Patent Application
20120281124
The present invention relates to solid-state imaging devices, methods for driving the solid-state imaging devices, and cameras, and, more particularly, to a solid-state imaging device which includes transfer control units for selectively transferring, to a horizontal transfer unit, signal charges transferred from any of a plurality of vertical transfer units.
In recent years, CCDs (Charge Coupled Device) having 12M pixels or more are dominant as solid-state imaging devices for use in digital still cameras. An increase in number of pixels miniaturizes horizontal transfer electrodes included in the horizontal transfer unit, and increases the number of pixels in the horizontal direction to about 4,000. This arises a problem that inter-electrode capacitance dramatically increases in commonly-used two-phase drive systems in which one packet of the horizontal transfer unit is formed to one column of a first vertical transfer unit 1, ending up increased power consumption.
Thus, at present, a system is proposed in which the number of transfer packets of the horizontal transfer unit is not the same as the number of columns of vertical transfer units unlike conventional and is, for example, ⅓ of the number of columns of the vertical transfer units, an operation of transferring signal charges from the vertical transfer units to the horizontal transfer unit and from the horizontal transfer unit to an output unit is divided into three times to separate a line of signal charges to provide interlaced output (For example, see PTL 1).
The system allows reduction in number of electrodes included in the horizontal transfer unit. This reduces the inter-electrode capacitance, thereby achieving low power consumption.
However, in solid-state imaging devices having such a configuration, the number of packets of the horizontal transfer unit is less than the number of columns of the vertical transfer units. Thus, a transfer control unit which selectively controls transfer of the signal charges from the vertical transfer units to the horizontal transfer unit is required. Specifically, a function is required which retains the signal charges in the transfer control unit while the first transfer operation is being performed.
Moreover, at present, in addition to an imaging mode in which signals in a light receiving part are extracted as a still image (hereinafter, referred to as a normal mode), a video mode for LCD monitor display and video recording is used. In the video mode, in general, a method is used in which signal charges obtained from a plurality of pixels are summed in an image pick-up device or signal charges to be read out from the pixels are selectively decimated. This reduces the number of output signals, thereby achieving a video having a high frame rate. For example, in the video mode, the following output are achieved: a VGA output (640×480) achieving 30 frames/second; and a 720 p output (1280×720) supporting an HD format both in which the number of output signals are reduced from the number of pixels (10M, for example) outputted for a still image.
As described above, the frame rate is two to three frames/second in the normal mode. However, image output achieving 30 frames/second is required in the video mode. Therefore, in the video mode, it is necessary to compress the image close to 1/10 as compared to the number of pixels outputted for a still image. Thus, the number of signal charges to be summed increases.
Moreover, in the solid-state imaging devices for digital still cameras, in general, the Bayer array is used and adjacent signal charges having a same color are summed. In the solid-state imaging devices, the signal charges are summed in the vertical direction in the vertical transfer units or the horizontal transfer unit, and the signal charges are summed in the horizontal direction in the horizontal transfer unit.
The pixel summing in the vertical direction in the vertical transfer units can be achieved by providing a plurality of vertical transfer electrodes which read pixels from the photoelectric conversion unit to the vertical transfer units and devising the drive timing. On the other hand, to achieve the pixel summing in the horizontal direction, it is required to provide, between the vertical transfer units and the horizontal transfer unit, a transfer control unit for selectively controlling the transfer of the signal charges.
Moreover, one example of the video mode is described in PTL 2. In particular, a method for summing nine pixels, described in PTL 2, in which signal charges of three vertical pixels and three horizontal pixels are summed, is useful because the method causes no shift in center of gravity after the summing and can achieve a video having high quality images and less moire.
As described above, in the current solid-state imaging devices for digital cameras, the transfer control unit is required to achieve the low power consumption and provide a video which has a high frame rate utilizing the pixel summing.
Hereinafter, details of a conventional solid-state imaging device set forth in PTL 1 will be described.
The solid-state imaging device shown in
An example of the operation of the solid-state imaging device having the configuration as set forth above will be described. In the example, the aforementioned transfer control unit is a region which includes the charge retention unit 101 and the VOG unit 104. Moreover,
The first vertical transfer units 1 transfer signal charges to the VOG unit 104 corresponding to the group Gr to which the first vertical transfer units 1 belong. Moreover, the VOG unit 104 transfers the signal charges to the unit transfer bit corresponding to the first vertical transfer units 1 from which the signal charges are transferred to the VOG unit 104. This allows any of the first vertical transfer units 1 of the group Gr to transfer the signal charges to the corresponding unit transfer bit via the VOG unit 104.
In the normal mode, as shown in
After the completion of transferring the signal charges on the column c, the signal charges on the column a are transferred, as shown in
That is, in the normal mode, a horizontal line of the signal charges is separated for every three signal charges and outputted.
On the other hand, in a mode of summing three horizontal pixels, as shown in
In the mode of summing the three horizontal pixels, the number of signal charges after the summing match the number of packets of the horizontal transfer units 2, and thus there is no need to separate the line of signal charges for every three signal charges for transfer as in the normal mode.
Moreover, in both the normal mode and the mode of summing three horizontal pixels, transferring the signal charges from the first vertical transfer units 1 to the horizontal transfer units 2 is performed via the VOG unit 104, and the first vertical transfer units 1 are coupled to the VOG unit 104.
However, in the conventional configuration described above, the plurality of first vertical transfer units is grouped at the VOG unit of the transfer control unit disposed above the horizontal transfer unit. Thus, upon transferring the signal charges from the VOG unit to the horizontal transfer unit, it is necessary that the vertical transfer units have shapes tapering toward horizontal transfer electrodes where the signal charges are received. If the tapering is too acute, the electric potential is shallow on the side of the horizontal transfer unit. This arises a problem that transfer degradations are present.
The present invention solves the above problems and an object of the present invention is to provide a solid-state imaging device which allows suppression of the transfer degradations in a configuration where a plurality of vertical transfer units is grouped, a method for driving the solid-state imaging device, and a camera.
To achieve the objects described above, the solid-state imaging device according to one embodiment of the present invention includes: photoelectric conversion units disposed in rows and columns and configured to convert light into signal charges; first vertical transfer units disposed in one-to-one correspondence with the columns and each configured to transfer in a vertical direction the signal charges obtained by the photoelectric conversion units converting the light, the photoelectric conversion units being disposed on a corresponding one of the columns; and transfer control units disposed in correspondence with the first vertical transfer units on m columns successive in a horizontal direction, where m is an integer greater than or equal to 2, and each configured to selectively transfer the signal charges transferred by any of the corresponding first vertical transfer units on the m columns; second vertical transfer units disposed in correspondence with the transfer control units and each configured to transfer the signal charges transferred by a corresponding one of the transfer control units; and a horizontal transfer unit configured to transfer in the horizontal direction the signal charges transferred by the second vertical transfer units, wherein each of the second vertical transfer units is disposed for two or more horizontal transfer electrodes forming a transfer packet of the horizontal transfer unit and has a region in which a transfer width tapers from the corresponding one of the transfer control units toward the horizontal transfer unit, and each of the second vertical transfer units is provided with a vertical transfer electrode independent of vertical transfer electrodes of the first vertical transfer units and the transfer control units.
