JP2011199426A - Solid-state image pickup element, image pickup device, and smear correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image pickup element that highly accurately executes smear correction.SOLUTION: The solid-state image pickup element 5 includes a plurality of pixel columns, comprising a plurality of pixels arranged in a column direction Y, in a row direction X. The solid-state image pickup element includes: a vertical charge transfer part provided corresponding to each pixel column; and a horizontal charge transfer part 53 for transferring charges, transferred from the vertical charge transfer part, in the row direction X. The vertical charge transfer part has a charge transfer part 52b exclusive for smear detection and charge transfer parts 52a other than the charge transfer part 52b. Each pixel column (a normal pixel column) corresponding to each charge transfer part 52a at least comprises pixels including photodiodes. A pixel column (a dummy pixel column) corresponding to the charge transfer part 52b at least comprises pixels not including photodiodes. A light-shielding film is provided above each pixel included in the normal pixel columns and the dummy pixel column. The light-shielding film is configured such that each opening is formed respectively above each pixel, including the photodiode, included in the normal pixel columns and above each pixel, not including the photodiode, included in the dummy pixel column.

Description

  The present invention relates to a solid-state imaging device, an imaging device, and a smear correction method.

  In recent years, solid-state imaging devices have been miniaturized and smear tends to increase. For this reason, improving the accuracy of smear correction is an important issue.

  Patent Document 1 discloses an imaging apparatus having a solid-state imaging device having a configuration in which a plurality of photoelectric conversion element arrays are provided and two vertical charge transfer units are provided corresponding to each photoelectric conversion element array. In this imaging apparatus, one vertical charge transfer unit is arranged on each of the left and right sides of the photoelectric conversion element array, and two vertical charge transfer units corresponding to the photoelectric conversion element array are formed from half the photoelectric conversion elements of the photoelectric conversion element array. The charge is read out to one of them (for example, the left side), and the two vertical charge transfer units are driven in the same manner to read out a signal corresponding to the charge. Then, smear correction is performed by subtracting the signal in the same row as the signal read from the other vertical charge transfer unit from the signal read from one vertical charge transfer unit.

Japanese Patent Laid-Open No. 6-197282

  In the solid-state imaging device described in Patent Document 1, two vertical charge transfer units exist between two adjacent photoelectric conversion element arrays, but the area between the two vertical charge transfer units is completely shielded from light. ing. For this reason, when attention is paid to a certain photoelectric conversion element array, the amount of smear generated in the vertical charge transfer section on the left side of the photoelectric conversion element array, and the vertical charge transfer section on the right side of the photoelectric conversion element array. There is a large difference in the amount of smear. Therefore, smear correction cannot be performed with high accuracy.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a solid-state imaging device, an imaging apparatus, and a smear correction method capable of performing smear correction with high accuracy.

  The solid-state imaging device according to the present invention is a solid-state imaging device including a plurality of pixel columns formed of a plurality of pixels arranged in a column direction in a row direction intersecting the column direction, and a plurality of pixels provided corresponding to each pixel column A vertical charge transfer unit, and a horizontal charge transfer unit that transfers the charges transferred from the plurality of vertical charge transfer units in the row direction, and the plurality of vertical charge transfer units are dedicated to smear detection charge transfer. A first charge transfer unit that is a portion and a second charge transfer unit other than the first charge transfer unit, and the pixel column corresponding to the second charge transfer unit (hereinafter referred to as a normal pixel column) includes a photodiode. Each pixel included in the normal pixel column is configured with at least a pixel not including a photodiode, and the pixel column corresponding to the first charge transfer unit (hereinafter referred to as a dummy pixel column). And said Dami A light-shielding film provided above each pixel included in the pixel column, wherein the light-shielding film includes an upper side of the pixel including the photodiode included in the normal pixel column and the dummy pixel column. Openings are respectively formed above the pixels not including the photodiode.

  The image pickup apparatus according to the present invention includes the solid-state image pickup device and a smear correction unit that corrects the first signal read from the normal pixel row based on at least the second signal read from the dummy pixel row. Are provided.

  The smear correction method of the present invention is a smear correction method of a signal output from the solid-state image sensor, wherein the first signal read from the normal pixel array of the solid-state image sensor is at least the dummy pixel array. And a smear correction step for correcting based on the second signal read from.

  According to the present invention, it is possible to provide a solid-state imaging device, an imaging apparatus, and a smear correction method capable of performing smear correction with high accuracy.

The figure which shows schematic structure of the imaging device for describing one Embodiment of this invention 1 is a schematic plan view showing a schematic configuration of a solid-state image sensor in the digital camera shown in FIG. The figure which showed the change of the drive speed of the vertical charge transfer part at the time of HD moving image imaging mode of the digital camera shown in FIG. The figure which graphed the signal level read from each pixel of the dummy pixel row | line | column of the solid-state image sensor shown in FIG. The figure which graphed the signal level read from each pixel of the normal pixel row | line | column of the solid-state image sensor shown in FIG. 2 is a diagram for explaining that the smear shape changes depending on the position of a high-luminance subject in the solid-state imaging device shown in FIG. The figure which shows the 1st modification of the solid-state image sensor 5 in the digital camera shown in FIG. The figure which shows the signal read from dummy pixel row D (2), (3) shown in FIG. The figure which showed the 2nd modification of the solid-state image sensor in the digital camera shown in FIG. The figure which showed the 3rd modification of the solid-state image sensor in the digital camera shown in FIG. The figure which showed the 4th modification of the solid-state image sensor in the digital camera shown in FIG. The figure which showed the 5th modification of the solid-state image sensor in the digital camera shown in FIG. The figure which shows a structure when the color filter is provided in the solid-state image sensor 5 shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an imaging apparatus for explaining an embodiment of the present invention. Examples of the imaging device include an imaging device such as a digital camera and a digital video camera, an imaging module mounted on an electronic endoscope, a camera-equipped mobile phone, and the like. Here, a digital camera will be described as an example.

