JP4675740B2 - Driving method of solid-state imaging device - Google Patents

Description

  The present invention relates to a method for driving a solid-state imaging device, and more particularly, to a method for driving a solid-state imaging device that transfers signal charges read from a photodiode as well as electrodes.

  In recent years, there are various scanning methods for solid-state imaging devices mounted on digital still cameras, digital video cameras, and the like. For example, as a scanning method at the time of capturing a still image that requires high accuracy, there is an interlace scan by field readout. Further, as a scanning method at the time of moving image capturing that requires high speed, there is a non-interlaced scan by thinning-out reading (for example, see Patent Document 1). Along with this, as shown in FIG. 10, for example, there are still driving, first type moving image driving, second type moving image driving and the like as driving methods of the solid-state imaging device.

  “Still driving” is a driving method used when, for example, still images are taken with high resolution, such as in the still mode. “First-type moving image driving” is a driving method used when shooting a moving image at a medium resolution, such as a monitor mode (30 fps). “Second-type moving image driving” is, for example, driving that realizes a high frame rate with pixel addition in the horizontal direction used when shooting a moving image at a low resolution, such as the double-speed monitor mode (60 fps). Is the method.

  Furthermore, in the still drive, in order to improve the resolution and dynamic range of a still image, it is necessary to perform the pixel addition in the horizontal / vertical directions and to use the maximum capacity of one photodiode.

  On the other hand, in the first type moving image driving and the second type moving image driving, pixel signals in the horizontal direction or the vertical direction and the horizontal direction are added by HCCD (Horizontal Charge Coupled Devices). Considering the capacity of HCCD and FD (Floating Diffusion), the capacity of one photodiode is not used to the maximum. For this reason, in the second type moving image driving, it is common to reduce the capacitance of the photodiode to a fraction of that in the case of still driving.

  That is, the first type moving image driving and the second type moving image driving indicate that the storage area formed in the VCCD (Vertical Charge Coupled Devices) does not require a large capacity as in the case of the still driving. It is considered that about 1/2 of the case of still driving is sufficient. However, if the capacity of the storage region is small, the signal will overflow in the still drive, so a certain size is required.

  On the other hand, in the case of driving with 8 types of driving pulses, a technique is disclosed in which accumulation is performed in a potential well formed across 6 gates, that is, in an accumulation region indicated by hatching in the figure. (For example, refer to Patent Document 2).

  Here, as an example, in still driving, signal charges are read out from a plurality of photodiodes to individual storage regions based on four-field driving. The plurality of read signal charges are accumulated in a potential well formed across six gates, that is, in an accumulation region indicated by hatching in the drawing. The signal charges accumulated in the accumulation region are transferred using eight kinds of drive pulses.

  In the first type moving image driving, signal charges are read from a plurality of photodiodes based on progressive driving. A plurality of read signal charges are mixed and accumulated in a potential well formed across two gates, that is, in an accumulation region indicated by hatching in the drawing. The signal charges accumulated in the accumulation region are transferred using eight kinds of drive pulses.

In the second type moving image driving, signal charges are read from a plurality of photodiodes based on progressive driving. A plurality of read signal charges are mixed in the vertical CCD at the time of reading, and stored in a potential well formed across six gates, that is, in a storage region indicated by hatching in the drawing. The signal charges accumulated in the accumulation region are transferred using eight kinds of drive pulses.
Japanese Patent Laid-Open No. 10-13742 JP-A-8-9266

  However, when forming a VCCD for a solid-state imaging device, a defective part may be formed during ion implantation. When a middle level (hereinafter referred to as “VM level”) voltage is applied to the vertical transfer electrode, if there is a defective portion under the electrode, many noise signals called dark current are generated from the defective portion. It is known to do. This noise signal causes an image defect phenomenon called VCCD scratch when generated. This is particularly noticeable when the second type moving image drive with few signals is used.

  Further, when this defective portion exists in the boundary portion between the accumulation region (potential well) and the barrier region (potential barrier), VCCD scratches are generated depending on the voltage application state to the two electrodes sandwiching the boundary portion. The presence or absence of changes. Furthermore, if the accumulation region and the barrier region are different for each driving method, the occurrence location of the VCCD scratch changes every time the driving method changes. In order to prevent the outflow of the defective product, it is necessary to operate with all driving methods at the time of inspection.