According to the above configuration, in the solid-state imaging device according to one embodiment of the present invention, since the second vertical transfer units each has a region in which a transfer width reduces from a corresponding transfer control unit to the horizontal transfer unit, the tapering of the vertical transfer unit on the side of the horizontal transfer unit can be set gradual, thereby preventing the electric potential from being shallow on the side of the horizontal transfer unit. Thus, the solid-state imaging device according to the present invention can suppress the transfer degradations.
Moreover, each of the transfer control units may include m of third vertical transfer units disposed in one-to-one correspondence with the m columns and each configured to transfer the signal charges transferred by the vertical transfer unit on a corresponding one of the m columns, and a distance, in the horizontal direction, between centers of m of the third vertical transfer units disposed adjacent to one another may be shorter than a distance, in the horizontal direction, between centers of the first vertical transfer units disposed adjacent to one another.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can form a narrow width of the second vertical transfer unit in the horizontal direction. This allows the solid-state imaging device according to one embodiment of the present invention to set angles of tapering of the second vertical transfer units to be gentle. This allows the solid-state imaging device according to one embodiment of the present invention to suppress the transfer degradations due to a fact that the electric potential becomes shallower along with the transfer direction.
Moreover, each of the second vertical transfer units may include: a fourth vertical transfer unit configured to transfer the signal charges transferred by a corresponding one of the transfer control units and having a region in which a transfer width tapers from the corresponding one of the transfer control units toward the horizontal transfer unit; and a fifth vertical transfer unit configured to transfer to the horizontal transfer unit the signal charges transferred by the fourth vertical transfer unit and having a constant transfer width, and vertical transfer electrodes independent of each other may be disposed above the fourth vertical transfer unit and the fifth vertical transfer unit.
According to the above configuration, by providing the fourth vertical transfer unit and the fifth vertical transfer unit with independent electrodes, the solid-state imaging device according to one embodiment of the present invention allows reduced lengths of electrodes in the fourth vertical transfer unit. This allows the solid-state imaging device according to one embodiment of the present invention to ensure the transfer electric field, thereby suppressing transfer failure in the fourth vertical transfer unit.
Moreover, each of the transfer control units may include m of third vertical transfer units disposed in one-to-one correspondence with the m columns and each configured to transfer the signal charges transferred by the vertical transfer unit on a corresponding one of the m columns, a sixth vertical transfer unit which is one of the third vertical transfer units on the m columns may include a first vertical transfer electrode to which a same transfer pulse as a pulse applied to any of the vertical transfer electrodes of the first vertical transfer units is applied, and m−1 of the third vertical transfer units other than the sixth vertical transfer unit included in the third vertical transfer units on the m columns may each include a signal charge storage electrode and a transfer blocking electrode which are independent of the vertical transfer electrodes of the first vertical transfer units and the second vertical transfer units.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention allows reduction in number of independent electrodes in the transfer control units.
Moreover, the sixth vertical transfer unit may include the first vertical transfer electrode only.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention allows reduction in number of independent electrodes in the transfer control units.
Moreover, a transfer width of an entire region below the first vertical transfer electrode of the sixth vertical transfer unit may increase from the corresponding one of the first vertical transfer units toward a corresponding one of the second vertical transfer units.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can improve the transfer electric field by utilizing narrow channel effects.
Moreover, a maximum transfer width of each of the second vertical transfer units may be larger than a width between outermost end portions of the first vertical transfer units disposed on outermost columns of the m columns.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can establish deep electric potential at end portions, in the horizontal direction, of the second vertical transfer units as with the horizontally central portion thereof. This allows the solid-state imaging device according to one embodiment of the present invention to suppress bad transfer from the transfer control units to the second vertical transfer units.
Moreover, each of the first vertical transfer units may include a first n-type impurities-doped region and a second n-type impurities-doped region, the first n-type impurities-doped region may be formed in each of the first vertical transfer units, each of the transfer control units, each of the transfer control units, and the horizontal transfer unit, and the second n-type impurities-doped region may be formed in each of the first vertical transfer units and each of the transfer control units and is not formed in each of the second vertical transfer units and the horizontal transfer unit.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can establish shallow electric potential of the second vertical transfer unit as compared to the case of forming the second vertical transfer unit using the same n-type impurity concentration as the first vertical transfer unit. Thus, the solid-state imaging device according to one embodiment of the present invention allows a large potential difference from the second vertical transfer unit to the horizontal transfer unit, thereby improving the transfer efficiency.
Moreover, a potential step may be formed in each of the second vertical transfer units so that electric potential on a side of a corresponding one of the transfer control units is shallower than electric potential on a side of the horizontal transfer unit.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention allows further improvement of the transfer efficiency of the second vertical transfer unit.
Moreover, a third n-type impurities-doped region may be formed in each of the second vertical transfer units on a side of the horizontal transfer unit to form the potential step.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can suppress the reduction of a potential difference between the transfer control unit and the second vertical transfer unit due to the formation of the potential step. Thus, the transfer efficiency from the transfer control unit to the second vertical transfer unit can be improved.
Moreover, a p-type impurities-doped region may be formed in each of the second vertical transfer units on a side of a corresponding one of the transfer control units to form the potential step.
Moreover, a third n-type impurities-doped region may be further formed in each of the second vertical transfer units.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can suppress the reduction of a potential difference between the transfer control unit and the second vertical transfer unit due to the formation of the potential step. Thus, the transfer efficiency from the transfer control unit to the second vertical transfer unit can be improved.
Moreover, a p-type impurities-doped region may be formed in each of the transfer control units.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can establish shallow electric potential of the transfer control unit. Thus, the solid-state imaging device according to one embodiment of the present invention allows enhancement of the transfer electric field from the transfer control unit to the second vertical transfer unit, thereby improving the transfer efficiency.
Moreover, first vertical transfer electrodes of the first vertical transfer units, the transfer control units, and the second vertical transfer units, and the two or more horizontal transfer electrodes of the horizontal transfer unit may be formed of a single layer.
According to the above configuration, the solid-state imaging device according to one embodiment of the present invention can facilitate the wiring layout.
Moreover, a method for driving a solid-state imaging device, the method includes during a period for which signal charges on one of m columns are horizontally transferred, transferring to a fourth vertical transfer unit the signal charges on other column of the m columns from a transfer control unit corresponding to the other column, wherein the method is a method for driving the solid-state imaging device described above.
According to the above configuration, since the signal charges can be transferred from the transfer control unit to the fourth vertical transfer unit over a long period of time, utilizing the horizontal transfer period for another column, the signal charge transfer efficiency from the transfer control unit to the fourth vertical transfer unit can be improved.
