JP5039475B2 - Method for driving solid-state imaging device and imaging apparatus - Google Patents

Description

  The present invention relates to a method for driving a solid-state imaging device and an imaging apparatus.

  For a solid-state imaging device (for example, a CCD (Charge Coupled Device)) used in a digital camera, it is an important issue to improve the frame rate. For example, for a still image, by increasing the frame rate, the time from pressing the shutter to reading the image can be shortened. As a result, the possibility of missing a photo opportunity is reduced. Further, the improvement of the frame rate can speed up operations such as photometry operation and autofocus operation. With regard to moving images, a smooth moving image with high image quality can be obtained by improving the frame rate.

  In recent years, with the improvement of CCD manufacturing technology, the increase in the number of pixels of a CCD has been promoted. As a result, there is an increasing demand for an improved frame rate. As a means for increasing the frame rate, it is conceivable to increase the drive frequency of the CCD. However, increasing the drive frequency can reduce the image quality due to the deterioration of the signal charge transfer efficiency in the CCD, and reduce the EMI (Electric Magnetic Interference). It causes deterioration.

  Therefore, there is a method for improving the frame rate by overlapping the horizontal effective scanning period and the vertical effective scanning period (see Patent Document 1). However, in this method, since the vertical transfer clock is output during the horizontal effective scanning period, crosstalk noise occurs at the rise and fall of the waveform in the vertical transfer clock.

Therefore, a technique has been proposed in which the rising and falling slopes of the waveform are set appropriately and a clock waveform having a transient speed ΔV / ΔT that can eliminate crosstalk noise with a correlated double sampling circuit is provided (Patent Document). 2). Here, ΔV is voltage and ΔT is time.
Japanese Patent No. 3715781 JP 2005-269060 A

  In the above-described method for improving the frame rate by overlapping the horizontal effective scanning period and the vertical effective scanning period, the signal charge is supplied to the electrode immediately before the horizontal transfer path on the vertical transfer path until just before the horizontal blanking period. Will be transferred. As a result, leakage of signal charges from the vertical transfer path to the horizontal transfer path is more likely to occur than when signal charges are transferred only during the horizontal blanking period. In particular, when the amount of charge to be transferred is large, such as when adding pixels or shooting a high-luminance subject, signal charges easily leak from the vertical transfer path to the horizontal transfer path.

  Furthermore, since signal charges are transferred on the vertical transfer path during the horizontal effective scanning period, the substrate voltage of the solid-state imaging device fluctuates, and signal charge leaks from the horizontal transfer path to the vertical transfer path or vice versa. Is more likely to do.

  An object of the present invention is to provide a driving method and an imaging apparatus for a solid-state imaging device capable of reducing leakage of signal charges from a vertical transfer path to a horizontal transfer path and improving a frame rate. is there.

To achieve the above Symbol object, the method for driving the solid-state imaging device of the present invention is arranged two-dimensionally in vertical and horizontal directions, a plurality of photoelectric conversion elements constituting the pixel, from the plurality of photoelectric conversion elements a plurality of vertical transfer paths, the method for driving the solid-state imaging device having a horizontal transfer path for transferring the plurality of signal charges from the vertical transfer paths respectively horizontally transferring signal charges in each vertical direction, photographing When the number of pixel additions in the mode is equal to or greater than a predetermined number, the vertical brightness during the horizontal blanking period depends on whether or not the subject brightness at the time of shooting is equal to or greater than a predetermined value. The first transfer mode for transferring the signal charge from the photoelectric conversion element through each of the transfer paths, and the vertical transfer path during the period from the horizontal effective scanning period to the subsequent horizontal blanking period. From among the second transfer mode for transferring signal charges from the photoelectric conversion element via the respectively selects either one transport mode of the pixel addition number of the photographing mode is below the predetermined number The second transfer mode is selected, and the solid-state imaging device is driven in the selected transfer mode.
In order to achieve the above object, a solid-state imaging device driving method according to the present invention includes a plurality of photoelectric conversion elements that are two-dimensionally arranged in a vertical direction and a horizontal direction and constitute pixels, and signals from the plurality of photoelectric conversion elements. A method for driving a solid-state imaging device, comprising: a plurality of vertical transfer paths for transferring charges in the vertical direction; and a horizontal transfer path for transferring signal charges from the plurality of vertical transfer paths in the horizontal direction. The vertical transfer is performed during the horizontal blanking period depending on whether or not the zoom magnification at the time of shooting is greater than or equal to a preset predetermined magnification. The vertical transfer path during a period extending from a first transfer mode for transferring the signal charge from the photoelectric conversion element through each of the paths, a horizontal effective scanning period, and a horizontal blanking period that follows. Either one of the transfer modes is selected from the second transfer modes in which the signal charges from the photoelectric conversion elements are transferred via each of them, and the pixel addition number in the photographing mode is less than the predetermined number In this case, the solid-state imaging device driving method, wherein the second transfer mode is selected and the solid-state imaging device is driven in the selected transfer mode.
In order to achieve the above object, a solid-state imaging device driving method according to the present invention includes a plurality of photoelectric conversion elements that are two-dimensionally arranged in a vertical direction and a horizontal direction and constitute pixels, and signals from the plurality of photoelectric conversion elements. A method for driving a solid-state imaging device having a plurality of vertical transfer paths for transferring charges in the vertical direction and a horizontal transfer path for transferring signal charges from the plurality of vertical transfer paths in the horizontal direction, respectively.
A first transfer mode in which signal charges from the photoelectric conversion elements are transferred through each of the vertical transfer paths during a horizontal blanking period based on the subject brightness at the time of shooting, a horizontal effective scanning period, and a subsequent horizontal One of the transfer modes is selected from the second transfer mode in which the signal charge from the photoelectric conversion element is transferred through each of the vertical transfer paths during the period spanning the blanking period, The solid-state imaging device is driven in the selected transfer mode.
In order to achieve the above object, a solid-state imaging device driving method according to the present invention includes a plurality of photoelectric conversion elements that are two-dimensionally arranged in a vertical direction and a horizontal direction and constitute pixels, and signals from the plurality of photoelectric conversion elements. A method for driving a solid-state imaging device, comprising: a plurality of vertical transfer paths for transferring charges in the vertical direction; and a horizontal transfer path for transferring signal charges from the plurality of vertical transfer paths in the horizontal direction. A first transfer mode in which signal charges from the photoelectric conversion elements are transferred through each of the vertical transfer paths during a horizontal blanking period, a horizontal effective scanning period, and a subsequent horizontal blanking. One of the transfer modes in the second transfer mode in which the signal charge from the photoelectric conversion element is transferred through each of the vertical transfer paths during the period. Select de, and drives the solid-state image pickup element at a transfer mode that is the selected.