  In other words, simply optimizing the storage capacity by each driving method results in poor inspection time, so even when using a plurality of driving methods with the same solid-state imaging device, the vertical charge transfer is stopped. It is important to unify the accumulation region and the barrier region over all driving methods.

  For example, as shown in FIG. 10, in order to align the VCCD scratch address, the boundary between the accumulation region (potential well) and the barrier region (potential barrier) is adjusted in the case of the first type moving image drive. Thus, if inspection is performed with the first type moving image drive, necessary and sufficient inspection can be performed for all modes. For this reason, even when the signal capacity at the time of still driving is designed to be necessary and sufficient for 4-gate storage, a large number of storage areas are used in order to match the storage area with the first-type moving image driving method. Even when the signal capacity is sufficient for two-gate accumulation as in the second type moving image driving, the capacity of the accumulation region is increased in accordance with the first type moving image driving method.

  On the other hand, as shown in FIG. 11A, if the capacity of the storage area in the still drive and the second type moving image drive is set to four gate storage, the inspection can be performed even if the first type moving image inspection is performed. Since the voltage application state with respect to the electrodes is different in this driving, the occurrence state of the VCCD scratches is different, and it is necessary to separately inspect whether the driving is still driving or second type moving image driving.

  Further, as shown in FIG. 11B, if the storage area capacity in the still drive and the second type moving image drive is unified to two gate storage, all VCCD scratches can be inspected by the first type moving image drive. However, in the still drive, the capacity of the storage area is insufficient.

  Even if there is no defect, a minute dark current is originally generated in the accumulation region. Furthermore, since the smear signal component from the photo diode flows, forming the accumulation region as a larger region than expected causes an increase in noise component, that is, deterioration of the S / N ratio, which causes image quality deterioration. . For this reason, it is preferable not to form an excessively large accumulation region in order to ensure good image quality. That is, it is preferable that the storage area has a necessary and sufficient capacity.

  Accordingly, the present invention has been made in view of the above problems, and provides a driving method for a solid-state imaging device capable of efficiently inspecting VCCD scratches and suppressing image quality deterioration due to dark current or smear. The purpose is to provide.

In order to achieve the above object, a solid-state imaging device driving method according to the present invention applies a driving pulse to a plurality of electrodes, and transfers signal charges read from a photo diode to the electrodes and accordingly to the vertical direction. Before stopping the vertical transfer of the signal charge, a drive pulse is applied to each electrode to divide the potential well in which the signal charge is accumulated, and to the well of the potential. A well having a first potential and a well having a second potential are formed by distributing and storing the accumulated signal charges.
Furthermore, in the solid-state imaging device driving method according to the present invention, the first potential well and the second potential well are electrodes to which the driving pulse is applied, and the signal charge is read out. It is formed under the electrode. Alternatively, in the case where a plurality of signal charges read from a plurality of photodiodes are individually transferred, a driving pulse is applied to each electrode, and the first potential well and the second potential well are respectively applied. It is characterized by forming. Alternatively, when the transfer of the signal charge is started, a drive pulse is applied to each electrode to divide the signal charge divided into the first potential well and the second potential well. A potential well is formed in a state.

  As a result, a large capacity signal can be divided and stored. Further, since there is no excessively large accumulation region (potential well), an increase in noise components can be suppressed. As a result, the degradation of the S / N ratio can be improved and good image quality can be ensured.

  According to the solid-state imaging device driving method of the present invention, when the transfer of signal charges is stopped, that is, when it is accumulated, one potential well is divided to form a plurality of potential wells. Thereby, a large-capacity signal can be divided and accumulated. Further, since there is no excessively large accumulation region (potential well), an increase in noise components can be suppressed. As a result, the degradation of the S / N ratio can be improved and good image quality can be ensured.

  Further, the accumulation region (potential well) and the barrier region (potential barrier) when the vertical transfer is stopped are formed in the VCCD in accordance with the first type moving image drive. Thereby, inspection can be unified over all driving methods, and VCCD scratches can be inspected efficiently.