Moreover, the method for driving the solid-state imaging device according to claim 15, the method may include: transferring to the fourth vertical transfer unit the signal charges on a center column, among the m columns, from the transfer control unit corresponding to the center column during a horizontal blanking period; and during a period for which the signal charges on the center column are transferred, transferring to the fourth vertical transfer unit the signal charges on an outermost column, among the m columns, from the transfer control unit corresponding to the outermost column.
According to the above configuration, the signal charge at end portions where the transfer failure is likely to occur can be transferred from the transfer control unit to the fourth vertical transfer unit over a long period of time. This allows suppression of transfer failure of the signal charges from the transfer control unit to the fourth vertical transfer unit.
Moreover, the camera according to one embodiment of the present invention includes the solid-state imaging device.
It should be noted that the present invention can be implemented as a semiconductor integrated circuit (LSI) achieving a part or the whole of the functionality of such a solid-state imaging device.
As described above, the present invention can provide a solid-state imaging device which allows suppression of transfer degradations in a configuration in which a plurality of vertical transfer units is grouped, a method for driving the solid-state imaging device, and a camera.
These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings that illustrate a specific embodiment of the present invention. In the Drawings:
Hereinafter, embodiments of the present invention will be described with accompanying drawings.
The solid-state imaging device 50 shown in
The pixel repetition unit 5 includes a plurality of photo-electric conversion units 3, a plurality of first vertical transfer units 1, and a plurality of first vertical transfer electrodes 4.
The plurality of photo-electric conversion units 3 is disposed in rows and columns, convert light into signal charges, and store the resultant signal charges therein.
The plurality of first vertical transfer units 1 is disposed in correspondence with respective columns, and each transfer the signal charges in the vertical direction which are obtained by the plurality of photo-electric conversion units 3, disposed on a corresponding column, converting the light.
The plurality of first vertical transfer electrodes 4 is formed above the plurality of first vertical transfer units 1.
The plurality of transfer control units 6 are each disposed for every m (m is an integer greater than or equal to 2) columns of the first vertical transfer units 1 successive in the horizontal direction, among the plurality of first vertical transfer units 1. Each transfer control unit 6 selectively transfers the signal charges transferred by corresponding any of the first vertical transfer units 1 on the m columns.
Each transfer control unit 6 includes m third vertical transfer units 6A each of which is disposed in one-to-one correspondence with each of the m columns and transfers the signal charges transferred by the first vertical transfer unit 1 on a corresponding column, m signal charge storage electrodes 7, and m transfer blocking electrodes 8.
The third vertical transfer unit 6A is disposed in one-to-one correspondence with each of the m columns to which the transfer control unit 6 corresponds. The third vertical transfer unit 6A transfers the signal charges transferred by the first vertical transfer unit 1 on a corresponding column.
The signal charge storage electrode 7 and the transfer blocking electrode 8 are formed above each third vertical transfer unit 6A.
The second vertical transfer unit 9 is disposed in one-to-one correspondence with each transfer control unit 6 and transfers the signal charges transferred by the corresponding transfer control unit 6. Moreover, the second vertical transfer unit 9 is disposed for every two or more horizontal transfer electrodes 14 which form one transfer packet of the horizontal transfer unit 2. Moreover, the second vertical transfer unit 9 has a region in which the transfer width reduces from the transfer control unit 6 toward the horizontal transfer unit 2. Moreover, the second vertical transfer unit 9 is provided with vertical transfer electrodes independent of the vertical transfer electrodes of the first vertical transfer unit 1 and the transfer control unit 6.
The second vertical transfer unit 9 includes a fourth vertical transfer unit 10, a fifth vertical transfer unit 11, a fourth vertical transfer electrode 12, and a vertical final electrode 13.
The fourth vertical transfer unit 10 transfers the signal charges transferred by the transfer control unit 6. Moreover, the fourth vertical transfer unit 10 has a region in which the transfer width reduces from the transfer control unit 6 toward the horizontal transfer unit 2.
The fifth vertical transfer unit 11 transfers the signal charges transferred by the fourth vertical transfer unit 10. Moreover, the fifth vertical transfer unit 11 has a fixed transfer width and is disposed straightforward in the horizontal direction.
The horizontal transfer unit 2 transfers, in the horizontal direction, the signal charges transferred by the second vertical transfer unit 9. The plurality of horizontal transfer electrodes 14 is formed above the horizontal transfer unit 2. Moreover, the horizontal transfer unit 2 transfers, to an output unit (not shown) included in the solid-state imaging device 50, the signal charges transferred by the second vertical transfer units 9.
The output unit converts the signal charges transferred thereto by the horizontal transfer unit 2 into voltage signals, and outputs the resultant voltage signals to outside.
In the embodiment 1 of the present invention, the second vertical transfer unit 9 groups three columns of the first vertical transfer units 1. Moreover, one unit transfer packet of the horizontal transfer unit 2 corresponds to one second vertical transfer unit 9. That is, the number of unit transfer packets of the horizontal transfer unit 2 is ⅓ of the number of columns of the first vertical transfer units 1. Thus, to output a line of the signal charges without summing, the signal charges are separated for every three signal charges to be outputted (horizontal 3:1 interlace).
Moreover, in
The four-phase drive allows reduction in length of the horizontal transfer electrodes 14 in a transfer direction as compared to the three-phase drive shown in the conventional example, and thus has advantages that a low voltage drive is possible. For example, if the size of pixels is about 1.5 μm, the use of the four-phase drive allows 1.8 V drive. The voltage 1.8 V is used also in other semiconductor devices incorporated in digital still cameras, and thus is advantageous as being easy to handle when designing cameras.
Moreover, as set forth in the description of Background Art, in the case of employing the horizontal interlace, an operation of retaining the signal charges during the horizontal transfer period is necessary. In particular, in the case of retaining the signal charges by one electrode (the signal charge storage electrode 7 in the present embodiment), it is required to reserve a necessary amount of saturation charges by increasing the length of the electrode storing the signal charges and/or increasing the width of the first vertical transfer unit 1 below the electrode in the horizontal direction larger than the width of the first vertical transfer unit 1 of the pixel repetition unit 5.
Merely increasing the lengths of the electrode reduces the transfer electric field, ending up undesirably reducing the transfer efficiency. Thus, it is desirable to increase the width of the first vertical transfer unit 1 to reserve the amount of saturation charges. For example, in
A first feature of the solid-state imaging device 50 according to the embodiment 1 of the present invention is that the second vertical transfer units 9 each have a region in which a transfer width reduces from the transfer control unit 6 toward the horizontal transfer unit 2. This produces gentle tapering of the second vertical transfer units 9 on a side of the horizontal transfer unit 2, thereby preventing the electric potential from being shallow on the side of the horizontal transfer unit 2. Thus, the solid-state imaging device 50 allows suppression of the transfer degradations.