  According to the present invention, it is possible to reduce leakage of signal charges from the vertical transfer path to the horizontal transfer path and to improve the frame rate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of a digital camera equipped with a solid-state imaging device according to the first embodiment of the present invention.

  As shown in FIG. 1, the imaging apparatus includes a lens unit 601 including a plurality of movable lens groups for performing a zoom operation, a focus adjustment operation, and the like, a mechanical shutter 603, an aperture 605, and a solid-state image sensor 606. The solid-state image sensor 606 is made of a CCD, for example, and converts an optical image formed through the lens unit 601, the mechanical shutter 603, and the diaphragm 605 into an electrical signal and outputs it. The electrical signal output from the solid-state image sensor 606 is input to the CDS / A / D circuit 607. The CDS / A / D circuit 607 performs correlated double sampling, gain adjustment, and A / D conversion in order to convert the input electrical signal into digital signals of R, G1, G2, and B colors.

  Each digital signal output from the CDS / A / D circuit 607 is input to the imaging signal processing circuit 608. The imaging signal processing circuit 608 performs various types of image processing on each input digital signal, compresses the digital signal as necessary, and outputs image data. Image data output from the imaging signal processing circuit 608 is sent to the memory 610, the display unit 613, the external I / F unit 615, the recording medium control I / F unit 612, and the control unit 611. A memory 610 is a memory for temporarily storing the image data. The display unit 613 includes a liquid crystal display panel for displaying various information such as image data and operation information. The external I / F unit 615 is an interface for connecting to an external device such as a PC (personal computer). The external I / F unit 615 performs processing such as communication with a connected external device and transmission of image data to the external device. The recording medium control I / F unit 612 is an interface that controls image data to be transferred to a recording medium 614 including a memory card and written based on a control signal from the control unit 611. The recording medium control I / F unit 612 performs control for reading image data from the recording medium 614.

  The control unit 611 includes a CPU (not shown) that executes a control program stored in the memory 616, and the CPU executes the control program to perform control of the entire imaging apparatus and individual processing. Based on the operation signal or image data input from the operation unit 617, the control unit 611 includes a lens driving unit 602, a shutter / aperture driving unit 604, a CDS / A / D circuit 607, a timing generation unit 609, and a recording medium control I. A control signal for each of the / F units 612 is generated.

  The lens driving unit 602 drives the corresponding movable lens group of the lens unit 601 based on the control signal from the control unit 611. The shutter / aperture driving unit 604 drives the mechanical shutter 603 and the aperture 605 based on a control signal from the control unit 611. The timing generator 609 generates and outputs drive pulses or timing signals corresponding to the solid-state imaging device 606 and the imaging signal processing circuit 608 based on the control signal from the controller 611.

  The operation unit 617 inputs operation information corresponding to an operation by a user, for example, an operation for setting or changing shooting information such as a shooting mode, an exposure condition, and a zoom magnification, and sends the operation information to the control unit 611. The operation unit 617 includes shutter switches SW1 and SW2 (not shown) that are multistage switches. The control unit 611 sets and changes shooting information based on the operation information from the operation unit 617, and controls various operations based on the shooting information.

  Next, the configuration of the solid-state imaging element 606 will be described with reference to FIGS. FIG. 2 is a diagram schematically illustrating a configuration example of the solid-state imaging device 606 of FIG. FIG. 3 is a diagram showing a part of the color filter array in the solid-state imaging device 606 of FIG.

