JP2001352490A - Image pickup element and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup element and an image pickup device, that are especially applied to a case with acquiring an image pickup result, having a wide dynamic range so as to effectively avoid deterioration in S/N at medium luminance level. SOLUTION: In this invention, a charge storage section 13 that temporarily stores transfer charges for a period in response to a ratio of a long exposure time to a short exposure time is placed between a 1st transfer register, such as a vertical transfer register 3 and a 2nd transfer register, such as a horizontal transfer register 4 and the image pickup result with high and low sensitivity is repeatedly outputted, even if the image pickup with the high sensitivity or the image pickup with the low sensitivity is switched within a video time period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device and an image pickup apparatus, and can be applied particularly to a case where an image pickup result having a wide dynamic range is obtained. The present invention relates to the first
For example, between a vertical transfer register which is a transfer register and a horizontal transfer register which is a second transfer register,
Switching between high-sensitivity imaging and low-sensitivity imaging within the video period by arranging a charge accumulation unit that temporarily holds the transfer charge during a period according to the long exposure time and the short exposure time Even so, it is possible to repeatedly output high-sensitivity and low-sensitivity imaging results, thereby effectively avoiding deterioration of the S / N ratio at a medium luminance level.

[0002]

2. Description of the Related Art Hitherto, a method of synthesizing an image having a wide dynamic range by synthesizing imaging results with different sensitivities in an imaging apparatus has been proposed. There has been proposed a method of imaging by switching the sensitivity in units of fields, a method of acquiring imaging results having different sensitivities by two imaging systems, and a method of switching the sensitivity in units of pixels by disposing filters.

Here, a method of imaging by switching the sensitivity on a field basis is, for example, a method of alternately repeating imaging with a short charge accumulation time and imaging with a long charge accumulation time. In this method, it is relatively simple. Although a low-sensitivity imaging result and a high-sensitivity imaging result can be obtained by a simple configuration, there is a disadvantage that the time resolution is reduced by combining the low-sensitivity imaging result and the high-sensitivity imaging result from different fields. is there.

[0004] On the other hand, a method of acquiring an imaging result by two imaging systems and synthesizing an image having a wide dynamic range is a method of obtaining a low-sensitivity imaging result and a high-sensitivity imaging result by different imaging systems. In this method, there is a disadvantage that the entire configuration is complicated due to the necessity of two imaging systems, and a high accuracy is required for the alignment of the two imaging systems. There are disadvantages that need to be addressed.

On the other hand, the method of switching the sensitivity on a pixel-by-pixel basis by arranging the filters is such that filters having different transmittances are regularly arranged in each pixel of the image sensor.
This is a method for obtaining a low-sensitivity imaging result and a high-sensitivity imaging result corresponding to the difference in transmittance. In the case of this method,
Although a relatively simple configuration can provide a low-sensitivity imaging result and a high-sensitivity imaging result, there is a disadvantage that the resolution, which is the spatial resolution, is reduced.

As a method for solving these drawbacks, there has been proposed a method using an all-pixel read-out IT-CCD having a vertical transfer register twice as many as the number of effective photoelectric conversion elements.

FIG. 8A is a plan view showing a schematic configuration of an all-pixel read-out IT-CCD applied to this method. In the all-pixel read-out type IT-CCD 1, photodiodes 2 serving as photoelectric conversion units constituting pixels are arranged in a matrix. In this photodiode 2, incident light is photoelectrically converted for a predetermined charge accumulation time and converted into an incident light amount. The corresponding charge is stored. Vertical transfer register 3
Are arranged between the photodiodes 2, receive the accumulated charges from the adjacent photodiodes 2, and sequentially transfer the accumulated charges to the horizontal transfer register 4. Horizontal transfer register 4
Outputs the accumulated charges transferred from the vertical transfer register 3 to the amplifier circuit 5 sequentially.