A second feature of the solid-state imaging device 50 is that three columns of the third vertical transfer units 6A in the transfer control unit 6 are disposed so as to have shorter repetition pitches therebetween than repetition pitches between the first vertical transfer units 1 of the pixel repetition unit 5. That is, in
This allows the solid-state imaging device 50 to form a width C of the fourth vertical transfer unit 10 in the horizontal direction to be narrow. Thus, the fourth vertical transfer unit 10 needs to taper along with the transfer direction for transferring the signal charges to the horizontal transfer unit 2, but there is an advantage that the angle of tapering can be set gentle. This allows the solid-state imaging device 50 to suppress undesirable effects in causing the electric potential to be shallower along with the transfer direction.
A third feature of the solid-state imaging device 50 is that the fourth vertical transfer unit 10 and the fifth vertical transfer unit 11 are provided with the fourth vertical transfer electrode 12 and the vertical final electrode 13, respectively, as independent electrodes. Moreover, since the transfer width of the fourth vertical transfer unit 10 tapers along with the transfer direction, the electric potential becomes shallower toward the side of the horizontal transfer unit 2. However, providing the fourth vertical transfer unit 10 and the fifth vertical transfer unit 11 with the fourth vertical transfer electrode 12 and the vertical final electrode 13, respectively, as independent electrodes shortens the electrode lengths. This ensures the transfer electric field, and thus suppression of the transfer failure in the fourth vertical transfer unit 10 is possible.
A fourth feature of the present embodiment is that a potential step is formed in the fourth vertical transfer unit 10 included in the second vertical transfer unit 9 so that an electric potential on a side of the transfer control unit 6 is shallower than an electric potential on a side of the horizontal transfer unit 2. For example, an n-type impurities-doped region is formed in the fourth vertical transfer unit 10 in consideration with the transfer efficiency, so that the electric potential of the fourth vertical transfer unit 10 on the side of the transfer control unit 6 is shallow. This allows further improvement in transfer efficiency of the fourth vertical transfer unit 10. The details will be described below.
A fifth feature of the solid-state imaging device 50 is that the n-type impurity concentration of the second vertical transfer unit 9 is lower than n-type impurity concentrations of the pixel repetition unit 5 and the transfer control unit 6. Specifically, the first vertical transfer unit 1 is formed of, for example, two n-type diffusion layers to suppress reduction in handling quantity of electric charges and the transfer efficiency degradation that are due to narrow channel effects in the pixel repetition unit 5 and to ensure, using one electrode, necessary handling quantity of electric charges in the transfer control unit 6. Moreover, either one of the two n-type diffusion layers that are used for forming the pixel repetition unit 5 is used as an n-type diffusion layer of the second vertical transfer unit 9.
This allows formation of a shallow electric potential of the second vertical transfer unit 9 as compared to the case of forming the second vertical transfer unit 9 using a same n-type impurity concentration as the pixel repetition unit 5. Thus, a large potential difference from the fifth vertical transfer unit 11 to the horizontal transfer unit 2 is possible, thereby improving the transfer efficiency. Details of the configuration will be described below.
A sixth feature of the present embodiment is that the n-type impurities-doped region is provided in the second vertical transfer unit 9 while n-type impurity concentration of the n-type impurities-doped region is lower than n-type impurity concentrations of the pixel repetition unit 5 and the transfer control unit 6 which are cited as the fifth feature. This increases a potential difference between the transfer control unit 6 and the fourth vertical transfer unit 10, thereby improving transfer efficiency at the transfer control unit 6 and the fourth vertical transfer unit 10. Alternatively, the p-type impurities-doped region is provided in the transfer control unit 6 while the n-type impurity concentration in the second vertical transfer unit 9 is low, so that the electric potential of the transfer control unit 6 is shallower than the electric potential when the pixel repetition unit 5 is expanded in the horizontal direction. This allows a large potential difference between the transfer control unit 6 and the fourth vertical transfer unit 10, thereby improving the transfer efficiency at the transfer control unit 6 and the fourth vertical transfer unit 10.
In the solid-state imaging device 50, transfer pulses φVST-L, φVST-C, and φVST-R are applied to the signal charge storage electrodes 7. Moreover, transfer pulses φVHLD-L, φVHLD-C, and φVHLD-R are applied to the transfer blocking electrodes 8. In
Hereinafter, an operation of the solid-state imaging device 50 configured as described above will be described.
First, an operation of the solid-state imaging device 50 in a normal mode will be described.
As shown in
Moreover, in the embodiment 1 of the present invention, the case is shown where the number of drive phases of the first vertical transfer units 1 is 12. In this case, in the horizontal transfer period, the signal charges are stored by eight of the first vertical transfer electrodes 4. Moreover, in
First, the solid-state imaging device 50 transfers the signal charges to the signal charge storage electrode 7 on each column. Specifically, at a time t0 shown in
Next, during a period from a time t1 to a time t2, the solid-state imaging device 50 maintains, at the low level, φVHLD-L and φVHLD-R, which are applied to the transfer blocking electrodes 8 on the columns L and R, respectively, and thereby the signal charges are retained by the signal charge storage electrodes 7. Moreover, the solid-state imaging device 50 transitions φVHLD-C, φVL2, and φVL, which are applied to the transfer blocking electrode 8 on the column C, the fourth vertical transfer electrode 12, and the vertical final electrode 13, respectively, to the middle level or a high level. Accordingly, the solid-state imaging device 50 transfers the signal charges on the column C to the horizontal transfer unit 2 (
Then, the solid-state imaging device 50 transfers the signal charges in the horizontal transfer unit 2 to the output unit to output the signal charges on the column C. In
Next, in a period from a time t3 to a time t4, the solid-state imaging device 50 maintains, at the low level, φVHLD-L which is applied to the transfer blocking electrode 8 on the column L to retain the signal charges on the column L by the signal charge storage electrode 7. Moreover, the solid-state imaging device 50 transitions φVHLD-R, φVL2, and φVL that are applied to the transfer blocking electrode 8 on the column R, the fourth vertical transfer electrode 12, and the vertical final electrode 13, respectively, to the middle level or the high level. Accordingly, the solid-state imaging device 50 transfers the signal charges on the column R to the horizontal transfer unit 2 (
Subsequently, in a period from a time t5 to a time t6, the solid-state imaging device 50 transitions φVHLD-L, φVL2, and φVL that are applied to the transfer blocking electrode 8 on the column L, the fourth vertical transfer electrode 12, and the vertical final electrode 13, respectively, to the middle level or the high level to transfer the signal charges on the column L to the horizontal transfer unit 2 (
The above-described operation allows a line of the signal charges to be outputted and the remaining signal charges to be sequentially outputted by the same operation.
Next, an operation of the solid-state imaging device 50 in a video mode will be described.