  The imaging system of the digital camera shown in the figure includes a photographic lens 1, a CCD type solid-state imaging device 5, a diaphragm 2 provided therebetween, an infrared cut filter 3, and an optical low-pass filter 4.

  A system control unit 11 that performs overall control of the electrical control system of the digital camera controls the flash light emitting unit 12 and the light receiving unit 13 and controls the lens driving unit 8 to adjust the position of the photographing lens 1 to the focus position and zoom. The exposure amount is adjusted by adjusting the aperture amount of the aperture 2 via the aperture drive unit 9.

  In addition, the system control unit 11 drives the solid-state imaging device 5 via the imaging device driving unit 10 and outputs a subject image captured through the photographing lens 1 as an imaging signal. An instruction signal from the user is input to the system control unit 11 through the operation unit 14.

  The electric control system of the digital camera further includes an analog signal processing unit 6 that performs analog signal processing such as correlated double sampling processing connected to the output of the solid-state imaging device 5, and RGB output from the analog signal processing unit 6. And an A / D conversion circuit 7 for converting the color signals into digital signals, which are controlled by the system control unit 11.

  Furthermore, the electric control system of this digital camera generates image data by performing main memory 16, memory control unit 15 connected to main memory 16, interpolation calculation, gamma correction calculation, RGB / YC conversion processing, and the like. A digital signal processing unit 17, a compression / decompression processing unit 18 that compresses image data generated by the digital signal processing unit 17 into a JPEG format or expands compressed image data, and an imaging signal output from the solid-state imaging device 5 A smear correction unit 19 for performing smear correction, an external memory control unit 20 to which a detachable recording medium 21 is connected, and a display control unit 22 to which a liquid crystal display unit 23 mounted on the back of the camera is connected. . The memory control unit 15, digital signal processing unit 17, compression / decompression processing unit 18, smear correction unit 19, external memory control unit 20, and display control unit 22 are mutually connected by a control bus 24 and a data bus 25, and system control is performed. It is controlled by a command from the unit 11.

  FIG. 2 is a schematic plan view showing a schematic configuration of the solid-state imaging device 5 in the digital camera shown in FIG.

  The solid-state imaging device 5 includes a pixel region 50, a horizontal charge transfer unit 53, and an output unit 54.

  In the pixel region 50, a plurality of pixels (pixels 51a, 51b, 51c) and a plurality of vertical charge transfer units (52a, 52b) are formed.

  The plurality of pixels arranged in the pixel region 50 are arranged in a two-dimensional shape (square lattice shape in the example of FIG. 2) in the column direction Y and the row direction X intersecting (crossing in the example of FIG. 2). . The plurality of pixels has an arrangement in which a plurality of pixel columns composed of a plurality of pixels arranged in the column direction Y are arranged in the row direction X.

  The plurality of pixel columns include a plurality of normal pixel columns and at least one dummy pixel column (one in the example of FIG. 2).

  The normal pixel column is composed of pixels 51a and black level detection pixels 51b (hereinafter also referred to as OB).

  The pixel 51a is a region where a photodiode is formed in a semiconductor substrate. A light shielding film (not shown) is provided above the pixel 51a, and an opening is formed in the light shielding film so that light can enter the pixel 51a.

  The black level detection pixel 51b is a pixel for detecting a black level. The pixel 51b may be a region where a photodiode is formed or a region where a photodiode is not formed.

  The light shielding film is provided above the black level detection pixel 51b. The light shielding film above the black level detection pixel 51b is not provided with an opening so that light does not enter the black level detection pixel 51b. That is, the black level detection pixel 51b is shielded from light by the light shielding film. Note that the black level detection pixel 51b is at least one (1 in the example of FIG. 2) at the end of the normal pixel column in the column direction Y (the end opposite to the horizontal charge transfer unit 53 in the example of FIG. 2). One) is provided.

  The dummy pixel column is composed of dummy pixels 51c and black level detection pixels 51b.

  The dummy pixel 51c is a region where the photodiode is not formed in the region where the photodiode is to be formed in the pixel 51a. The dummy pixel 51c can be formed by not performing ion implantation of impurities forming a photodiode in a region where the dummy pixel 51c is to be formed. More specifically, in the case of a solid-state imaging device using electrons as signal charges, a high-concentration P-type region is formed on the surface of a P-type silicon substrate, and an N-type region is formed below the high-concentration P-type region. However, the formation of the photodiode can be omitted by not performing ion implantation of impurities for forming the N-type region.

  The light shielding film is provided above the dummy pixel 51c. An opening is formed in the light shielding film above the dummy pixel 51c so that light can enter the dummy pixel 51c. This opening size is the same as the size of the light shielding film opening above the pixel 51a. Thus, the only structural difference between the dummy pixel 51c and the pixel 51a is the presence or absence of a photodiode in the semiconductor substrate.

  The vertical charge transfer section 52a is composed of a CCD, and one vertical charge transfer section 52a is provided corresponding to the normal pixel column. In the example of FIG. 2, the vertical charge transfer unit 52 a is disposed on the right side of the normal pixel column corresponding thereto.