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

  The driving method of the solid-state imaging device according to the present embodiment is a driving method of the solid-state imaging device in which a driving pulse is applied to a plurality of electrodes, and signal charges read from the photodiodes are transferred vertically along the electrodes and accordingly. Before stopping the vertical transfer of signal charge, a drive pulse is applied to each electrode to divide the potential well in which the signal charge is accumulated, and the signal charge accumulated in the potential well is distributed A well having a first potential and a well having a second potential are formed.

  Based on the above points, a method for driving the solid-state imaging device in the present embodiment will be described.

  FIG. 1 is a diagram illustrating a configuration of a solid-state imaging device according to the present embodiment. As shown in FIG. 1, the solid-state imaging device 100 includes a solid-state imaging device 101 and a drive unit 102. Furthermore, the solid-state imaging device 101 includes a photo diode 111, a VCCD (Vertical Charge Coupled Devices) 112, an HCCD (Horizontal Charge Coupled Devices) 113, and the like.

  The photo diode 111 converts light into signal charges and accumulates signal charges obtained by the conversion. The VCCD 112 has a plurality of driving electrodes, is supplied with a plurality of driving signals from the driving unit 102, reads out signal charges accumulated in each photodiode, and transfers the read signal charges to the HCCD 113. Here, the read signal charges are vertically transferred using eight types of transfer pulses. The HCCD 113 horizontally transfers the signal charges vertically transferred from each VCCD.

  Each electrode forms a region (potential well) for accumulating charges under an electrode with an oxide film (insulating portion) interposed therebetween when a middle level (hereinafter referred to as VM level) voltage is applied. When a voltage of a low level (hereinafter referred to as a VL level) is applied, a barrier region (potential barrier) is formed under the electrode across the oxide film (insulating portion).

  The VCCD 112 forms a high potential portion (accumulation region) and a low potential portion (barrier region) when an appropriate drive pulse is applied to eight terminals with the electrodes ΦV1 to ΦV8 as one set. Move the electrode as well as the storage region (potential well).

  The drive unit 102 supplies drive pulses to the VCCD 112 and the HCCD 113. Here, as an example, driving pulses are supplied according to the following driving methods (1) to (3).

(1) Still driving “Still driving” is a driving method used when, for example, a still image is captured at a high resolution such as in a still mode. Here, as an example, there is a driving method in which signal charges are read out from a plurality of photodiodes to individual storage regions based on four-field driving, and the read-out signal charges are individually transferred.

  At this time, the drive unit 102 supplies eight types of transfer pulses to the VCCD 112. Accordingly, the VCCD 112 forms a storage region (potential well) while forming a storage region (potential well) extending over four gates and a barrier region (potential barrier) of at least one gate during vertical transfer. ) Is transferred vertically to the electrodes and accordingly to the signal. In addition, when vertical transfer is stopped, the storage region (potential well) extending over 4 gates or more is divided into 2 storage regions (potential wells) extending over 2 gates and 2 barrier regions (potential barriers) extending over 2 gates. The signal charges accumulated in the accumulation region (potential well) extending over 4 gates are distributed and accumulated in the two accumulation regions (potential well).

(2) First-type moving image drive The “first-type moving image drive” is a driving method used when shooting a moving image at a medium resolution, such as a monitor mode (30 fps). Here, an example is a driving method in which signal charges are read from a plurality of photodiodes based on progressive driving, and the read signal charges are mixed and transferred by a vertical CCD. In many cases, the number of horizontal lines output in the first type moving image drive exceeds the number of horizontal lines output in one field in the still drive.

  At this time, the driving unit 102 supplies eight types of driving pulses or two sets of four types of driving pulses to the VCCD 112. Accordingly, the VCCD 112 in the vertical transfer execution state forms an accumulation region (potential barrier) while forming an accumulation region (potential well) extending over two gates or more and a barrier region (potential barrier) of at least one gate or more. The signal charge stored in the well) is transferred along the electrodes accordingly. In the vertical transfer stop state, an accumulation region (potential well) straddling two gates and a barrier region (potential barrier) straddling two gates are formed, and signal charges are accumulated in the accumulation region (potential well) straddling two gates. Accumulate.

(3) Second Type Moving Image Driving “Second type moving image driving” is a driving method used when shooting a moving image at a low resolution, for example, in the double-speed monitor mode (60 fps). Here, as an example, there is a driving method in which signal charges are read from a plurality of photodiodes based on progressive driving, and the plurality of read signal charges are mixed and transferred. However, the number of pixels to be read in the vertical direction, that is, the number of horizontal lines to be output is smaller than in the first type moving image driving.

