JP2008148022A - Method for driving solid-state image pickup device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To position a segmenting area when electronic blurring correction is performed per line. <P>SOLUTION: This solid-state image pickup device of honeycomb pixel array is provided with a first driving mode for reading, transferring signal electric charges from pixels of even-numbered lines, to the adjacent electric charge transfer paths and reading the signal electric charges from pixels of odd-numbered lines to the adjacent electric charge transfer path when the signal electric charges are transferred to positions of the odd-numbered lines and a second driving mode for reading, transferring the signal electric charges from the pixels of the odd-numbered lines to the adjacent electric charge transfer path when the signal electric charges are transferred to positions of the even-numbered lines and both modes are switched based on predetermined conditions. Thus, positioning of the segmenting area becomes possible per line even in the case of the solid-state image pickup device of the honeycomb pixel array. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving method of a solid-state imaging device in which pixels in odd-numbered rows are shifted by 1/2 pitch with respect to pixels in even-numbered rows, and an imaging device equipped with the solid-state imaging device, and in particular, electronic camera shake. The present invention relates to a driving method of a solid-state imaging device and an imaging apparatus capable of performing correction with high accuracy.

  FIG. 6 is an explanatory diagram of electronic camera shake correction performed in an imaging apparatus using a CCD solid-state imaging device. In the effective imaging area 1 of the solid-state imaging device, a plurality of pixels (not shown) arranged in a two-dimensional array and a plurality of vertical charge transfer paths (VCCD: not shown) provided in parallel in each pixel column are arranged. ), The signal charges detected by each pixel are transferred to the horizontal charge transfer path 2 by the vertical charge transfer path, and then these signal charges are transferred to the output amplifier 3 along the horizontal charge transfer path 2. The output amplifier 3 outputs a voltage value signal corresponding to each signal charge amount as a captured image signal.

  When electronic camera shake correction is performed, the effective imaging area 1 is made larger than the actual imaging screen, and, for example, when camera shake occurs during moving image imaging, the cutout range for cutting out the imaging screen is moved according to the camera shake correction amount. Is done.

  In the example shown in the figure, when a camera shake occurs and the fixed object image 5 in the first captured image of a certain frame appears as the fixed object image 6 in the second captured image of the next frame, the first captured image and the second captured image If the image is cut out with the same cutout range 7, the same fixed object image moves as “5 → 6” in the captured image, resulting in a moving image that is difficult to see.

  Therefore, when the first captured image is cut out at the cutout range 7, and then the second picked up image is cut out, the camera shake amount k is detected, and the cutout range 7 is moved by the camera shake amount k, and the cutout range 8 is moved. By cutting out the two captured images, the fixed object images 5 and 6 in the captured image are in the same position, and a moving image without camera shake can be obtained.

  Such a movement of the cutout range is performed rather than reading out the picked-up image signal for each frame of the effective image pickup region 1 to the frame memory outside the solid-state image pickup device and cutting out the picked-up image in the frame memory. When the captured image signal is read out from the solid-state image sensor, the frame rate is set to read out the captured image signal in the cut-out range (= reading range) while setting the cut-out range and sweeping out the unnecessary range of signal readout. This improves the real-time performance of moving image capturing.

  When such electronic camera shake correction is performed, for example, a so-called honeycomb pixel-arranged solid-state imaging device as described in Patent Document 1 below has a problem that high-precision electronic camera shake correction cannot be performed. This will be described next.

  FIG. 7 is a schematic view of the surface of a solid-state imaging device in which even-numbered pixels are shifted by ½ pitch with respect to honeycomb pixel arrangement, that is, odd-numbered pixels (photoelectric conversion elements). R, G, and B in the figure indicate colors of color filters (R = red, G = green, B = blue) stacked on each pixel. A meandering vertical charge transfer path (VCCD) 11 is provided next to the pixel columns arranged in the vertical direction.

  The vertical charge transfer path 11 is composed of a buried channel (not shown) formed on a semiconductor substrate and a vertical transfer electrode film 12 stacked thereon via a gate insulating film (not shown). . In the illustrated example, four transfer electrode films 12 are provided per pixel, and transfer pulses Vφ1, Vφ2, Vφ3, and Vφ4 are applied to the four transfer electrode films 12, respectively.