  The vertical charge transfer unit 52b is composed of a CCD, and one vertical charge transfer unit 52b is provided corresponding to the dummy pixel column. In the example of FIG. 2, the vertical charge transfer unit 52b is disposed on the right side of the corresponding dummy pixel column. Although the vertical charge transfer unit 52a and the vertical charge transfer unit 52b have the same structure, in FIG. 2, the vertical charge transfer unit 52b is shaded to distinguish them.

  The horizontal charge transfer unit 53 transfers the charges transferred from the vertical charge transfer units 52a and 52b in the row direction X, and is composed of a CCD.

  The output unit 54 converts the charge transferred from the horizontal charge transfer unit 53 into a signal corresponding to the charge amount and outputs the signal.

  In the solid-state imaging device 5 having such a configuration, the dummy pixel 51c does not include a photodiode, and an opening is formed in the light shielding film above the dummy pixel 51c similarly to the pixel 51a. The positional relationship between the dummy pixel column and the vertical charge transfer unit 52b is the same as the positional relationship between the normal pixel column and the vertical charge transfer unit 52a. For this reason, only a signal corresponding to a smear amount included in a signal read from the normal pixel column can be read from the dummy pixel column.

  This digital camera has an HD moving image capturing mode for capturing an HD (high definition) moving image. In the HD moving image capturing mode, a normal moving image has an aspect ratio of 4: 3, whereas a moving image having an aspect ratio of 16: 9 is generated.

  In the solid-state imaging device 5, when signals are read from all pixels, the signals have an aspect ratio of 4: 3. For this reason, in the normal moving image capturing mode, by performing thinning-out reading from all the pixels of the solid-state imaging device 5, a moving image having an aspect ratio of 4: 3 is generated at a high frame rate.

  On the other hand, in the HD moving image capturing mode, for example, thinning-out reading is not performed, signals that are not used in the moving image are read at high speed, and other signals are read at normal speed, so that a high-definition moving image with an aspect ratio of 16: 9 is high. It can be obtained at the frame rate.

  In order to obtain a high-definition moving image with an aspect ratio of 16: 9 at a high frame rate, the image sensor driving unit 10 performs the following driving (referred to as HD driving) in the HD moving image capturing mode. After the exposure is completed, the image sensor driving unit 10 reads out charges from each pixel of the solid-state image sensor 5 to the vertical charge transfer unit corresponding to each pixel. Thereafter, while changing the drive speed (drive frequency) of the vertical charge transfer unit stepwise, the charge is transferred to the horizontal charge transfer unit 53, the charge is transferred to the output unit 54, and a signal corresponding to the charge is sent. Output.

  FIG. 3 is a diagram showing a change in driving speed of the vertical charge transfer unit when the digital camera shown in FIG. 1 is in the HD moving image capturing mode.

  As shown in FIG. 3, the image sensor driving unit 10 first reads out charges from each pixel to the vertical charge transfer unit, and then transfers the charges at a drive frequency four times that in normal times. All charges read from each pixel on the horizontal charge transfer unit 53 side among the pixels other than the pixels for obtaining a signal necessary for the HD moving image during the period in which the vertical charge transfer unit is driven at the drive frequency of 4 times. Is transferred to the horizontal charge transfer unit 53 and a signal corresponding to the charge is output from the solid-state imaging device 5.

  When this period ends, the image sensor driving unit 10 changes the driving speed to the normal speed (1 time) and starts transferring the charge remaining in the vertical charge transfer unit. During the period in which the vertical charge transfer unit is driven at the drive frequency of 1 times, all the charges read from each pixel for obtaining a signal necessary for the HD moving image are transferred to the horizontal charge transfer unit 53, and according to the charge. The output signal is output from the solid-state imaging device 5.

  When this period ends, the image sensor drive unit 10 changes the drive speed to four times the normal speed and starts transferring the charge remaining in the vertical charge transfer unit. During the period in which the vertical charge transfer unit is driven at this four times the driving frequency, reading is performed from each pixel on the side opposite to the horizontal charge transfer unit 53 side among the pixels other than the pixels for obtaining signals necessary for HD moving images. All of the charged charges are transferred to the horizontal charge transfer unit 53 and a signal corresponding to the charges is output from the solid-state imaging device 5.

  By transferring all the charges to the horizontal charge transfer unit 53 in this way, a high-definition moving image can be obtained at a high frame rate. The example of changing the driving speed shown in FIG. 3 is an example, and the present invention is not limited to this.

  As described above, when the HD drive is performed, the drive frequency of the vertical charge transfer unit changes between the start of transfer of charge from the vertical charge transfer unit to the horizontal charge transfer path and the end of transfer. For this reason, the amount of smear included in the signal read from each pixel also changes depending on the position in the column direction Y of each pixel.

  FIG. 4 is a graph in which the signal level (smear amount) read from each pixel of the dummy pixel column of the solid-state imaging device illustrated in FIG. 2 is graphed with the position in the column direction Y as the horizontal axis. 4, the left end indicates the position of the dummy pixel at the end on the horizontal charge transfer portion 53 side. FIG. 4 is a graph when it is assumed that strong light enters the upper half of the screen (VCCD side).

  As shown in FIG. 4, when the HD drive is performed, the drive frequency is mixed with periods of 4 times and 1 time, so that the shading in the column direction Y occurs in the smear amount generated in each pixel.

