JP2004112723A - Imaging device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device and an imaging apparatus in which picture quality is improved while suppressing an increase in cost. <P>SOLUTION: Horizontal transfer paths H1 and H2 are provided on the upside and the downside of a vertical transfer path V. The vertical transfer path V is capable of vertically transferring signal charges and further transfers the signal charges mutually oppositely in even-numbered streams and odd-numbered streams. The transfer direction is inverted at the interval of one field and the vertical transfer direction is inverted between odd-numbered fields and even-numbered fields. The occurrence of smear caused by a high luminance part is fixed upward or downward for the high luminance part. In a portion without smear, signals on the upper and lower horizontal transfer paths H1 and H2 are composed to constitute an image. In a portion where smear occurs, between the signals on the upper and lower horizontal transfer paths H1 and H2, only the signal on the side which is not affected by smear is used to complement data such that the image is constituted. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an imaging device and an imaging device using a charge-coupled device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a CCD solid-state imaging device (hereinafter, referred to as a CCD) is generally used as an image sensor of an imaging device such as a video camera or a digital still camera. This CCD is widely used because of its excellent balance between cost and performance.
[0003]
On the light-receiving surface of the CCD, there are provided a number of pixels as light-receiving elements that are arranged in a grid and accumulate signal charges according to the intensity of light, and a plurality of vertical transfer units that read and transfer signal charges from these pixels. And a horizontal transfer path for transferring the signal charge transferred from each vertical transfer path to the output unit.
[0004]
Here, since the vertical transfer path is also sensitive to light, smear charges, which are noise charges, are generated in the vertical transfer path by light passing through the light shielding structure in a light receiving region where an extremely strong light is imaged. Then, in the process of transferring the signal charges to the output section, the smear charges are added to the signal charges being transferred, and the smear (a high-luminance portion spreads in a band shape at a position along the vertical transfer path in the output image). There is a problem that a phenomenon called “smear) occurs.
[0005]
In this regard, the two CCDs are arranged upside down with respect to each other, and the image-forming light passing through the same optical system is divided into two by a prism or the like to form an image on each CCD, and is provided in the direction opposite to the horizontal transfer path. There is known a method of adding an operation of sweeping smear to a drain, and obtaining one image from which smear is removed from these two images (for example, see Patent Document 1).
[0006]
However, in such a configuration using two CCDs, although the area and structure of each CCD do not greatly differ from those of a normal CCD in terms of manufacturing cost, there is a problem that the cost increases because two CCDs are used. Have. Further, the power consumption of an imaging device using two CCDs increases. Furthermore, multi-axis position adjustment for obtaining exactly the same light receiving angle of view between two CCDs requires high precision, and as a result, causes a significant increase in cost. Further, since the incident light is divided into two, the sensitivity is reduced by half, and particularly, the signal-to-noise ratio (S / N ratio) in a dark condition is deteriorated, and the image quality is deteriorated. In addition, in the case of sensitivity and color between two CCDs, an adjustment process for compensating for a characteristic difference such as a spectral transmission characteristic is required, which causes a problem of increasing costs.
[0007]
In this regard, in order to prevent this smear, a light-shielding storage unit for one screen whose entire surface is completely shielded from light is provided separately from the light-receiving surface. There has been proposed a CCD called a frame interline transfer system having a configuration for transferring data to a CCD.
[0008]
However, such a frame interline transfer type CCD requires a chip area for two screens, requires a complicated structure and a special high-speed driving operation, and it is difficult to reduce the manufacturing cost of the element. have. In addition, although the smear can be largely suppressed by combining with the aperture mechanism of the optical system, there is a problem that the smear cannot always be sufficiently removed depending on the intensity of light.
[0009]
[Patent Document 1]
Japanese Patent No. 3108702
[0010]
[Problems to be solved by the invention]
As described above, the configuration using two CCDs causes problems such as an increase in power consumption, a decrease in sensitivity, and a need for high-precision adjustment, resulting in a significant increase in cost. Further, in the configuration using the frame interline transfer type CCD, it is difficult to reduce the manufacturing cost of the element, and there is a problem that smear cannot always be sufficiently removed.
[0011]
SUMMARY An advantage of some aspects of the invention is to provide an imaging device and an imaging device that can improve image quality while suppressing an increase in cost.
[0012]
[Means for Solving the Problems]
The image pickup device according to claim 1 includes a plurality of pixels each of which photoelectrically converts and accumulates a signal charge, and a charge-coupled device that reads the signal charge from these pixels and transfers the read signal charge in a forward direction and a reverse direction. A plurality of vertical transfer paths grouped into a plurality of groups that transfer signal charges in opposite directions, and signal charges are transferred from one end of each of the vertical transfer paths, and the transferred signal charges are transferred. Signal charges are transferred from the first horizontal transfer path to be output to the first output section and the other end of each of the vertical transfer paths. The transferred signal charges are transferred and output to the second output section. And a second horizontal transfer path.
[0013]
In this configuration, the signal charges read from the pixels to the respective vertical transfer paths are alternately transferred in the forward and reverse directions by the respective vertical transfer paths, whereby the signal charges are transferred to the first horizontal transfer path. And output from the second horizontal transfer path via each output unit. Thus, an image is obtained by processing these output signals. Then, the signal charges read from the pixels are alternately transferred in each of the vertical transfer paths in the forward direction and the reverse direction, and the signal charges are transferred by using the first horizontal transfer path and the second horizontal transfer path. In the case where the amount of transfer is easily improved and the smear in which another signal is added to the signal charge being transferred in a part of the vertical transfer path, the direction in which the smear is generated is controlled, and the transfer is performed through the vertical transfer path. Smear is prevented from occurring in all signal charges. Therefore, by processing the output signal, smear can be suppressed and image quality can be improved.