  As illustrated in FIG. 2, the solid-state imaging element 606 includes a plurality of photodiodes (photoelectric conversion elements) 401, a plurality of vertical transfer paths 402, a horizontal transfer path 403, and an output unit 404. Each photodiode 401 is two-dimensionally arranged in the vertical direction and the horizontal direction, and each pixel constitutes one pixel. Hereinafter, the photodiode 401 is referred to as a pixel 401.

  Each vertical transfer path 402 has transfer electrodes V1, V2, V3, and V4 to which drive pulses φV1, φV2, φV3, and φV4 are applied. Each vertical transfer path 402 is provided with a buffer storage cell 405 and a transfer gate 406. The buffer storage cell 405 and the transfer gate 406 have transfer electrodes BS and TG to which drive pulses φBS and φTG are applied, respectively. The horizontal transfer path 403 includes transfer electrodes H1 and H2 to which two-phase drive pulses φH1 and φH2 are applied.

  The signal charge photoelectrically converted by each pixel 401 is sent to the vertical transfer path 402 by a read pulse, and is sequentially transferred to the horizontal transfer path 403 by drive pulses φV1, φV2, φV3, φV4, φBS, and φTG. The horizontal transfer path 403 transfers the signal charges for one row transferred from the vertical transfer path 402 to the output unit 404 by two-phase drive pulses φH1 and φH2. The output unit 404 converts the signal charge transferred from the horizontal transfer path 403 into a voltage and outputs the voltage.

  A color filter array as shown in FIG. 3 is used for the solid-state imaging device 606. The color filter array includes a first color filter or red filter (R), a second color filter or green filter (G), a third color filter or green filter (G), and a fourth color filter or blue filter. (B) is arranged. The arrangement of the color filters in this color filter array is particularly called a Bayer arrangement and has high resolution and excellent color reproducibility.

  The imaging apparatus according to the present embodiment has a first transfer mode and a second transfer mode as modes for driving the solid-state imaging device 606. The first transfer mode is a transfer mode in which signal charges from each pixel 401 are transferred in the vertical direction only during the horizontal blanking period. The second transfer mode is a transfer mode in which signal charges from each pixel 401 are transferred in a vertical direction during a period extending from a horizontal effective scanning period to a horizontal blanking period that follows the horizontal effective scanning period.

  Further, the imaging apparatus of the present embodiment has four shooting modes A, B, C, and D. The shooting mode A is a mode for shooting a high-sensitivity still image with 4-pixel addition, and the shooting mode B is a mode for shooting a still image without pixel addition. In addition, the shooting mode C is a mode for shooting a high-sensitivity moving image with 4-pixel addition, and the shooting mode D is a mode for shooting a moving image with 2-pixel addition. At the time of shooting, one of the shooting modes A, B, C, and D is selected by the user. Here, the pixel addition is to add signal charges corresponding to a predetermined number of pixel additions of the same color. For example, the 4-pixel addition is to add signal charges of four pixels of the same color.

  Either one of the first transfer mode and the second transfer mode is selected according to the number of pixels added in the shooting mode selected by the user, and the solid-state imaging device is selected according to the selected transfer mode. 606 is driven. In the present embodiment, the first transfer mode is selected in shooting modes A and C in which the number of added pixels is 4 or more. In the case of drive modes B and D in which the number of added pixels is less than 4, the second transfer mode is selected.

  Next, the first transfer mode and the second transfer mode will be described with reference to FIGS. FIG. 4 is a timing chart when the solid-state image sensor 606 is driven using the first transfer mode in which the signal charges from the pixels 401 of the solid-state image sensor 606 are transferred in the vertical direction only during the horizontal blanking period. FIG. FIG. 5 is a diagram showing a potential state of each transfer electrode at time tb in FIG. FIG. 6 shows the solid-state image sensor 606 using the second transfer mode in which the signal charges from the pixels 401 of the solid-state image sensor 606 are transferred in the vertical direction during a period in which the horizontal blanking period and the horizontal effective scanning period overlap. It is a figure which shows the timing chart in the case of driving. FIG. 7 is a diagram showing a potential state of each transfer electrode at time ta in FIG.

  In the case of the first transfer mode, the signal charge from each pixel 401 of the solid-state image sensor 606 is transferred in the vertical direction only during the horizontal blanking period. Specifically, as shown in FIG. 4, during the horizontal blanking period Tb, the vertical drive pulses φV1 to φV4, φBS, and φTG are applied to the transfer electrodes V1 to V4, BS, and TG of the vertical transfer path 402, respectively. The As a result, the signal charge waiting on the transfer electrode V1 of the vertical transfer path 402 is transferred to the transfer electrode H1 of the horizontal transfer path 403 via the vertical transfer path 402. Here, the pulse HD in FIG. 4 is a pulse indicating the timing of transferring one horizontal line of the image.

  Here, each of the transfer electrodes V1 to V4, BS, TG, H1, and H2 at time tb in FIG. 4 shows a potential state as shown in FIG. At time tb, the signal charge is transferred to the transfer electrode V1, and there is a sufficient potential barrier up to the horizontal transfer path 403. Therefore, even when the total amount of signal charge increases due to pixel addition, the charge may leak out. Is low.