[0008] The all-pixel read-out type IT-CCD 1 transfers the accumulated charges of two pixels adjacent in the vertical direction according to the evenness of the frame when the accumulated charges are transferred in the vertical direction by the vertical transfer register 3 in this manner. Are added, thereby generating an interlaced imaging result. Further, when the accumulated charge for one pixel is transferred to the horizontal transfer register 4 by the vertical transfer register 3 in the vertical direction, the accumulated charge thus transferred is driven to transfer one line in the horizontal direction. Outputs the imaging result by the method.

Such an all-pixel read-out IT-CCD
In the case of acquiring a high-sensitivity imaging result and a low-sensitivity imaging result at short time intervals according to 1, as shown in FIGS. 8B and 8C, accumulated charge is accumulated between video periods, At the end time point t1-1, for example, the accumulated charge of the odd-numbered line is transferred to the odd-numbered register 3a of each vertical transfer register 3. At the subsequent time point t1-2, the stored charges transferred in this manner are transferred by one pixel toward the horizontal transfer register 4. At the subsequent time point t1-3, the stored charges of the even lines remaining are stored in the even number lines of the vertical transfer register 3. The third register 3b
Transfer to This enables all-pixel readout IT-CCD
1 adds the photoelectric conversion results of two pixels adjacent in the vertical direction in the even-numbered register 3b of the vertical transfer register 3,
The high-sensitivity imaging result corresponding to the interlace method is held in the even-numbered register 3b of the vertical transfer register 3.

In the subsequent vertical blanking period V.V. BLK
During the vertical blanking period V.D. At the end time t2-1 of the BLK, the vertical transfer register 3
Is transferred to the odd-numbered register 3a. At the subsequent time point t2-2, the accumulated charge transferred to the odd-numbered register 3a and the accumulated charge held in the even-numbered register 3b are transferred by one pixel toward the horizontal transfer register 4, and the subsequent time point t2-2. At t2-3, the remaining accumulated charges of the even-numbered line are transferred to the even-numbered register 3b of the vertical transfer register 3. Accordingly, the all-pixel read-out IT-CCD 1 adds the photoelectric conversion results of two pixels adjacent in the vertical direction by the even-numbered register 3 b of the vertical transfer register 3, and vertically converts the low-sensitivity imaging result corresponding to the interlace method. Even-numbered register 3 of transfer register 3
b and the corresponding high-sensitivity imaging result of the interlace method is held in the odd-numbered register 3a of the vertical transfer register 3.

In this method, in the following video period, the odd-numbered and even-numbered registers 3a and 3b
While sequentially transferring and outputting the high-sensitivity imaging results held by the photodiode 2 to the horizontal transfer register 4, the high-sensitivity imaging results for the subsequent fields are acquired by the photodiode 2. Thus, the all-pixel read-out IT-CCD 1 is configured to repeatedly output the imaging results obtained by time-division multiplexing the high-sensitivity and low-sensitivity imaging results in line units in field units.

The imaging apparatus separates the high-sensitivity imaging result and the low-sensitivity imaging result that are repeatedly obtained in this manner, and then corrects the signal level to combine them, thereby obtaining an imaging result having a wide dynamic range. Have been made to generate.

That is, in the high-sensitivity imaging result obtained by the long-time exposure obtained as described above, as shown in FIGS. 9 (A1) and 9 (B1), the signal level is saturated in the high luminance portion. On the other hand, sufficient sensitivity can be ensured in the low-luminance portion (FIG. 8).
(B)). On the other hand, in the low-sensitivity imaging result corresponding to the vertical blanking period, FIGS.
As shown in 2), a sufficient gradation can be obtained for a high luminance portion, but it is difficult to secure a sufficient gradation for a low luminance portion. Thus, in the case of this method, by correcting and combining the signal levels of these imaging results, an imaging result having a wide dynamic range can be generated as shown in FIG. 9C. .

[0014]

In the case of obtaining a low-sensitivity imaging result in the vertical blanking period as described above, a low-sensitivity exposure time is shorter than about 1/1000 second. As a result, the exposure time ratio between the high-sensitivity imaging result and the low-sensitivity imaging result in the repetitively obtained imaging result significantly increases, and as a result, the low-sensitivity imaging result is amplified by a large gain to increase the high-sensitivity imaging result. There is a drawback that the image must be combined with the imaging result.