[0014]
According to a second aspect of the present invention, in the image sensor of the first aspect, the vertical transfer path transfers signal charges in the opposite direction for each column.
[0015]
In this configuration, by transferring the signal charges in the opposite direction for each column, it is possible to accurately complement a smeared signal and improve the image quality.
[0016]
According to a third aspect of the present invention, in the image sensor of the first aspect, the vertical transfer paths are grouped by a plurality of columns, and each group transfers signal charges in the same direction.
[0017]
In this configuration, by transferring the signal charges through the vertical transfer paths grouped by a plurality of columns, it becomes possible to process a plurality of columns of signals as a group.
[0018]
According to a fourth aspect of the present invention, in the image sensor according to any one of the first to third aspects, the pixels include a photosensitive pixel arranged in a light receiving region and a light-shielded pixel that blocks light. .
[0019]
Then, in this configuration, by measuring the signal of the light-shielded pixel, it is easily determined whether or not a smear in which another signal is added to the signal charge has occurred.
[0020]
According to a fifth aspect of the present invention, there is provided an imaging device according to any one of the first to fourth aspects, wherein the imaging device is controlled to reverse the transfer direction of each vertical transfer path for each screen, and A control unit configured to process a signal output from each output unit of the imaging element to form an image.
[0021]
In this configuration, since the image pickup device according to any one of claims 1 to 4 is used, the signal charges read out from the pixels of the image pickup device to the respective vertical transfer paths are transferred in the forward and reverse directions by the respective vertical transfer paths. , The signal charges are output from the first horizontal transfer path and the second horizontal transfer path via the respective output units. Then, an image is obtained by processing these output signals by the control means. Then, the signal charges read from the pixels are alternately transferred in each of the vertical transfer paths in the forward direction and the reverse direction, so that a smear occurs in which a signal is being transferred and another signal is added to a part of the vertical transfer paths. Also in this case, the direction in which the smear is generated is controlled, so that the smear is prevented from being generated in all the signal charges transferred in the vertical transfer path. Thus, by processing the output signal, smear can be suppressed and image quality can be improved.
[0022]
According to a sixth aspect of the present invention, in the imaging apparatus according to the fifth aspect, the control unit determines a smeared signal to which a signal other than the signal charge read from the pixel is added, and determines the smeared signal. , From the signals of other pixels.
[0023]
In this configuration, it is possible to suppress smear to which a signal other than the signal charge read from the pixel is added.
[0024]
According to a seventh aspect of the present invention, in the imaging device according to the sixth aspect, the pixel includes a photosensitive pixel disposed in the light receiving region and a light-shielded pixel whose light is shielded, and the control unit controls a signal of the light-shielded pixel. The charge is monitored to determine a smeared signal to which a signal other than the signal charge read from the pixel is added.
[0025]
In this configuration, the control unit monitors and measures the signal of the light-shielded pixel, so that it is easy to determine whether or not a smear in which another signal is added to the signal charge has occurred.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an imaging device and an imaging device of the present invention will be described with reference to the drawings.
[0027]
In FIG. 2, reference numeral 1 denotes an imaging device, which is, for example, a digital video camera that captures, records, and displays a moving image. The image pickup apparatus 1 includes a CCD 10 as an image pickup device, a CCD drive circuit 11 constituting control means for driving the CCD 10, a pair of analog processing circuits 12 constituting image processing means to which an output of the CCD 10 is inputted, 13, analog-digital (A / D) converters 14 and 15 to which the outputs of the analog processing circuits 12 and 13 are input, and a memory controller 18 to which the outputs of the analog-digital converters 14 and 15 are input. Further, the memory controller 18 is connected with a memory 19 for temporarily storing image data and the like, an image processing circuit 20 constituting a control means for processing the image data, and a recording unit interface 22 for inputting and outputting image data. You. Further, a display interface 23 to which an output of the memory controller 18 is input is connected to the memory controller 18. Further, an image recording unit 25 for recording and reproducing image data is connected to the recording unit interface 22, and an image display unit 26 for displaying image data and setting status is connected to the display unit interface 23. Further, a CPU 21 constituting control means for controlling these components is connected to the CCD driving circuit 11, the analog processing circuits 12, 13, the memory controller 18, the image processing circuit 20, and the like. Further, although not shown, the imaging device 1 includes operation means such as a release button and a changeover switch, a power supply device, an input / output device, an optical system such as a lens and an aperture mechanism, and a housing.
[0028]
The CCD 10 is a charge transfer type solid-state imaging device and a CCD image sensor using a charge coupled device. As shown in FIG. 1, the CCD 10 has a two-dimensional grid on a light receiving surface. And a plurality of pixels e each of which accumulates signal charges according to the intensity of light. Between the columns of the pixels e, a plurality of vertical transfer paths (vertical CCDs) V, that is, a plurality of vertical transfer paths (vertical CCDs) for reading signal charges from the pixels e and transferring the signal charges in a predetermined direction (hereinafter, referred to as a vertical direction or a vertical direction). The first to eighth (n) th vertical transfer paths V1 to V8 (n) are connected to the upper and lower ends of these vertical transfer paths V, that is, disposed at the lower part and upper part of the light receiving surface and orthogonal to a predetermined direction. A pair of upper and lower horizontal transfer paths (horizontal CCDs) H for transferring signal charges in a direction (hereinafter referred to as a horizontal direction), that is, a lower horizontal transfer path H1 as a first horizontal transfer path and an upper part as a second horizontal transfer path. And a horizontal transfer path H2.