  In a solid-state imaging device having a honeycomb pixel arrangement, as shown in the drawing, a pixel column in which B pixels / R pixels are alternately provided and a pixel column having only G pixels are arranged alternately, and the G pixel is R pixel / B. The pixel is provided at a position shifted in the vertical direction by two transfer electrode films.

  When the signal charge of each pixel is read and transferred in the vertical direction with such a solid-state imaging device, first, a read pulse Vφ1 is applied, and the signal charge of the G pixel is applied to the buried channel under the adjacent vertical transfer electrode film. Read out. When this signal charge (referred to as G signal charge) is transferred in the vertical direction by two electrode films, when a read pulse Vφ3 is applied, the signal charges of the R pixel and the B pixel are placed under the adjacent vertical transfer electrode film. Read to the embedded channel. As a result, R—G—B—G—R— and signal charges are arranged in a horizontal line, or B—G—R—G—B— and signal charges are arranged in a horizontal line. Thereafter, the signal charges of each row are transferred together in the vertical direction.

JP-A-10-136391

  As described above, in the solid-state imaging device having the honeycomb pixel array, after reading out the G signal charge, only the two transfer electrodes are transferred in the vertical direction, and at this time, the R signal charge and the B signal charge are read out. Two rows of the pixel row and the next R / B pixel row are transferred together.

  Therefore, when the cutout range shown in FIG. 6 is determined, as shown in FIG. 8, the accuracy is in units of two rows, and there is a problem that the cutout range cannot be positioned with an accuracy of two rows or less.

  An object of the present invention is to provide a driving method of a solid-state imaging device and an imaging apparatus capable of positioning a cut-out range in units of one row.

According to the solid-state imaging device driving method of the present invention, a plurality of pixels are formed in a two-dimensional array, and even-numbered pixels and odd-numbered rows of pixels are formed so as to be shifted by ½ pitch. In the driving method of the solid-state imaging device in which the charge transfer paths that are provided adjacent to each other and charge transfer paths for receiving and transferring the signal charges read from the pixels of the pixel column are formed, respectively.
When the signal charge of the pixel is read from the pixels in the even-numbered row to the adjacent charge transfer path and transferred along the charge transfer path, and the signal charge on the charge transfer path is transferred to the position of the odd-numbered row The signal charges of the pixels are read from the pixels of the odd rows to the adjacent charge transfer paths, and the signal charges of the even rows of pixels and the signal charges of the odd rows of pixels on the charge transfer paths are set to the same horizontal position. A first drive mode in which charge transfer is performed while maintaining
When the signal charge of the pixel is read from the odd row pixel to the adjacent charge transfer path and transferred along the charge transfer path, and the signal charge on the charge transfer path is transferred to the even row position The signal charges of the pixels are read from the pixels of the even rows to the adjacent charge transfer paths, and the signal charges of the pixels of the even rows and the signal charges of the pixels of the odd rows on each charge transfer path are in the same horizontal position. And switching to the second drive mode in which charge transfer is performed based on a predetermined condition.

  The predetermined condition in the driving method of the solid-state imaging device of the present invention is that a range narrower than the imaging area is cut out from the imaging area in which the pixels arranged in the two-dimensional array are provided in order to perform electronic camera shake correction. It is the position of the charge transfer direction boundary line in the range at that time.

  In the solid-state image sensor in the solid-state image sensor driving method of the present invention, a green filter is mounted on one pixel of the even-numbered row and the odd-numbered row, and a red filter and a blue filter are mounted on the other pixels of the even-numbered row and the odd-numbered row. And are mounted alternately.

  In the imaging device of the present invention, a plurality of pixels are formed in a two-dimensional array, and even-numbered pixels and odd-numbered rows of pixels are formed by being shifted by 1/2 pitch, and provided adjacent to each pixel column. In the imaging device including the solid-state imaging device in which the charge transfer paths for receiving and transferring the signal charges read from the pixels in the pixel column are formed, the first drive mode and the second drive described in any of the above An image sensor drive unit that generates and supplies drive pulses for each mode to the solid-state image sensor, and a control unit that determines the predetermined condition and outputs a switching instruction to the image sensor drive unit.

