JP2005269060A - Method for driving CCD solid-state image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method of a CCD solid-state image pickup device which realizes a high frame rate by greatly shortening a horizontal blanking period.
A driving method of a CCD solid-state imaging device according to the present invention vertically transfers signal charges of pixels arranged in a matrix for each horizontal line via a vertical transfer register, and performs signal charges for each horizontal line. In the driving of the CCD solid-state imaging device that outputs the signal in the horizontal effective scanning period 3, the signal charges are vertically transferred in the horizontal effective scanning period 3, and the vertical transfer register at the time of the vertical transfer has a drive clock waveform. Drive clock waveform with rising and falling slopes at a transient speed ΔV / ΔT (where ΔV is voltage and ΔT is time) so that cross-talk noise generated at the rise and fall can be removed by the correlated double sampling circuit It is characterized by the fact that it is supplied.
[Selection] Figure 2

Description

  The present invention relates to a method for driving a CCD solid-state imaging device that enables a high frame rate.

  In recent years, a video camera equipped with a CCD solid-state image sensor is strongly demanded to perform a slow reproduction by imaging the camera portion at a high speed irrespective of a TV (television) system, and a digital still camera equipped with a CCD solid-state image sensor. However, it is regarded as a problem that the continuous shooting speed decreases as the number of pixels increases, and there is a demand for speeding up the image sensor.

FIG. 9 shows an example of a conventional CCD solid-state imaging device and its driving method. FIG. 9A shows a main part applied to an interline transfer (IT) type CCD solid-state imaging device, that is, a main part from the imaging region to the horizontal transfer register and further to the output unit.
In the CCD solid-state imaging device 30 of this example, a plurality of light receiving sensors 31 serving as pixels are arranged in a matrix, and a plurality of CCD structure vertical transfer registers 33 are formed corresponding to each light receiving sensor column. A horizontal transfer register 34 having a CCD structure is formed so as to be connected to the final stage of the vertical transfer register 33, and an output unit 36 is connected to the subsequent stage of the horizontal transfer register 34.

  The vertical transfer register 33 is formed so that two vertical transfer electrodes correspond to one light receiving sensor 31, and is configured to transfer and drive signal charges in the vertical direction by four-phase vertical transfer pulses φV1, φV2, φV3, and φV4. Composed. That is, vertical transfer pulses φV1, φV2, φV3, and φV4 are applied to the four transfer electrodes 32 [321, 322, 323, 324], respectively. In this example, transfer electrodes 321 and 323 are formed corresponding to the position of the light receiving sensor 31. The light receiving sensor 31 located at the end in the vertical direction corresponds to the transfer electrode 321 to which the vertical transfer pulse φV1 is applied.

  The vertical transfer register 33 is connected to the horizontal transfer register 34 via transfer electrodes (transfer electrodes to which φV1 to φV4 are applied) 321 to 324 for one bit in the final stage. Each transfer electrode 321 to 324 is formed to extend in the horizontal direction so as to be common to each vertical transfer register 33.

  The horizontal transfer register 34 is configured so that two horizontal transfer electrodes 35 [351, 352] correspond to each vertical transfer register 33, and signal charges are horizontally transmitted by two-phase horizontal drive pulses φH1, φH2. It is configured to be driven to transfer.

  In the CCD solid-state imaging device 30, light received by the light receiving sensor 31 is subjected to photoelectric conversion, and signal charges corresponding to the amount of received light are accumulated. The signal charge of the light receiving sensor 31 is read from the light receiving sensor 31 to the vertical transfer register 33 during the vertical blanking period, and thereafter, the signal charge for each horizontal line is vertically transferred during the horizontal blanking period, so-called vertical line shift. Is transferred to the horizontal transfer register 34. Then, the signal charges transferred to the horizontal transfer register 34 are transferred in the horizontal direction during the horizontal effective transfer period, and output through the output unit 36.