[0029]
The pixels e are mostly light-sensitive pixels e1 that are exposed to light, but light-shielded pixels (horizontal light-shielded lines) e2 that are not exposed to light due to a light-shielding structure are provided at upper and lower ends of each column. . Further, a lower output section OP1 as a first output section and an upper output section OP2 as a second output section are provided at the downstream end, which is one end of each of the horizontal transfer paths H1 and H2, respectively. Analog signals constituting the image signal are output simultaneously. Although the number of pixels e is extremely small in FIG. 1 for ease of explanation, the number of pixels e is actually set, for example, from tens of thousands to several millions. You. Further, the number of pixels e is not limited to these, and is set as appropriate.
[0030]
Further, although not shown, the CCD 10 drives the vertical transfer path V, and includes a gate wiring as a wiring unit accompanied by a charge reading operation. The gate lines are independent of each other in a group of odd columns indicated by vertical transfer paths V1, V3, V5 and V7 and a group of even columns indicated by vertical transfer paths V2, V4, V6 and V8. Each system is provided with a necessary number of systems so that signal charges can be freely transported in the forward and reverse directions. That is, in the present embodiment, as shown by an arrow in FIG. 1, for example, the groups of the odd-numbered vertical transfer paths V1, V3, V5, and V7 are simultaneously moved in the forward direction (downward) by the drive signal from the CCD drive circuit 11. ), And the group of the even-numbered vertical transfer paths V2, V4, V6, and V8 are simultaneously driven in the opposite direction (upward), and the odd-numbered vertical transfer paths V1, V3, V5, and V7 are simultaneously driven. The vertical transfer directions of the even-numbered vertical transfer paths V2, V4, V6, and V8 can be opposite to each other. In addition, a group of odd-numbered columns can be transferred in a reverse direction, and a group of even-numbered columns can be transferred in a normal direction in a direction opposite to the arrow in FIG. 1 by a drive signal from the CCD drive circuit 11.
[0031]
Note that the gate wiring is not limited to a configuration in which the odd lines and the even lines are alternately and independently controlled for each column. For example, the gate lines are repeated every two columns (V1, V2, V5, V6, and V3, V4, V7 and V8 are conveyed in the same direction as a group), or repeated every three rows, or repeated one row and two rows (V1, V4, V7 and V2, V3, V5, V6, V8 are conveyed in the same direction). Further, the configuration of the gate wiring is set according to the color filter array of the pixels and whether the processing is interlace processing or progressive processing.
[0032]
In the imaging device 1, a signal output from the lower output unit OP1 of the CCD 10 is input to an analog processing circuit 12, where analog processing such as correlated double sampling and signal amplification by an amplifier is performed. Next, this signal is input to the analog-to-digital converter 14 and converted from an analog signal to a digital signal (hereinafter, referred to as digital image data or simply image data). Next, the image data is temporarily stored in the memory 19 by the memory controller 18. Similarly, the signal output from the upper output unit OP2 of the CCD 10 passes through the analog processing circuit 13 and the analog-to-digital converter 15, and is temporarily stored in the memory 19 by the memory controller 18.
[0033]
In the present embodiment, in capturing a moving image, of the signal charges that are simultaneously read from the pixels e to the vertical transfer path V, for example, in the first field as one screen, the odd-numbered column vertical transfer path V1 is used. , V3, V5, and V7 are transferred to the lower side and output from the lower output unit OP1 via the lower horizontal transfer path H1. At the same time, the signal charges of the vertical transfer paths V2, V4, V6, and V8 in the even columns are transferred upward and output from the upper output unit OP2 via the upper horizontal transfer path H2. In the subsequent second field as one screen, the signal charges of the odd-numbered vertical transfer paths V1, V3, V5, and V7 are transferred to the upper side, and conversely to the first field, and are transferred through the upper horizontal transfer path H2. In addition to being output from the output unit OP2, the signal charges of the even-numbered vertical transfer paths V2, V4, V6, and V8 are transferred to the lower side, and output from the lower output unit OP1 via the lower horizontal transfer path H1. Subsequently, the third field is the same as the first field, the fourth field is the same as the second field, and so on. The operation of alternately reciprocating in the direction is repeated.
[0034]
Here, for example, assuming that the image data P0 shown in FIG. 3 is an original image, the digital image data for one field temporarily stored in the memory 19 is shown in FIG. The image data is divided into two groups, i.e., odd-numbered image data P1 and even-numbered image data P2 shown in FIG. The image processing circuit 20 stores the two groups of image data P1 and P2 from the memory 19 before performing so-called general image processing (hereinafter, referred to as image processing) as performed by a conventional imaging apparatus. The image data P0 shown in FIG. 3 is read out and the field of one completed screen is reconstructed from the image data P1 and P2, that is, the image data P0 shown in FIG. The image processing may be performed after the reconstruction of the image data P0 is completed as described above, or the image processing may be performed simultaneously while partially reconstructing the image data P0.
