JP2007306071A - Solid electronic imaging apparatus, and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an image portion such as a blemish in a subject image. <P>SOLUTION: A mechanical shutter is opened during time points t1-t2 to execute exposure. Unwanted electrons accumulated in a vertical transfer passage of a CCD are swept out at a high speed during time points t3-t4 and t6-t7. An L level of vertical transfer pulses ϕV1-ϕV8 is decreased from -8v as a normal level to -7.5v (increased in a time chart) at each of finish time points t4 and t7 of the high-speed sweeping. Thus, since the signal charges do not move even if potential variation occurs at the finish time points t4 and t7 of high-speed sweeping, a blemish in the subject image due to the potential variation can be prevented from occurring at the time points of high-speed sweeping. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state electronic imaging device and a control method thereof.

If the exposure is performed for a long time, a lot of unnecessary charges may be accumulated in the vertical transfer path of the solid-state electronic imaging device. For this reason, there is one that prevents an increase in unnecessary charges (Patent Document 1).
JP 2001-352491 A

  In recent digital still cameras, the number of pixels is increasing even though the size of the solid-state electronic imaging device is small. In the vertical transfer path, since it is necessary to transfer the signal charges in a small area so as not to be mixed, the depth of the potential well for transferring the signal charges becomes deep. As the depth of the potential well increases, potential fluctuations are likely to occur when unnecessary charge sweeping is completed from the vertical transfer path. If unnecessary charges remain, the remaining unnecessary charges may leak into the potential well, and this leakage may appear as scratches on the subject image.

  An object of the present invention is to prevent image portions such as so-called scratches from being generated in a subject image.

  According to a first aspect of the present invention, there is provided a control device for a solid-state electronic image pickup device, wherein a plurality of photodiodes are arranged in a column direction and a row direction, and a solid-state electronic image pickup device including a vertical transfer path adjacent to each column of photodiodes. In response to the end of exposure, the solid-state electronic imaging is performed so as to sweep out the accumulated unnecessary charges using a vertical transfer pulse whose absolute value level at the end of unnecessary charge sweeping is smaller than the absolute value level at other times. First control means for controlling the device, and the solid state so as to shift the signal charge accumulated in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. Second control means for controlling the electronic imaging device, and a signal shifted to the vertical transfer path under the control of the second control means Load and characterized in that it comprises a third control means for controlling the solid-state electronic imaging device so as to output a video signal and transferred in the vertical direction on the basis of the given vertical transfer pulses.

  The first invention also provides a control method suitable for the control device of the solid-state electronic imaging device. That is, this method is a method for controlling a solid-state electronic imaging device including a plurality of photodiodes arranged in a column direction and a row direction, and including a vertical transfer path adjacent to each column of the photodiodes. In response to the completion of exposure to the photodiode, the accumulated unnecessary charges are swept away by using a vertical transfer pulse whose absolute value level at the end of unnecessary charge sweeping is smaller than the absolute value level at other times. The solid-state electronic image pickup device is controlled, and the second control means causes the signal charge accumulated in the photodiode to be transferred to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. The solid-state electronic image pickup device is controlled to shift, and the third control means shifts the vertical transfer path under the control of the second control means. The signal charges, and transferred in the vertical direction on the basis of the given vertical transfer pulses so as to control the solid-state electronic image sensing device so as to output a video signal.

  According to the first invention, when the exposure of the photodiode is completed, the signal charge accumulated in the vertical transfer path is swept before the signal charge accumulated in the photodiode is shifted to the vertical transfer path ( Unnecessary charge sweeping). In the vertical transfer pulse given to the vertical transfer path in the unnecessary charge sweeping, the absolute value level at the end of the unnecessary charge sweeping is smaller than the absolute value level at other points in time. For this reason, the depth of the potential well at the end of unnecessary charge sweeping is shallower than the depth of the potential well at other times. Potential fluctuation is less likely to occur, and unnecessary charges are prevented from leaking into the potential well. A subject image having no image portion such as a so-called scratch is obtained.