  On the other hand, in the case of the second transfer mode, signal charges from each pixel 401 of the solid-state image sensor 606 are transferred in the vertical direction during each period of the horizontal effective scanning period and the horizontal blanking period. Specifically, as shown in FIG. 6, vertical transfer is performed by four-phase vertical drive pulses φV1 to φV4 during a period Ta1 (horizontal effective scanning period and vertical effective scanning period overlap) in the horizontal effective scanning period. The signal charge waiting on the transfer electrode V1 of the path 402 is transferred to the transfer electrode V4. Then, during the horizontal blanking period Ta2, the drive pulse φBS is applied to the transfer electrode BS of the buffer storage cell 405, and the drive pulse φTG is applied to the transfer electrode TG of the transfer gate 406. As a result, the signal charge on the transfer electrode V4 is transferred to the transfer electrode H1 of the horizontal transfer path 403. Here, the pulse HD in FIG. 6 is a pulse indicating the timing of transferring one horizontal line of the image.

  Compared with the first transfer mode, the second transfer mode makes it possible to reduce the transfer time by a period Ta1 in which the horizontal effective scanning period and the vertical effective scanning period overlap each line transfer. . This makes it possible to increase the frame rate.

  Here, each of the transfer electrodes V1 to V4, BS, TG, H1, and H2 at time ta in FIG. 6 shows a potential state as shown in FIG. At time ta, the signal charge reaches the transfer electrode V4, and only the transfer electrode BS exists as a potential barrier. For this reason, when the amount of charge to be transferred is large, such as when pixel addition is being performed or when a high-luminance subject is being photographed, the signal charge passes over the transfer electrode BS and is transferred from the vertical transfer path 402 to the horizontal transfer path. The possibility of leaking to 403 increases.

  Furthermore, since charge transfer is performed on the vertical transfer path 402 during the horizontal effective scanning period, the substrate voltage of the solid-state imaging device 606 fluctuates, and charge leakage from the horizontal transfer path 403 to the vertical transfer path 402 or vice versa occurs. The possibility increases. In particular, the possibility of such charge leakage increases as the amount of charge to be transferred increases, and abnormalities occur in the captured image.

  Thus, the second transfer mode can shorten the transfer time and increase the frame rate compared to the first transfer mode. However, when the amount of charge to be transferred increases, the possibility that the charge leaks from the vertical transfer path 402 to the horizontal transfer path 403 or vice versa increases.

  Therefore, in the present embodiment, as described above, in the shooting modes A and C in which the number of added pixels is 4 or more, the first leak is eliminated in order to eliminate charge leakage due to the large amount of charge to be transferred. The transfer mode is used. On the other hand, in the shooting modes B and D in which the number of added pixels is less than 4, the second transfer mode is used in order to increase the frame rate by shortening the transfer time.

  Next, the photographing operation in the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the procedure of the photographing operation of the image pickup apparatus of FIG. The procedure shown in the flowchart of FIG. 8 is executed by the control unit 611 according to a program stored in the memory 616.

  As shown in FIG. 8, the control unit 611 first performs initialization (step S101). In this initialization, for example, initialization information of variables necessary for processing in the imaging signal processing circuit 608, setting information such as a drive mode and zoom magnification is stored in the memory 616. Then, the control unit 611 activates EVF (Electric View Finder) (step S102). The EVF displays an image currently captured by the solid-state image sensor 606 on the display unit 610.

  Next, the control unit 611 waits for the shutter switch SW1 of the operation unit 617 to be turned on (step S103). When the shutter switch SW1 is turned on, the control unit 611 refers to the setting information in the memory 616 to determine whether or not the number of added pixels in the shooting mode to be set is greater than or equal to a predetermined number (step S104). . In the present embodiment, 4 is set as the predetermined number. Here, the drive mode in which the number of added pixels is 4 or more is a shooting mode A for shooting a high-sensitivity still image with 4-pixel addition or a shooting mode C for shooting a high-sensitivity moving image with 4-pixel addition. On the other hand, the shooting mode in which the number of added pixels is less than 4 is a shooting mode B for shooting a still image without pixel addition or a shooting mode D for shooting a moving image with 2 pixel addition.

  When it is determined in step S104 that the pixel addition number of the set shooting mode is equal to or greater than a predetermined number (= 4), the control unit 611 selects the first transfer mode (step S105). Then, the control unit 611 controls the timing generator 609 so as to generate a driving pulse (FIG. 4) for the solid-state imaging device 606 corresponding to the first transfer mode.

  On the other hand, when it is determined that the pixel addition number is less than the predetermined number (= 4), the control unit 611 selects the second transfer mode (step S106). Then, the control unit 611 controls the timing generator 609 so as to generate a drive pulse (FIG. 6) for the solid-state imaging device 606 corresponding to the second transfer mode.