[0035]
In FIG. 4A and FIG. 4B, in order to clearly represent the odd-numbered row image data P1 and the even-numbered row image data P2, a blank stripe-shaped blank data area is shown. However, in the memory 19, valid image data is continuously recorded without gaps, and such a blank data area does not exist.
[0036]
Further, if the image data P2 in the even-numbered column is recorded in the memory 19 as it is in the output order of the data without any special treatment, the image data P2a shown in FIG. Although the top and bottom are in a state opposite to that of P2, the memory controller 18 considers the address given to the memory 19 at the time of recording or reading to the memory 19 so as to be upside down. It can be handled as image data in the same state as the image data P2 shown, ie, in the same direction as the image data P1 in the odd-numbered columns. Hereinafter, these processes will not be particularly described for ease of explanation.
[0037]
The processed image data that has been reconstructed and subjected to image processing as described above is temporarily recorded again using a part of the memory 19 as a video memory, or the above-described image processing is completed. The data is sent to the display interface 23 immediately and sequentially from the pixel unit data, and is displayed as an image by the image display unit 26. Further, in some cases, the image data is subjected to image data compression processing or the like in accordance with a user operation or the like, and then is recorded as image data for recording in the image recording unit 25 via the recording unit interface 22. Here, the image recording unit 25 is constituted by a non-volatile recording medium such as a magnetic tape, a magnetic disk, a magneto-optical disk, an optical disk, and a flash memory. It has become so.
[0038]
Next, the appearance of smear according to the present embodiment and the principle thereof will be described.
[0039]
First, as in the shooting condition (scene) of the image P10 shown in FIG. 6, when shooting a scene such as the sun in which a high-brightness portion BS which is a very bright luminescent spot exists in the screen, that is, on the light receiving surface of the CCD 10, In the case where there is a light receiving area (bright point) where an extremely strong light is imaged, the smear S which is a defect has a high luminance as shown in FIG. Spread both above and below the part BS.
[0040]
On the other hand, in the present embodiment, for each vertical transfer path V, the lower horizontal transfer path H1 and the upper horizontal transfer path H2 in the explanatory diagram of the CCD 10 in FIG. 1 are alternately selected, and the transfer direction of each vertical transfer path V is changed. Since the image is turned upside down for each field, when shooting a scene such as the sun where the high-brightness portion BS which is a remarkably bright luminescent spot exists, such as the sun, as in the shooting condition (scene) of the image P10 shown in FIG. That is, when there is a light receiving area where extremely intense light forms an image on the light receiving surface of the CCD 10, the obtained image data is, for example, in the case of an odd field, image data P11 of an odd column shown in FIG. With the even-numbered image data P12 shown in FIG. 7B, the direction in which the smear S occurs with respect to the high luminance portion BS in the screen is fixed to one of the upper and lower directions. For example, as shown in FIG. 7, in the case of an odd-numbered field, the smear S is generated in the odd-numbered row from the high-luminance part BS to the lower side of the screen, and in the even-numbered row, from the high-luminance part BS to the upper side of the screen. In an even-numbered field, these relations are reversed. In an odd-numbered row, smear S is generated from the high-brightness part BS toward the upper side of the screen, and in an even-numbered row, a smear S is generated from the high-brightness part BS toward the lower side of the screen. In this way, by setting the transfer direction of the vertical transfer path V alternately in the opposite direction for each field, the direction in which the smear S is generated with respect to the high luminance portion BS on the screen can be fixed to one of the upper and lower directions.
[0041]
Here, the reason why the generation direction of the smear S can be fixed by the operation of the vertical transfer path V of the present embodiment will be described.
[0042]
FIGS. 9A to 11A to 11N illustrate one of the internal structure of the CCD 10 shown in FIG. 1 in which an odd column of the pixel e and the vertical transfer path V is extracted. Also, numbers 1 to 14 are assigned in order from the bottom to make it easier to understand the transfer state of the signal charges of the pixel e. That is, here, the upper and lower ends 1 and 14 are light-shielded pixels e2, and the other 2 to 13 pixels are photosensitive pixels e1. Further, a circle indicates a high-brightness portion BS having a light amount sufficient to generate smear S. Here, a high-brightness image is formed in the vicinity of the ninth pixel e. I have.
[0043]
FIG. 9 is an explanation of a conventional general operation in which the vertical transfer path V is always transferred in one direction, that is, downward.
[0044]
First, from the state of FIG. 9A, the signal charges of the respective pixels e are simultaneously read out to the vertical transfer path V by the charge readout pulse as shown in FIG. 9B. Next, as shown in FIG. 9C, the signal charges are transferred to the lower side by one stage on the vertical transfer path V, and further, as shown in FIG. 9D, the signal charges are transferred on the vertical transfer path V. It is transferred one step down. Here, as shown in FIGS. 9C and 9D, the signal charge of the tenth pixel e was not affected by the high-luminance part BS at the time of being read out to the vertical transfer path V. 5 shows that when the light passes through the high-luminance portion BS in the process of moving in the vertical transfer path V, the state changes to a state in which smear (smear charge) S is added to the original signal charge. Note that the mixed signal charges of smear S are indicated by oblique lines. Further, as shown in FIGS. 9 (E), 9 (F), and 9 (G), when the vertical transfer is advanced, the light is originally shielded and immediately after readout to the vertical transfer path V shown in FIG. 9 (B). Then, as shown in black, the pixel signals that were initially above the high-brightness portion BS, including the signal charges of the 14th pixel e whose signal charges were almost 0, were all smear S during the transfer process. The state is added. Further, as the vertical transfer proceeds, as shown in FIGS. 9 (H) and 9 (I), the smear S is also formed in the empty portion of the vertical transfer path V, that is, in the area where the transfer of the signal charge of each pixel e has been completed. When the reading of the signal charges of all the pixels e is completed, the smear S is provided on the lower vertical transfer path V with respect to the high-brightness part BS as shown in FIG. Is stored.