  The vertical line shift of the signal charge in the conventional CCD solid-state imaging device is designed to be driven to transfer with vertical transfer pulses (ΦV1 to ΦV4) during a TV system horizontal blanking period. The drive timing of the vertical line shift is shown in FIG. 9B. As shown in FIG. 9B, the vertical line shift of the signal charge is caused by the horizontal phases waiting in the transfer electrodes 322 and 323 corresponding to φV2 and φV3, for example, by the four-phase vertical drive pulses φV1 to φV4 in the horizontal blanking period Hb. The line is shifted to the transfer register 34. That is, the signal charge is transferred to the transfer electrode 351 to which each horizontal drive pulse φH1 of the horizontal transfer register 34 is applied at the fall of the vertical drive pulse φV4 of the transfer electrode 324. Although not shown, the rising and falling slopes ΔV / ΔT (ΔV is a voltage and ΔT is a voltage) of each vertical drive pulse φV1 to φV4 applied to the vertical transfer electrodes 321 to 324 in the horizontal blanking period during the vertical line shift. The so-called transient speed (ΔV / ΔT) is the same as the transient speed (ΔV / ΔT) of the vertical transfer pulses φV1 to φV4 applied to the vertical transfer electrodes 321 to 324 in the vertical blanking period. In FIG. 9B, the drive pulse is shown as a rectangular pulse that rises vertically and falls.

  On the other hand, for example, in an electronic camera shake correction operation of a video camera using a CCD solid-state image sensor or a frame interline transfer (FIT) type CCD solid-state image sensor for broadcasting business, high-speed vertical transfer is performed during the vertical blanking period. Need.

In addition, it has been proposed to perform vertical line shift with a four-phase vertical transfer pulse in a horizontal blanking period in a CCD imaging device (see, for example, FIG. 3 of Patent Document 1).
JP 2000-138943 A

Conventionally, in the CCD solid-state imaging device described above, vertical line shift and vertical high-speed transfer are driven by a vertical drive scanning circuit having the same characteristics, that is, a so-called vertical driver. Generally, a CMOS type vertical driver having a high speed is used. It has been. Therefore, if this vertical transfer is performed during the horizontal effective scanning period, noise due to crosstalk occurs in the CCD solid-state imaging device at the moment when the vertical transfer pulses (ΦV1 to ΦV4) are applied. That is, when performing vertical transfer during the horizontal effective scanning period, the transient speed at the rising and falling edges of the driver waveform, that is, the rising and falling slopes ΔV / ΔT of the vertical transfer pulses (ΦV1 to ΦV4) is large. Crosstalk noise is added to the CCD output signal, and vertical line image noise appears.
However, when vertical line shifting is performed, the application of the vertical transfer pulses (ΦV1 to ΦV4) has no adverse effect on an image during the horizontal blanking period. It has been designed with an electrode resistance value that is transferred during the ranking period.

When the TV system was mainstream, the horizontal blanking period was defined in the TV system, so it was sufficient if the vertical line shift could be performed within the horizontal blanking period.
However, when trying to increase the number of pixels and increase the frame rate regardless of the TV system, the horizontal blanking period necessary for the vertical line shift becomes useless time, which is an obstacle to the increase in the frame rate. For this reason, it is necessary to shorten the horizontal blanking period, but this requires a reduction in the resistance of the transfer electrode. In order to reduce the resistance, it is necessary to increase the thickness of the transfer electrode. For this reason, the step around the sensor opening becomes high, and when light is incident, vignetting of oblique light occurs, which causes a problem that sensitivity is lowered and shading occurs.

  As described above, when the frame rate is increased, in an electronic device such as a digital still camera using a CCD solid-state imaging device that is not a TV system, even if the signal output rate is increased, the horizontal blanking time increases, and it exceeds a certain level. I couldn't make it faster.

  In view of the above-described points, the present invention provides a method for driving a CCD solid-state imaging device that significantly shortens the horizontal blanking period and realizes a high frame rate.

  According to the driving method of the CCD solid-state imaging device according to the present invention, the signal charges of the pixels arranged in a matrix are vertically transferred for each horizontal line via the vertical transfer register, and the signal charge for each horizontal line is horizontally effective scanned. In the drive of the CCD solid-state imaging device that outputs during the period, vertical transfer of the signal charge is performed during the horizontal effective scanning period, and the vertical transfer register during the vertical transfer is generated at the rise and fall of the drive clock waveform. A drive clock waveform having rising and falling slopes at a transient speed ΔV / ΔT (where ΔV is a voltage and ΔT is a time) that can be eliminated by a correlated double sampling circuit is supplied. It is characterized by that.