  When the transfer mode is selected according to the number of pixels added in the shooting mode in this way, the control unit 611 performs distance measurement and photometry (step S107). Here, each shooting parameter is set to a predetermined value, and the solid-state imaging device 606 is driven in the selected transfer mode while performing pixel addition according to the number of pixel additions in the set shooting mode. Then, provisional shooting is performed, and a subject image (image data) is acquired. From the acquired subject image, subject distance information L, subject brightness value Bv, and maximum subject brightness value Ymax are calculated. Here, the subject brightness value Bv is calculated from the brightness value Y of the acquired subject image, the set predetermined aperture value Av0, and the set predetermined exposure time Tv0. In calculating the maximum subject luminance value Ymax, the acquired subject image is divided into a plurality of regions, and the luminance value of each region is calculated. The maximum value among the calculated luminance values is set as the maximum subject luminance value Ymax.

  Next, the control unit 611 performs focusing control and exposure control (step S108). Here, based on the calculated subject distance information L, the lens driving unit 602 is controlled so that the corresponding movable lens group of the lens unit 601 is driven and the lens unit 601 is focused on the subject. Further, the aperture value Av and the exposure time Tv are determined based on the subject luminance value Bv. The subject distance information L, subject brightness value Bv, maximum subject brightness value Ymax, aperture value Av, exposure time Tv, and the like calculated at this time are stored in the memory 616.

  Next, the control unit 611 determines whether or not the shutter switch SW2 of the operation unit 617 has been turned on (step S109). If the shutter switch SW2 is not turned on, the control unit 611 returns to step S103.

  When it is determined in step S109 that the shutter switch SW2 is turned on, the control unit 611 performs shooting (step S110). Here, the control unit 611 controls the shutter / aperture driving unit 604 so as to operate the aperture 605 and the mechanical shutter 603 with the aperture value Av and the exposure time Tv stored in the memory 616. Then, a subject image is captured by the solid-state image sensor 606 at the aperture value Av and the exposure time Tv. Here, the solid-state imaging device 606 is driven in the transfer mode selected in step S105 or step S106.

  Next, the control unit 611 sequentially performs development processing (step S111), compression processing (step S112), and recording of the subject image on the recording medium 614 (step S113). In recording the subject image on the recording medium 614, the control unit 611 controls the recording medium control I / F unit 612 to record the captured subject image on the recording medium 614. Then, the control unit 611 returns to step S103.

  Thus, according to the present embodiment, the frame rate is increased for shooting modes with a pixel addition number less than a predetermined number, and for shooting modes with a pixel addition number of a predetermined number or more, Leakage of signal charges from the vertical transfer path 402 to the horizontal transfer path 403 is reduced.

  In the present embodiment, the predetermined number with respect to the pixel addition number serving as a selection criterion for the transfer mode is set to 4, but instead, for example, the predetermined number may be 2, 3, 5, or more. .

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a flowchart showing a part of the procedure of the photographing operation of the imaging apparatus according to the second embodiment of the present invention.

  In the first embodiment, either the first transfer mode or the second transfer mode is selected based on the pixel addition value in the shooting mode. On the other hand, in the present embodiment, either the first transfer mode or the second transfer mode is selected based on the pixel addition value, the subject brightness value Bv, and the maximum subject brightness value Ymax in the shooting mode. When the subject brightness is high, leakage of signal charges on the vertical transfer path and the horizontal transfer path occurs, and this may cause bright lines and color blurring that do not exist in the original subject, leading to image degradation. . Therefore, in order to reduce the possibility of image degradation due to the leakage of signal charges when the subject brightness is high, the subject brightness value Bv and the maximum subject brightness value Ymax are further used as transfer mode selection criteria.

  In this respect, the present embodiment is different from the first embodiment, but is otherwise the same as the first embodiment. Therefore, in the present embodiment, the same parts as those in the first embodiment will be described using the same reference numerals.

  In the present embodiment, as in the first embodiment described above, the control unit 611 proceeds from step S101 in FIG. 8 to step S103 through step S102, and the shutter switch SW1 of the operation unit 617 is turned on. Wait for. Here, when the shutter switch SW1 is turned on, as shown in FIG. 9, the control unit 611 refers to the setting information in the memory 616, and the number of added pixels of the set shooting mode is a predetermined number (= 4). ) It is determined whether or not the above is true (step S201). The shooting mode is one of four shooting modes A, B, C, and D, as in the first embodiment.

  The case where it is determined in step S201 that the pixel addition number is equal to or larger than the predetermined number is a case where either the shooting mode A or the shooting mode C is set. In this case, the control unit 611 determines whether or not a relationship of Bv ≧ Bth is established (step S202). Here, Bth is a predetermined threshold value, and the threshold value is set to a subject luminance value at which signal charges start to leak into the surrounding pixels. The subject brightness value Bv is acquired during a loop period from when the shutter switch SW1 is turned on until the shutter switch SW2 is turned on, and is stored in the memory 616.

  When it is determined in step S202 that the relationship of Bv ≧ Bth is established (a predetermined value or more), the control unit 611 selects the first transfer mode (step S204). Then, the control unit 611 controls the timing generator 609 so as to generate a driving pulse (FIG. 4) for the solid-state imaging device 606 corresponding to the first transfer mode.