  At this time, the drive unit 102 supplies eight types of drive pulses to the VCCD 112. Accordingly, the VCCD 112 forms a storage region (potential well) while forming a storage region (potential well) of two or more gates and a barrier region (potential barrier) of at least three gates in the vertical transfer state. ) To transfer the signal charge stored in the electrode. In the vertical transfer stop state, an accumulation region (potential well) extending over 2 gates and a barrier region (potential barrier) extending over 6 gates are formed, and a signal charge is applied to the accumulation region (potential well) extending over 2 gates. Accumulate.

  In the still driving method, the sum of signal charges stored in a plurality of storage regions is set to a necessary and sufficient capacity for the maximum capacity of one photodiode.

  FIG. 2 is a diagram showing a potential distribution when shifting from the vertical transfer execution state to the vertical transfer stop state in the VCCD in the present embodiment. As shown in FIG. 2, in the still driving method, the VCCD 112 has a potential well across four gates (hatches in the figure) in accordance with eight types of driving pulses applied from the driving unit 102 when vertical transfer is performed. ), And a potential barrier (projection shown in white in the figure) across the four gates is formed. Then, the signal charge is accumulated and transferred to the formed potential well.

  Further, the VCCD 112 forms a plurality of potential wells from the potential wells extending over the four gates when shifting from the vertical transfer execution state to the vertical transfer stop state. Here, two potential wells extending over two gates are formed. At this time, the potential well and the potential barrier formed in the still driving method are formed in accordance with the potential well and the potential barrier formed in the first type moving image driving method. Here, when the vertical transfer is stopped in the still drive, the state of the drive electrode that forms the storage region and the boundary between the storage region and the barrier region is the same as or includes the state of the drive electrode under another drive condition. . Thus, the polarity of the voltage applied to the boundary between the potential well and the potential barrier can be made uniform, and the inspection of the VCCD scratch can be unified.

  When shifting from the vertical transfer execution state to the vertical transfer stop state, the VCCD 112 forms a potential barrier across the two gates and divides it into a plurality of regions with respect to the potential well across the four gates. Two wells of potential across two gates are formed. That is, the signal is divided into two potential wells. At this time, a potential barrier across two gates is formed between the potential well and the potential well. Thus, in the vertical transfer stopped state, by forming a potential barrier and forming a barrier, generation of dark current and inflow of a smear signal in the barriered region can be suppressed.

  On the other hand, in the second type moving image driving method, the VCCD 112 forms every other potential well with respect to the potential well formed in the first type moving image driving method. That is, by forming every other potential barrier and partially forming a barrier, generation of dark current and inflow of a smear signal in the barriered region can be suppressed.

  That is, in the still driving method, in the vertical transfer stop state, the signal charge is divided and accumulated in a plurality of accumulation regions (potential wells), and the necessary and sufficient capacity is secured by the sum of the plurality of accumulation regions, The still driving method satisfies the required performance. As a result, it is possible to suppress deterioration of the S / N ratio due to dark current and smear, and to improve image quality deterioration.

  FIG. 3 is a diagram showing an outline of signal charges transferred by the still driving method in the present embodiment. During the horizontal blank (HBLK) period, the photo diode is omitted and only the VCCD is shown. As shown in FIG. 3, the VCCD 112 indicates the signal charge read from the photodiode in the direction of the arrow during the vertical transfer stop (T) to the vertical transfer stop (T + 1), that is, during the HBLK period. To be transferred. At this time, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a storage region (potential well) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112. Then, the signal charges accumulated in the accumulation region (potential well) are transferred to the electrodes and accordingly to the VCCD 112.

  Furthermore, the VCCD 112 distributes and accumulates signal charges to a plurality of accumulation regions (potential wells) when vertical transfer is stopped (T + 1). At this time, before stopping the transfer of signal charges, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a plurality of accumulation regions (potential wells) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112.