  According to the driving method of the CCD solid-state imaging device according to the present invention, the signal charges of the pixels arranged in a matrix are vertically transferred for each horizontal line via the vertical transfer register, and the signal charge for each horizontal line is horizontally effective scanned. In the drive of the CCD solid-state image sensor output during the period, the vertical transfer of the signal charge is performed in the horizontal effective scanning period, and the vertical transfer register at the time of the vertical transfer rises from the drive clock waveform of the high-speed transfer during the blanking period. In addition, a drive clock waveform having a small falling slope is supplied.

  The drive clock waveform preferably has rising and falling slopes at which the transient speed ΔV / ΔT is 50 mV / nsec or less (not including 0). As the drive clock waveform at the time of vertical transfer, it is preferable to use a drive clock waveform in which the rising and falling corners are rounded. For vertical transfer, it is preferable to use constant current driving.

  In the CCD solid-state imaging device driving method of the present invention, the vertical transfer of signal charges is performed in the horizontal effective scanning period, and the vertical transfer register at the time of vertical transfer is slow enough to eliminate crosstalk noise with a correlated double sampling circuit. By supplying a drive clock waveform with a small rising and falling slope, the transient speed at the rising and falling is slowed down, and even if crosstalk noise occurs in the CCD output, this crosstalk noise Becomes a low-frequency noise, and can be removed by a correlated double sampling circuit in the subsequent stage. For this reason, the horizontal blanking period can be shortened and the speed can be increased.

  According to the driving method of the CCD solid-state imaging device according to the present invention, the signal charges of the pixels arranged in a matrix are vertically transferred for each horizontal line via the vertical transfer register, and the signal charge for each horizontal line is horizontally effective scanned. In the drive of the CCD solid-state image sensor output during the period, vertical transfer of signal charge is performed in the horizontal effective scanning period, and the vertical transfer register at the time of vertical transfer has a stepped rise that varies in the reset period without fluctuation in the signal period And a drive clock waveform having a falling edge. For vertical transfer, it is preferable to use pulse current drive.

  In the method for driving a CCD solid-state imaging device according to the present invention, the vertical transfer of signal charge is performed in the horizontal effective scanning period, and the vertical register at the time of vertical transfer has a stepped shape that does not change in the signal period but changes in the reset period. A drive clock waveform having a rising edge and a falling edge is supplied. At the stepped rise and fall, there is no change in the drive clock during the signal period, and the crosstalk noise during each reset period is not affected by the period between the clamp pulse and the sample hold pulse of the correlated double sampling circuit. It is not superimposed on the output of the double sampling circuit. For this reason, the horizontal blanking period can be shortened and the speed can be increased.

According to the driving method of the CCD solid-state imaging device of the present invention, the horizontal blanking period can be shortened and a high frame rate can be realized. The vertical transfer pulse may be operated at a relatively low speed, and the vertical transfer electrode can be thinned. Therefore, since the step around the sensor opening can be reduced, the light collection efficiency of oblique light can be improved and the sensitivity can be improved.
Since the vertical transfer electrode can be made thin, the step around the sensor opening can be reduced, and the pixel cells can be made finer, the number of pixels can be increased, and the speed can be increased.

When using a drive clock waveform with a small rising and falling slope and rounded corners of the waveform as the drive clock waveform, the transient speed is further reduced, and the crosstalk noise becomes lower frequency noise. Is easily removed by the correlated double sampling circuit.
By using constant current driving for vertical transfer, a drive clock waveform having a small rising and falling slope is obtained, and vertical transfer within the horizontal effective transfer period described above is made possible.

  In addition, by using the fact that there is a reset period and a signal period, it is driven by a pulse current in the reset period, and the rising and falling edges of the drive clock waveform are stepped so as to change in the reset period without changing in the signal period. Thus, it is possible to eliminate a change in the driving clock during the signal period, and to further reduce crosstalk noise. Thereby, the horizontal blanking period can be shortened, and a high frame rate can be realized. By using the pulse current drive for the vertical transfer, the drive clock waveform having the stepped rise and fall is obtained, and the vertical transfer within the horizontal effective transfer period is enabled.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing an embodiment of a CCD solid-state imaging device according to the present invention. FIG. 1 shows a main part applied to an interline transfer (IT) type CCD solid-state imaging device, that is, a main part from an imaging region to a horizontal transfer register and further to an output unit.
In the CCD solid-state imaging device 10 according to the present invention, a plurality of light receiving sensors 11 serving as pixels are arranged in a matrix, and a plurality of CCD structure vertical transfer registers 13 are formed corresponding to each light receiving sensor column, A horizontal transfer register 14 having a CCD structure is formed so as to be connected to the final stage of each vertical transfer register 13, and an output unit 16 and a correlated double sampling (CDS) circuit 17 are connected to the subsequent stage of the horizontal transfer register 14. t _out is an output terminal.