When the low-sensitivity imaging result is amplified with a large gain and combined with the high-sensitivity imaging result as shown in FIG.
As shown in the figure, in the synthesis result, in the vicinity where the high-sensitivity imaging result is saturated (hereinafter, referred to as a medium luminance level), the S / N ratio is significantly deteriorated, whereby the image quality is deteriorated and perceived. There is.

The present invention has been made in view of the above points, and it is an object of the present invention to propose an image pickup device and an image pickup apparatus capable of effectively avoiding deterioration of the S / N ratio at a middle luminance level.

[0017]

According to a first aspect of the present invention, there is provided an image pickup device, comprising: a first transfer register provided between a first transfer register and a second transfer register;
A charge accumulation section for temporarily storing transfer charges is provided for a period corresponding to a ratio between a long exposure time and a short exposure time.

According to the second aspect of the present invention, the present invention is applied to an image pickup apparatus, wherein an image pickup element is provided between a first transfer register and a second transfer register for a long exposure time and a short exposure time. , A charge accumulating section for temporarily storing transfer charges is arranged.

According to the first aspect of the present invention, the present invention is applied to an image pickup device, and is provided between a first transfer register and a second transfer register according to a long exposure time and a short exposure time. By arranging the charge accumulation unit that temporarily holds the transfer charge during the period, even if switching between long-time imaging and short-time imaging is performed in the middle of the video period, the subsequent long-time imaging result is not At the time of transfer to the one transfer register, the transfer of the stored charge in the first transfer register can be completed by the charge storage unit. As a result, the S / N ratio of a low-sensitivity imaging result can be improved by lengthening the short exposure time, and deterioration of the S / N ratio at a middle luminance level can be effectively avoided.

According to the configuration of the second aspect, by applying the present invention to an image pickup apparatus, it is possible to effectively avoid deterioration of the S / N ratio at a middle luminance level and obtain an image pickup result of a wide dynamic range.

[0021]

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

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 2 is a block diagram showing an imaging apparatus according to an embodiment of the present invention. The imaging device 11 can repeatedly obtain imaging results by long-time exposure and short-time exposure from the image-capturing element 12, combine the imaging results by long-time exposure and short-time exposure, and output an imaging result with a wide dynamic range in a field cycle. I do.

Here, the image pickup device 12 drives a high-sensitivity image pickup result and a low-sensitivity image pickup result in pixel units by driving by the drive circuit 14, similarly to the all-pixel read-out IT-CCD described with reference to FIG. The divisionally multiplexed imaging result is repeatedly output in frame units. As shown in FIG. 3 in comparison with FIG. 8, a predetermined number of registers are arranged between the vertical transfer registers 3A and 3B and the horizontal transfer register 4 to form the charge storage unit 13 of the image sensor 12. (FIG. 3A).

In this embodiment, the image pickup device 12
The photodiode 2 is arranged so as to output an imaging result according to the number of scanning lines according to the NTSC system, and the ratio of the long exposure time to the short exposure time is set to 1: 5. (FIG. 3 (B)). Thus, the imaging element 12 starts high-sensitivity imaging for a long imaging time Tl from the start of the video period, and then starts the vertical blanking period V. The high-sensitivity imaging is terminated before the start of the BLK, and then the low-sensitivity imaging is started with the short imaging time Ts.

Thus, in the image pickup apparatus 11, the charge accumulation time allocated to the image pickup with low sensitivity is longer than before in the range where the image pickup result is not saturated in the high luminance portion.
The S / N ratio is improved for low-sensitivity imaging results.

Even when switching between high-sensitivity imaging and low-sensitivity imaging in the middle of a video period as described above, the charge storage unit 13 outputs these imaging results during the subsequent video period. When the sensitivity imaging result is transferred from the photodiode 2 to the vertical transfer register 3A,
The number of register stages is set so that the transfer of the accumulated charge is completed in the vertical transfer register 3A.