  On the other hand, when it is determined in step S202 that the relationship of Bv ≧ Bth is not established (less than a predetermined value), the control unit 611 determines whether the relationship of Ymax ≧ Yth is established (step S203). . Here, Yth is a predetermined threshold value, and the threshold value Yth is set to the maximum subject luminance value at which leakage of electric charge into surrounding pixels starts to occur. The maximum subject luminance value Ymax is acquired during the loop period from when the shutter switch SW1 is turned on to when the shutter switch SW2 is turned on, and is stored in the memory 616.

  When it is determined in step S203 that the relationship of Ymax ≧ Yth is established, the control unit 611 selects the first transfer mode (step S204). Then, the control unit 611 controls the timing generator 609 so as to generate a driving pulse (FIG. 4) for the solid-state imaging device 606 corresponding to the first transfer mode.

  As described above, when a shooting mode (shooting modes A and C) having a pixel addition number of 4 or more is set, if the relationship of Bv ≧ Bth or Ymax ≧ Yth is satisfied, there is a possibility that charge leaks into the surrounding pixels. Becomes very high. Therefore, the first transfer mode is selected by giving priority to the prevention of leakage of charges into peripheral pixels over the improvement of the frame rate.

  On the other hand, when it is determined in step S203 that the relationship of Ymax ≧ Yth is not established, the control unit 611 selects the second transfer mode (step S205). Then, the control unit 611 controls the timing generator 609 so as to generate a drive pulse (FIG. 6) for the solid-state imaging device 606 corresponding to the second transfer mode. This is because in the shooting mode (shooting modes A and C) where the number of added pixels is 4 or more, the amount of charge to be transferred increases, but the relationship of Bv ≧ Bth or Ymax ≧ Yth does not hold, so This is because it is determined that the possibility of leaking into the pixel is not high. Therefore, the improvement of the frame rate is prioritized over the prevention of leakage of signal charges to the peripheral pixels, and the second transfer mode is selected.

  The case where it is determined in step S201 that the pixel addition number is not equal to or greater than the predetermined number (= 4) is a case where either the shooting mode B or the shooting mode D is set. In this case, the control unit 611 selects the second transfer mode, and controls the timing generator 609 so as to generate a driving pulse (FIG. 6) for the solid-state imaging device 606 corresponding to the second transfer mode. (Step S205). That is, in this case, since the amount of charge to be transferred is small, the second transfer mode is selected, and the frame rate can be increased.

  When the transfer mode is selected in this way, the control unit 611 proceeds to step S107 in FIG.

  As described above, according to the present embodiment, if the subject brightness is sufficiently high (when Bv ≧ Bth or Ymax ≧ Yth is established) in the driving mode in which the number of added pixels is 4 or more, the first transfer mode Is selected. Thereby, it is possible to reduce the occurrence of image deterioration due to leakage of signal charges on the horizontal transfer path and the vertical transfer path.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a flowchart showing a part of the procedure of the photographing operation of the imaging apparatus according to the third embodiment of the present invention.

  In the first embodiment, either the first transfer mode or the second transfer mode is selected based on the pixel addition value in the shooting mode. On the other hand, in this embodiment, either the first transfer mode or the second transfer mode is selected based on the pixel addition value and the zoom magnification in the shooting mode. For example, when the zoom magnification K is high and the ratio of the high-brightness subject to the whole subject becomes high, signal charges leak on the vertical transfer path and the horizontal transfer path. This may cause bright lines, color blurs, etc. that do not exist in the original subject, leading to image degradation. Therefore, in order to reduce the occurrence of image degradation due to the leakage of signal charges when the zoom magnification K is high, the zoom magnification K is further used as the transfer mode selection criterion.

  In this respect, the present embodiment is different from the first embodiment, but is otherwise the same as the first embodiment. Therefore, in the present embodiment, the same components as those in the first embodiment are described using the same reference numerals.

  In the present embodiment, as in the first embodiment described above, the control unit 611 proceeds from step S101 in FIG. 8 to step S103 through step S102, and the shutter switch SW1 of the operation unit 617 is turned on. Wait for. Here, when the shutter switch SW1 is turned on, as shown in FIG. 10, the control unit 611 refers to the setting information in the memory 616, and the number of added pixels in the set shooting mode is a predetermined number (= 4). ) It is determined whether or not this is the case (step S301). The shooting mode is one of four shooting modes A, B, C, and D, as in the first embodiment.

  The case where it is determined in step S301 that the pixel addition number is greater than or equal to the predetermined number (= 4) is a case where either the shooting mode A or the shooting mode C is set. In this case, the control unit 611 reads the zoom magnification K from the memory 616, and determines whether or not the relationship of K ≧ Kth is satisfied (step S302). Here, Kth is a predetermined threshold value, and the threshold value is set to a magnification at which a high brightness subject such as the sun occupies a predetermined ratio or more of the angle of view and the signal charge starts to leak into surrounding pixels. Yes. The zoom magnification K is a magnification set by the user via the operation unit 617.

  When the relationship of K ≧ Kth is established in step S302 (above a predetermined magnification), the control unit 611 selects the first transfer mode (step S303). Then, the control unit 611 controls the timing generator 609 so as to generate a driving pulse (FIG. 4) for the solid-state imaging device 606 corresponding to the first transfer mode.

