JP3050223B2 - Solid-state imaging device and driving method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device and a driving method thereof, and more particularly, to a solid-state imaging device using an all-pixel read-out solid-state imaging device that collectively reads out signal charges of unit pixels and a driving method thereof. About.

[0002]

2. Description of the Related Art A conventional solid-state imaging device of this type includes:
This will be described with reference to FIGS. FIG. 9 is a diagram showing the overall configuration of a conventional all-pixel readout solid-state imaging device. Referring to FIG. 9, the solid-state imaging device shown in FIG. 9 includes a photoelectric conversion region (RGB Bayer array type filter) 6 for converting light into signal charges, an optical black level region 7 serving as a reference level of an image, A vertical surplus charge sweeping drain 1 and a horizontal surplus charge sweeping drain 2 for sweeping out surplus charges, and an input diode 3 capable of forcibly inputting a signal
, Horizontal transfer register 5, output amplifier 4, and FIG.
The vertical transfer register 8 shown in FIG.

The operation of a solid-state imaging device using the above-described solid-state imaging device will be described below with reference to FIG. The vertical transfer register transfer electrode is shown in FIG.
As shown in (a), the electrodes φV1 and φV
V2, φV3, and φV4. And
The signal charge of the unit pixel is read out at φV3 and stored under two of the four electrodes. FIG. 10 (b)
4 shows a timing chart of drive pulses applied to each of the four electrodes. This solid-state imaging device is a four-phase drive in which the solid-state imaging device is driven by four different pulses. However, regarding the signal charge readout electrode of each pixel, it is considered that the one-phase drive in which pixels in which charge readout is repeatedly performed by the combination of the same one kind of pulse (φV1, φV2, φV3, φV4) is performed. I can say. In the following description, for ease of understanding, reference numerals φV1, φV2,..., ΦVn represent electrodes or drive pulses applied to the electrodes in a one-to-one correspondence.

FIG. 10 (c) shows how the charges move when reading and transferring the signal charges from the unit pixels, corresponding to the unit pixels. Here, from time t1 to time t
2 respectively correspond to FIG. The signal charge photoelectrically converted by the photodiode of the unit pixel is at time t.
1 and read out to the electrode φV3,
It is stored under V4. The pulse φV1 is turned on at time t2 and then turned off at time t3, whereby one electrode is transferred. By repeating this operation, the signal charges are sequentially transferred, and at time t9, the unit pixels are transferred.

Here, by changing the driving pulse, the number of signal charges is swept away by っ て in the vertical direction and only １ ／ is used as the signal charge to convert the vertical resolution to １ ／. A method for performing the above will be described. FIG. 11 shows all pixels, a pixel area 11 to be swept away in a vertical half,
2 shows a pixel region 12 used as 1/2 signal charge. FIGS. 12A and 12B show driving pulses applied to the electrodes φV1, φV2, φV3, φV4 of the vertical transfer register and the electrodes φH1, φH1 of the horizontal transfer register, respectively.
The drive pulses respectively applied to φH2 are shown.

First, at time t1 in FIGS. 12 (a) and 12 (b)
In, the signal charge is read out to the vertical transfer register by a read pulse. Next, between time t2 and t3,
At a transfer rate for transferring all the pixels, the signal charge area 12 in the vertical direction 示 す shown in FIG. 11 is transferred to the horizontal transfer register. Then, the signal charges in the area 11 to be swept away in the vertical half in FIG. 11 are horizontally transferred by the vertical high-speed drive pulse shown at time t3 to t4 in FIG. 12B until the next frame starts. High-speed transfer to the register. The signal charges transferred at a high speed are discarded by a surplus charge discharging drain 2 formed below the horizontal transfer register. Note that the destination of discharging the electric charge is not limited to the surplus electric charge discharging drain 2 formed below the horizontal transfer register, and the high-speed transfer to the output circuit 4 may be performed by the horizontal transfer register.
At this time, the unused signal charges are not used for the image, and are the same as those that have been swept away. Alternatively, the unused signal charges in the vertical transfer register may be reversely transferred at high speed to the surplus charge discharging drain 1 on the upper side of the vertical transfer register and on the side opposite to the horizontal transfer register, and may be discarded.