That is, the charge accumulating unit 13 has a stage number N = 525 × (1/1) for 525 scanning lines and 485 effective scanning lines in one frame of the NTSC system.
6) It is set to 47 stages calculated by-(525-485). As a result, the image pickup device 12 temporarily holds the accumulated charge output from the vertical transfer register 3A in the charge accumulation unit 13 for a period corresponding to the ratio of the exposure time for high sensitivity to the exposure time for low sensitivity, and The data is transferred to the transfer register 4.

The image sensor 12 transfers the accumulated charge of the odd-numbered line to the odd-numbered register 3a of each of the vertical transfer registers 3 at time tl-1 immediately after the end of the high-sensitivity imaging. At the subsequent time point tl-2, the accumulated charges transferred in this manner are transferred by one pixel toward the horizontal transfer register 4, and at the subsequent time point tl-3, the accumulated charges of the even-numbered lines are transferred to the even number lines of the vertical transfer register 3. Transfer to the third register 3b. Thereby, the image pickup device 12 adds the photoelectric conversion results of two pixels adjacent in the vertical direction by the even-numbered register 3b of the vertical transfer register 3 and outputs the high-sensitivity image pickup result corresponding to the interlace method to the vertical transfer register 3.
In the even-numbered register 3b.

At time ts-1 immediately after the end of low-sensitivity imaging, the accumulated charge of the odd-numbered line is transferred to the odd-numbered register 3a of the vertical transfer register 3. At the subsequent time point ts-2, the accumulated charges transferred to the odd-numbered register 3a and the even-numbered register 3
b, the stored charge for one pixel is stored in the horizontal transfer register 4.
And the accumulated charges of the even lines remaining at the subsequent time point ts-3 are stored in the even-numbered registers 3 of the vertical transfer registers 3.
b. Accordingly, the image sensor 12 holds the low-sensitivity imaging result corresponding to the interlace method in the even-numbered register 3b of the vertical transfer register 3, and stores the corresponding high-sensitivity imaging result in the odd-numbered register 3a of the vertical transfer register 3. To hold.

As shown in FIGS. 1A and 1B, when the even-numbered and odd-numbered registers 3a and 3b of each vertical transfer register 3 hold the low-sensitivity and high-sensitivity imaging results as described above, At time ts-3), the imaging element 12 transfers the accumulated charge to the horizontal transfer register 4 at a high speed, thereby starting the image period ts- immediately after the time ts-4.
In 4, the imaging result can be output from the horizontal transfer register 4.

In the image pickup device 12, during the subsequent video period starting from the time ts-4, the image pickup result obtained by time-division multiplexing of the high-sensitivity and low-sensitivity image results in line units is repeatedly output in field units. I do. Here, in the case where the accumulated charge is transferred in this manner, in this embodiment, since the number of registers in the charge accumulation unit 13 is set as described above, the subsequent high-sensitivity imaging is performed at time tl-0. When the result is transferred to the vertical transfer register 3, the transfer of the accumulated charge has been completed in the vertical transfer register 3. Thereby, in this embodiment, the imaging element 12 increases the imaging time allocated to the low-sensitivity imaging result, switches between high-sensitivity imaging and low-sensitivity imaging during the video period, and It is designed to be able to sequentially output low-sensitivity imaging results in frame units.

In the image pickup apparatus 11 (FIG. 2), the pre-processing circuit 16 subjects the output signal S1 of the image pickup device 12 to current-voltage conversion processing and correlated double sampling processing, amplifies the output signal S1 with a predetermined gain, and further corresponds to a pixel. An analog-to-digital conversion process is performed at a sampling period to output image data.

A switching circuit (SW) 17 converts the image data into time expansion circuits 18L and 18L in line units.
By alternately outputting to S, the image data DL based on the high-sensitivity imaging result and the image data DS based on the low-sensitivity imaging result are separated and output.

The time expansion circuits 18L and 18S convert the sampling periods of the image data DL and DS, respectively, extend the time axis, and output them at the same timing.