  According to the present invention, even if positioning of the cutout range is performed in units of one line, a picked-up image signal can be generated by reading out a picked-up image signal in the cutout range, and electronic camera shake correction can be performed with high accuracy. It becomes possible.

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

  FIG. 1 is a functional block configuration diagram of a digital camera according to an embodiment of the present invention. The digital camera includes an imaging unit 21, an analog signal processing unit 22 that performs analog processing such as automatic gain adjustment (AGC) and correlated double sampling processing on analog image data output from the imaging unit 21, and an analog signal processing unit. An analog / digital conversion unit (A / D) 23 that converts analog image data output from the digital image data into digital image data, and an A / D 23, an analog signal processing unit 22, according to instructions from a system control unit (CPU) 29 described later, A driving unit (including a timing generator TG) 24 that controls driving of the imaging unit 21 and a flash 25 that emits light in response to an instruction from the CPU 29 are provided.

  The imaging unit 21 collects light from the object field, a diaphragm or a mechanical shutter 21b that condenses the light that has passed through the optical lens system 21a, and a diaphragm that is condensed by the optical lens system 21a. A CCD type solid-state imaging device 100 that receives the received light and outputs captured image data (analog image data).

  The digital camera according to the present embodiment further includes a digital signal processing unit 26 that takes in digital image data output from the A / D 23 and performs interpolation processing, white balance correction, RGB / YC conversion processing, and the like. A compression / expansion processing unit 27 that compresses or reversely compresses image data, a display unit 28 that displays menus, displays through images and captured images, and a system control unit that controls the entire digital camera ( CPU) 29, an internal memory 30 such as a frame memory, and a media interface (I / F) unit 31 that performs interface processing between a recording medium 32 that stores JPEG image data and the like, and a bus that interconnects them 40, and an operation unit 23 for inputting an instruction from the user is connected to the system control unit 29. It has been.

  FIG. 2 is a schematic plan view of the solid-state imaging device 100 shown in FIG. In the solid-state imaging device 100 shown in the figure, a large number of photodiodes (photoelectric conversion elements) 101 are arranged in a two-dimensional array on a semiconductor substrate. They are arranged shifted by two pitches (so-called honeycomb pixel arrangement).

  “R”, “G”, and “B” illustrated on each photodiode 101 represent the color of the color filter (red = R, green = G, blue = B) stacked on each photodiode. The diode 101 accumulates signal charges corresponding to the amount of received light of one of the three primary colors. Although an example in which a primary color filter is mounted will be described, a complementary color filter may be mounted.

  In the horizontal direction of the semiconductor substrate surface, vertical transfer electrodes are laid to meander to avoid each photodiode 101. In the semiconductor substrate, a buried channel (not shown) is formed to meander in the vertical direction so as to avoid the photodiode 101 at the side of the photodiode row arranged in the vertical direction. A vertical transfer path (VCCD) 102 is formed by the buried channel and a vertical transfer electrode provided on the buried channel and arranged in a meandering manner in the vertical direction.

  A horizontal transfer path (HCCD) 103 is provided on the lower side of the semiconductor substrate. The horizontal transfer path 103 is also composed of a buried channel and a horizontal transfer electrode provided thereon, and the horizontal transfer path 103 is driven in two phases by a transfer pulse output from the drive unit 24. At the output end of the horizontal transfer path 103, an amplifier 104 that outputs a voltage value signal corresponding to the signal charge amount as a captured image signal is provided.

  The arrangement of the pixel array and the transfer electrode film of the solid-state imaging device according to this embodiment is the same as that described with reference to FIG.

  Note that a line memory as described in, for example, Japanese Patent Application Laid-Open No. 2002-112119 may be provided between the transfer end of each vertical transfer path 102 and the horizontal transfer path 103. In this embodiment, The present invention can be applied to the case where the line memory is provided or not provided.

  In addition, although the terms “vertical” and “horizontal” are used for explanation, this only means “one direction” along the surface of the semiconductor substrate and “a direction substantially perpendicular to the one direction”.

  FIG. 3 is a flowchart showing a processing procedure when the system control unit 29 shown in FIG. 1 performs electronic camera shake correction. First, a camera shake correction amount is detected (step S1). This detection may be obtained by image processing of a picked-up image signal read out as a through image from the solid-state image pickup device 100, or may be obtained by a camera shake correction amount detector provided separately in the image pickup apparatus. Does not matter.