  FIG. 4 is a diagram showing an outline of signal charges transferred by the first type moving image driving method in the present embodiment. As in FIG. 3, during the HBLK period, the photodiode is omitted and only the VCCD is shown. As shown in FIG. 4, the VCCD 112 indicates the signal charge read from the photodiode in the direction of the arrow during the vertical transfer stop (T) to the vertical transfer stop (T + 1), that is, during the HBLK period. To be transferred. At this time, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a storage region (potential well) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112. The signal charge accumulated in the accumulation region (potential well) is transferred to the VCCD 112.

  The VCCD 112 accumulates the signal charge without dividing it into a plurality of accumulation regions (potential wells) when the vertical transfer is stopped (T + 1).

  That is, the drive unit 102 also stores other storage methods (potential wells) formed when the vertical transfer is stopped in the first type moving image driving method when the vertical transfer is stopped, also for other driving methods other than the first type moving image driving method. The drive pulse is supplied to the VCCD 112 so as to be the same as or part of the boundary between the barrier region (potential barrier).

  5A shows a case where the signal charge read from the electrode ΦV1 is transferred in the still driving method, and FIG. 5B shows a signal charge read from the electrode ΦV3 in the still driving method. FIG. 6 is a diagram illustrating an example of a timing chart of drive pulses applied to each electrode in the case of transferring. FIG. 6A shows the signal charge read from the electrode ΦV5 in the still driving method, and FIG. 6B shows the signal charge read from the electrode ΦV7 in the still driving method. FIG. 6 is a diagram illustrating an example of a timing chart of drive pulses applied to each electrode in the case of transferring.

  As shown in FIG. 5A, the drive unit 102 applies a voltage of Hi level (hereinafter referred to as VH level) to the electrode ΦV1, and outputs a signal from a photodiode connected to the electrode ΦV1. Read the charge. Then, either the VM level voltage or the VL level voltage is applied to the electrodes ΦV1 to ΦV8 while properly using the VM level voltage and the VL level voltage, and the read signal charges are applied to the electrodes in accordance with the order of the electrodes. Let it be transferred. Then, before stopping the vertical transfer, two storage regions (potential wells) are formed from the storage region (potential well) in which signal charges are stored, and the two storage regions (potential wells) formed are formed. The signal charge is distributed and accumulated in the.

  At this time, the drive unit 102 applies a VM level voltage to the electrodes ΦV1 and ΦV2 to form an accumulation region (potential well) extending over two gates. Further, a VM level voltage is applied to the electrodes ΦV5 and ΦV6 to form a storage region (potential well) extending over two gates. A voltage of VL level is applied to the electrodes ΦV3 and ΦV4 to form a barrier region (potential barrier) extending over two gates. A voltage of VL level is applied to the electrodes ΦV7 and ΦV8 to form a barrier region (potential barrier) extending over two gates.

  Further, as shown in FIG. 5B, the drive unit 102 applies a voltage of VH level to the electrode ΦV3, and reads the signal charge from the photodiode connected to the electrode ΦV3. Then, either the VM level voltage or the VL level voltage is applied to the electrodes ΦV1 to ΦV8 while properly using the VM level voltage and the VL level voltage, and the read signal charges are applied to the electrodes in accordance with the order of the electrodes. Let it be transferred. Then, before stopping the vertical transfer, two storage regions (potential wells) are formed from the storage region (potential well) in which signal charges are stored, and the two storage regions (potential wells) formed are formed. The signal charge is distributed and accumulated in the. At this time, it is the same as the case shown in FIG.

  Further, as shown in FIG. 6A, the drive unit 102 applies a voltage of VH level to the electrode ΦV5, and reads the signal charge from the photodiode connected to the electrode ΦV5. Then, either the VM level voltage or the VL level voltage is applied to the electrodes ΦV1 to ΦV8 while properly using the VM level voltage and the VL level voltage, and the read signal charges are applied to the electrodes in accordance with the order of the electrodes. Let it be transferred. Then, before stopping the vertical transfer, two storage regions (potential wells) are formed from the storage region (potential well) in which signal charges are stored, and the two storage regions (potential wells) formed are formed. The signal charge is distributed and accumulated in the. At this time, it is the same as the case shown in FIG.