The solid-state imaging device 50 in the video mode performs a 3-pixel summing on the signal charges which are adjacent to one another in the horizontal direction and have a same color. Similarly to the normal mode, in a horizontal blanking period shown in
First, as indicated at a time to in
Next, in a period from a time tb to a time tc, the solid-state imaging device 50 maintains, at the low level, φVHLD-L and φVHLD-R which are applied to the transfer blocking electrodes 8 on the columns L and R, respectively, and thereby the signal charges are retained by the signal charge storage electrode 7. Moreover, the solid-state imaging device 50 transitions φVHLD-C, φVL2, and φVL, which are applied to the transfer blocking electrode 8 on the column C, the fourth vertical transfer electrode 12, and the vertical final electrode 13, respectively, to the middle level or the high level. Accordingly, the solid-state imaging device 50 transfers the signal charges on the column C to the horizontal transfer unit 2 (
Then, in a period from a time tc to a time td, the solid-state imaging device 50 transfers the signal charges in the horizontal transfer unit 2 in the left direction by three columns (
Subsequently, in a period from a time te to a time tf, the solid-state imaging device 50 transitions φVHLD-L and φVHLD-R that are applied to the transfer blocking electrodes 8 on the columns L and R, respectively, φVL2 applied to the fourth vertical transfer electrode 12, and φVL applied to the vertical final electrode 13, to the middle level or the high level. Accordingly, the solid-state imaging device 50 transfers the signal charges on the columns L and R to the horizontal transfer unit 2, thereby summing the signal charges of three pixels (
Moreover, the solid-state imaging device 50 is provided with a plurality of readout electrodes in the first vertical transfer units 1, and performs the 3-pixel summing in the first vertical transfer units 1 by devising how to drive the plurality of readout electrodes. Thus, the solid-state imaging device 50 achieves the operation of a 9-pixel summing in combination with the aforementioned summing of the three horizontal pixels. The example is aforementioned in which, as the operation of summing the horizontal signals, the signal charges on the column C are first transferred and added together with the signal charges on the columns L and R in the horizontal transfer unit 2. However, the signal charges on the columns L and R can first be transferred and then added together with the signal charges on the column C in the horizontal transfer unit 2.
Moreover, the case is shown in
Moreover, in the case of the three-phase drive, the horizontal transfer unit 2 may receive the signal charges from the second vertical transfer unit 9 after one or two of three horizontal transfer electrodes 14 have been brought to the high level. Moreover, in the case of the two-phase drive, the horizontal transfer unit 2 may receive the signal charges after one of two horizontal transfer electrodes 14 has been brought to the high level. As described above, the number of horizontal transfer electrodes 14 that can be set to the high level and the width of the electrodes in the horizontal blanking period vary depending on the number of drive phases. However, the structure, in which the first vertical transfer units 1 are grouped at the second vertical transfer unit 9, can advantageously accommodate a plurality of drive methods having different numbers of phases, by changing the width of the fifth vertical transfer units 11 and the layout of the fourth vertical transfer unit 10.
Operations of the first vertical transfer units 1, the transfer control unit 6, the second vertical transfer unit 9, and the horizontal transfer unit 2 are controlled by a drive unit not shown. That is, the aforementioned φV1 to φV12, φVST-C, φVST-L, φVST-R, φVHLD-C, φVHLD-L, φVHLD-R, φVL, φVL2, φH1 to φH4, and the like are generated by the drive unit. The drive unit may be included in the solid-state imaging device 50 or formed outside the solid-state imaging device 50.
Moreover, as the second feature of the present embodiment, three columns of the third vertical transfer units 6A in the transfer control unit 6 are disposed so as to have shorter repetition pitches B therebetween than repetition pitches B between the first vertical transfer units 1 of the pixel repetition unit 5. However, the repetition pitches B are not limited by the third vertical transfer unit 6A being disposed perpendicular to the horizontal transfer unit 2 as shown in
Here, the repetition pitch B is a distance between the centers, at any position in the vertical transfer direction, of adjacent two third vertical transfer units 6A among three columns of the third vertical transfer units 6A.
The solid-state imaging device 50 according to the embodiment 1 of the present invention may include all or any one or more of the first to sixth features described above.
Next, reasons why the solid-state imaging device 50 can improve the degradations of transfer from a VOG unit (the second vertical transfer unit 9) grouping the plurality of first vertical transfer units 1 to the horizontal transfer unit 2 will be described for each of the first to sixth features, with reference to the accompanying drawings.
First, effects will be described which are obtained by incorporating a configuration which is the first feature in which the second vertical transfer unit 9 has a region where the transfer width reduces from the transfer control unit 6 toward the horizontal transfer unit 2.
The solid-state imaging device 51 does not have the second feature and the third feature. That is, the repetition pitches B between three columns of the third vertical transfer units 6A are the same as the repetition pitches between the first vertical transfer units 1. Moreover, the solid-state imaging device 51 includes a second vertical transfer unit 9A instead of the second vertical transfer unit 9. In addition, one second vertical transfer electrode 12A to which φVOG is applied is formed above the second vertical transfer unit 9.
The above configuration allows the solid-state imaging device 51 to have the horizontal transfer unit 2 gently tapering along with the transfer direction, and thus prevents the electric potential from being shallow on the side of the horizontal transfer unit 2. Thus, the solid-state imaging device 50 can prevent the occurrence of the transfer degradations.
Next, effects will be described which are obtained by incorporating a configuration set forth as the second feature in which three columns of the first vertical transfer units 1 in the transfer control unit 6 are disposed so as to have shorter repetition pitches therebetween than repetition pitches between the first vertical transfer units 1 of the pixels repetition unit 5.
First, the potential distribution when the signal charges are transferred from the second vertical transfer unit 9A to the horizontal transfer unit 2 in the solid-state imaging device 51 shown in
The second vertical transfer unit 9A has a transfer width tapering along with the transfer direction, and thus the electric potential becomes shallower near the horizontal transfer unit 2. Moreover, in the case where the second vertical transfer unit 9A includes a first n-type impurities-doped region 15 and a second n-type impurities-doped region 16 as with the pixel repetition unit 5, the electric potential at application of a middle level voltage (for example, 0 V) is very deep. This reduces a difference in potential between the horizontal transfer unit 2 when a high level voltage is applied to the horizontal transfer electrodes 14 and the second vertical transfer unit 9A when a low level voltage is applied to the second vertical transfer unit 9A.
Because of this, a potential barrier is present as indicated by the dotted line in
In contrast, in the solid-state imaging device 52 which has the second feature as shown in
As shown in
In
Even in the case described above where the width of the second vertical transfer unit 9A tapers starting from points X (thick line) at a boundary between the third vertical transfer unit 6A and the second vertical transfer unit 9A at left and right end portions thereof, by having the second feature, an angle of tapering is similarly gentle and also the electric potential gradient is reduced. In this case, however, the electric potential near the points X of the second vertical transfer unit 9A reduces due to the effect of the surrounding P-type region. Thus, there is a concern that the transfer efficiency from the transfer blocking electrode 8 to the second vertical transfer unit 9A may be worsen. Preferably, the second vertical transfer unit 9A has a region that has a constant width on the side of the transfer control unit 6 so that the electric potential does not thus decrease.