  The vertical transfer register 13 is formed so that two vertical transfer electrodes correspond to one light receiving sensor 11, and is configured to transfer and drive signal charges in the vertical direction by four-phase vertical transfer pulses φV1, φV2, φV3, and φV4. Composed. That is, the vertical transfer pulses φV1, φV2, φV3, and φV4 are applied to the four transfer electrodes 12 [121, 122, 123, 124], respectively. In this example, transfer electrodes 121 and 123 are formed corresponding to the position of the light receiving sensor 11. The light receiving sensor 11 located at the end in the vertical direction corresponds to the transfer electrode 123 to which the vertical transfer pulse φV3 is applied.

  The vertical transfer register 13 is connected to the horizontal transfer register 14 via a storage gate part STG and a hold gate part HLG formed at the subsequent stage of the final stage transfer electrode (transfer electrode to which φV4 is applied) 124. The transfer electrodes 121 to 124, the transfer electrode 21 of the storage gate unit STG, and the transfer electrode 22 of the hold gate unit HLG are formed to extend in the horizontal direction so as to be common to the vertical transfer registers 13, respectively.

  The horizontal transfer register 14 is configured so that two horizontal transfer electrodes 15 [151, 152] correspond to each vertical transfer register 13, and the signal charges are horizontally transmitted by two-phase horizontal drive pulses φH1, φH2. It is configured to be driven to transfer.

  In the present embodiment, as shown in the timing chart of FIG. 2, in particular, vertical transfer of signal charges in the vertical transfer register 13, that is, vertical line shift is performed during the horizontal effective scanning period 3, and the horizontal blanking period. 4 is shortened. Therefore, as described above, the storage gate portion STG and the hold gate portion HLG are provided between the transfer portion having the transfer electrode 124 at the final stage of the vertical transfer register 13 and the horizontal transfer register 14.

  At the time of vertical line shift, four-phase vertical transfer pulses φV1 to φV4 are applied to the transfer electrodes 121 to 124, and a straight gate voltage φVSTG and a hold gauge voltage φVHLG are applied to the straight gauge portion STG and the hold gate portion HLG, respectively.

  On the other hand, in the present embodiment, since vertical line shift is performed during the horizontal effective scanning period 3, vertical drive pulses φV1 to φV4 in the CCD transfer unit, that is, rise and fall Tf of the clock waveform, so-called transients. It is necessary to eliminate the influence of crosstalk noise. Therefore, in the present embodiment, as shown in FIG. 2A, the slopes ΔV / ΔT of the rising Tr and the falling Tf in the vertical drive pulses φV1 to φV4 of the vertical line shift (ΔV is the pulse voltage, and ΔT is the time). To reduce the transient speed. Here, the transient speed ΔV / ΔT is set to a low speed such that the CDS circuit 17 can remove the crosstalk noise generated when the vertical transfer pulses φV1 to φV4 are applied.

  When the transient speed of the vertical drive pulses φV1 to φV4 was slowed and the experiment was conducted, if the transient speed ΔV / ΔT was 50 mV / 1 nsec or less (excluding 0), the crosstalk generated at the time of vertical line shift. It was confirmed that the noise was removed by the CDS circuit 17 and that the influence of the image noise (vertical stripe) on the CCD output of the solid-state imaging device was eliminated even if the vertical line shift was performed during the horizontal effective scanning period 3. That is, the crosstalk noise due to the vertical drive pulse having the transient speed ΔV / ΔT of 50 mv / 1 nsec or less (not including 0) does not have a high frequency component and is sufficiently removed by the CDS circuit 17.

  Incidentally, the transient speed ΔV / ΔT of the vertical transfer pulse of the conventional vertical line shift is about 1 V / 1 nsec, and the crosstalk noise caused by such a vertical transfer pulse has a high frequency component and cannot be removed by the CDS circuit.