  Here, let us consider a case where strong light enters the region on the left side of the dummy pixel column in the solid-state imaging device 5. In this case, for example, when the amount of smear included in the signal read from the normal pixel column at the left end of the solid-state imaging device 5 shown in FIG. 2 is graphed, the smear amount is as shown by the broken line in FIG. Since intense light enters the region on the left side of the dummy pixel column, the amount of smear contained in the signal obtained from the normal pixel column in this region is larger than the amount of smear obtained from the dummy pixel column.

  In FIG. 5, the smear amount obtained from the normal pixel row is illustrated, but the signal read from the normal pixel row includes the signal amount read from the photodiode in addition to the smear amount. Therefore, in practice, the shading shape shown by the broken line in FIG. 5 cannot be directly obtained.

  In the broken line graph shown in FIG. 5, only the OB signal obtained from the black level detection pixel 51b in the normal pixel column can be directly obtained from the signal output from the solid-state imaging device 5. Therefore, by comparing this OB signal with the OB signal read from the black level detection pixel 51b of the dummy pixel 51c, the amount of smear contained in the signal read from the normal pixel column can be calculated from the dummy pixel column. It is possible to determine how much it is higher than the read smear amount.

  Therefore, in this digital camera, the smear correction unit 19 uses a signal read from the black level detection pixel 51b (hereinafter referred to as an OB signal) out of signals read from the normal pixel row and a dummy pixel row. Based on the read signal, a smear amount (smear correction data) included in the signal read from the normal pixel column is calculated.

  Specifically, the smear amount included in the signal read from the normal pixel column is calculated as follows.

  First, the smear correction unit 19 divides the OB signal obtained from the black level detection pixel 51b in the normal pixel row by the OB signal obtained from the black level detection pixel 51b in the dummy pixel row. Next, the smear correction unit 19 multiplies the signal level obtained from each pixel of the dummy pixel column by the value obtained by this division. By doing in this way, the smear shape shown with the broken line of FIG. 5 can be calculated | required from the smear shape shown with the continuous line of FIG. Using the data obtained by this multiplication as smear correction data, smear correction is performed on the signal read from the normal pixel array.

  The smear correction unit 19 subtracts the smear amount corresponding to the position of each pixel of the calculated smear correction data from the signal obtained from each pixel of the normal pixel row. The smear correction unit 19 performs such smear correction processing on the signal obtained from each normal pixel column.

  In the example of FIG. 2, only one dummy pixel column is provided. For this reason, as shown in FIG. 5, there is a possibility that the smear shape generated in each pixel column is different at the position in the row direction X.

  However, if the dummy pixel columns are uniformly arranged in the pixel region 50, the difference due to the smear-shaped position as shown in FIG. 5 does not occur. Therefore, in such a case, the smear correction is performed simply by subtracting the signal obtained from each pixel of the dummy pixel column closest to the normal pixel column from the signal obtained from each pixel of the normal pixel column. Can be done. In this case, the black level detection pixel 51b may not be provided in each pixel column.

  As described above, according to this digital camera, since the solid-state imaging device 5 is provided with the dummy pixel column, a signal substantially equal to the smear amount included in the signal read from the normal pixel column is obtained from the dummy pixel column. be able to. For this reason, highly accurate smear correction is possible.

  Further, in this digital camera, a black level detection pixel 51 b is provided in each pixel column of the solid-state imaging device 5. For this reason, even if the number of dummy pixel columns is small, the smear amount included in the signal read from the normal pixel column can be accurately calculated using the OB signal read from the black level detection pixel 51b.

  Signals corresponding to the respective pixels of the dummy pixel column can be interpolated with signals obtained from the normal pixel columns around the dummy pixel column. However, if the number of dummy pixel columns increases too much, the number of interpolated signals increases and image quality deteriorates. For this reason, it is preferable to minimize the number of dummy pixel columns. In this case, it is effective to provide the black level detection pixels 51b.

  Further, according to this digital camera, the vertical charge transfer unit 52b corresponding to the dummy pixel column is used as a dedicated transfer unit for detecting the smear amount. The solid-state imaging device described in Patent Document 1 uses a charge transfer unit for reading a signal as a charge transfer unit for detecting a smear amount. For this reason, there is a possibility that a larger amount of smear than the actual amount of smear may be detected because a part of the signal read from the photodiode remains in this charge transfer section. According to this digital camera, no charge is read from the photodiode to the vertical charge transfer unit 52b. For this reason, it is difficult for charge transfer residue and the like on the vertical charge transfer unit 52b to occur, and smear information can be obtained accurately.

  Next, a modification of the digital camera shown in FIG. 1 will be described.

(First modification)
The digital camera shown in FIG. 1 performs HD driving. At this time, the shape of the smear changes depending on where in the angle of view the high-intensity light is. FIG. 6 is a diagram for explaining that the smear shape changes depending on the position of the high brightness subject.

  FIG. 6 is a diagram showing a signal shape obtained from a dummy pixel column when high luminance light enters the lower half of the pixel region 50 of the solid-state imaging device 5 on the side opposite to the horizontal charge transfer unit 53 side. It is. As can be seen from FIGS. 4 and 6, in the solid-state imaging device 5, the smear shape changes according to the position in the pixel region 50. For this reason, in consideration of this, it is preferable that two or more dummy pixel columns are provided in the solid-state imaging device 5.

  FIG. 7 is a diagram showing a first modification of the solid-state imaging device 5 in the digital camera shown in FIG. In FIG. 7, the dummy pixel row shown in FIG.