  For example, the first control means may be configured such that the absolute value level of the vertical transfer pulse is set at another time from the end of exposure to the photodiode to the end of video signal output based on the third control means. The solid-state electronic imaging device is controlled so that the unnecessary charge is swept out using a vertical transfer pulse smaller than the absolute value level of the vertical transfer pulse in FIG.

  The first control means is configured such that the absolute value level of the vertical transfer pulse is the level of the vertical transfer pulse at other time points from the start time of the unnecessary charge sweeping to the end time of the video signal output based on the third control means. The solid-state electronic imaging device may be controlled so as to sweep out the unnecessary charge using a vertical transfer pulse smaller than the absolute value level.

  In the first control means, the absolute value level of the vertical transfer pulse gradually decreases from the start point of the unnecessary charge sweeping to the end point of the unnecessary charge sweeping, and the video signal output based on the third control means is reduced. Control the solid-state electronic imaging device so that the unnecessary charge is swept away by using the vertical transfer pulse whose absolute value level is lower than the absolute value level of the vertical transfer pulse at other time points until the end point. You may do it.

  The third control means uses, for example, a vertical transfer pulse having an absolute value level larger than the absolute value level of the vertical transfer pulse at the end of the unnecessary charge sweeping used in the control of the first control means, The signal charge shifted to the vertical transfer path is transferred in the vertical direction.

  In the first control means, the absolute value level gradually decreases from the unnecessary charge sweep start time to the unnecessary charge sweep end time, and the signal charge performed under the control of the third control means. The solid-state electronic imaging device may be controlled so that the unnecessary charge is swept out by using a vertical transfer pulse whose absolute value level gradually increases before the start of the vertical transfer.

  According to a second aspect of the present invention, there is provided a control device for a solid-state electronic image pickup device, wherein a plurality of photodiodes are arranged in a column direction and a row direction, and a solid-state electronic image pickup device including a vertical transfer path adjacent to each column of photodiodes. In response to the completion of the exposure, the solid-state electronic imaging device is controlled so as to sweep out the accumulated unnecessary charges by using a vertical transfer pulse whose period at the end of unnecessary charge sweeping is longer than the period at other times. The solid-state electronic imaging device is configured to shift the signal charge stored in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means and the first control means. Second control means for controlling, and signal charge shifted to the vertical transfer path under the control of the second control means Characterized in that it comprises a third control means for controlling the solid-state electronic imaging device so as to output a video signal and transferred in the vertical direction based on the straight-forward pulse.

  The second invention also provides a control method suitable for the control device of the solid-state electronic imaging device. That is, this method is a control method for a solid-state electronic image pickup device in which a large number of photodiodes are arranged in a column direction and a row direction, and includes a vertical transfer path adjacent to each column of photodiodes. In response to completion of exposure to the diode, the solid-state electronic image pickup device sweeps out the accumulated unnecessary charges by using a vertical transfer pulse whose period at the end of unnecessary charge sweeping is longer than the period at other time points. And the second control means shifts the signal charge stored in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. The solid-state electronic image pickup device is controlled, and the third control unit applies the signal charge shifted to the vertical transfer path under the control of the second control unit. And controls the solid-state electronic image sensing device so as to output a video signal and transferred in the vertical direction based on the vertical transfer pulses to be.

  According to the second invention, when the exposure to the photodiode is completed, the signal charge accumulated in the vertical transfer path is swept before the signal charge accumulated in the photodiode is shifted to the vertical transfer path ( Unnecessary charge sweeping). The vertical transfer pulse applied to the vertical transfer path in the unnecessary charge sweeping has a longer period at the end of unnecessary charge sweeping than the period at other time points. For this reason, at the end of unnecessary charge sweeping, potential fluctuations are less likely to occur, and unnecessary charge is prevented from leaking into the potential well. A subject image having no image portion such as a so-called scratch is obtained.

  FIG. 1 shows an embodiment of the present invention and is a part of a schematic diagram of a CCD.

  The CCD 1 is provided with a large number of photodiodes 2 in the horizontal and vertical directions. The CCD 1 in this embodiment is of a so-called honeycomb arrangement, in which odd-numbered rows are provided with photodiodes 2 in odd-numbered columns, and even-numbered rows are provided with photodiodes 2 in even-numbered columns. Of course, odd-numbered rows may be provided with photodiodes in even-numbered columns, and even-numbered rows may be provided with photodiodes 2 in odd-numbered columns. 2 may be provided.