  Further, as shown in FIG. 6B, the driving unit 102 applies a VH level voltage to the electrode ΦV7, and reads the signal charge from the photodiode connected to the electrode ΦV7. Then, either the VM level voltage or the VL level voltage is applied to the electrodes ΦV1 to ΦV8 while properly using the VM level voltage and the VL level voltage, and the read signal charges are applied to the electrodes in accordance with the order of the electrodes. Let it be transferred. Then, before stopping the vertical transfer, two storage regions (potential wells) are formed from the storage region (potential well) where signal charges are stored, and the two storage regions (potential wells) formed are formed. The signal charge is distributed and accumulated in the. At this time, it is the same as the case shown in FIG.

  FIG. 7A is a diagram showing an example of a timing chart of drive pulses applied to each electrode in the HBLK period at the time of still drive, and FIG. 7B is a diagram showing signal charge transfer.

  As shown in FIG. 7A, when the drive unit 102 stops the transfer of the signal charge read from the photodiode, it applies a VM level voltage to the electrodes ΦV1 and ΦV2 and applies it to the VCCD 112. A well of potential across two gates is formed. A voltage of a VL level is applied to the electrodes ΦV3 and ΦV4 to form a potential barrier across the two gates in the VCCD 112. A voltage of a VM level is applied to the electrodes ΦV5 and ΦV6 to cause the VCCD 112 to form a potential well across two gates. A voltage of VL level is applied to the electrodes ΦV7 and ΦV8, and the VCCD 112 is formed with a potential barrier across two gates. Then, during the HBLK period, a VM level voltage is applied to the electrodes indicated by hatching in the drawing, and a VL level voltage is applied to the electrodes indicated by white in the drawing to read out the signal charges. As well as the electrode as a result.

  At this time, as shown in FIG. 7B, when stopping the transfer of signal charges, the VCCD 112 divides one potential well to form a potential well straddling two two gates, The signal charge is distributed and accumulated in the formed potential well. When resuming the transfer of signal charges, the VCCD 112 combines two potential wells to form one potential well (t1 to t3), and the signal charges accumulated in the formed potential wells are electroded. And transfer accordingly (t4 to t16). Before stopping the transfer of signal charges, the VCCD 112 divides one potential well to form two potential wells, distributes the signal charge to the formed two potential wells, and performs vertical transfer. Stop (t17 to t20).

  As described above, according to the driving method of the solid-state imaging device in the present embodiment, when the transfer of the signal charge is stopped, one potential well is divided to form a plurality of potential wells. Thereby, a large-capacity signal can be divided and accumulated. Further, since there is no excessively large accumulation region (potential well), an increase in noise components can be suppressed. As a result, the degradation of the S / N ratio can be improved and good image quality can be ensured.

  Further, the drive unit 102 causes the VCCD 112 to form an accumulation region (potential well) and a barrier region (potential barrier) when vertical transfer is stopped in accordance with the case where the first type moving image driving method is used. Thereby, the inspection process of the VCCD scratch can be unified.

(Embodiment 2)
Next, Embodiment 2 according to the present invention will be described with reference to the drawings.

  In the driving method of the solid-state imaging device according to the present embodiment, after the signal charge read from the photodiode is distributed and accumulated, the vertical transfer restart of the signal charge distributed and accumulated in the plurality of potential wells is resumed. Sometimes transfer without recombination.

  Based on the above points, a method for driving the solid-state imaging device in the present embodiment will be described. Note that the configuration of the solid-state imaging device in the present embodiment is the same as that of the solid-state imaging device in the first embodiment, and the description thereof is omitted.

  FIG. 8 is a diagram showing an outline of signal charges transferred by the still driving method in the present embodiment.

  As shown in FIG. 8, the VCCD 112 indicates the signal charge read from the photodiode in the direction of the arrow during the vertical transfer stop (T) to the vertical transfer stop (T + 1), that is, during the HBLK period. To be transferred. At this time, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a storage region (potential well) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112. Then, the signal charges accumulated in the accumulation region (potential well) are transferred to the electrodes and accordingly to the VCCD 112.

  Further, the VCCD 112 distributes and accumulates signal charges in a plurality of accumulation regions (electron wells) when vertical transfer is stopped (T + 1). At this time, before stopping the transfer of signal charges, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a plurality of accumulation regions (potential wells) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112.

  Then, the VCCD 112 transfers the data while being distributed and accumulated in a plurality of accumulation regions (potential wells). At this time, after being divided into a plurality of accumulation regions (potential wells), the driving unit 102 transfers the divided regions to the VCCD 112 while being divided.