  In the example shown in FIG. 7, four dummy pixel columns D are provided in the pixel region 50. Note that at least two dummy pixel columns D may be provided. However, these at least two dummy pixel columns D are arranged so as to include one or more normal pixel columns between the dummy pixel columns D.

  Two dummy pixel columns D are provided at both ends in the row direction X of the pixel region 50, and the remaining two dummy pixel columns D are disposed between the two dummy pixel columns D. .

  In FIG. 7, the leftmost dummy pixel column D is (1), the second dummy pixel column D from the left end is (2), the third dummy pixel column D from the left end is (3), and the rightmost dummy pixel Column D is (4). An area where the normal pixel column between the dummy pixel column D (1) and the dummy pixel column D (2) is arranged is (a), and the dummy pixel column D (2) and the dummy pixel column D (3) are arranged. (B) is the area where the normal pixel column between and the dummy pixel column D (3) and the dummy pixel column D (4) is located (c). Yes.

  When the dummy pixel column is arranged as shown in FIG. 7, the smear correction unit 19 performs the smear correction as follows.

  For example, smear correction of a signal obtained from a normal pixel column in area (b) will be described.

  First, the smear correction unit 19 starts from two dummy pixel columns (in the example of FIG. 7, dummy pixel columns D (2) and (3)) adjacent to each other in the row direction X with the normal pixel column to be smear corrected. Get the read signal. FIG. 8 is a diagram showing signals read from the dummy pixel columns D (2) and (3) shown in FIG.

  As shown in FIG. 8, the signal read from the dummy pixel column D (2) and the signal read from the dummy pixel column D (3) may have different shapes.

  The smear correction unit 19 reads a signal read from each pixel of the dummy pixel column D (2) and a signal read from the pixel having the same position in the column direction Y as each pixel of the dummy pixel column D (3). Are added and divided by 2, and the average of both signals is calculated. The data obtained by this calculation is a graph indicated by a broken line in FIG.

  Although the average of the two signals is simply taken here, the two signals may be weighted averaged. For example, the average may be calculated so that the weight of the signal of the dummy pixel column D closer to the normal pixel column to be corrected becomes larger.

  Based on the calculated data and the OB signal read from the black level detection pixel 51b of the normal pixel column, the smear correction unit 19 includes a smear amount ( Smear correction data) is calculated. Then, the smear correction unit 19 performs smear correction by subtracting the smear amount at each pixel position of the smear correction data from the signal read from each pixel of the normal pixel row.

  As described above, according to the digital camera described in the first modification, smear correction can be accurately performed even when the smear shape varies depending on the position.

(Second modification)
FIG. 9 is a diagram showing a second modification of the solid-state imaging device 5 in the digital camera shown in FIG.

  The solid-state imaging device shown in FIG. 9 is different from the solid-state imaging device shown in FIG. 2 in that a plurality of color filters are provided above each pixel. Further, the positions where the dummy pixel columns are provided are also different from those shown in FIG.

  In FIG. 9, a pixel marked “R” is a pixel provided with a color filter (R filter) that transmits red light above. Pixels with “G” indicate pixels on which a color filter (G filter) that transmits green light is provided above. A pixel marked “B” is a pixel provided with a color filter (B filter) that transmits blue light above.

  In the example of FIG. 9, color filters provided above each pixel are arranged in a Bayer shape.

  The color filters provided above the odd-numbered pixel columns from the left in FIG. 9 are composed of R and G filter patterns. The color filter provided above the even-numbered pixel column from the left is composed of a B filter and a G filter pattern.

  Thus, in this solid-state imaging device, each pixel column is divided into two groups (an odd column group and an even column group) according to the color filter pattern (color combination) thereabove.

  Each group is provided with at least one dummy pixel column (one in the example of FIG. 9).

  In this way, when a plurality of color filters are provided above each pixel, the shape of the smear generated in the normal pixel column also changes depending on the color filter pattern above the pixel column adjacent to the normal pixel column. The reason for this will be described below.

  In the solid-state imaging device shown in FIG. 9, light enters the pixel obliquely from the center toward the periphery. For example, a part of the light incident on the normal pixel column adjacent to the right of the leftmost dummy pixel column also enters the leftmost dummy pixel column. Similarly, a part of the light incident on the normal pixel column adjacent to the left of the rightmost dummy pixel column is also incident on the rightmost dummy pixel column.

  As described above, in the solid-state imaging device shown in FIG. 9, the smear shape generated in each pixel column strongly influences the color filter pattern above the adjacent pixel column on the solid-state imaging device center side of each pixel column. Will receive.

  For this reason, when smear correction is performed on the normal pixel column, the pixel pixel above the adjacent pixel column on the side on which the normal pixel column strongly influences (the side opposite to the solid-state image sensor center side of the normal pixel column). By using a signal obtained from a dummy pixel column having the same pattern as the color filter pattern, it is possible to improve the accuracy of smear correction.

  Therefore, in the digital camera in which the solid-state imaging device 5 is changed to the one shown in FIG. 9, the smear correction unit 19 performs smear correction as follows.

  For the signals read from each normal pixel column of each group, the smear correction unit 19 is a dummy belonging to the same group as the pixel column existing on the side opposite to the solid-state image sensor center side of each normal pixel column. Smear correction data is generated from the signal read from the pixel column and the signal read from the black level detection pixel 51b of the normal pixel column. Then, the smear correction unit 19 performs smear correction by subtracting the smear amount based on the smear correction data from the signal read from each pixel of the normal pixel row.