  On the light receiving surface of the odd-numbered photodiodes 2, a filter having a characteristic of transmitting a green light component is formed (labeled “G”). On the light receiving surfaces of the photodiodes 2 in the even-numbered rows, a filter having a characteristic of transmitting a blue light component (reference symbol “B” is attached) and a filter having a characteristic of transmitting a red light component (reference symbol “B”). R "). Of course, it is needless to say that such a filter arrangement is not necessary.

  A vertical transfer path 5 is formed on the right side of the photodiodes 2 in each column. On the vertical transfer path 5, vertical transfer electrodes V1 to V8 are periodically formed in the order of these electrodes V1 to V8. Vertical transfer electrodes V1 and V8 are formed on the right side of the filter that transmits the green light component. Vertical transfer electrodes V2 and V3 or V4 and V5 are formed on the right side of the filter that transmits the blue light component or the filter that transmits the red light component.

  A horizontal transfer path 6 is formed below the vertical transfer path 5. An amplifier circuit 7 is connected to the left end of the horizontal transfer path 6.

  The signal charge accumulated in the photodiode 2 is shifted to the vertical transfer path 5 by applying a read pulse, but unnecessary charges accumulated in the vertical transfer path 5 are swept out at a high speed before this shift. . After the unnecessary charge is swept out, the signal charge accumulated in the photodiode 2 is shifted to the vertical transfer path 5. By applying vertical transfer pulses φV1 to φV8 to the vertical transfer electrodes V1 to V8 of the vertical transfer path 5, signal charges are transferred in the vertical direction in the vertical transfer path 5. The signal charge output from the vertical transfer path 5 is applied to the horizontal transfer path 6, transferred in the horizontal direction, and output as a video signal via the amplifier circuit 7.

  FIG. 2 shows the principle that a so-called flaw is generated in a subject image by sweeping out unnecessary charges accumulated in the vertical transfer path at high speed.

  As described above, the vertical transfer pulses φV1 to φV8 are applied to the vertical transfer electrodes V1 to V8. Then, the potential well 10 is formed in the vertical transfer path 5 and the signal charge is transferred in the vertical direction. Since the number of pixels is increased without increasing the size of the CCD 1, the L level (VL) of the vertical transfer pulses φV1 to φV8 is set higher than the ground level (VM) so that the potential well 10 is deepened. (E.g., -8v).

  If unnecessary charge sweeping is performed at high speed, potential fluctuation may occur at the end of unnecessary charge sweeping, and the signal charge 11 may leak to the potential well 10. This leakage is a cause of scratches on the subject image.

  FIG. 3 is a time chart showing how the potential fluctuation occurs.

  Between time t1 and time t2, the mechanical shutter in front of the CCD 1 is opened, and signal charges are accumulated in the photodiode 2 of the CCD 1. Thereafter, a vertical transfer pulse for sweeping out unnecessary charges accumulated in the vertical transfer path between time t3 and t4 at a high speed is applied. The potential fluctuation of the vertical transfer pulse occurs at the start time t3 and the end time t4 of the high-speed sweep. As described above, the signal charge leaks to the potential well, which causes damage to the subject image, due to the potential fluctuation at the end time t4.

  A so-called idle transfer is performed between time t4 and time t5 when signal charges for several lines can be swept out. At time t <b> 5, a read pulse is applied to the odd-numbered photodiodes 2, whereby the signal charges accumulated in the odd-numbered photodiodes 2 are shifted to the vertical transfer path 5. By driving the CCD 1 between time t5 and time t6, the video signal of the first field (odd field) is output from the CCD 1.

  When the output of the video signal of the first field is completed at time t6, the unnecessary charges accumulated in the vertical transfer path are quickly swept out. The potential fluctuation occurs at the start time t6 and the end time t7 of the high-speed sweep, and the signal charge leaks to the potential well causing the kiss of the subject image due to the potential fluctuation at the end time t7.