FIGS. 13 to 20 show another method of sweeping out signal charges. FIG. 13 shows a case in which the upper half signal charges are used in the vertical direction and the lower half is swept away. On the other hand, FIG. 14 shows a case where the left half signal charge in the horizontal direction is used and the right half is swept away.
FIG. 15 shows a case where the right half in the horizontal direction is used and the left half is swept away. In addition, the horizontal direction and the vertical direction may be combined. FIG. 16 shows that the upper 1/4 and the lower 1/4 in the vertical direction are swept away, and the left 1/4 and the right 1/4 in the horizontal direction are removed. 4 shows a case in which the central portion of all pixels is used as signal charges by sweeping away 4 and 4. FIG.
Shows a case where the upper half of the vertical direction and the right half of the horizontal direction are swept away and the lower left of all pixels is used as signal charges. FIG. 18 shows a case in which the upper half and the left half in the vertical direction are swept away, and the lower right of all pixels is used as signal charges. FIG. 19 shows the lower half of the vertical direction and the lower right half of the horizontal direction.
2 shows a case where 2 is swept away and the upper left of all pixels is used as signal charges. FIG. 20 shows a case where the lower half of the vertical direction and the left half of the horizontal direction are swept away and the upper right of all the pixels is used as the signal charge.

Both methods are basically the same, and the signal charges to be used are transferred at high speed in the vertical and horizontal transfer registers, so that the signal charges are swept out to the drain or are not used. .

[0009]

In the conventional driving method of the solid-state image pickup device described above, it is necessary to sweep out the signal charges other than the selected necessary signal charges. Therefore, the signal is wasted. Further, since only a part of all pixels is used as signal charges, the size of the image becomes smaller than that when all pixels are used, and the angle of view changes. In addition, the drive circuit must have a high capacity for high-speed transfer due to the sweeping out of signal charges, and power consumption cannot be reduced as a solid-state imaging device. Therefore, there is a problem that a load is imposed on the design of the element, and the yield rate is reduced.

[0010]

SUMMARY OF THE INVENTION The present invention provides first, second, and third aspects.
A first transfer register provided adjacent to the first to fourth pixels, a first transfer register provided adjacent to the first to fourth pixels, and a first transfer register provided adjacent to the first to fourth pixels. A transfer electrode for reading out electric charges at first to fourth positions of a first transfer register adjacent to the pixel, and the electric charges read out to the first transfer register are transferred from the fourth position to the first position. In a method for driving a solid-state imaging device transferred toward a position,
At the timing, the charge of the third pixel is read out to the third position, the charge of the third pixel is transferred from the third position to the second position at the second timing, and the charge of the first pixel is transferred to the third position. 1
And the electric charge of the fourth pixel is read to the fourth position, and the electric charge of the third pixel is read at the third timing to the second position.
And the charge of the fourth pixel is transferred from the fourth position to the third position, and the charge of the second pixel is read to the second position.

Further, the above-mentioned solid-state imaging device further has a second transfer register for receiving charges output from the first position of the first transfer register, and charges of the third pixel are discharged at a third timing. It is characterized by being held in a second transfer register.

Further, according to a preferred embodiment of the present invention, the charge of the first pixel, the charge of the third pixel, the charge of the second pixel, and the charge of the fourth pixel are stored in the second transfer register. Each is added.

Further, the solid-state imaging device according to the present invention has a first
A first pixel that is provided adjacent to the first pixel, a second pixel that is provided adjacent to the first pixel, and a first color that is provided adjacent to the second pixel. Third
Pixel, a transfer register that accumulates the charges of the first to third pixels at the first to third positions provided adjacent to each other, and the first drive pulse becomes the first level. A first transfer electrode for reading the charge of the third pixel to a third position of the transfer register; and a charge of the first pixel when the second drive pulse goes to the first level.
And a second transfer electrode to be read out at a position of the second drive pulse, wherein the second drive pulse changes from the second level to the first level after the first drive pulse changes from the first level to the second level The transfer register transfers the charge of the third pixel accumulated at the third position to the second position when the first drive pulse changes from the first level to the second level. I do.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an electrode configuration of a vertical transfer register in the solid-state imaging device according to the first embodiment. FIG. 2A shows a timing chart of driving pulses applied to each electrode of the vertical transfer register.
(B) shows how signal charges are read and rearranged. FIG. 3 shows how the original image is converted to a vertical resolution of そ れ ぞ れ.

Referring to FIG. 1, the solid-state imaging device used in this embodiment has a color filter configuration of an RGB Bayer array type, and has φV1, φV2, φV3A, φV3B, φV3.
It is driven by six-phase pulses of C and φV4. However, when reading the signal charge from the photodiode 9 to the charge transfer unit, as shown in the figure, (φV1, φV2, φV
3A, φV4), a pixel from which charge reading is performed by a combination of pulses, (φV1, φV2, φV3B, φV4), a pixel from which charge reading is performed,
V1, φV2, φV3C, φV4), three types of pixels from which charge is read out by a combination of pulses are periodically arranged. In other words, it can be said that the combination of the pulses for signal reading is three types of three-phase driving.