  Further, the clock waveforms of the vertical transfer pulses φV1 to φV4 during the horizontal effective scanning period 3 will be described with reference to FIG. FIG. 3 shows changes in voltage ΔV and time ΔT of rising Tr and falling Tf for one clock waveform. The inclination of the rising Tr and the falling Tf, that is, the transient speed ΔV / ΔT is slowed (the inclination is made gentle), so that when the vertical transfer pulses ΦV1 to φV4 are applied and the vertical line shift is performed, the CCD solid-state imaging device 10 Can be removed by the CDS circuit 17 connected to the output side.

Next, a method for driving the CCD solid-state imaging device according to the above-described embodiment will be described.
In the CCD solid-state imaging device 10, the light receiving sensor 11 receives light and performs photoelectric conversion, and signal charges corresponding to the amount of received light are accumulated in the light receiving sensor 11. The signal charge of the light receiving sensor 11 is read from the light receiving sensor 11 to the vertical transfer register 13 in the vertical blanking period 5, and the signal charge corresponding to the light receiving sensor 11 located at the lowermost end is transferred to the vertical transfer register 13 and the horizontal transfer register. 14 is transferred to the storage gate part STG between 14.
Thereafter, in the horizontal blanking period 4, signal charges for each horizontal line are vertically transferred, so-called vertical line shift is performed, and transferred to the horizontal transfer register 14. The signal charges transferred to the horizontal transfer register 14 are transferred in the horizontal direction during the horizontal effective scanning period 3 and output from the output terminal t _out through the output unit 16 and the CDS circuit 17.

  The vertical line shift described above is performed in the horizontal effective scanning period 3 in which the signal charges in the horizontal transfer register 14 are transferred in the horizontal direction, and transferred to the storage gate unit STG. The signal charge can be transferred to the horizontal transfer register 14 only by transferring it from the storage gate portion STG to the horizontal transfer register 14 by the storage gate voltage φVSTG and the hold gauge voltage φVHLG. Is shortened.

  Further, since the transient speeds ΔV / ΔT of the vertical transfer pulses φV1 to φV4 applied at the time of the vertical line shift are slow, the crosstalk noise generated at the time of the vertical line shift becomes a low frequency component, and as described above, the CDS circuit 17 is sufficient. Will be removed.

FIG. 5 shows a rising waveform and a constant current waveform in which the rising portion of the slope of the vertical transfer pulse φV shown in FIG. 3 is enlarged, and horizontal transfer pulses φH1 and φH2, a reset pulse φRG, a CCD output, and a CDS circuit. It is a timing chart of clamp pulse SHP, sample hole pulse SHD, and CDS output.
By driving with the constant current i1, the transient speed ΔV1 / ΔT1 of the vertical transfer pulse φV can be slowed (a gentle slope). The signal charges transferred to the floating diffusion region with the two-phase driving horizontal transfer pulses φH1 and φH2 are read out after being subjected to charge-voltage conversion and then reset for each pixel with a reset gate pulse φRG applied in the reset period 6 Is done. In the SHD circuit 17, a good CDS output can be obtained by applying the clamp pulse SHP and the sample hole pulse SHD during the signal period 7 of the CCD output.

  In the present embodiment, it is important to set the vertical transfer pulse so that the transient speed ΔV / ΔT is slowed and the change is minimized. The vertical transfer pulses φV1 to φV4 having a drive waveform having a slow transient speed ΔV / ΔT are driven by a constant current, for example, by using the fact that the transfer electrodes 121 to 124 having a CCD structure serve as a capacitive load instead of a normal CMOS driver. By doing so, a constant slope ΔV / ΔT = a constant drive waveform can be formed. That is, as shown in FIG. 3, by applying a constant current i1 (rectangular wave) to the transfer electrodes 121 to 124, vertical transfer pulses φV1 to φV4 having a drive waveform with a constant slope ΔV / ΔT are obtained.

  If the vertical line of the crosstalk noise is a problem due to the change at the end of the constant current, as shown in FIG. 4, a change (ΔV2) that rounds the corner of the waveform of ΔV / ΔT at the rising Tr2 and the falling Tf2 / ΔT2) A current i2 having a waveform that gradually reduces the current so as to be 2 may be applied to the transfer electrodes 121-124.