  As described above, according to the method for driving the solid-state imaging device according to the present embodiment, after distributing and accumulating the signal charges read from the photodiodes, the signal charges distributed and accumulated in the plurality of potential wells are stored. Forward. Thereby, it is possible to omit the coupling of the divided signal charges. Further, since there is no excessively large accumulation region (potential well), an increase in noise components can be suppressed. As a result, the degradation of the S / N ratio can be improved and good image quality can be ensured.

  Further, the drive unit 102 causes the VCCD 112 to form an accumulation region (potential well) and a barrier region (potential barrier) when vertical transfer is stopped in accordance with the case where the first type moving image driving method is used. Thereby, the inspection process of the VCCD scratch can be unified.

(Embodiment 3)
Next, Embodiment 3 according to the present invention will be described with reference to the drawings.

  In the solid-state imaging device driving method according to the present embodiment, the storage area divided and used when the vertical transfer is stopped in the first and second embodiments described above is partially used during a specific driving. In addition, another storage area that is not used is used as a barrier area.

  Based on the above points, a method for driving the solid-state imaging device in the present embodiment will be described. Note that the configuration of the solid-state imaging device in the present embodiment is the same as that of the solid-state imaging device in the first embodiment, and the description thereof is omitted.

  FIG. 9 is a diagram showing an outline of signal charges transferred by the second type moving image driving method in the present embodiment.

  As shown in FIG. 9, the VCCD 112 shows the signal charge read from the photodiode in the direction of the arrow during the vertical transfer stop (T) to the vertical transfer stop (T + 1), that is, during the HBLK period. To be transferred. At this time, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a storage region (potential well) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112. Then, the signal charges accumulated in the accumulation region (potential well) are transferred to the electrodes and accordingly to the VCCD 112.

  Further, the VCCD 112 distributes and accumulates signal charges in a plurality of accumulation regions (electron wells) when vertical transfer is stopped (T + 1). At this time, before stopping the transfer of signal charges, the drive unit 102 applies a VM level voltage to the electrodes indicated by hatching in the drawing to form a storage region (potential well) in the VCCD 112. In addition, a voltage of VL level is applied to the electrode indicated by white in the figure, and a barrier region (potential barrier) is formed in the VCCD 112. However, every other storage region (potential well) is formed with respect to the storage region (potential well) formed in the first type moving image driving method, and a barrier region (potential barrier) is formed otherwise. Let it form.

  In the figure, the drive unit 102 causes the VCCD 112 to form an accumulation region (potential well) extending over 2 gates and a barrier region (potential barrier) extending over 6 gates in the second type moving image driving method. .

  As described above, according to the driving method of the solid-state imaging device according to the present embodiment, the two types of moving image driving method are different from the two accumulation regions (potential wells) formed in the first type moving image driving method. One is formed as an accumulation region (potential well), and the other is formed as a barrier region (potential barrier). As a result, the storage region (potential well) can be formed in a necessary and sufficient capacity without forming an excessively large storage region (potential well). Further, since there is no excessively large accumulation region (potential well), an increase in noise components can be suppressed. As a result, the degradation of the S / N ratio can be improved and good image quality can be ensured.

  Further, the drive unit 102 causes the VCCD 112 to form an accumulation region (potential well) and a barrier region (potential barrier) when the vertical transfer is stopped, in accordance with the case of the first type moving image driving method. Thereby, even if it is an accumulation region in the first type moving image driving method, if it is a barrier region in the second type moving image driving method, the influence of the VCCD scratch can be ignored, so the inspection process of the VCCD scratch is unified. be able to.

(Other)
In the embodiment according to the present invention, as an example, eight types of drive pulses have been described as drive pulses. However, the present invention is not limited to this, and eight or more types of drive pulses may be used as drive pulses.

  The present invention can be used as a method for driving a solid-state imaging device, particularly as a method for driving a solid-state imaging device that transfers signal charges read from a photodiode as well as electrodes.