The gain correction circuit 19 multiplies the low-sensitivity image data DS by a predetermined value and outputs the multiplied value, thereby changing the gain of the low-sensitivity image data DS to the gain corresponding to the high-sensitivity image data DL. And output.

The mixing processing circuit 20 combines the low-sensitivity image data DS and the high-sensitivity image data DL on a pixel-by-pixel basis, thereby outputting image data D2 having a wide dynamic range.

(1-2) Operation of First Embodiment In the above configuration, in the imaging device 11 (FIGS. 2 and 3), imaging with high sensitivity starts at the start of the video period, and On the way, the operation of the image sensor 12 is switched from high-sensitivity imaging to low-sensitivity imaging. In the imaging device 11, during the switching of the operation, the accumulated charge imaged with high sensitivity is transferred to the vertical transfer register 3, and the vertical transfer register 3 is transferred by the interlace method.
In the state held in the even-numbered register 3a, imaging with low sensitivity is executed. When an imaging result with low sensitivity is obtained, the imaging result with low sensitivity is transferred to the vertical transfer register 3, and the imaging results with high sensitivity and low sensitivity are held in the even-numbered and odd-numbered registers 3b and 3a, respectively. .

In the image pickup device 11 (FIG. 1), the charge storage section 13 disposed between the vertical transfer register 3 and the horizontal transfer register 4 corresponds to the high sensitivity and low sensitivity held in the vertical transfer register 3 in this manner. After the sensitivity imaging result is transferred at a high speed, the accumulated charges held in the vertical transfer register 3 and the charge accumulation unit 13 are sequentially input to the horizontal transfer register 4 line by line in the subsequent video period, and the horizontal transfer register 4
Are sequentially output. Thus, in the imaging device 11, high-sensitivity and low-sensitivity imaging results are time-division multiplexed and output from the imaging device 12 in line units.

In transferring and outputting the accumulated charge in this manner, in the image sensor 12, the exposure time between the high sensitivity and the low sensitivity is set between the vertical transfer register 3 and the horizontal transfer register 4. Since the charge accumulating units 13 in which registers are connected in series by the number of stages corresponding to the ratio are arranged, immediately after transferring the imaging result with lower sensitivity to the vertical transfer register 3, the charge accumulating units 13 are used. Due to the high-speed transfer of the accumulated charges toward the horizontal transfer register 4 (time ts-4), the time tl at which the high-sensitivity imaging result is transferred to the vertical transfer register 3 in the subsequent video period.
When the value is -1, the transfer of the accumulated charge has been completed in the vertical transfer register 3.

Thus, in this embodiment, even if the imaging time allocated to the low-sensitivity imaging result is lengthened to switch between high-sensitivity imaging and low-sensitivity imaging during the video period, the high-sensitivity and low-sensitivity imaging can be performed. Low sensitivity imaging results can be sequentially output.

In the imaging device 11, after the imaging result S1 obtained in this way is separated into a high-sensitivity imaging result and a low-sensitivity imaging result and the signal level is corrected, the imaging result having a wide dynamic range is obtained. Synthesized. At this time, in the low-sensitivity imaging result, the charge accumulation time is longer than that of the related art in a range in which the high-brightness portion is not saturated.
As a result, the deterioration of the S / N ratio at the middle luminance level can be effectively avoided in the imaging result with a wide dynamic range correspondingly obtained.

(1-3) Effects of the Embodiment According to the above configuration, a long-time exposure is performed between the vertical transfer register as the first transfer register and the horizontal transfer register as the second transfer register. By arranging the charge accumulation unit for temporarily storing the transfer charge during the period corresponding to the ratio between the time and the short exposure time, it is possible to switch between high-sensitivity imaging and low-sensitivity imaging within the video period. In addition, high-sensitivity and low-sensitivity imaging results can be repeatedly output, thereby effectively avoiding deterioration of the S / N ratio at a middle luminance level.