  Empty transfer is performed between time t7 and t8. At time t <b> 8, a read pulse is applied to the photodiodes 2 in the even rows, so that the signal charges accumulated in the photodiodes 2 in the even rows are shifted to the vertical transfer path 5. When the CCD 1 is driven between time t8 and t9, the video signal of the second field (even field) is output from the CCD 1.

  FIG. 4 is a time chart of video signal output according to the embodiment of the present invention.

  In this embodiment, the mechanical shutter is closed at time t2, and the L level of the vertical transfer pulses φV1 to φV8 is slightly lowered until time t9 (it rises on the time chart, and the absolute value level is It has been reduced.) For example, the L level that was -8v is set to the -7.5 level. Since the L level of the vertical transfer pulses φV1 to φV8 is slightly lowered, the depth of the potential well is slightly reduced. It is possible to prevent signal charges from leaking into the potential well even if potential fluctuation occurs at the end times t4 and t7 of the high-speed sweeping of unnecessary charges. It is possible to prevent scratches on the subject image.

  FIG. 5 shows another embodiment and is a time chart of video signal output.

  In this embodiment, the L level of the vertical transfer pulses φV1 to φV8 is slightly lowered from the time t3 of unnecessary charge sweeping before the transfer of the signal charge of the first field to the time t9. At times t4 and t7, which are the end points of high-speed sweeping, the L level of the vertical transfer pulse is slightly lowered (increased on the time chart), so that scratches in the subject image have not occurred as described above. Can be prevented.

  FIG. 6 shows still another embodiment and is a time chart of video signal output.

  In this embodiment, the L level of the vertical transfer pulses φV1 to φV8 is gradually lowered slightly from the start time t3 to the end time t4 of the unnecessary charge sweeping performed before transferring the signal charge of the first field ( It is rising on the time chart). From time t4 to time t9, the state in which the L level of the vertical transfer pulses φV1 to φV8 is slightly lowered is maintained, and then returned to the original level. Also in this case, since the L level of the vertical transfer pulses φV1 to φV8 is lowered at the end times t4 and t7 of the high-speed transfer sweeping out, it is possible to prevent the subject image from being damaged.

  FIG. 7 shows still another embodiment and is a time chart of video signal output.

  In this embodiment, the output of the video signal of the second field is started from the time point t4 when the first high-speed sweep ends to the output start time t5 of the video signal of the first field and from the time t7 of the second high-speed sweep end. Until the time point t8, the L level of the vertical transfer pulses φV1 to φV8 is lowered (increases on the time chart). During the period from time t5 to t6 when the video signal of the first field is output and from time t8 to t9 when the video signal of the second field is output, the L level of the vertical transfer pulses φV1 to φV8 is the original level. (Returned on the time chart). While the video signal is output, the L level of the vertical transfer pulses φV1 to φV8 is returned to the original level, so that the potential well is deep. It is possible to prevent the signal charges of different pixels from being mixed.

  FIG. 8 shows still another embodiment and is a time chart of video signal output.

  In this embodiment, the L level of the vertical transfer pulses φV1 to φV8 gradually decreases (increases on the time chart) from the respective time points from the high-speed sweep start time points t3 and t6, and the high-speed sweep end points t4 and t7. The L level of the vertical transfer pulses φV1 to φV8 is the lowest (−7.5 v) at each time point in FIG. Thereafter, the L level of the vertical transfer pulses φV1 to φV8 gradually increases (decreases on the time chart) by the respective end times t5 and t8 of the empty transfer. Even in this case, while the video signal is output, the L level of the vertical transfer pulses φV1 to φV8 is returned to the original level, so that the potential well is deep. It is possible to prevent the signal charges of different pixels from being mixed.

  FIG. 9 shows still another embodiment and is a time chart of video signal output.