Next, effects will be described which are the third feature and obtained by providing the fourth vertical transfer unit 10 and the fifth vertical transfer unit 11 with the fourth vertical transfer electrode 12 and the vertical final electrode 13, respectively, as independent electrodes.
Moreover,
As shown in
Here, in the solid-state imaging device 52 shown in
Therefore, the fourth vertical transfer electrode 12 and the vertical final electrode 13 are formed above the second vertical transfer unit 9 shown in
Moreover, as shown in
Next, effects will be described which are the fourth feature and obtained by forming a potential step in the fourth vertical transfer unit 10.
As shown in
Next, effects will be described which are a fifth feature and obtained by providing an impurities-doped region such that the second vertical transfer unit 9 has lower n-type impurity concentration than the first n-type impurities-doped region 15 and the second n-type impurities-doped region 16 which are included in the pixel repetition unit 5 and the transfer control unit 6, respectively.
Specifically, to suppress the reduction in handling quantity of electric charges and the transfer efficiency degradation due to the narrow channel effects in the pixel repetition unit 5, and also to ensure necessary handling quantity of electric charges using one electrode in the transfer control unit 6, for example, two n-type diffusion layers (the first n-type impurities-doped region 15 and the second n-type impurities-doped region 16) are used to form the first vertical transfer unit 1 and the third vertical transfer unit 6A. Moreover, for the n-type diffusion layer of the second vertical transfer unit 9, among the diffusion layers used to form the pixel repetition unit 5, a layer (the first n-type impurities-doped region 15) that is shared with the horizontal transfer unit 2 is used.
The solid-state imaging device 55 can form a shallow electric potential of the second vertical transfer unit 9 as shown in
Next, effects obtained by incorporating a sixth feature of the present embodiment will be described.
A first example of the sixth feature of the present embodiment is that a third n-type impurities-doped region 18 as shown in
In the solid-state imaging device 56 shown in
Moreover, as another example, in a solid-state imaging device 57 shown in
Moreover,
Here, in the solid-state imaging device 55 incorporating the fifth feature which is shown in
In contrast, the solid-state imaging devices 56 and 57 are provided the third n-type impurities-doped region 18 in the second vertical transfer unit 9 to ensure a sufficient potential difference between the transfer blocking electrode 8 and the fourth vertical transfer unit 10, provided that concentration of the third n-type impurities-doped region 18 is set lower than the concentration of the second n-type impurities-doped region 16. Accordingly, the solid-state imaging devices 56 and 57 ensure a sufficient potential difference also at a boundary between the horizontal transfer unit 2 and the second vertical transfer unit 9.
A second example of the sixth feature is that, as shown in
This allows the solid-state imaging device 58 to establish the electric potential of the transfer control unit 6 to be shallow by an amount indicated by H (H2-H1) as shown in
Moreover, the first vertical transfer units 1 have narrow widths and narrow electrode lengths as shown in
Moreover, the addition of the second p-type impurities-doped region 19 to establish a shallow electric potential of the transfer control unit 6 allows the solid-state imaging device 58 to establish a shallow electric potential below the second vertical transfer unit 9 as compared to the solid-state imaging devices 56 and 106. Thus, it is possible for the solid-state imaging device 58 to establish a large potential difference between a position below the vertical final electrode 13 and the horizontal transfer unit 2.
Here, the example is given in which the second p-type impurities-doped region 19 is further formed in addition to the configuration of the solid-state imaging device 57 shown in
Moreover, the n-type impurities-doped region and the p-type impurities-doped region are each a region formed by a single impurity implantation step. That is, forming a plurality of impurities-doped regions in a region (the first vertical transfer unit 1 or the like) is performing the impurity implantation on a region multiple number of times. Moreover, the types of the impurities and the impurities-implanted regions (the regions and the depths) in the multiple numbers of impurities implantations may be different or may be the same.
Moreover, as in the case of the embodiment 1 according to the present invention where the electrodes to which different transfer pulses are applied are disposed close to one another, if each electrode includes two layers, overlap between the electrodes impedes the wiring layout. Thus, preferably, the first vertical transfer electrodes 4, the signal charge storage electrodes 7, the transfer blocking electrodes 8, the fourth vertical transfer electrode 12, the vertical final electrode 13, and the horizontal transfer electrodes 14 are formed of a single layer.
As described above, according to the embodiment 1 of the present invention, in the configuration provided with the transfer control unit 6 which selectively controls transfer of the signal charges from the first vertical transfer unit 1 to the horizontal transfer unit 2, and the second vertical transfer unit 9, the solid-state imaging device can be achieved which allows the horizontal interlace achieving the suppression of the transfer degradations and the low power consumption and also allows the signal charge summing that is required in the video mode and the like.
The solid-state imaging device 60 shown in
The horizontal direction extension 20 extends the width of the fourth vertical transfer unit 10 in the horizontal direction on a side adjacent to the transfer control unit 6. The horizontal direction extension 20 extends a width I of the fourth vertical transfer unit 10 in the horizontal direction on the side adjacent to the transfer control unit 6 so as to be larger than a total length J of three columns of the first vertical transfer units 1 (the third vertical transfer unit 6A) in the horizontal direction (I>J). That is, a maximum transfer width of the second vertical transfer unit 9 is larger than a width between outer end portions of the first vertical transfer units 1 positioned outermost among the three columns of the first vertical transfer units 1.
Here, at end portions of the fourth vertical transfer unit 10, the electric potential is shallow as compared to the vicinity of the central portion of the fourth vertical transfer unit 10 due to the effects of the surrounding p-type impurities. Thus, there is a problem that in transferring the signal charges from the transfer control unit 6 to the fourth vertical transfer unit 10, electric field decreases at the end portions as compared to the central portion.
On the other hand, the solid-state imaging device 60 allows the electric potential to be deep at the end portions as well as the central portion by using the above-described configuration. This allows the solid-state imaging device 60 to suppress bad transfer of the signal charges from the transfer control unit 6 to the fourth vertical transfer unit 10. The above-described configuration is effective in particular in the solid-state imaging devices 55, 56, and 57 that are shown in
In the solid-state imaging device 60, an amount of tapering of the fourth vertical transfer unit 10 toward the horizontal transfer unit 2 is large, but which does not cause any problem in transferring the signal charges insofar as the potential step is provided in the fourth vertical transfer unit 10 as shown in the embodiment 1.
Moreover, the example is given in which the solid-state imaging device 50 further includes the horizontal direction extension 20. However, the solid-state imaging devices 51 to 58 according to the embodiment 1 may further include the horizontal direction extension 20.
In the embodiment 1, as with the columns R and L, the signal charge storage electrode 7 and the transfer blocking electrode 8 are disposed on the column C through which the signal charges are first transferred from the transfer control unit 6 to the horizontal transfer unit 2 in the normal mode and the video mode. However, on the column C through which the signal charges are first transferred, the signal charges are not necessarily retained. Thus, the same transfer pulse as the transfer pulse applied to the pixel repetition unit 5 can be applied to the electrodes of the transfer control unit 6 on the column C.