Hereinafter, addition of signal charges in the present embodiment will be described. Referring to FIG. 2, signal charge R31 read into the vertical transfer register at time t1 is:
At time t2, the data is transferred to the position of the unit pixel G21. At the same time, the signal charges R11 and G41 are read. At time t3, the signal charges R11, R31, and G41 are respectively transferred to the positions of the unit pixels OB, R11, and R31, and at the same time, the signal charges G21 are read. From below, R1
The pixels in the order of 1, G21, R31, and G41 are rearranged by the read and transfer method, as shown in FIG. 3, in the order of vertical signal data R11, R31, G21, and G41. That is, the signals of the pixels of the same type of color filter arranged at a distance of one pixel are rearranged so as to be adjacent to each other.

Further, as shown in FIG. 4, the rearranged signal charges are transferred by two lines within a horizontal blanking period, and
11 + R31, G21 + G41, so that the signal charges of the pixels of the same type of filter are added by the horizontal transfer register, and the signals of the pixels separated by one pixel in the horizontal direction are also determined by an external circuit or image processing software. By rearranging them so that they are adjacent to each other and taking the sum of the pixel signals of the same type of filter, an image having a vertical and horizontal resolution of で き る can be obtained. This series of situations,
FIG. 5 shows division diagrams (a), (b), and (c) in this order.

At this time, unlike the conventional method of driving the solid-state imaging device according to the conventional technique, since a certain area of all pixels is not swept away, the resolution is reduced to に without changing the angle of view at all. Is converted. In other words, this is the same as using a solid-state imaging device having both vertical and horizontal pixels of 1/2 without changing the angle of view. For example, conversion between VGA and SIF of the computer display standard can be easily performed. . In this case, since the original four pixels are added and treated as one pixel, the sensitivity is four times and the saturation output is also four times.
Therefore, if the standard output setting in the image at the time of switching is the same as that of the original image, the dynamic range becomes four times the original image. If an electronic shutter is used in combination and the accumulation time of the photodiode is reduced to 1/4, it can be handled in the same manner as the original image.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows an electrode configuration of a vertical transfer register in a solid-state imaging device according to the second embodiment. FIG. 7 shows a timing chart of driving pulses applied to each electrode of the vertical transfer register at the top,
The manner in which signal charges are read and rearranged is shown at the bottom of the page. FIG. 8 shows how the original image is converted to a vertical resolution of 1/3.

Referring to FIG. 6, the solid-state imaging device according to the present embodiment also has a color filter configuration of an RGB Bayer array type, and includes φV1, φV2, φV3A, φV3B, φB3C,
It is driven by seven-phase pulses of φV3D and φV4. However,
The reading of the signal charge from the photodiode to the charge transfer unit is similar to (φV1, φV2, φV3A, φV
4) a pixel from which charge reading is performed by a combination of pulses, (φV1, φV2, φV3B, φV4), a pixel from which charge reading is performed, and (φV1, φ
V2, φV3C, φV4), and three types of pixels (φV1, φV4) from which charge is read out by a combination of pulses
2, .phi.V3D, .phi.V4), the pixels from which the electric charge is read out by the combination of the pulses are periodically arranged. That is, the combination of pulses for signal reading is 4
It can be said that this is a three-phase drive.

Hereinafter, addition of signal charges in the present embodiment will be described. Referring to FIG. 7, signal charge R5 read into the vertical transfer register at time t1
1 is transferred to the position of the unit pixel G41 at time t2. At the same time, the signal charges R31 and G61 are read. By the time t3, the charges R31, R51, and G61 are respectively transferred to the positions of the unit pixels G21, R31, and R51, and at the same time, the signal charges R11 are read. Further, the charges R11, R31, R51, and G6 by time t4.
1 is transferred to the positions of the unit pixels OB, OB, R11, R31, respectively, and at the same time, the signal charges G41, G21 are read, respectively. R11, G21, R3 from below
The pixels in the order of 1, G41, R51, and G61 are read out and transferred to R11, R31, R51, and G2.
1, G61, and G41. This is shown in FIG.
As shown in the figure, 3 times in the vertical direction during the horizontal blanking period.
Lines are transferred, and R11, R31,
By adding R51 and adding G21, G41, and G61, the resolution in the vertical direction becomes 1 without changing the angle of view.
/ 3.

It should be noted that, although the example of color has been described so far, the resolution can be switched without changing the angle of view even in the case of black and white.

[0023]

As described above, the present invention uses an all-pixel readout type solid-state imaging device, has three or more readout electrodes, and applies three drive pulses to each readout electrode as a solid-state imaging device. As the phase or more, the signal charges in the vertical direction are rearranged by driving. Thus, the resolution can be switched without changing the angle of view.

According to the present invention, the sensitivity and the saturation output can be significantly improved by taking the sum of the rearranged signal charges when the resolution is switched.
When an electronic shutter is used together, it is possible to switch the image angle of view and the resolution without changing the sensitivity and the dynamic range.

