end performed by the third scanning means is short, and from the second scanning means when short. An imaging device characterized by starting.   2. The imaging apparatus according to claim 1, wherein scanning is always started from the first scanning unit regardless of the FD accumulation time and the PD accumulation time. An imaging device having a light receiving portion that generates and accumulates photocharge according to the amount of received light, and a storage portion that temporarily stores the photocharge of the light receiving portion, and a first scanning unit that initializes a signal of the storage portion; A second initialization unit that starts charge accumulation in the light receiving unit, a third transfer unit that ends accumulation of the image sensor by transferring photocharges in the light receiving unit to the storage unit, In the imaging apparatus having the fourth scanning means for reading out the signal,
The storage unit is initialized by the first scanning unit, the accumulation is started by the second initialization unit, the transfer is performed by the third transfer unit, and the reading is performed by the fourth scanning unit after the transfer is completed. An imaging apparatus characterized in that the time from initialization of the signal of the storage section to the readout is the same in rows or columns.   5. The imaging apparatus according to claim 4, wherein the second initialization is performed with respect to an FD accumulation time defined by initialization of an accumulation unit performed by the first scanning unit and readout performed by the fourth scanning unit. Scanning is started from the first scanning means when the PD accumulation time defined by the charge accumulation start of the light receiving unit performed by the means and the accumulation end performed by the third transfer means is short, and the second initialization means when short An imaging apparatus characterized by starting operation from   5. The imaging apparatus according to claim 4, wherein scanning is always started from the first scanning means regardless of the FD accumulation time and the PD accumulation time.