  In the above-described embodiment, the L level of the vertical transfer pulses φV1 to φV8 is slightly lowered at the end of the high-speed sweep, but in this embodiment, the vertical transfer pulses in the first high-speed sweep period t3-4 φV1 to φV8 are set to have a low frequency (long cycle) for a predetermined first period t3 to t31 from the start time, and then to a high frequency (short cycle) from a predetermined second period t31 to t32. From t32 to t4 at the end of the high-speed sweep after the end of the second period, the frequency is again low (long period). Since the frequency of the vertical transfer pulses φV1 to φV8 is low at the end point t4 of the high-speed sweeping, the potential fluctuation can be suppressed. Further, since the intermediate period t31 to t32 has a high frequency, unnecessary charges can be swept out quickly. Similarly, in the second high-speed sweep period t6 to t7, the frequency of the vertical transfer pulses φV1 to φV8 is lowered in the period including the start time t6 and the period including the end time t7, and the vertical transfer pulse is set in the middle period. By speeding up the frequencies of φV1 to φV8, it is possible to sweep out unnecessary charges while suppressing potential fluctuation.

  In the above-described embodiment, the period including the start point of the high-speed sweep is the low-frequency vertical transfer pulses φV1 to φV8. However, if the period including the end point of the high-speed sweep is the low-frequency vertical transfer pulses φV1 to φV8, Needless to say, it is good.

  FIG. 10 is a block diagram showing an electrical configuration of a digital still camera using the CCD 1 described above.

  The overall operation of the digital still camera is controlled by the CPU.

  The digital still camera includes a shutter switch 29 and a switch 30 including a power button and the like. Output signals from these switches and the like are input to the CPU 28 via the main bus. The digital still camera includes a memory 24 for temporarily storing operation programs and data. Further, the digital still camera also includes an audio input / output interface 28 for inputting and outputting audio.

  In front of the CCD 1, an imaging system mechanical unit 21 including the mechanical shutter, the imaging lens, the barrier, the diaphragm and the like described above is provided. The imaging system machine unit 21 is driven by a drive circuit 26. The subject image is formed on the light receiving surface of the CCD 1. The CCD 1 is driven by a drive circuit 26. A video signal representing the subject image is output from the CCD 1. The drive circuit 26 is supplied with a modulation control signal output from the VL modulation circuit 27. By applying the modulation control signal to the drive circuit 26, the L level of the vertical transfer pulses φV1 to φV8 applied to the vertical transfer path of the CCD 1 is adjusted as described above, or the frequency of the vertical transfer pulses φV1 to φV8 is controlled. Is done.

  The video signal output from the CCD 1 is subjected to predetermined digital signal processing such as white balance adjustment, gamma correction, and analog / digital conversion in the digital signal processing circuit 23 and is output as digital image data. The digital image data is given to the image display device 32. The subject image obtained by imaging is displayed on the display screen of the image display device 32.

  When the shutter switch 29 is pressed, the digital image data obtained as described above is given to the memory card 33 via the memory card interface 31 and recorded. The subject image represented by the image data recorded on the memory card 33 has the scratches removed as described above.

It is a schematic diagram of CCD. The relationship between the vertical transfer electrode and the potential well is shown. It is a time chart of a video signal output. It is a time chart of a video signal output. It is a time chart of a video signal output. It is a time chart of a video signal output. It is a time chart of a video signal output. It is a time chart of a video signal output. It is a time chart of a video signal output. It is a block diagram which shows the electric constitution of a digital still camera.

Explanation of symbols

1 CCD
2 Photodiode 5 Vertical transfer path
26 Drive circuit
27 VL modulation circuit V1 to V8 vertical transfer electrode φV1 to φV8 vertical transfer pulse

Claims (9)