(2) Second Embodiment FIG. 4 is a schematic diagram for explaining an operation of an image pickup device applied to an image pickup apparatus according to a second embodiment of the present invention. is there. In this imaging device, imaging results of high sensitivity, medium sensitivity, and low sensitivity are output by time division multiplexing in line units. In FIG. 4, the times of imaging at high sensitivity, medium sensitivity, and low sensitivity are denoted by T, respectively.
Indicated by L, TM and TS. In the example of FIG. 4, low-sensitivity imaging is performed during the vertical blanking period V. It shall be assigned to BLK.

In this image pickup device, the number of stages of the registers in the vertical transfer register 3 and the charge storage section 13 is 1.5 times as large as that of the image pickup device 12 according to the first embodiment. When the imaging with the high sensitivity is completed, the accumulated charges of the odd-numbered lines are
The accumulated charge transferred to the 3N-th register 3a is transferred to the N-th register 3a (time point tl-1), and further transferred to the horizontal transfer register 4 for one stage.
Transfer to the (+1) th register 3b. Further, the accumulated charges of the even-numbered lines are transferred to the 3N + 1-th register 3b, whereby the high-sensitivity imaging result by the interlace method is held in the 3N + 1-th register 3b (time t).
1-2).

When the subsequent imaging with the medium sensitivity is completed,
The accumulated charges of the odd-numbered lines are transferred to the 3N-th register 3a of each vertical transfer register 3 (time tm-1).
The accumulated charge transferred to the third register 3a is calculated as 3N + 1
Transfer to the third register 3b. Further, the accumulated charges of the even lines are transferred to the 3N + 1-th register 3b.
As a result, the high- and medium-sensitivity imaging results by the interlace method are stored in the 3N + 2nd registers 3c and 3N + 1.
In the third register 3b (time tm−
2).

When the subsequent imaging with low sensitivity is completed,
The accumulated charge of the odd-numbered line is transferred to the 3N-th register 3a of each vertical transfer register 3 (time point ts-1).
The accumulated charge transferred to the third register 3a is calculated as 3N + 1
Transfer to the third register 3b. Further, the accumulated charges of the even lines are transferred to the 3N + 1-th register 3b.
As a result, the high-, medium-, and low-sensitivity imaging results of the interlace method are stored in the 3N + third registers 3a,
N + 2nd register 3c, 3N + 1th register 3
b (time ts-2).

Thereafter, the charge stored in the vertical transfer register 3 is transferred at a high speed toward the horizontal transfer register 4 by the charge storage section 13, and in the subsequent video period, the image pickup result transferred in this manner is transferred to the horizontal transfer register 4. The same processing is repeated while sequentially outputting.

In this embodiment, an imaging result having a wide dynamic range is output by separating and synthesizing the imaging results of high sensitivity, medium sensitivity, and low sensitivity output as described above.

According to the configuration shown in FIG. 4, by switching the sensitivity in three stages and synthesizing an image having a wide dynamic range, in addition to the effect of the above-described embodiment, the noise level is further suppressed and the noise level is further increased. High quality imaging results can be obtained.

(3) Third Embodiment FIG. 5 is a schematic diagram for explaining the operation of an image sensor 22 according to a third embodiment of the present invention in comparison with FIG. In this image sensor 22, odd-numbered and even-numbered vertical transfer registers 3A and 3B are allocated for high sensitivity and low sensitivity, respectively.

That is, the imaging element 22 ends high-sensitivity imaging at time t1-1 in the middle of the video period, and transfers the odd-numbered line or even-numbered line accumulated charge only to the odd-numbered vertical transfer register 3A. At the subsequent time point t1-2, the accumulated charge transferred in this manner is transferred by one pixel toward the horizontal transfer register 4. At the subsequent time point t1-3, the accumulated charge of the even-numbered line or the odd-numbered line and the vertical transfer register are transferred. 3
Add with A. As a result, the high-sensitivity imaging result corresponding to the interlace method is transferred to the odd-numbered vertical transfer register 3A.
To hold.