[0045]
In the description with reference to FIG. 9, the upper side or the lower side of the high-brightness portion BS is an expression in the drawing direction of the drawing, that is, the vertical direction of the CCD 10 arranged with respect to the optical system. . Therefore, since the subject image passing through the optical system is formed on the CCD 10 in a state where the top and bottom are reversed, the top and bottom relation of the screen of the image actually shot is reversed. For example, FIGS. 9A to 9J show a situation in which smear S occurs in the 9th to 14th pixels e in the upward direction of the high-brightness portion BS. In the image obtained at this time, F1 in FIG. As shown, the occurrence of smear S is seen in the lower direction of the screen. As described above, FIGS. 9A to 9J show the situation until F1 in FIG. 10 which is the first field in which a moving image is captured is obtained.
[0046]
Next, a state in which the signal charges of the respective pixels e in the second field are output from the state of FIG. 9J, that is, the state in which the output of the signal charges of all the pixels e in the first field is completed. . That is, in FIG. 9 (J), due to the above-described operation, the electric charges due to the smear S already exist in the region below the high luminance portion BS of the vertical transfer path V. Here, as shown in FIG. 9 (K), the signal charges of the respective pixels e in the second field are simultaneously read out to the vertical transfer path V. Then, the signal charges of the first to ninth pixels e are already affected by the smear S here. From this state, as shown in FIGS. 9 (L), 9 (M) to 9 (N), vertical transfer is performed in the same manner as in the first field, and the signal charge of the pixel e is output. As described above, the signal charges of all the pixels e are affected by the smear S. Thereafter, reading is performed in the state of FIG. 9 (N), so that the same result is obtained in the third and subsequent fields.
[0047]
As described above, when a moving image is photographed by the conventional operation, if the high-brightness portion BS that is the source of the smear S exists at any one point of the vertical transfer path V, all signal charges passing through the vertical transfer path V Will be affected by smear S. In this way, as shown in FIG. 8, the smear S spreads above and below the high luminance portion BS.
[0048]
Next, the operation of the present embodiment for reversing the direction of the vertical transfer between the odd field and the even field will be described with reference to FIGS. Here, A in FIG. 11 shows the state of J in FIG. 9, that is, the state immediately after the image shown in F1 in FIG. 12 has already been obtained after outputting the first field. Then, from the state shown in FIG. 11A, as shown in FIG. 11B, the signal charges of the pixels e in the second field are simultaneously read out to the vertical transfer path V, and the state shown in FIGS. As shown in J), vertical transfer is performed in the direction opposite to the first field. At this time, the signal charges of the tenth to fourteenth pixels e located above the high luminance portion BS are output without being affected by the smear S at all. At this time, as shown by F2 in FIG. 12, an image in which smear S has occurred in the direction opposite to the previous F1 is obtained. Further, in the third field, as shown in FIGS. 11 (K) to 11 (N), vertical transfer is performed again in the same direction as in the first field, and as shown in F3 in FIG. An image in which smear S has occurred is obtained. By repeating such an operation, the direction in which the smear S is generated can be fixed in the odd-numbered field and the even-numbered field, that is, guided in one of the upper and lower directions. Then, similarly to the description of the odd-numbered column, the direction in which the smear S occurs can be fixed by the same operation in the even-numbered column. Since the transfer direction of the vertical transfer is always reversed between the odd columns and the even columns, the direction of the smear S generated on the obtained image is also reversed.
[0049]
Subsequently, the smear suppressing operation according to the present embodiment will be described with reference to FIGS.
[0050]
FIG. 13 shows a value e2L of a smear detection state by a light-shielded pixel (horizontal light-shielded line) e2 described later and a vertical transfer path V of a column in which the smear S has occurred, in image data P11 of an odd-numbered column of an odd field in which smear S has occurred. Is combined with a graph of a value eL indicating a luminance situation along the line. FIG. 14 is a combination of image data P12 of an even-numbered column of an odd field in which smear S has occurred and a graph of a value eL indicating a luminance situation along the vertical transfer path V of the column in which smear S has occurred. is there.
[0051]
That is, among the image signals whose signal charges output from the lower horizontal transfer path H1 are converted into digital signals by the analog-to-digital converter 14, they correspond to the light-shielded pixels (horizontal light-shielded lines) e2 of the CCD 10 in FIG. The image signal of the partial pixel e is recorded in the specific area of the memory 19 described above. Here, the horizontal light-shielding lines are light-shielded pixels in line units provided above and below the light receiving surface of the CCD 10. Since these horizontal light-shielding lines are originally light-shielded, the signal level of this part is equal to dark. However, when the CCD 10 generates smear S, the light-shielding part is described above. A bright signal output e2La appears at a portion equal to the horizontal position where the smear S is generated due to the influence of the smear charge due to the operation principle. The detection of the occurrence position of the smear S is performed when the upper horizontal transfer path H2 is selected, that is, when the image is of an even column of an odd field or an odd column of an even field. Is the same as above. In FIG. 13, Vc is the center line of smear S in the horizontal direction, e2L is the smear detection state by the horizontal light-shielding line on the lower side of the screen, that is, the upper side of CCD 10, and eL is the center line Vc of smear S in the horizontal direction. It shows the luminance situation on the screen that has been scanned vertically in the upper direction. Further, Ws is the horizontal width of the smear S detected on the horizontal light shielding line, SL is the left smear boundary, SR is the right smear boundary, and Ds is the smear reference level.