Specifically, in the normal mode, φVST-C and φV12 have the same drive timing as shown in
In addition, the third vertical transfer unit 6A on the column C is not required to retain the signal charges and therefore may have a narrow width as compared to the third vertical transfer units 6A on the columns R and L.
Therefore, as in the embodiment 1 described above, the solid-state imaging device 61 shown in
The third vertical transfer unit 6B includes solely the third vertical transfer electrode 7A to which V12 is applied. Moreover, the entire region below the third vertical transfer electrode 7A of the third vertical transfer unit 6B has a transfer width increasing from the first vertical transfer unit 1 toward the second vertical transfer unit 9.
As described above, the solid-state imaging device 61 utilizes the narrow channel effects thereby improving the transfer electric field. This allows the solid-state imaging device 61 to include on the column C one sheet of the vertical transfer electrode that has the electrode length combining the lengths of two sheets of the electrodes on the columns L and R.
If the drive timing in the video mode that is shown in
As described above, according to the embodiment 3 of the present invention, the solid-state imaging device 61 having a reduced number of independent electrodes in the transfer control unit 6 can be achieved.
In the configuration of the embodiment 3 according to the present invention, solely the third vertical transfer unit 6B is disposed on the column C. However, as shown in
Moreover, the configuration of the embodiment 3 according to the present invention may be applied to the solid-state imaging devices 51 to 58 according to the embodiment 1 and the solid-state imaging device 60 according to the embodiment 2.
As described in the embodiment 1, if it is difficult to transfer the signal charges from the transfer control unit 6 to the second vertical transfer unit 9, the improvement of the transfer is possible by using a drive shown in
In a horizontal transfer period for the signal charges on one of the three columns, a solid-state imaging device according to an embodiment 4 of the present invention transfers the signal charges on another column from the transfer control unit 6 to the fourth vertical transfer unit 10.
Here, the vicinity of the central portion of the fourth vertical transfer unit 10 has a deepest electric potential, and thus a potential difference between the third vertical transfer unit 6A and the fourth vertical transfer unit 10 on the column C is large. Therefore, large transfer electric fields of the third vertical transfer unit 6A and the fourth vertical transfer unit 10 on the column C can be ensured, and thus it is easier to transfer the signal charges on the column C than on outermost columns (the columns R and L).
Thus, for example, in the case of 3:1 interlace in which a line of signals is separated for every three signals and horizontally transferred, the signal charges on the center column C are transferred in a first horizontal blanking period, from the first vertical transfer unit 1 to the horizontal transfer unit 2 via the transfer control unit 6 and the second vertical transfer unit 9 as shown in
In the second horizontal blanking period, the signal charges on the column L are transferred from the signal charge storage electrode 7 to the transfer blocking electrode 8. Moreover, the horizontal transfer period for the column L is used to transfer the signal charges on the column L from the transfer blocking electrode 8 to the fourth vertical transfer unit 10. Moreover, signals on the column L are transferred to the horizontal transfer unit 2 in a third horizontal blanking period.
As described above, according to the embodiment 4 of the present invention, it is possible to transfer the signal charges in the third vertical transfer units 6A on the outermost columns on which the transfer failure is likely to occur, to the fourth vertical transfer unit 10 in the horizontal transfer period over a long period of time. Thus, the solid-state imaging device which suppresses the transfer failure can be achieved.
The present invention is also applicable to the case where a plurality of the horizontal transfer units 2 is provided. In particular, to achieve a mode requiring a high-speed signal output among video modes, for example, a video output at 30 frames/second for pixels (1920×1080) used for full HD video, it is important to reduce the horizontal transfer frequency by providing the plurality of horizontal transfer units 2. This allows the low voltage drive of the horizontal transfer units 2 while suppressing the bad transfer, and this is advantageous in achieving low power consumption. Moreover, an increase of output signal frequency can be suppressed and thus the timing setting for sample-and-hold in CDS (correlated double sampling) can be facilitated. Moreover, the present invention supports commercially available AFE (Analog Front End) chips, which advantageously allow a set to be readily configured and low cost. Furthermore, the frame rate for outputting a still image which is the normal mode can be improved and thus dark currents present in the first vertical transfer units 1 can be suppressed. Thus, noise reduction is also possible.
The solid-state imaging device 62 shown in
The first horizontal transfer unit 21 and the second horizontal transfer unit 22 are of the four-phase drive.
The first horizontal transfer electrode 24 and the second horizontal transfer electrode 25 are provided above and below the distribution transfer unit 23, respectively. Different transfer pulses φH1a and φH1b are applied to the first horizontal transfer electrode 24 and the second horizontal transfer electrode 25, respectively. Moreover, transfer pulses having the same phase and the same voltage are applied to the first horizontal transfer electrode 24 and the second horizontal transfer electrode 25 when horizontally transferring the signal charges. Moreover, to transfer the signal charges between the first horizontal transfer unit 21 and the second horizontal transfer unit 22 via the distribution transfer unit 23, it is required to establish a potential difference, and therefore different transfer pulses are applied to the first horizontal transfer electrode 24 and the second horizontal transfer electrode 25.
The horizontal transfer electrodes 14 are shared between the first horizontal transfer unit 21 and the second horizontal transfer unit 22, and φH2, φH3, and φH4 are applied to the horizontal transfer electrodes 14. Meanwhile, φHHT is applied to the distribution transfer electrode 26. The transfer control unit 6 is configured in units of four columns (from the left, the column L, a column CL, a column CR, and the column R). φST-L, φST-CL, and φST-R are applied to three signal charge storage electrodes 7 included in a unit of the transfer control unit 6 in order starting from a leftmost signal charge storage electrode in the unit. Moreover, φHLD-L, φHLD-CL, and φHLD-R are applied to three transfer blocking electrodes 8 included in a unit of the transfer control unit 6 in order starting from a leftmost transfer blocking electrode in the unit. Moreover, in the embodiment 5, a transfer pulse φVx which is the same pulse applied to the pixel repetition unit 5 is applied to the electrode on the column CR of the transfer control unit 6 as shown in the embodiment 3.
In the solid-state imaging device 62 according to the embodiment 5 of the present invention, four horizontal transfer electrodes 14 included in a packet correspond to four columns of the first vertical transfer units 1. That is, the solid-state imaging device 62 has a horizontal 4:1 interlace structure in which a line of signals are separated for every four signals and transferred.
Here, to generate data which corresponds to full HD videos and has (1920×1080) pixels using the structure and drive described in the embodiment 1 where the 3-pixel summing is performed in the horizontal direction, 5,760 pixels are required in the horizontal direction. Moreover, to support an aspect ratio 4:3 employed in digital still cameras, 4,320 pixels are required in the vertical direction. Thus, a total of about 25M pixels are required. However, the currently prevailing number of pixels is about 12M pixels to about 16M pixels, and thus the horizontal 2-pixel mixing is commonly used. Thus, the horizontal 2-pixel summing will be described for the case of outputting video in the present embodiment.