  In the next step S2, the cutout range described in FIG. 6 is determined based on the camera shake correction amount obtained in step S1. For example, the cutout range 8 shown in FIG. 6 is determined. In the next step S3, it is determined according to the position of the lower end line of the cut-out range 8 whether or not the G signal charge pre-reading mode is set.

  Whether or not it is the G signal charge pre-reading mode is determined as follows. When the position indicated by the broken line in FIG. 4A is the position of the lower end line of the cut-out range 8 and the pixel row arranged immediately below the broken line (on the horizontal transfer path side) is the G pixel row, It is determined that the pre-reading mode is set. When the pixel row arranged immediately below the position indicated by the broken line in FIG. 4B is an alternately arranged row of R pixels / B pixels, it is assumed that the RB signal charge prefetch mode is used instead of the G signal charge prefetch mode. judge.

  In the case of the G signal charge pre-reading mode, the process proceeds from step S3 to step S4 to instruct the driving unit 24 of FIG. As a result, the drive unit 24 generates a G prefetch mode drive pulse shown in FIG. 5A and outputs it to the solid-state imaging device 100.

  According to the drive pulse chart shown in FIG. 5A, as described with reference to FIG. 7, the read pulse P1 is applied to the electrode film Vφ1, and first the G signal charge is read to the vertical charge transfer path, and then When the transfer pulse is applied to the electrode films Vφ2 and Vφ3 and the G signal charge is transferred in the vertical direction by two electrode films, the read pulse P2 is superimposed on the electrode film Vφ3, whereby the R signal charge, B The signal charge is read out to the vertical charge transfer path.

  Thereafter, the signal charge in the pre-sweep portion shown in FIG. 6 is driven at high speed, and then the signal charge in the cut-out range is output, and then the signal charge in the post-sweep portion is driven at high speed. . As a result, every two rows of signal charges indicated by broken lines in FIG. 4A are transferred to the horizontal transfer path 103, and taken into the digital signal processor (DSP) 26 of FIG.

  The digital signal processing unit 26 has a G image signal perpendicular to the R image signal and the B image signal in the data sequence of R—G—B—G—R— of the captured image signal captured from the solid-state image sensor 100. If it can be known that it is in the upper side of the direction (the state of FIG. 4A), the captured image can be reproduced.

  Therefore, the system control unit 29 notifies the digital signal processing unit 26 of the G prefetching mode in step S5 after step S4, and ends this processing. Thereby, the digital signal processing unit 26 performs image processing on the data string read from the solid-state imaging device 100 in accordance with this notification, and reproduces the captured image.

  If the result of determination in step S3 is that there is no G look-ahead mode, processing proceeds from step S3 to step S6. In step S6, the RB prefetch mode is instructed to the drive unit 24 of FIG. As a result, the drive unit 24 generates a G prefetch mode drive pulse shown in FIG. 5B and outputs it to the solid-state imaging device 100.

  According to the drive pulse chart shown in FIG. 5B, the read pulse P3 is applied to the electrode film Vφ3, and first, the R signal charge and the B signal charge are read to the vertical charge transfer path, and then the electrode film Vφ4. , Vφ1 and the transfer pulse is applied to the electrode film Vφ1 when the R signal charge and the B signal charge are transferred in the vertical direction by two vertical electrode films, so that the G signal Charge is read out to the vertical charge transfer path.

  Thereafter, the signal charge in the pre-sweep portion shown in FIG. 6 is driven at high speed, and then the signal charge in the cut-out range is output, and then the signal charge in the post-sweep portion is driven at high speed. . As a result, every two rows of signal charges indicated by broken lines in FIG. 4B are transferred to the horizontal transfer path 103 and taken into the digital signal processor (DSP) 26 of FIG.

  The digital signal processing unit 26 has a G image signal perpendicular to the R image signal and the B image signal in the data sequence of R—G—B—G—R— of the captured image signal captured from the solid-state image sensor 100. If it can be known that it is below the direction (state of FIG. 4B), the captured image can be reproduced.