  As described above, in the case where the shooting mode (shooting modes A and C) with the pixel addition number of 4 or more is set, if the relationship of K ≧ Kth is established, the signal charge may leak into the surrounding pixels. Get higher. Therefore, the prevention of leakage of signal charges to surrounding pixels is prioritized over the improvement of the frame rate, and the first transfer mode is selected.

  On the other hand, when it is determined in step S302 that the relationship K ≧ Kth is not satisfied (less than the predetermined magnification), the control unit 611 selects the second transfer mode (step S304). Then, the control unit 611 controls the timing generator 609 so as to generate a drive pulse (FIG. 6) for the solid-state imaging device 606 corresponding to the second transfer mode. This is because, in the shooting mode (shooting modes A and C) in which the number of added pixels is 4 or more, the amount of charge to be transferred increases, but since the relationship K ≧ Kth is not established, the signal charge leaks to the surrounding pixels. This is because it is judged that there is no high possibility of being included. Therefore, higher frame rate is prioritized over prevention of leakage of charges to surrounding pixels, and the second transfer mode is selected.

  The case where it is determined in step S301 that the pixel addition number is not equal to or greater than the predetermined number (= 4) is a case where either the shooting mode B or the shooting mode C is set. In this case, the control unit 611 selects the second transfer mode (step S304). Then, the control unit 611 controls the timing generator 609 so as to generate a drive pulse (FIG. 6) for the solid-state imaging device 606 corresponding to the second transfer mode.

  When the transfer mode is selected in this way, the control unit 611 proceeds to step S107 in FIG.

  Thus, according to the present embodiment, when the zoom magnification K (K ≧ Kth) is set such that the ratio of the high-brightness subject to the entire subject is high in the shooting mode in which the pixel addition number is 4 or more. The first transfer mode is selected. Thereby, it is possible to reduce the occurrence of image deterioration due to leakage of signal charges on the horizontal transfer path and the vertical transfer path.

It is a block diagram which shows the structure of the digital camera carrying the solid-state imaging device which concerns on the 1st Embodiment of this invention. It is a figure which shows typically the structural example of the solid-state image sensor 606 of FIG. FIG. 3 is a diagram illustrating a part of a color filter array in the solid-state imaging device 606 in FIG. 2. FIG. 10 is a timing chart when driving the solid-state image sensor 606 using a first transfer mode in which signal charges from the pixels 401 of the solid-state image sensor 606 are transferred in the vertical direction only during the horizontal blanking period. is there. FIG. 5 is a diagram illustrating a potential state of each transfer electrode at time tb in FIG. 4. When driving the solid-state image sensor 606 using the second transfer mode in which the signal charges from the respective pixels 401 of the solid-state image sensor 606 are transferred in the vertical direction during a period in which the horizontal blanking period and the horizontal effective scanning period overlap. It is a figure which shows the timing chart. It is a figure which shows the state of the potential of each transfer electrode in the time ta in FIG. 2 is a flowchart illustrating a procedure of a shooting operation of the imaging device in FIG. 1. It is a flowchart which shows a part of procedure of imaging | photography operation | movement of the imaging device which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows a part of procedure of imaging | photography operation | movement of the imaging device which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

401 Photodiode 402 Vertical transfer path 403 Horizontal transfer path 404 Output unit 405 Buffer storage cell 406 Transfer gate 606 Solid-state imaging device 611 Control unit

Claims (8)