A solid-state electronic image pickup device including a plurality of photodiodes arranged in a column direction and a row direction and including a vertical transfer path adjacent to each column of the photodiodes;
In response to the completion of exposure to the photodiode, the accumulated unnecessary charges are swept away by using a vertical transfer pulse whose absolute value level at the end of unnecessary charge sweeping is smaller than the absolute value level at other times. First control means for controlling the solid-state electronic imaging device,
Second control for controlling the solid-state electronic image pickup device so as to shift the signal charge accumulated in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. And a signal charge shifted to the vertical transfer path under the control of the second control means in the vertical direction based on a given vertical transfer pulse to output a video signal. Third control means for controlling the electronic imaging device;
A control device for a solid-state electronic imaging device. The first control means is configured such that the absolute value level of the vertical transfer pulse is vertical at other times from the end of exposure of the photodiode to the end of video signal output based on the third control means. The solid-state electronic imaging device is controlled to sweep out the unnecessary charge using a vertical transfer pulse smaller than the absolute value level of the transfer pulse,
The control apparatus of the solid-state electronic imaging device of Claim 1. The first control means is configured such that the absolute value level of the vertical transfer pulse is the level of the vertical transfer pulse at other time points from the start time of the unnecessary charge sweeping to the end time of the video signal output based on the third control means. The solid-state electronic imaging device is controlled so as to sweep out the unnecessary charge by using a vertical transfer pulse smaller than an absolute value level.
The control apparatus of the solid-state electronic imaging device of Claim 1. In the first control means, the absolute value level of the vertical transfer pulse gradually decreases from the start point of the unnecessary charge sweeping to the end point of the unnecessary charge sweeping, and the video signal output based on the third control means is reduced. The solid-state electronic imaging device is controlled so that the unnecessary charge is swept out by using the vertical transfer pulse whose absolute value level of the vertical transfer pulse is smaller than the absolute value level of the vertical transfer pulse at other time points until the end point. To do,
The control apparatus of the solid-state electronic imaging device of Claim 1. The third control means uses the vertical transfer pulse having an absolute value level larger than the absolute value level of the vertical transfer pulse at the end of the unnecessary charge sweeping used in the control of the first control means. The signal charge shifted to the transfer path is transferred in the vertical direction.
The control apparatus of the solid-state electronic imaging device of Claim 1. In the first control means, the absolute value level gradually decreases from the unnecessary charge sweep start time to the unnecessary charge sweep end time, and the signal charge performed under the control of the third control means. The solid-state electronic imaging device is controlled so that the unnecessary charge is swept out by using a vertical transfer pulse whose absolute value level gradually increases before the start of the vertical transfer.
The control apparatus of the solid-state electronic imaging device of Claim 1. A solid-state electronic image pickup device including a plurality of photodiodes arranged in a column direction and a row direction and including a vertical transfer path adjacent to each column of the photodiodes;
In response to the completion of exposure to the photodiode, the solid-state electrons are swept out by using a vertical transfer pulse whose period at the end of unnecessary charge sweeping is longer than the period at other time points. First control means for controlling the imaging device;
Second control for controlling the solid-state electronic image pickup device so as to shift the signal charge accumulated in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. And a signal charge shifted to the vertical transfer path under the control of the second control means in the vertical direction based on a given vertical transfer pulse to output a video signal. Third control means for controlling the electronic imaging device;
A control device for a solid-state electronic imaging device. In a method for controlling a solid-state electronic imaging device including a plurality of photodiodes arranged in a column direction and a row direction and including a vertical transfer path adjacent to each column of the photodiodes,
In response to the completion of exposure to the photodiode, the first control means stores the vertical value using the vertical transfer pulse whose absolute value level at the end of unnecessary charge sweeping is smaller than the absolute value level at other times. Controlling the solid-state electronic image pickup device so as to sweep away unnecessary electric charge,
The solid-state electronic imaging device so that the second control means shifts the signal charge stored in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. Control
The third control means outputs the video signal by transferring the signal charge shifted to the vertical transfer path under the control of the second control means in the vertical direction based on the applied vertical transfer pulse. To control the solid-state electronic imaging device,
Control method of solid-state electronic imaging device. In a control method of a solid-state electronic imaging device including a plurality of photodiodes arranged in a column direction and a row direction and including a vertical transfer path adjacent to each column of the photodiodes,
In response to the completion of exposure to the photodiode, the first control means uses the vertical transfer pulse whose period at the end of unnecessary charge sweeping end is longer than the period at other time points, and accumulates unnecessary charges. Control the solid-state electronic imaging device to sweep out
The solid-state electronic imaging device so that the second control means shifts the signal charge stored in the photodiode to the vertical transfer path after sweeping out unnecessary charges performed under the control of the first control means. Control
The third control means outputs the video signal by transferring the signal charge shifted to the vertical transfer path under the control of the second control means in the vertical direction based on the applied vertical transfer pulse. To control the solid-state electronic imaging device,
Control method of solid-state electronic imaging device.

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