A driving method in which crosstalk noise is further reduced is shown in FIGS. FIG. 6 shows one clock waveform of the vertical transfer pulse φV corresponding to FIG. 3 described above. FIG. 7 corresponds to FIG. 5 described above, and shows a rising waveform and a pulse current waveform in which the rising portion of the vertical transfer pulse φV of FIG. 6 is enlarged, each pulse φH1, φH2, φRG, SHP, SHD, CCD output, and CDS output. It is a timing chart.
The clock waveform of the vertical transfer pulse φV has a stepped rise and fall, and the overall inclination of the rise and fall portions, that is, the transient speed ΔV / ΔT is slowed as described in FIG. It is a waveform. In this case, using the reset period 6 and the signal period 29, the rising and falling waveforms do not change in the signal period 29 (see flat state 27) and change in the reset period 6 (see state 26 with a certain slope). ) A stepped waveform.

The vertical transfer pulses φV1 to φV4 having a drive waveform having such stepped rise and fall can be formed by pulse current driving. That is, by applying a pulse current i3 synchronized with the reset pulse φRG to the vertical transfer electrodes 121 to 124, the vertical transfer pulses φV1 to V1 having a rising edge and a falling edge in a step shape and a gentle inclination of the entire inclination ΔV / ΔT. φV4 is obtained. ΦV when one pulse current i3 is applied
Becomes a state 26 having a certain slope, and φV remains flat until the next pulse current i3 is applied, and a rising waveform (falling waveform) of φV is obtained by repeating the pulse current i3 a plurality of times. Is also a gentle stepped waveform.
By using such pulse current driving, there is no change in the driving clock in the signal period 29 in the stepped waveform, and the crosstalk noise 28 in the reset period corresponding to the rising time point and the falling time point is caused by the CDS circuit 17. Since it does not affect the period between the clamp pulse SHP and the sampling hold pulse SHD, it is not superimposed on the CDS output.

  In this embodiment, the vertical transfer electrode usually has four-phase driving (φV1 to φV4). For example, the number of transients in one vertical line shift is eight times, and the amplitude is 7.5V and 0.05V. In the case of / nsec (= 50 mV / 1 nsec), a period of 8 × 7.5 ÷ 0.05 = 1.2 μs or more is sufficient, that is, a period necessary for V transfer for one line is shown. Since the horizontal effective period of the TV is about 53 μs, the speed can be increased several tens of times.

  In this embodiment, the transient speed of the vertical drive pulse applied to the transfer electrode is slowed by the vertical line shift in the horizontal effective scanning period 3, but as shown in FIG. 2B, the vertical blanking period 5, the transient speed of the drive pulses φV1 to φV4 to be applied to the transfer electrode is increased to enable high-speed transfer. For example, in the case of an electronic camera shake correction operation of a camcorder that requires high-speed operation or a frame interline transfer (FIT) type CCD solid-state imaging device for broadcasting business, which will be described later, high-speed driving is performed during the vertical blanking period 5. There is a need to do. High-speed driving in the vertical blanking period in such a case is performed by applying vertical driving pulses φV1 to φV4 having a high transient speed to the vertical transfer electrodes 121 to 124 by a normal CMOS driver.

  In order to achieve both high-speed operation in the vertical blanking period 5 and low-speed operation in the horizontal blanking period 3, a driver having a 2-speed switching function can be used.