  For example, among the pixel columns shown in FIG. 9, for the fourth normal pixel column from the left end, a signal from the leftmost dummy pixel column, which is the same group as the normal pixel column on the left side of the normal pixel column, is used. To generate smear correction data. In addition, among the pixel columns shown in FIG. 9, the third normal pixel column from the left end uses a signal from the rightmost dummy pixel column which is the same group as the normal pixel column adjacent to the left of the normal pixel column. To generate smear correction data.

  As described above, smear correction data of a pixel column to be subjected to smear correction is generated according to a group to which a pixel column adjacent to the pixel column belongs, thereby enabling highly accurate smear correction.

  Such a smear correction method can also be implemented in combination with the correction method described in the first modification.

  In this case, for example, as shown in FIG. 10, two dummy pixel columns are provided in each group of the solid-state imaging device shown in FIG. However, at least one normal pixel column is arranged between the two dummy pixel columns.

  In the digital camera in which the solid-state imaging device 5 is changed to the solid-state imaging device shown in FIG. 10, the smear correction unit 19 first uses the method described above to output a dummy pixel column from which a signal used for generating smear correction data is generated. decide. In this case, since there are two dummy pixel columns in the same group, two dummy pixel columns are determined. Next, an average of signals respectively obtained from the determined two dummy pixel columns is calculated, smear correction data is generated from the average and the OB signal of the normal pixel column, and smear correction is performed according to the smear correction data.

  In the example of FIG. 10, two dummy pixel columns are provided in each group, but three or more dummy pixel columns may be provided. For example, in the configuration shown in FIG. 7, two dummy pixel columns having different groups may be provided in each of the regions shown in (1) to (4). In this case, for example, for the area (a), an average of signals from the same two dummy pixel columns in the group arranged in the area (1) and the area (2) is obtained, and a smear is calculated from the average and the OB signal. Correction data may be generated.

  Note that the arrangement of the color filters illustrated in FIGS. 9 and 10 is an example, and is not limited thereto. For example, as shown in FIG. 11, an R filter is provided above each pixel in the leftmost dummy pixel row in FIG. 9, a G filter is provided above each pixel in the second normal pixel row from the left end, and 3 pixels from the left end. A stripe-arranged color filter provided with a G filter may be used above each pixel of the second normal pixel column. In this case, each pixel column is divided into three groups: a group having an R filter above, a group having a G filter above, and a group having a B filter above. Therefore, as shown in FIG. 11, smear correction can be performed by the above-described method by providing at least one dummy pixel column in each group.

  Also, as shown in FIG. 12, in the solid-state imaging device 5 shown in FIG. 1, the odd-numbered columns are arranged so as to be shifted in the column direction Y by 1/2 of the pixel pitch of each pixel column with respect to the even-numbered columns. Alternatively, the color filters above the odd columns may be configured as a Bayer array, and the color filters above the even columns may be configured as the Bayer array. In this case, each pixel column is divided into two groups: a group having an R filter and a G filter above and a group having an G filter and a B filter above. For this reason, as shown in FIG. 12, smear correction can be performed by the above-described method by providing at least one dummy pixel column in each group. In FIG. 12, each vertical charge transfer unit has a linear shape, but may have a meandering shape.

  Further, the type of color filter is not limited to the primary color filter, and complementary color filters such as cyan, magenta, and yellow may be used.

  Finally, a method of interpolating signals obtained from each pixel of the dummy pixel column in the solid-state imaging device having the color filter as shown in FIGS. 9 to 12 will be described.

  The solid-state imaging device described so far is provided with a dummy pixel column. However, if a signal obtained from this dummy pixel column is used as it is for image generation, it becomes defective data. Therefore, in a digital camera equipped with a solid-state imaging device as shown in FIGS. 9 to 12, the digital signal processing unit 17 sends a signal corresponding to the dummy pixel 51c to the pixels 51a around the dummy pixel 51c. Thus, interpolation generation is performed using a signal obtained from the pixel 51a having a color filter of the same color as the color filter above the dummy pixel 51c.

  FIG. 13 is a diagram illustrating a configuration when a color filter is provided in the solid-state imaging device 5 illustrated in FIG. 2. In the case of the configuration shown in FIG. 13, the digital signal processing unit 17 does not use this signal for the signal corresponding to the dummy pixel 51c having the R filter (G filter, B filter) above, The signal is interpolated using a signal obtained from the surrounding pixel 51a having an R filter (G filter, B filter).

  In this case, as a signal interpolation method, a well-known method (for example, calculating an average of signals obtained from surrounding pixels 51a) or the like may be used.

  In the description so far, the pixels of the solid-state imaging device 5 are arranged in a square lattice shape. However, as illustrated in FIG. The arrangement may be such that it is shifted in the column direction Y by ½.

  As described above, the following items are disclosed in this specification.

  The disclosed solid-state imaging device is a solid-state imaging device including a plurality of pixel columns formed of a plurality of pixels arranged in a column direction in a row direction intersecting the column direction, and a plurality of solid-state imaging devices provided corresponding to each pixel column A vertical charge transfer unit, and a horizontal charge transfer unit that transfers the charges transferred from the plurality of vertical charge transfer units in the row direction, and the plurality of vertical charge transfer units are dedicated to smear detection charge transfer. A first charge transfer unit that is a portion and a second charge transfer unit other than the first charge transfer unit, and the pixel column corresponding to the second charge transfer unit (hereinafter referred to as a normal pixel column) includes a photodiode. Each pixel included in the normal pixel column is configured with at least a pixel not including a photodiode, and the pixel column corresponding to the first charge transfer unit (hereinafter referred to as a dummy pixel column). And the da A light-shielding film provided above each pixel included in the pixel column, the light-shielding film included above the pixel including the photodiode included in the normal pixel column and included in the dummy pixel column Openings are respectively formed above the pixels not including the photodiode.