1 is a diagram illustrating a configuration of a solid-state imaging device according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating a potential distribution in a vertical transfer stop state from a vertical transfer execution state during still driving and a potential distribution in a vertical transfer stop state of first type moving image driving and second type moving image driving in the VCCD in the first embodiment. . 6 is a diagram showing how signal charges transferred by the still driving method in Embodiment 1 are divided. FIG. 5 is a diagram showing an outline of signal charges transferred by the first type moving image driving method in Embodiment 1. FIG. (A) shows the timing of the drive pulse applied to each electrode when the signal charge read from the electrode ΦV1 is transferred, and (b) shows the signal charge read from the electrode ΦV3. It is a figure which shows a chart. (A) shows the timing of the drive pulse applied to each electrode when the signal charge read from the electrode ΦV5 is transferred, and (b) shows the signal charge read from the electrode ΦV7. It is a figure which shows a chart. (A) is a timing chart of drive pulses applied to each electrode for recombining the signals when the vertical transfer is performed from the state where the signals are divided and stored, and dividing and storing the signals again when the vertical transfer is stopped. FIG. 5B is a diagram illustrating signal charge transfer. FIG. 11 is a diagram showing an outline of signal charges transferred by a still driving method in a second embodiment. FIG. 11 is a diagram showing an outline of signal charges transferred by the second type moving image driving method in the third embodiment. It is a figure which shows the electric potential distribution based on the conventional drive method. (A) It is a figure which shows potential distribution at the time of using 4 gate accumulation | storage in still drive and 2nd type moving image drive, (b) It is a figure which shows potential distribution at the time of unifying to 2 gate accumulation | storage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Solid-state imaging device 101 Solid-state image sensor 102 Drive part 111 Photo diode 112 VCCD
113 HCCD

Claims (6)

A driving method of a solid-state imaging device in which a driving pulse is applied to a plurality of electrodes, and a signal charge read from a photodiode is vertically transferred along the electrodes, and accordingly,
Before stopping the vertical transfer of the signal charge, a drive pulse is applied to each electrode to divide the potential well in which the signal charge is accumulated, and the signal charge accumulated in the potential well is Forming a first potential well and a second potential well to be distributed and stored ;
The first potential well and the second potential well are formed under an electrode to which the drive pulse is applied and from which the signal charge is read out. Device driving method. When resuming the transfer of the signal charge, a drive pulse is applied to each electrode to combine the first potential well and the second potential well, The method for driving a solid-state imaging device according to claim 1, wherein a potential well in which signal charges distributed to the second potential well are accumulated is formed. A driving method of a solid-state imaging device, in which a driving pulse is applied to a plurality of electrodes, and signal charges read from a plurality of photodiodes are transferred vertically in the electrodes and accordingly
Before stopping the vertical transfer of the signal charge, a drive pulse is applied to each electrode to divide the potential well in which the signal charge is accumulated, and the signal charge accumulated in the potential well is Forming a first potential well and a second potential well to be distributed and stored;
When resuming the transfer of the signal charge, a drive pulse is applied to each electrode to combine the first potential well and the second potential well, Forming a potential well in which signal charges distributed to the second potential well are accumulated;
Further, in the case where a plurality of signal charges read from a plurality of photodiodes are individually transferred, a drive pulse is applied to each electrode, and the first potential well and the second potential well are respectively applied. the driving method of the solid-state image pickup element you and forming. A drive pulse is applied to each electrode in accordance with the position of a potential well formed by a readout method in which a plurality of signal charges read from a plurality of photodiodes are mixed and transferred, and the well of the first potential is applied. The solid-state imaging device driving method according to claim 3, wherein the first potential well and the second potential well are respectively formed. In the case where the capacity of the signal charge to be read is smaller than that of the reading method and a plurality of read signal charges are mixed and transferred, each of the potential wells formed by the reading method is adjusted to every other position. The solid-state imaging device driving method according to claim 4, wherein a driving pulse is applied to the electrode to form a potential well in which the signal charge is accumulated. A driving method of a solid-state imaging device in which a driving pulse is applied to a plurality of electrodes, and a signal charge read from a photodiode is vertically transferred along the electrodes, and accordingly,
Before stopping the vertical transfer of the signal charge, a drive pulse is applied to each electrode to divide the potential well in which the signal charge is accumulated, and the signal charge accumulated in the potential well is Forming a first potential well and a second potential well to be distributed and stored;
When the transfer of the signal charge is started, a drive pulse is applied to each electrode, and the signal charge divided into the first potential well and the second potential well is divided. the driving method of the solid-state image pickup element you and forming a potential well.

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