According to the driving method of the CCD solid-state imaging device according to the present embodiment, the vertical line shift is performed by slowing down and changing the vertical transfer pulses ΦV1 to ΦV4 during the horizontal effective scanning period 3, that is, by reducing the transient speed ΔV / ΔT. Therefore, the crosstalk noise generated by applying the vertical transfer pulses φV1 to φV4 can be removed by the CDS circuit 17 at the subsequent stage. This eliminates image noise (vertical stripes). Further, since the signal charge can be transferred to the horizontal transfer register 14 only by driving with the storage gate voltage ΦVSTG and the hold gate voltage ΦVHLD, the horizontal blanking period 4 can be shortened. As a result, a high frame rate can be achieved. Further, since the storage gate part STG and the hold gate part HLG can be designed regardless of the vertical pixel pitch, the electrode widths of the storage gate electrode 21 and the hold gate electrode 22 can be increased. Therefore, the resistance of the electrodes 21 and 22 can be reduced, and the transfer of signal charges from the storage gate portion STG to the horizontal transfer register 14 can be facilitated. In addition, backing wiring can be easily performed, so that the resistance of the electrodes 21 and 22 can be further reduced, and the transfer speed can be increased. Furthermore, signal charges can be transferred to the horizontal transfer register 14 in a short horizontal blanking period 4. As a result, it is possible to further increase the frame.
In addition, since the vertical line shift can be performed slowly with the vertical transfer pulses φV1 to φV4 with a reduced transient speed, the vertical transfer electrodes 121 to 124 can be formed with a thin film thickness. Therefore, as shown in FIG. 8, a CCD solid-state imaging device having a light receiving sensor 11, a reading gate unit 23, and a vertical transfer register 13 composed of a buried channel region 24 and a transfer electrode 12 [121 to 124] on the gate insulating film 25. In the element 10, by making the film thickness d1 of the transfer electrode 12 thinner than the conventional film thickness d2, the step around the sensor opening Q is reduced, and the oblique incident light (solid line) L1 is less kicked. Therefore, the sensor opening Q is substantially widened, the efficiency of collecting obliquely incident light is improved, and high sensitivity can be achieved. L2 shows the kicked state of the conventional oblique incident light. Since the obliquely incident light is hardly kicked, the occurrence of shading can be reduced.

  According to the driving method of the CCD solid-state imaging device according to the present embodiment, the low-speed and the high-speed driving are provided as the vertical driving, so that the image noise (vertical stripe) is generated even if the vertical line shift is performed during the horizontal effective period. Thus, the horizontal blanking period 4 can be significantly shortened to achieve a higher frame rate. Therefore, the driving method of the CCD solid-state imaging device according to the present embodiment can be applied even when high-speed operation such as electronic camera shake operation of a camcorder and FIT for broadcasting business is required.

  In the above example, the driving method of the CCD solid-state imaging device of the present embodiment is applied to the CCD solid-state imaging device of the interline transfer method, but in addition, an imaging region having a light receiving sensor and a vertical transfer register, and a signal in the imaging region A frame inner line transfer (FIT) type CCD solid-state imaging device having a storage area consisting only of a vertical transfer register for temporarily transferring charges at a high speed and a horizontal transfer register connected to the storage area. Can be applied. In this frame inner line transfer method, signal charges in the imaging region are transferred (frame shift) at high speed to the storage region during the vertical blanking period. For this reason, the vertical transfer electrode is configured to be applied with the drive waveform having a low transient speed for low-speed drive in the vertical line shift and the drive waveform having a high transient speed for high-speed drive in the frame shift. The

  The driving method of the CCD solid-state imaging device according to the present embodiment includes, for example, a light receiving sensor, a vertical transfer register corresponding to each light receiving sensor array, and an output amplifier for connecting the signal charge from each vertical transfer register to each vertical transfer register. The present invention can also be applied to driving of a CCD solid-state imaging device that outputs a signal charge for each line during the horizontal effective scanning period through the horizontal scanning circuit.

  In the above description, the storage gate portion 21 and the hold gate portion 22 are provided between the vertical transfer register 13 and the horizontal transfer register 14. In addition, φV4 at the final stage of the vertical transfer electrode 12 instead of the storage gate portion 13. If the transfer part of the transfer electrode 124 to which is applied is used for signal charge accumulation, the storage gate part 13 can be omitted. In this case, the transfer electrode 124 to which the final stage φV4 is applied can have a function similar to that of the storage gate portion 13 by making it wide or different from the shunt wiring line.

  Note that the present embodiment can also be applied to high-speed vertical transfer in the horizontal blanking period 3.

1 is a configuration diagram according to an embodiment of a CCD solid-state imaging device according to the present invention. FIG. A is a timing chart (low speed) according to an embodiment of a method for driving a CCD solid-state imaging device according to the present invention. B is a timing chart (high speed) according to an embodiment of a method for driving a CCD solid-state imaging device according to the present invention. It is a wave form diagram which shows the relationship between the vertical transfer pulse (phi) V and the constant current i1 in a horizontal effective scanning period. It is a wave form diagram which shows the relationship between the vertical transfer pulse (phi) V and the constant current i2 in a horizontal effective scanning period. FIG. 4 is a timing chart of a rising waveform and a pulse current waveform in which a rising portion of a vertical transfer pulse φV corresponding to FIG. 3 is enlarged, and each pulse φH1, φH2, φRG, SHP, SHD, CCD output, and CDS output. It is a wave form diagram which shows the relationship between the vertical transfer pulse (phi) V and the constant current i3 during a horizontal effective scanning period. FIG. 7 is a timing chart of a rising waveform and a pulse current waveform in which the rising portion of the vertical transfer pulse φV corresponding to FIG. 6 is enlarged, and each pulse φH1, φH2, φRG, SHP, SHD, CCD output, and CDS output. 1 is a configuration diagram of a CCD solid-state imaging device according to the present invention. A is a block diagram of a conventional CCD solid-state imaging device. It is a timing chart figure of the drive method of the conventional CCD solid-state imaging device.