[0052]
Then, the CPU 21 compares the value e2L of the horizontal light-shielded line with a predetermined smear reference level Ds, and determines the area of the data of the horizontal light-shielded line that exceeds the smear reference level Ds as smear S. The horizontal center line Vc of the generated smear S is determined from the horizontal boundaries SL and SR of the smear S region and the width Ws. Next, from the image data recorded in the memory 19, the image data P11 is scanned from the lower side of the screen along the vertical direction of the screen on the horizontal center line Vc to obtain a value eL indicating the luminance situation. obtain. When the region eLa having the highest level is detected from the value eL of the smear S on the center line Vc in the horizontal direction, the position of the portion eLb where the level of the image data falls on the upper side of the screen therefrom is determined as the high luminance which is the smear generating source. It is recognized as the upper end Yso of the unit BS. When the high-level area eLa is in contact with the upper end of the screen, the upper end Yso of the high-luminance part BS is determined to be the uppermost part of the screen. Then, the CPU 21 determines that the area surrounded by the upper end Yso and the left and right smear boundaries SL and SR is the area So in which the odd columns of the odd field are affected by the smear S.
[0053]
Next, as shown in FIG. 14, the CPU 21 scans the horizontal center line Vc of the smear S obtained earlier from the upper side of the screen with respect to the image data P12 of the even-numbered column of the odd-numbered field, and In a similar process, the lower end Yse of the high-luminance portion BS, which is the smear generating source, is detected. Further, an area surrounded by the lower end Yse and the left and right smear boundaries SL and SR is represented by an even-numbered column of an odd field. It is determined that the area S1 is affected by S.
[0054]
Next, the CPU 21 obtains a vertical position at an equal distance from the upper end Yso and the lower end Yse of the high luminance portion BS, and sets the vertical position as the vertical center line Hc of the high luminance portion BS. Then, the occurrence state of the smear S obtained in this way is notified to the image processing circuit 20.
[0055]
Until the occurrence of smear S is detected, the image processing circuit 20 performs normal processing, that is, odd-numbered image data P1 shown in FIG. 4A and even-numbered image data P1 shown in FIG. The image of the image data P0 shown in FIG. 3 is reproduced by a method of simply interpolating all the regions of the screen using the image data P2 of FIG. On the other hand, when the occurrence and the occurrence state of the smear S are notified by the CPU 21, the image processing circuit 20 switches the processing method from the normal processing to the smear suppression image processing described below.
[0056]
That is, the areas in the screen are classified into areas where no smear S occurs, areas where smear S occurs in odd rows, and areas where smear S occurs in even rows, based on notification from the CPU 21. . For example, in the examples shown in FIGS. 13 and 14, as shown in FIG. 15, regions I and II where smear S does not occur, region III where smear S occurs in odd columns, and smear S in even columns. Are classified into the region IV in which The boundary between the region III and the region IV is the vertical center line Hc of the high-brightness portion BS previously obtained. Then, the image processing circuit 20 reproduces an image from the odd-numbered columns and the even-numbered columns in the areas I and II where no smear S is generated by the normal processing. For III, the image is reproduced only from the even columns, and for the region IV where the smear S occurs in the even columns, the image is reproduced only from the odd columns.
[0057]
That is, in the region III, the smear S occurs only in the odd-numbered columns, and the image in the even-numbered columns is not affected by the smear S. Therefore, in this area III, the odd-numbered column data is discarded, and blank odd-numbered column data is calculated and used only from the even-numbered columns by, for example, an interpolation process such as a linear interpolation method. Similarly, in the region IV, smear S occurs only in the even-numbered columns, and the image in the odd-numbered columns is not affected by the smear S. Therefore, in this region IV, the data of the even-numbered columns is discarded, and blank even-numbered column data is calculated and used only from the odd-numbered columns by, for example, an interpolation process such as a linear interpolation method. In this manner, by performing image reproduction from the odd-numbered column image data and the even-numbered column image data while considering the occurrence state of the smear S, the smear S is normally not generated as in the image P20 shown in FIG. Odd field images without smear S can be obtained even under the shooting conditions that occur, and the image P10 shown in FIG. 6 can be reproduced.
[0058]
Then, similarly to the description of the odd field, in the even field, the smear suppression process is performed by the same method as that of the odd field, considering that the vertical transfer directions of the odd column and the even column are reversed. Can be obtained.
[0059]
As described above, according to the driving method of the image pickup device of the present embodiment, the CCD 10 has the electrode wiring capable of reversing the transfer direction for each column, for example, the odd column and the even column, and the output unit at the upper and lower parts. A smear S is placed on the opposite side of the high-brightness portion BS by a structure in which two are provided, a transfer method for alternately reversing the vertical transfer direction for each field, that is, an odd field and an even field, and image processing according to these. By generating the image alternately and using an area where no smear S is generated, in the conventional configuration, the smear S generated from the high-brightness portion BS of the screen overlaps with the main subject, making it difficult to determine the subject. Thus, even under the photographing conditions such as, the smear S can be reliably removed, that is, the smear S can be effectively suppressed, and the image quality can be easily improved.