  Therefore, the system control unit 29 notifies the digital signal processing unit 26 of the RB prefetching mode in step S7 after step S6, and ends this processing. Thereby, the digital signal processing unit 26 performs image processing on the data string read from the solid-state imaging device 100 in accordance with this notification, and reproduces the captured image.

  As described above, according to the present embodiment, as shown in FIGS. 4A and 4B, the accuracy of the cutout range can be controlled in units of one pixel row, so that high-precision camera shake correction is performed. Can be done.

  The method for driving a solid-state imaging device according to the present invention is useful when applied to a digital camera or the like because electronic camera shake correction can be performed with high accuracy.

It is a functional block block diagram of the digital camera which concerns on one Embodiment of this invention. It is a surface schematic diagram of the solid-state image sensor of honeycomb pixel arrangement | positioning shown in FIG. It is a flowchart which shows the process sequence at the time of the electronic camera shake correction | amendment which the system control part shown in FIG. 1 performs. It is a figure which shows the determination of the extraction range in the unit of 1 pixel row, and the reading order of an imaging signal when performing electronic camera shake correction. It is a timing chart of G prefetch mode drive pulse (a) and RB prefetch mode drive pulse (b). It is explanatory drawing of electronic camera-shake correction. It is explanatory drawing of the signal charge read-out and transfer of the pixel in a honey-comb pixel arrangement | sequence. FIG. 6 is a diagram for explaining a problem during electronic camera shake correction when a solid-state imaging device having a honeycomb pixel array is used.

Explanation of symbols

21 Imaging unit 24 Drive unit 26 Digital signal processing unit (DSP)
29 System Controller (CPU)
100 solid-state imaging device 101 pixel (photoelectric conversion device)
102 Vertical charge transfer path (VCCD)
103 horizontal charge transfer path 104 output amplifier P1, P4 G signal charge read pulse P2, P3 RG signal charge read pulse

Claims (4)

A plurality of pixels are formed in a two-dimensional array, and even-numbered pixels and odd-numbered rows of pixels are formed by being shifted by ½ pitch, and are provided adjacent to each pixel column, respectively. In the solid-state imaging device driving method in which the charge transfer paths for receiving and transferring the read signal charges are respectively formed,
When the signal charge of the pixel is read from the pixels in the even row to the adjacent charge transfer path and transferred along the charge transfer path, and the signal charge on the charge transfer path is transferred to the position of the odd row The signal charges of the pixels are read from the pixels of the odd rows to the adjacent charge transfer paths, and the signal charges of the even rows of pixels and the signal charges of the odd rows of pixels on the charge transfer paths are set to the same horizontal position. A first drive mode in which charge transfer is performed while maintaining
When the signal charge of the pixel is read from the odd-numbered row pixel to the adjacent charge transfer path and transferred along the charge transfer path, and the signal charge on the charge transfer path is transferred to the even-numbered row position The signal charges of the pixels are read from the pixels of the even rows to the adjacent charge transfer paths, and the signal charges of the pixels of the even rows and the signal charges of the pixels of the odd rows on each charge transfer path are in the same horizontal position. The solid-state imaging device driving method, wherein the second driving mode in which charge transfer is performed while maintaining the switching state based on a predetermined condition.   The predetermined condition is that the boundary in the charge transfer direction of the range when the range narrower than the imaging region is cut out from the imaging region in which the pixels arranged in the two-dimensional array are provided to perform electronic camera shake correction The solid-state imaging device driving method according to claim 1, wherein the driving method is a line position.   The green filter is mounted on one pixel of the even and odd rows, and the red filter and the blue filter are alternately mounted on the other pixel of the even and odd rows. The method for driving a solid-state imaging device according to claim 1 or 2.   A plurality of pixels are formed in a two-dimensional array, and even-numbered pixels and odd-numbered rows of pixels are formed by being shifted by ½ pitch, and are provided adjacent to each pixel column, respectively. 4. The first drive mode and the second drive mode according to claim 1, wherein the first drive mode and the second drive mode are mounted in a solid-state image pickup device in which a charge transfer path for receiving and transferring the read signal charge is formed. An imaging device comprising: an imaging element driving unit that generates and supplies the driving pulses to the solid-state imaging element; and a control unit that determines the predetermined condition and outputs a switching instruction to the imaging element driving unit. .

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