Explanation of symbols

  2 .. Change 3 .. Horizontal effective scanning period 4.. Horizontal blanking period 5.. Vertical blanking period 6. Reset period 7... CCD output signal period 10. Element 11... Light receiving sensor 12 [121, 122, 123, 124] Transfer electrode 13. Vertical transfer register 14 Horizontal transfer register 16 Output unit 17 Correlated double sampling (CDS) circuit, 21... Storage gate electrode, 22... Hold gate electrode, 23... Readout gate section, 24... Buried channel region, 25. ..Flat state, 28..Crosstalk noise, 29..Signal period, 30..CCD solid state imaging device, 31..Light receiving sensor, 321, 322, 323, 324..Transfer power , 33 ... vertical transfer register, 34 ... horizontal transfer register, 35 [351, 352] ... horizontal transfer electrodes, 36 ... output unit

Claims (11)

In driving a CCD solid-state imaging device that vertically transfers signal charges of pixels arranged in a matrix for each horizontal line via a vertical transfer register and outputs the signal charges for each horizontal line in a horizontal effective scanning period.
Performing a vertical transfer of the signal charge in the horizontal effective scanning period;
In the vertical transfer register at the time of the vertical transfer, a transient speed ΔV / ΔT (where ΔV is a voltage and ΔT is a voltage that can eliminate crosstalk noise generated at the rising and falling edges of the drive clock waveform by a correlated double sampling circuit). A driving method of a CCD solid-state imaging device, characterized in that a driving clock waveform having rising and falling slopes is provided. In driving a CCD solid-state imaging device that vertically transfers signal charges of pixels arranged in a matrix for each horizontal line via a vertical transfer register and outputs the signal charges for each horizontal line in a horizontal effective scanning period.
Performing a vertical transfer of the signal charge in the horizontal effective scanning period;
A CCD solid-state imaging device, wherein a driving clock waveform having a rising and falling slope smaller than a driving clock waveform for high-speed transfer during a blanking period is supplied to the vertical transfer register during the vertical transfer. Device driving method. 2. The CCD solid-state imaging device according to claim 1, wherein the drive clock waveform has rising and falling slopes at which the transient speed ΔV / ΔT is 50 mV / nsec or less (not including 0). Driving method. The method of driving a CCD solid-state imaging device according to claim 1, wherein the driving clock waveform at the time of vertical transfer uses a driving clock waveform with rounded corners of rising and falling edges. 3. The method of driving a CCD solid-state imaging device according to claim 2, wherein the driving clock waveform at the time of vertical transfer uses a driving clock waveform with rounded corners of rising and falling edges. The method for driving a CCD solid-state imaging device according to claim 1, wherein constant current driving is used for the vertical transfer. The method for driving a CCD solid-state imaging device according to claim 2, wherein constant current driving is used for the vertical transfer. The method for driving a CCD solid-state imaging device according to claim 4, wherein constant current driving is used for the vertical transfer. The method for driving a CCD solid-state imaging device according to claim 5, wherein constant current driving is used for the vertical transfer. In driving a CCD solid-state imaging device that vertically transfers signal charges of pixels arranged in a matrix for each horizontal line via a vertical transfer register and outputs the signal charges for each horizontal line in a horizontal effective scanning period.
Performing a vertical transfer of the signal charge in the horizontal effective scanning period;
A driving method for a CCD solid-state imaging device, wherein a driving clock waveform having a staircase rise and fall that fluctuates in a reset period without being changed in a signal period is supplied to the vertical transfer register during the vertical transfer . The method for driving a CCD solid-state imaging device according to claim 10, wherein pulse current driving is used for the vertical transfer.

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