[0060]
That is, (1) two horizontal transfer paths H1 and H2 are provided above and below the light receiving region, and the pixels e of the light receiving section are divided into two columns of vertical transfer paths V, for example, an even column and an odd column. A CCD 10 provided with a vertical transfer path V capable of transferring signal charges toward the upper horizontal transfer path H2 and the lower horizontal transfer path H1 simultaneously in the opposite directions, and (2) vertical transfer paths in each column for each field. By making the vertical transfer direction of V the opposite direction to the previous field, the smear S generation direction can be fixed in one of the upper and lower directions with respect to the high-brightness portion BS. The occurrence position of the smear S can be mutually exclusive with the image. (3) For each field, the generation state of the smear S on the even-numbered row, odd-numbered row image, so-called column image, is determined. The output column images are combined, that is, interpolated, and in an area where only one of the smears S is generated, a complementation process is performed using only the column image on the side where no smear S is generated, and one image is obtained. Complete the field image of Then, by repeating the operation (3), a good continuous field image without smear S can be obtained.
[0061]
Further, regarding the determination of the occurrence state of the smear S, since the light shielding pixel (horizontal light shielding line) e2 is provided above or below the light receiving surface, the horizontal coordinate and the width of the smear S can be easily obtained from the signal state of the light shielding pixel e2. By scanning the smear S in the vertical direction, the generation reference position on the vertical coordinate of the smear S is specified from the change in brightness, that is, the portion falling from the portion having the highest luminance is determined by the smear S. As the boundary, the vertical coordinate and the width can be easily specified, and the occurrence area of the smear S on the screen can be accurately determined.
[0062]
Further, by adopting a configuration in which the CCD 10 is provided with two horizontal transfer paths H1 and H2, that is, two output units, the reading speed of signal charges per pixel e, that is, the vertical transfer path V Without increasing the transfer speed of the horizontal transfer paths H1 and H2, the frame rate that is twice the conventional rate, that is, the signal charge read time can be reduced to half of the conventional rate, and the number of frames per second can be reduced. Can easily be doubled. In addition, this configuration can double the number of frames per second to photograph a fast-moving subject with high time resolution, and if the frame rate is unchanged, the readout speed per pixel remains unchanged. However, even a CCD having twice as many pixels as a conventional CCD can be handled. In other words, it is possible to easily obtain a high-definition image having a larger number of pixels and a high spatial resolution, and it is possible to realize extremely high overall image quality including suppression of smear S.
[0063]
Further, in the present embodiment, it is possible to minimize the complexity of the structure and suppress an increase in cost such as manufacturing cost.
[0064]
That is, as compared with the frame interline transfer type CCD in which the chip area is doubled, the chip area remains the same, so that it is possible to suppress an increase in cost and to remove smear S more effectively and almost completely.
[0065]
Further, as compared with the configuration using two CCDs, the number of CCDs 10 is one, so that the cost can be simply reduced. This eliminates the need for adjustment for compensating for the characteristic difference between the CCDs, thereby reducing costs, suppressing an increase in power consumption by the second CCD, and preventing a decrease in sensitivity due to splitting of incident light. .
[0066]
Furthermore, since a moving image with a high frame rate without smear S can be obtained, it is possible to realize functional operations such as high-speed and high-precision automatic exposure control and auto-focusing, which have not been achieved in the past.
[0067]
In the above-described embodiment, the imaging device 1 is described as a digital video camera that shoots a moving image. However, the present invention is not limited to this configuration, and can be widely applied to devices using a CCD. For example, the smear S can be reduced without using a mechanical shutter or the like for a digital camera capable of shooting a still image.
[0068]
Further, in the above-described embodiment, the removal of the smear S caused by the high-brightness portion BS has been described. However, the present invention is not limited to this configuration. Even when the transfer of the signal charge has a failure, an image can be obtained except for the failure portion.
[0069]
【The invention's effect】
According to the image pickup device of the first aspect, the signal charges read from the pixels to the respective vertical transfer paths are alternately transferred in the forward direction and the reverse direction by the respective vertical transfer paths. The signals are output from the first horizontal transfer path and the second horizontal transfer path via each output unit. Thus, an image is obtained by processing these output signals. Then, the signal charges read from the pixels are alternately transferred in each of the vertical transfer paths in the forward direction and the reverse direction, and the signal charges are transferred by using the first horizontal transfer path and the second horizontal transfer path. The transfer amount can be easily improved, and even when a smear in which a signal charge being transferred is added to another signal occurs in a part of the vertical transfer path, the direction in which the smear is generated can be controlled, and the transfer is performed using the vertical transfer path. Smear can be prevented from occurring in all signal charges. Therefore, by processing the output signal, it is possible to suppress smear and improve image quality.
[0070]
According to the imaging element of the second aspect, in addition to the effect of the first aspect, by transferring the signal charges in the opposite direction for each column, it is possible to accurately complement the smeared signal and improve the image quality.
[0071]
According to the image pickup device of the third aspect, in addition to the effect of the first aspect, by transferring the signal charges through the vertical transfer paths grouped by a plurality of columns, it is possible to process the signals of the plurality of columns as a group. become.
[0072]
According to the imaging device of the fourth aspect, in addition to the effect of any one of the first to third aspects, since the pixel includes the photosensitive pixel disposed in the light receiving area and the light-shielded pixel that blocks light, By measuring the signal of the light-shielded pixel, it is possible to easily determine whether or not smear in which another signal is added to the signal charge has occurred.