At a point in the middle of the video period, imaging with low sensitivity is started, and the vertical blanking period V.V. BL
At the end time point t2-1 of K, the even-numbered vertical transfer register 3
Only for B, the charge stored in the odd line or the even line is transferred. At the subsequent time point t2-2, the accumulated charges transferred in this manner are transferred by one pixel toward the horizontal transfer register 4. At the subsequent time point t2-3, the accumulated charges of the even-numbered line or the odd-numbered line and the vertical transfer register are transferred. Add by 3B. As a result, a low-sensitivity imaging result corresponding to the interlace method is held in the even-numbered vertical transfer registers 3B.

The image pickup device 22 ends the high-sensitivity and low-sensitivity imaging in this manner, and holds the interlaced imaging result in the corresponding vertical transfer registers 3A and 3B. At the start time, the accumulated charges are transferred by the vertical transfer registers 3A and 3B so that the accumulated charges obtained by time-division multiplexing of these imaging results in pixel units are output from the horizontal transfer register 4.

That is, as shown in FIG. 6 in comparison with FIG. 5, when the high-sensitivity image pickup result is held in the vertical transfer register 3A at the time tl-3 by the interlace method, the image pickup device 12 causes the remaining vertical transfer register 3 Until the time point ts-1 at which the transfer of the stored charge is started to 3B, the stored charges are transferred toward the horizontal transfer register 4 by the number of registers in the charge storage unit 13 (FIGS. 1A and 1B). ). Thus, at the time when the low-sensitivity imaging result is transferred from the photodiode 2, the imaging element 12 transfers the accumulated charge so that the horizontal transfer register 4 can output the high-sensitivity imaging result.

When the low-sensitivity imaging result is transferred to the vertical transfer register 3B, the accumulated charge is transferred to the horizontal transfer register 4 so as to correspond to the high-sensitivity imaging result by high-speed transfer. At the time ts-4 immediately before the start time ts-5, the transfer of the accumulated charge due to the low sensitivity is completed.

Further, when the following video period starts, the image pickup device 22 moves the vertical transfer register 3 as indicated by the arrow.
The transfer of the stored charge in A and 3B and the transfer of the stored charge in the horizontal transfer register 4 sequentially accumulate the high-sensitivity imaging result and the low-sensitivity imaging result in a time-division multiplexing manner in pixel units. Transfer and output charge (Fig. 5
(C)).

The same effects as in the first embodiment can be obtained by processing high-sensitivity and low-sensitivity imaging results in units of vertical transfer registers as in the configuration of FIG.

(4) Other Embodiments In the above-described third embodiment, a case has been described in which the charge storage section is arranged not only on the high-sensitivity imaging result but also on the low-sensitivity imaging result side. However, the present invention is not limited to this, and the point is that the charge storage unit takes charge of the accumulated charge by switching between high-sensitivity imaging and low-sensitivity imaging at a time earlier than the start of the vertical blanking period. By enabling continuous output of imaging results,
If necessary, the charge storage unit may be omitted on the imaging result side with low sensitivity.

In the second embodiment described above,
Although the case where high-, medium-, and low-sensitivity imaging results are processed in units of registers constituting the vertical transfer register has been described, the present invention is not limited to this, and as shown in FIG. High sensitivity, medium sensitivity,
You may make it process the imaging result of low sensitivity. That is, in this case, the vertical transfer registers are sequentially circulated with high sensitivity,
Allocated to the medium-sensitivity and low-sensitivity imaging, and when each imaging is completed, in the same manner as described above, the accumulated charges are transferred to the corresponding vertical transfer registers 3A, 3B, and 3C, and the imaging results by the interlace method are respectively assigned to the corresponding vertical transfer registers. It is held in the transfer registers 3A, 3B, 3C. The imaging with higher sensitivity is performed in the vertical blanking period V. A continuous output is guaranteed by the number of stages of the charge storage unit 13 for the end at a point earlier than the start point of the BLK.