In the case of the horizontal 4:1 interlace, horizontal transfer is required four times if there is one horizontal transfer unit 2. On the other hand, in the solid-state imaging device 62 according to the embodiment 5, two horizontal transfer units are provided in parallel, and thus a line of the signal charges can be outputted by performing the horizontal transfer twice. Moreover, since two horizontal transfer units are provided in parallel, a line of the signal charges can be outputted by performing the horizontal transfer once in the case of the horizontal 2-pixel summing.
As described above, the solid-state imaging device 62 operating in the horizontally interlaced manner allows an increased length in the transfer direction of the horizontal transfer electrode. Furthermore, unlike in the two-phase drive conventionally used, the four-phase drive is applied to the solid-state imaging device 62, and therefore it is not necessary to form a barrier region below each horizontal transfer electrode. This allows the signal charges to be stored in all regions below the horizontal transfer electrodes. Thus, the widths of the horizontal transfer units 2 necessary to ensure the handling quantity of electric charges can be reduced. In particular, in the solid-state imaging device 62, the reduction of the widths of the first horizontal transfer units 21 is advantageous in facilitating the transfer of the signal charges from the first horizontal transfer unit 21 to the distribution transfer unit 23. Furthermore, the capacitance of the horizontal transfer electrode can largely be reduced. Thus, the solid-state imaging device 62 allows the reduction in capacitance of the horizontal transfer electrodes, reduction in voltage due to the use of the four-phase drive, and suppression of the increase in horizontal transfer frequency due to the use of parallel output, thereby achieving the low power consumption.
As shown in
The signal charges on the column CR are transferred to the first horizontal transfer unit 21 and further transferred from the first horizontal transfer unit 21 to the second horizontal transfer unit 22 via the distribution transfer unit 23 (
Next, the solid-state imaging device 62 transfers the signal charges on the column R to the first horizontal transfer unit 21 and then performs the first horizontal transfer of the signal charges to the output amplifier (
Then, the solid-state imaging device 62 transfers the signal charges on the column L to the first horizontal transfer unit 21, and further transfers the signal charges from the first horizontal transfer unit 21 to the second horizontal transfer unit 22 via the distribution transfer unit 23 (
Next, the distribution transfer between the horizontal transfer units shown in
In the first horizontal transfer unit 21, the first horizontal transfer electrode 24 to which φH1a is applied receives the signal charges transferred from the vertical final electrode 13. Thus, in the horizontal blanking period, φH1a is first brought to the high level, and then φVL which is applied to the vertical final electrode 13 is brought to the middle level at a time t11. That is, it is desirable that φHHT which is applied to the distribution transfer electrode 26 is brought to the high level and φH1b which is applied to the second horizontal transfer electrode 25 is brought to also the high level at a time t10 which is prior to a time (the time t11) at which the signal charges are transferred below the vertical final electrode 13 from an imaging unit side. This forms a transfer path to the second horizontal transfer electrode 25 for the signal charges by a time (the time t11) at which the vertical final electrode 13 has been brought to the middle level.
Then, by sequentially bringing φVL, φH1a, and φHHT to the low level at a time t12, a time t13, and a time t14, respectively, the signal charges are transferred below the second horizontal transfer electrode 25 to which φH1b remaining at the high level is being applied. This is the end of the operation of transferring the signal charges from the vertical final electrode 13 to the second horizontal transfer unit 22.
The transfer pulse φHHT applied to the distribution transfer electrode 26 remains at the low level even in the subsequent horizontal transfer period. This prevents the signal charges transferred to the second horizontal transfer unit 22 from mixing with the signal charges to be transferred subsequently from the vertical final electrode 13 to the first horizontal transfer unit 21.
Moreover, φH1a applied to the first horizontal transfer electrode 24 which receives again the signal charges is transitioned to the high level at a time t15, φVL applied to the vertical final electrode 13 is transitioned to the middle level at a time t16, and then φVL is transitioned to the low level at a time t17. This is the end of the operation of transferring the signal charges from the vertical final electrode 13 to the first horizontal transfer unit 21. Moreover, the solid-state imaging device 62 thereafter transfers the signal charges horizontally.
Moreover, as shown in
Next, an operation of the solid-state imaging device 62 in the video mode will be described.
The solid-state imaging device 62 in the video mode performs the 2-pixel summing on the signal charges which are adjacent to each other in the horizontal direction and have a same color.
First, as shown in
Moreover, the signal charges obtained by summing the signal charges on the columns CR and L that have been transferred to the first horizontal transfer unit 21 are transferred to the second horizontal transfer unit 22 via the distribution transfer unit 23.
Next, as shown in
The operation performed as described above is the end of summing, in the horizontal direction, two pixels having a same color. Then, the signal charges are transferred horizontally once to sequentially output to the output amplifier a line of the signal charges obtained by summing the two horizontal pixels.
As described above, the solid-state imaging device 62 according to the embodiment 5 of the present invention can reduce the inter-capacitance between the horizontal transfer electrodes by operating in the horizontally interlaced manner, and suppress the increase of the horizontal transfer frequency by transferring the signal changes in parallel using two horizontal transfer units. Furthermore, by employing the four-phase drive, the solid-state imaging device 62 can reduce the width of the horizontal transfer units and drive the horizontal transfer units at low voltages, thereby achieving the low power consumption. Furthermore, the solid-state imaging device 62 can support videos having a large number of pixels and reduce the transfer failure between the horizontal transfer units.
Moreover, the solid-state imaging device according to the embodiments 1 to 5 is implemented as an LSI which is an integrated circuit.
The solid-state imaging device according to the embodiments of the present invention has been described above. The present invention, however, is not limited to the embodiments described above.
For example, while corners and sides of each component are depicted in a linear manner in the figures, for manufacturing reasons, components having rounded corners and rounded lines are also included in the present invention.
Moreover, at least part of the functionality of the solid-state imaging devices according to the embodiments 1 to 5 and part of the functionality of each modification may be combined.
Moreover, numerals used in the above are merely illustrative for specifically describing the present invention and the present invention is not limited thereto.
Moreover, the present invention may be implemented as a camera such as digital still cameras or digital video cameras which includes any of the solid-state imaging devices according to the embodiments 1 to 5 and the modification thereof.
Moreover, the present invention may be implemented as a solid-state imaging device driving method for driving the solid-state imaging devices according to the embodiments 1 to 5, and the modification thereof.
The present invention is applicable to solid-state imaging devices and is useful in particular as solid-state imaging devices for digital still cameras.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-004418 | Jan 2010 | JP | national |
This is a continuation application of PCT Patent Application No. PCT/JP2010/006177 filed on Oct. 19, 2010, designating the United States of America, which is based on and claims priority of Japanese Patent Application No. 2010-004418 filed on Jan. 12, 2010. The entire disclosures of the above-identified applications, including the specifications, drawings and claims are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2010/006177 | Oct 2010 | US |
| Child | 13546798 | US |