[0073]
According to the imaging device of the fifth aspect, since the imaging device of any one of the first to fourth aspects is used, the signal charges read from the pixels of the imaging device to the respective vertical transfer paths are transferred by the respective vertical transfer paths. By alternately transferring the signal charges in the forward direction and the reverse direction, these signal charges are output from the first horizontal transfer path and the second horizontal transfer path via each output unit. Then, an image can be obtained by processing these output signals by the control means. Then, the signal charges read from the pixels are alternately transferred in each of the vertical transfer paths in the forward direction and the reverse direction, so that a smear occurs in which a signal is being transferred and another signal is added to a part of the vertical transfer paths. Also in this case, the direction in which the smear is generated can be controlled, and it is possible to prevent the smear from being generated in all the signal charges transferred through the vertical transfer path. Therefore, by processing the output signal, smear can be suppressed and image quality can be improved.
[0074]
According to the imaging device of the sixth aspect, in addition to the effect of the fifth aspect, the control means determines a smeared signal to which a signal other than the signal charge read from the pixel is added, and determines that there is a smear. Since the signal is complemented from the signal of another pixel, smear to which a signal other than the signal charge read from the pixel is added can be suppressed.
[0075]
According to the imaging device of the seventh aspect, in addition to the effect of the sixth aspect, the pixel includes a photosensitive pixel disposed in the light receiving area and a light shielding pixel of which light is shielded, and the control unit controls the light shielding pixel. Monitor the signal charge of the pixel and determine the smeared signal to which a signal other than the signal charge read from the pixel has been added. it can.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing one embodiment of an image sensor of the present invention.
FIG. 2 is a configuration diagram of an imaging device including the imaging element according to the first embodiment.
FIG. 3 is an explanatory diagram of an image captured by the image capturing device.
FIG. 4 is an explanatory diagram of image data imaged by the imaging device according to the first embodiment. (A) is image data of an odd-numbered column of an odd field, and (b) is image data of an even-numbered column of an odd field.
FIG. 5 is an explanatory diagram of image data of an even-numbered column of an odd-numbered field captured by the imaging device.
FIG. 6 is an explanatory diagram of an image captured by the imaging device.
FIG. 7 is an explanatory diagram of image data captured by the image capturing device.
(A) is image data of an odd column of an odd field
(B) Image data of an even column of an odd field
FIG. 8 is an explanatory diagram of image data in which smear has occurred.
FIG. 9 is an explanatory diagram showing a process in which smear occurs.
FIG. 10 is an explanatory diagram showing a process in which a smear occurs.
FIG. 11 is an explanatory diagram illustrating an operation of the imaging device of the present invention.
FIG. 12 is an explanatory diagram showing an operation of the imaging element.
FIG. 13 is an explanatory diagram showing an operation of the imaging device of the above.
FIG. 14 is an explanatory diagram showing an operation of the imaging device in Embodiment 1;
FIG. 15 is an explanatory diagram showing an operation of the imaging device.
FIG. 16 is an explanatory diagram of image data from which smear has been removed by the image pickup device;
[Explanation of symbols]
1 Imaging device
10 CCD as image sensor
11 CCD drive circuit constituting control means
20 Image processing circuit constituting control means
21 CPU constituting control means
e pixel
e1 photosensitive pixel
e2 Shading pixel
H1 Lower horizontal transfer path as first horizontal transfer path
H2 Upper horizontal transfer path as second horizontal transfer path
OP1 Lower output section as first output section
OP2 Upper output section as second output section
S smear
V Vertical transfer path

Claims (7)

A plurality of pixels each of which photoelectrically converts and accumulates signal charges,
A plurality of vertical transfer paths which are provided with a charge-coupled device for reading signal charges from these pixels and transferring the read signal charges in a forward direction and a reverse direction, and which are grouped into a plurality of groups for transferring the signal charges in opposite directions; ,
A first horizontal transfer path for transferring signal charges from one end of each of the vertical transfer paths, transferring the transferred signal charges, and outputting the transferred signal charges to a first output unit;
A second horizontal transfer path for transferring signal charges from the other end of each of the vertical transfer paths, transferring the transferred signal charges and outputting the transferred signal charges to a second output section. element. 2. The image sensor according to claim 1, wherein the vertical transfer path transfers the signal charges in the opposite direction for each column. 2. The image sensor according to claim 1, wherein the vertical transfer paths are grouped by a plurality of columns, and transfer signal charges in the same direction for each of the groups. Pixels are
A photosensitive pixel arranged in the light receiving area,
The image pickup device according to claim 1, further comprising a light-shielded pixel that blocks light. An image sensor according to any one of claims 1 to 4,
A control unit configured to control the image pickup device so that the transfer direction of each vertical transfer path is set to the opposite direction for each screen, and to process a signal output from each output unit of the image pickup device to form an image. An imaging device, comprising: 6. The control unit according to claim 5, wherein the control unit determines a smeared signal to which a signal other than the signal charge read from the pixel is added, and complements the smeared signal from a signal of another pixel. Imaging device. The pixel includes a photosensitive pixel arranged in the light receiving area, and a light-shielded pixel in which light is shielded,
7. The imaging apparatus according to claim 6, wherein the control unit monitors the signal charge of the light-shielded pixel and determines a smeared signal to which a signal other than the signal charge read from the pixel is added.

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