  With this configuration, an opening is formed in the light-shielding film above the pixels of the dummy pixel column that do not include the photodiode, so that the pixel is obtained from the first charge transfer unit corresponding to the dummy pixel column. By using the received signal, it is possible to accurately estimate the shape of the smear included in the normal pixel column. For this reason, highly accurate smear correction is possible.

  In the disclosed solid-state imaging device, the normal pixel column includes pixels including the photodiodes and black level detection pixels, and the dummy pixel column includes pixels not including the photodiodes and black level detection pixels. The aperture is not formed in the light shielding film above the black level detection pixel.

  With this configuration, it is possible to know the difference between the level of the smear signal obtained from the normal pixel column and the level of the smear signal obtained from the dummy pixel column. Therefore, smear correction can be performed in consideration of this level difference, and high-precision smear correction can be performed.

  In the disclosed solid-state imaging device, a plurality of the first charge transfer units are provided with at least one second charge transfer unit interposed therebetween.

  With this configuration, a plurality of smear signals can be obtained from the plurality of first charge transfer units. Since the smear shape may differ depending on the pixel position, such a configuration makes it possible to accurately estimate the smear shape included in the signal obtained from the normal pixel column, and to improve the smear correction accuracy. it can.

  The disclosed imaging device includes the solid-state imaging device and a smear correction unit that corrects the first signal read from the normal pixel row based on at least the second signal read from the dummy pixel row. Are provided.

  With this configuration, highly accurate smear correction can be performed.

  In the disclosed imaging device, the normal pixel row includes pixels including the photodiodes and black level detection pixels, and the dummy pixel row includes pixels not including the photodiodes and black level detection pixels. No opening is formed in the light shielding film above the black level detection pixel, and the smear correction unit is configured to detect the black level of the first signal read from the normal pixel column. The smear correction of the first signal is performed based on the signal read from the detection pixel and the second signal.

  With this configuration, highly accurate smear correction can be performed.

  In the disclosed imaging device, a plurality of the first charge transfer units are provided with at least one second charge transfer unit interposed therebetween, and the smear correction unit includes two adjacent first first transfer units. For the signal read from the normal pixel column corresponding to the second charge transfer unit between the two charge transfer units, each of the two first charge transfer units is used as the second signal. The signals read from the dummy pixel columns corresponding to are used.

  With this configuration, highly accurate smear correction can be performed.

  In the disclosed imaging apparatus, the solid-state imaging device includes a plurality of color filters provided above the pixels, and the plurality of pixel columns are colors of the color filters above the pixel columns. Are divided into a plurality of different groups, each of the plurality of groups is provided with at least one dummy pixel column, and the smear correction unit is a signal read from each normal pixel column of each group As for the second signal, the signal read from the dummy pixel column belonging to the same group as the pixel column existing on the opposite side of the center side of the solid-state imaging device of each normal pixel column Is used.

  The disclosed imaging apparatus includes a signal interpolation unit that interpolates a signal corresponding to each pixel of the dummy pixel column using a signal read from the normal pixel column around the dummy pixel column. .

  With this configuration, it is possible to prevent the occurrence of pixel defects due to the provision of the dummy pixel column.

  The disclosed imaging device includes a drive unit that performs driving to transfer charges accumulated in the vertical charge transfer units in the column direction while changing the drive frequency of the vertical charge transfer units in stages. The smear correction unit performs the correction when the driving is performed.

  With this configuration, even when the driving frequency of the vertical charge transfer unit is changed stepwise during signal readout from each pixel, the first obtained from the normal pixel column is based on the signal from the dummy pixel column. The shape of the smear contained in the signal can be known. Therefore, even in such a case, smear can be corrected with high accuracy.

  In the disclosed imaging apparatus, the driving unit performs the driving at the time of HD moving image capturing.

  The disclosed smear correction method is a smear correction method for a signal output from the solid-state image sensor, and the first signal read from the normal pixel array of the solid-state image sensor is at least the dummy pixel array. And a smear correction step for correcting based on the second signal read from.

  In the disclosed smear correction method, the normal pixel column includes pixels including the photodiodes and black level detection pixels, and the dummy pixel column includes pixels not including the photodiodes and black level detection pixels. In the smear correction step, the black signal of the first signal read from the normal pixel column is not formed in the light shielding film above the black level detection pixel. The smear correction of the first signal is performed based on the signal read from the level detection pixel and the second signal.

  In the disclosed smear correction method, a plurality of the first charge transfer units are provided with at least one second charge transfer unit interposed therebetween. In the smear correction step, As for the signal read from the normal pixel column corresponding to the second charge transfer unit between the one charge transfer units, the second signal is used as the second signal. Signals read out from the corresponding dummy pixel columns are used.

  In the disclosed smear correction method, the solid-state imaging device includes a plurality of color filters provided above the pixels, and the plurality of pixel columns are located above the pixel columns. The combination of colors is divided into a plurality of different groups, and at least one dummy pixel column is provided in each of the plurality of groups. In the smear correction step, read out from each normal pixel column of each group As for the signal, the second signal was read out from the dummy pixel column belonging to the same group as the pixel column that is adjacent to the center side of the solid-state imaging device of each normal pixel column. A signal is used.