A plurality of photoelectric conversion elements that are two-dimensionally arranged in the vertical direction and the horizontal direction and constitute pixels, a plurality of vertical transfer paths that respectively transfer signal charges from the plurality of photoelectric conversion elements in the vertical direction, and the plurality of vertical A solid-state imaging device driving method having a horizontal transfer path for transferring signal charges from the transfer path in the horizontal direction,
When the pixel addition number in the shooting mode is equal to or greater than a predetermined number set in advance, depending on whether or not the subject luminance at the time of shooting is equal to or higher than a predetermined value set in the horizontal blanking period In each of the vertical transfer paths during a period of a first transfer mode in which signal charges from the photoelectric conversion elements are transferred through the vertical transfer paths, and a horizontal effective scanning period and a subsequent horizontal blanking period. When one of the transfer modes is selected from the second transfer modes in which the signal charges from the photoelectric conversion elements are transferred via the imaging mode, and the pixel addition number in the shooting mode is less than the predetermined number A method for driving a solid-state imaging device , wherein the second transfer mode is selected and the solid-state imaging device is driven in the selected transfer mode. The first transfer mode is selected when the subject brightness is equal to or higher than the predetermined value, and the second transfer mode is selected when the subject brightness is lower than the predetermined value. 2. A method for driving a solid-state imaging device according to 1 . A plurality of photoelectric conversion elements that are two-dimensionally arranged in the vertical direction and the horizontal direction and constitute pixels, a plurality of vertical transfer paths that respectively transfer signal charges from the plurality of photoelectric conversion elements in the vertical direction, and the plurality of vertical A solid-state imaging device driving method having a horizontal transfer path for transferring signal charges from the transfer path in the horizontal direction,
When the number of pixels added in the shooting mode is equal to or greater than a predetermined number set in advance, depending on whether or not the zoom magnification at the time of shooting is equal to or higher than a preset predetermined magnification, the horizontal blanking period In each of the vertical transfer paths during a period of a first transfer mode in which signal charges from the photoelectric conversion elements are transferred through the vertical transfer paths, and a horizontal effective scanning period and a subsequent horizontal blanking period. through from the second transfer mode for transferring signal charges from the photoelectric conversion element, select either one transport mode of, if the pixel addition number of the photographing mode is below the predetermined number It said second selecting the transfer mode, the driving method of the solid-state image pickup element you and drives the solid-state imaging device in the selected transfer mode. The first transfer mode is selected when the zoom magnification is greater than or equal to the predetermined magnification, and the second transfer mode is selected when the zoom magnification is less than the predetermined magnification. 4. A method for driving a solid-state imaging device according to 3 . A plurality of photoelectric conversion elements that are two-dimensionally arranged in the vertical direction and the horizontal direction and constitute pixels, a plurality of vertical transfer paths that respectively transfer signal charges from the plurality of photoelectric conversion elements in the vertical direction, and the plurality of vertical A solid-state imaging device driving method having a horizontal transfer path for transferring signal charges from the transfer path in the horizontal direction,
A first transfer mode in which signal charges from the photoelectric conversion elements are transferred through each of the vertical transfer paths during a horizontal blanking period based on the subject brightness at the time of shooting, a horizontal effective scanning period, and a subsequent horizontal One of the transfer modes is selected from the second transfer mode in which the signal charge from the photoelectric conversion element is transferred through each of the vertical transfer paths during the period spanning the blanking period, A method for driving a solid-state imaging device, wherein the solid-state imaging device is driven in the selected transfer mode. A plurality of photoelectric conversion elements that are two-dimensionally arranged in the vertical direction and the horizontal direction and constitute pixels, a plurality of vertical transfer paths that respectively transfer signal charges from the plurality of photoelectric conversion elements in the vertical direction, and the plurality of vertical A solid-state imaging device driving method having a horizontal transfer path for transferring signal charges from the transfer path in the horizontal direction,
Based on the zoom magnification at the time of shooting, a first transfer mode in which signal charges from the photoelectric conversion elements are transferred through the vertical transfer paths during a horizontal blanking period, a horizontal effective scanning period, and a subsequent horizontal One of the transfer modes is selected from the second transfer mode in which the signal charge from the photoelectric conversion element is transferred through each of the vertical transfer paths during the period spanning the blanking period, A method for driving a solid-state imaging device, wherein the solid-state imaging device is driven in the selected transfer mode. A solid-state image sensor, and the solid-state image sensor is two-dimensionally arranged in a vertical direction and a horizontal direction, and transfers a plurality of photoelectric conversion elements constituting a pixel and signal charges from the plurality of photoelectric conversion elements in a vertical direction. An imaging device having a plurality of vertical transfer paths and a horizontal transfer path for transferring signal charges from the plurality of vertical transfer paths in a horizontal direction, respectively.
When the pixel addition number in the shooting mode is equal to or greater than a predetermined number set in advance, depending on whether or not the subject luminance at the time of shooting is equal to or higher than a predetermined value set in the horizontal blanking period In each of the vertical transfer paths during a period of a first transfer mode in which signal charges from the photoelectric conversion elements are transferred through the vertical transfer paths, and a horizontal effective scanning period and a subsequent horizontal blanking period. When one of the transfer modes is selected from the second transfer mode for transferring the signal charge from the photoelectric conversion element through the imaging mode, the pixel addition number in the shooting mode is less than the predetermined number, Transfer mode selection means for selecting the second transfer mode ;
An imaging apparatus comprising: a driving unit that drives the solid-state imaging device in the selected transfer mode. A solid-state image sensor, and the solid-state image sensor is two-dimensionally arranged in a vertical direction and a horizontal direction, and transfers a plurality of photoelectric conversion elements constituting a pixel and signal charges from the plurality of photoelectric conversion elements in a vertical direction. An imaging device having a plurality of vertical transfer paths and a horizontal transfer path for transferring signal charges from the plurality of vertical transfer paths in a horizontal direction, respectively.
When the number of pixels added in the shooting mode is equal to or greater than a predetermined number set in advance, depending on whether or not the zoom magnification at the time of shooting is equal to or higher than a preset predetermined magnification, the horizontal blanking period In each of the vertical transfer paths during a period of a first transfer mode in which signal charges from the photoelectric conversion elements are transferred through the vertical transfer paths, and a horizontal effective scanning period and a subsequent horizontal blanking period. When one of the transfer modes is selected from the second transfer mode for transferring the signal charge from the photoelectric conversion element through the imaging mode, the pixel addition number in the shooting mode is less than the predetermined number, Transfer mode selection means for selecting the second transfer mode ;
An imaging apparatus comprising: a driving unit that drives the solid-state imaging device in the selected transfer mode.

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