The present invention is applicable to all types of solid-state imaging devices equipped with an all-pixel readout type solid-state imaging device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an electrode configuration of a vertical transfer register of a solid-state imaging device according to a first embodiment of the present invention.

FIGS. 2A and 2B are a timing chart of a driving pulse according to the first embodiment and a diagram showing a transfer state of signal charges.

FIG. 3 is a diagram showing how an original image is converted to a vertical resolution of に お い て in the first embodiment.

FIG. 4 is a diagram illustrating a timing diagram of a driving pulse and a transfer state of a signal charge according to the first embodiment.

FIG. 5 is a diagram showing how vertical and horizontal resolutions are converted to １ ／ in the first embodiment.

FIG. 6 is a diagram illustrating an electrode configuration of a vertical transfer register of a solid-state imaging device according to a second embodiment of the present invention.

FIGS. 7A and 7B are a timing chart of a driving pulse and a diagram showing a transfer state of a signal charge in the second embodiment.

FIG. 8 is a diagram showing a state in which an original image is converted to a vertical resolution of 1/3 in the second embodiment.

FIG. 9 is a diagram illustrating a configuration of an example of a solid-state imaging device in a solid-state imaging device according to a conventional technique, and a diagram illustrating an electrode configuration of a vertical transfer register.

10A and 10B are a timing chart of a pulse for driving a conventional solid-state imaging device and a diagram showing a transfer state of signal charges.

FIG. 11 is a diagram for explaining a first method of resolution switching in a conventional solid-state imaging device.

FIG. 12 is a timing chart of driving pulses and a diagram showing a transfer state of signal charges in a first method of resolution switching.

FIG. 13 is a diagram for explaining a second method of resolution switching in a conventional solid-state imaging device.

FIG. 14 is a diagram for explaining a third method of resolution switching in a conventional solid-state imaging device.

FIG. 15 is a diagram for explaining a fourth method of resolution switching in a conventional solid-state imaging device.

FIG. 16 is a diagram for explaining a fifth method of resolution switching in a conventional solid-state imaging device.

FIG. 17 is a diagram for explaining a sixth method of resolution switching in a conventional solid-state imaging device.

FIG. 18 is a diagram for explaining a seventh method of resolution switching in a conventional solid-state imaging device.

FIG. 19 is a diagram for explaining an eighth method of resolution switching in a conventional solid-state imaging device.

FIG. 20 is a diagram for explaining a ninth method of resolution switching in a conventional solid-state imaging device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Vertical excess charge drain 2 Horizontal excess charge drain 3 Input diode 4 Output amplifier 5 Horizontal transfer register 6 Photoelectric conversion area 7 Optical black level area 8 Vertical transfer register 9 Photodiode 11 Area to be discarded 12 Area to be used as signal charge

Claims (4)

(57) [Claims] 1. A first to a fourth pixel provided side by side in a first, second, third, and fourth order, and a first pixel provided adjacent to the first to fourth pixels. A transfer register, and transferring the charge of the first to fourth pixels to the first pixel adjacent to the pixel.
And a transfer electrode to be read out at each of the first to fourth positions of the transfer register, and the charge read out to the first transfer register is transferred from the fourth position toward the first position. A method for driving a solid-state imaging device, comprising reading out the charge of the third pixel at a first timing to the third position, and reading the charge of the third pixel at a second timing at the third position. From the first pixel to the second position, and further reads the charge of the first pixel to the first position and reads the charge of the fourth pixel to the fourth position. Transfer the charge of the pixel from the second position to the first position and transfer the charge of the fourth pixel from the fourth position to the third position, and further transfer the charge of the second pixel Read out to the second position. The driving method of the image device. 2. The solid-state imaging device further includes a second transfer register that receives a charge output from a first position of the first transfer register, and the second transfer register receives the charge at the third timing. 2. The method according to claim 1, wherein electric charges are held in the second transfer register. 3. The charge of the first pixel and the charge of the third pixel, and the charge of the second pixel and the charge of the fourth pixel are added by the second transfer register, respectively. 3. The driving method for a solid-state imaging device according to claim 2, wherein: 4. A first pixel indicating a first color, a second pixel indicating a second color provided adjacent to the first pixel, and an adjacent pixel adjacent to the second pixel. A third pixel provided for displaying the first color, a transfer register for accumulating electric charges of the first to third pixels at first to third positions provided adjacent to each other, A first transfer electrode for reading out the electric charge of the third pixel to a third position of the transfer register when the drive pulse of the first level is at the first level, and the second drive pulse is at the first level. And a second transfer electrode for reading out the charge of the first pixel to a first position of the transfer register when the first drive pulse is applied. After changing from the first level to the second level, the second level changes to the second level. Changes to the level of the transfer register and the second the first drive pulse from the first level
Wherein the charge of the third pixel accumulated at the third position is transferred to the second position when the level changes to the second position.