5 Solid-state image sensor 51a Pixel 51b Black level detection pixel 51c Dummy pixels 52a, 52b Vertical charge transfer unit 19 Smear correction unit

Claims (14)

A solid-state imaging device including a plurality of pixel columns composed of a plurality of pixels arranged in a column direction in a row direction intersecting the column direction,
A plurality of vertical charge transfer units provided corresponding to each pixel column;
A horizontal charge transfer unit that transfers the charges transferred through the plurality of vertical charge transfer units in the row direction,
The plurality of vertical charge transfer units include a first charge transfer unit that is a charge transfer unit dedicated to smear detection, and a second charge transfer unit other than that,
The pixel column corresponding to the second charge transfer unit (hereinafter referred to as a normal pixel column) is composed of at least pixels including a photodiode,
The pixel column corresponding to the first charge transfer unit (hereinafter referred to as a dummy pixel column) is composed of at least pixels that do not include a photodiode,
A light shielding film provided above each pixel included in the normal pixel column and each pixel included in the dummy pixel column;
Solid-state imaging in which openings are formed in the light shielding film above the pixels including the photodiodes included in the normal pixel column and above the pixels not including the photodiodes included in the dummy pixel column, respectively. element. The solid-state imaging device according to claim 1,
The normal pixel row is composed of pixels including the photodiodes and black level detection pixels,
The dummy pixel row is composed of pixels not including the photodiode and black level detection pixels,
A solid-state imaging device in which an opening is not formed in the light shielding film above the black level detection pixel. The solid-state imaging device according to claim 1 or 2,
A solid-state imaging device in which a plurality of the first charge transfer units are provided with at least one second charge transfer unit interposed therebetween. A solid-state imaging device according to claim 1;
An image pickup apparatus comprising: a smear correction unit that corrects a first signal read from the normal pixel column based on at least a second signal read from the dummy pixel column. The imaging apparatus according to claim 4,
The normal pixel row is composed of pixels including the photodiodes and black level detection pixels,
The dummy pixel row is composed of pixels not including the photodiode and black level detection pixels,
No opening is formed in the light shielding film above the black level detection pixel,
The smear correction unit, based on the first signal read from the normal pixel column, the signal read from the black level detection pixel and the second signal, An imaging device that performs smear correction of a signal. The imaging apparatus according to claim 4 or 5, wherein
A plurality of the first charge transfer units are provided with at least one second charge transfer unit interposed therebetween,
The smear correction unit is configured to use, as a second signal, a signal read from the normal pixel column corresponding to the second charge transfer unit between the two adjacent first charge transfer units. An imaging device that uses signals read from the dummy pixel columns corresponding to the two first charge transfer units, respectively. The imaging apparatus according to claim 4 or 5, wherein
The solid-state imaging device includes a plurality of color filters provided above the pixels,
The plurality of pixel columns are divided into a plurality of groups each having a different color pattern of the color filter above each pixel column,
At least one dummy pixel column is provided in each of the plurality of groups;
The smear correction unit, next to the signal read from each normal pixel column of each group, as the second signal, next to the side opposite to the center side of the solid-state imaging device of each normal pixel column An imaging apparatus using a signal read from the dummy pixel column belonging to the same group as the existing pixel column. The imaging device according to any one of claims 4 to 7,
An image pickup apparatus including a signal interpolation unit that interpolates signals corresponding to the respective pixels of the dummy pixel column using signals read from the normal pixel column around the dummy pixel column. The imaging apparatus according to any one of claims 4 to 8,
A drive unit for driving to transfer the charge accumulated in each vertical charge transfer unit in the column direction while changing the drive frequency of each vertical charge transfer unit stepwise;
The smear correction unit is an imaging device that performs the correction when the drive is performed. The imaging device according to claim 9,
An imaging apparatus in which the driving unit performs the driving at the time of HD moving image imaging. A smear correction method for a signal output from the solid-state imaging device according to claim 1,
A smear correction method comprising a smear correction step of correcting a first signal read from the normal pixel row of the solid-state imaging device based on at least a second signal read from the dummy pixel row. It is a smear correction method of Claim 11, Comprising:
The normal pixel row is composed of pixels including the photodiodes and black level detection pixels,
The dummy pixel row is composed of pixels not including the photodiode and black level detection pixels,
No opening is formed in the light shielding film above the black level detection pixel,
In the smear correction step, based on the signal read from the black level detection pixel of the first signal read from the normal pixel column and the second signal, the first signal A smear correction method that performs smear correction of signals. The smear correction method according to claim 11 or 12,
A plurality of the first charge transfer units are provided with at least one second charge transfer unit interposed therebetween,
In the smear correction step, a signal read from the normal pixel column corresponding to the second charge transfer unit between two adjacent first charge transfer units is used as the second signal. A smear correction method using a signal read from each of the dummy pixel columns corresponding to each of the two first charge transfer units. The smear correction method according to claim 11 or 12,
The solid-state imaging device includes a plurality of color filters provided above the pixels,
The plurality of pixel columns are divided into a plurality of groups each having a different color combination of the color filters above each pixel column,
At least one dummy pixel column is provided in each of the plurality of groups;
In the smear correction step, a signal read from each normal pixel column of each group is adjacent to a side opposite to the center side of the solid-state imaging device of each normal pixel column as the second signal. A smear correction method using a signal read from the dummy pixel column belonging to the same group as the existing pixel column.

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