In the above-described embodiment, the case where the exposure time ratio of the high sensitivity and the low sensitivity is set to 1: 5 has been described. However, the present invention is not limited to this, and various ratios may be used as necessary. It can be set, and can be widely applied to changing the ratio as needed.

In the above-described embodiment, the case where the image pickup result by the interlace method is output has been described. However, the present invention is not limited to this, and can be widely applied to the case where the image pickup result by the non-interlace method is output. Can be.

In the above-described embodiment, the case of processing continuous imaging results has been described. However, the present invention is not limited to this. For example, a signal processing circuit for processing continuous imaging results of a video camera or the like may be used. Thus, the present invention can be widely applied to a case where an electronic still camera is configured.

[0063]

As described above, according to the present invention, a long exposure time and a short exposure time are provided between a first transfer register, for example, a vertical transfer register and a second transfer register, a horizontal transfer register. By arranging the charge accumulation unit that temporarily holds the transfer charge during the period according to the ratio of the exposure time to the high sensitivity and high sensitivity even when switching between high sensitivity imaging and low sensitivity imaging within the video period. It is possible to repeatedly output a low-sensitivity imaging result.
Deterioration of the N ratio can be effectively avoided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the operation of an image sensor according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an imaging apparatus using the imaging device of FIG. 1;

FIG. 3 is a schematic diagram for explaining the operation of the imaging apparatus of FIG. 2;

FIG. 4 is a schematic diagram for explaining the operation of an image sensor according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram for explaining the operation of an image sensor according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating transfer of accumulated charges in the image sensor of FIG. 6;

FIG. 7 is a schematic diagram illustrating the operation of an image sensor according to a fourth embodiment of the present invention.

FIG. 8 is a schematic diagram used to explain driving of a conventional image sensor.

FIG. 9 is a schematic diagram for explaining a combination of a high-sensitivity imaging result and a low-sensitivity imaging result.

[Explanation of symbols]

1, 12, 22... Imaging element, 2... Photodiode, 3, 3A, 3B... Vertical transfer register, 4... Horizontal transfer register, 11.

Claims (3)

[Claims] An image pickup device that time-divisionally multiplexes an image pickup result obtained by a long exposure time and an image pickup result obtained by a short exposure time and repeatedly outputs the same, comprising: a photoelectric conversion unit arranged in a matrix; A first transfer register disposed between the photoelectric conversion units so as to extend in the row direction and sequentially transferring accumulated charges accumulated in the corresponding photoelectric conversion units; and a first transfer register transferred by the first transfer register. A second transfer register for transferring the accumulated charge in a direction orthogonal to a transfer direction of the first transfer register, wherein the first transfer register transfers at least an imaging result based on a long exposure time; A charge accumulation unit for temporarily storing the accumulated charge is provided between the second transfer register and a period corresponding to a ratio between a long exposure time and a short exposure time. An imaging device characterized by the above. 2. An imaging apparatus for driving an imaging device to acquire an imaging result based on a long exposure time and an imaging result based on a short exposure time, wherein the imaging device includes an imaging result based on the long exposure time. And the imaging result by the short exposure time are time-division multiplexed and repeatedly output, and between the photoelectric conversion units arranged in a matrix and the photoelectric conversion units so as to extend in a column direction or a row direction. A first transfer register arranged and sequentially transferring accumulated charges accumulated in the corresponding photoelectric conversion unit; and a transfer direction of the accumulated charges transferred by the first transfer register by the first transfer register. Comprises a second transfer register for transferring in a direction orthogonal to the first transfer register, wherein the first transfer register and the second transfer register for transferring at least an imaging result based on a long exposure time. Imaging device comprising, during a period corresponding to the ratio of the long-time exposure time and short exposure time, that the charge storage portion for temporarily holding the accumulated charge is disposed between. 3. The method according to claim 2, wherein at least a point of time when the accumulated charge due to the long exposure time is transferred to the first transfer register.
The stored charge is transferred from the first transfer register to the second transfer register via the charge storage unit so that the transfer of the stored charge in the first transfer register is completed. The imaging device according to claim 2, wherein: