JPH09200628A - Solid-state imaging device and driving method thereof - Google Patents

Abstract

(57) Abstract: Since the application interval of the read pulse to the solid-state image pickup device is set to a predetermined value, it is impossible to eliminate the insufficient exposure in the light receiving section. A solid-state imaging device and a solid-state imaging device.
Solid-state imaging device 1 having a timing generator 20 for generating a read pulse for reading charges from the light receiving section 11 of
Further, the timing generator 20 has a switching means 30 for switching the setting of the photographing mode to the normal mode or the high sensitivity mode, and the timing generator 20 generates a read pulse at every time interval corresponding to a field in the normal mode and reads in the high sensitivity mode. The pulse generation is stopped for a period corresponding to a predetermined field. As a result, the charge accumulation time in the light receiving unit 11 of the solid-state imaging device 10 is extended by the amount of stopping the application of the read pulse.

Description

Detailed Description of the Invention

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a solid-state imaging device and a driving method thereof.

[0002]

2. Description of the Related Art FIG. 9 is a schematic configuration diagram showing an example of a solid-state image pickup device incorporated in, for example, a video camera. As shown in this figure, the solid-state imaging device 9 includes a solid-state imaging device 10
And a timing generator 20 '. The solid-state imaging device 10 includes a light receiving unit 11 that accumulates received light as electric charges, a vertical transfer unit 12 and a horizontal transfer unit 13 that transfer the electric charges read from the light receiving unit 11, and charge transferred from these transfer units to a voltage. Charge-voltage converter 1 for converting into
4, and an output unit 15 for outputting the converted voltage signal. And the timing generator 20 'is
A read pulse, a transfer pulse, or the like used to drive the solid-state imaging device 10 is generated and applied to the vertical transfer unit 12, the horizontal transfer unit 13, or the like.

A method of driving the solid-state image pickup device 9 will be described with reference to the timing charts shown in FIGS. 9 and 10 (1) and 10 (2). Here, the driving method will be described taking the case where the vertical transfer unit 12 is two-phase driving as an example. In addition, each transfer electrode of the vertical transfer unit 12 also serves as a read gate electrode for reading charges from each light receiving unit. Therefore, the read pulses 71 and 72 are superimposed on each transfer pulse 70. First, in the first half of each frame 21, 22, ... Set at a predetermined time interval (about 15 msec) defined by the NTSC system, that is, in the odd field o, the timing generator 20 'is arranged in an odd row of the solid-state image sensor 10. The read pulse 71 is applied to the vertical transfer unit 12 beside the light receiving unit 11 thus selected, and the charges accumulated in these light receiving units 11 are read out to the vertical transfer unit 12. Thereafter, the transfer pulse 70 is applied from the timing generator 20 ′ to the vertical transfer unit 12, and further, a transfer pulse (not shown in the chart) is applied to the horizontal transfer unit 13 to vertically transfer the charges to the charge-voltage conversion unit 14. The data is transferred and horizontally transferred and output from the output unit 15.

On the other hand, in the latter half of each of the frames 21, 22, ..., That is, in the even field e, the read pulse 72 is applied to the light receiving portions 11 arranged in the even rows of the solid-state image pickup device 10 and accumulated in these light receiving portions 11. Vertical transfer unit 12
Read out. Following this, Timing Generator 2
A transfer pulse 70 is applied to the solid-state image sensor 10 from 0 ′ and the read charges are output from the output unit 15. In the driving method based on the frame reading method, each of the frames 2
The read pulses 71 and 72 are applied at intervals of 1, 22, ... Then, the output waveforms read out as described above are output signals 81, 82 ... Read out from the light receiving sections arranged in odd rows and the light receptions arranged in even rows as shown in FIG. Output signals 91, 92 ...
And are alternately output once each.

Further, in the driving method based on the field read method, first, the read pulse 71 is applied to all the light receiving parts which are the combination of the light receiving parts arranged in the odd and even rows adjacent to each other in the odd field o shown in FIG. Then, after the charges are read out from all the light receiving parts, the charges are mixed between the adjacent light receiving parts.
Next, in the even field e, the combination of the light receiving portions is changed and the read pulse 72 is applied to all the light receiving portions to read out the charges from all the light receiving portions. In this driving method, the read pulse is applied twice to all the light receiving units at each time interval of each frame. Then, an output waveform in which the output signals read from the respective combinations of the light receiving units are alternately output is obtained. Read pulse 7 explained in each driving method above
The application intervals of 1, 72 are the same even when the charge storage time in the light receiving portion is shortened by using, for example, an electronic shutter.

[0006]

However, in the above solid-state image pickup device and its driving method, although the charge accumulation time can be shortened by using the electronic shutter, the time interval set in each field in each frame is reduced. The charge accumulation time cannot be increased more than that. Therefore,
Even if the amount of exposure is insufficient in each light receiving unit when the illumination intensity is insufficient, the above-mentioned solid-state imaging device cannot solve the insufficient amount of exposure.

[0007]

Therefore, the solid-state image pickup device of the present invention is provided with a switching means for switching the setting of the photographing mode to the normal mode or the high sensitivity mode. And
The timing generator of the solid-state imaging device is configured to generate a read pulse at each time interval corresponding to each field in the normal mode, and stop the generation of the read pulse for a predetermined field equivalent period in the high sensitivity mode. According to the solid-state imaging device, the high-sensitivity mode is selected by the switching unit when the illumination light intensity is insufficient at the time of shooting, so that the charge accumulation time in the light-receiving portion of the solid-state imaging device stops the generation of the read pulse. Corresponding to the period corresponding to the field of, is increased to an integral multiple of the normal mode.

Further, the solid-state imaging device repeatedly outputs the storage means for storing the output signal output from the solid-state imaging device and the output signal stored in the storage means immediately before the predetermined field period. And an output control means for controlling. According to this solid-state imaging device, the output signal stored immediately before is output even to a field in which the output signal cannot be obtained because the read pulse is stopped during shooting in the high sensitivity mode. Therefore, the output signal is output to all fields.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, description will be made on the basis of an embodiment in which the present invention is applied to a solid-state image pickup device incorporated in a video camera and a driving method thereof. The solid-state imaging device according to the present invention is not limited to the solid-state imaging device incorporated in the video camera. Then, here, the case where the vertical transfer unit is driven by two phases will be described as an example, but the present invention is also applicable to multiphase driving of three or more phases. Further, in the embodiments described below, the same components as those of the above-described conventional technique are denoted by the same reference numerals, and duplicate description will be omitted. FIG. 1 is a schematic configuration diagram of a solid-state imaging device according to the first embodiment of the present invention, and FIG. 2 is a timing chart for explaining shooting in a high sensitivity mode in a driving method of this solid-state imaging device. In the following first embodiment, an example of the solid-state imaging device according to claim 1 will be described with reference to these drawings.

The solid-state image pickup device 1 has a solid-state image pickup element 10, a timing generator 20, and a switching means 30. The solid-state image sensor 10 is the same as that described in the related art. Further, in the normal mode, the timing generator 20 transfers the read pulses 71 and 72 to the solid-state image sensor 10 and transfers them to the solid-state image sensor 10 at time intervals corresponding to the fields o and e according to the frame read method or the field read method described in the related art. It is configured to generate the pulse 70. On the other hand, in the high sensitivity mode, the generation of the read pulses 71 and 72 is stopped for a period corresponding to a predetermined field.

The switching means 30 switches the photographing mode to either the normal mode or the high sensitivity mode. Then, by selecting either the normal mode or the high-sensitivity mode by the switching means, the timing generator 20 switches the generation state of the read pulses 71 and 72 as described above. Further, in addition to the above, the switching means 30 may be provided with a selection key (not shown) capable of arbitrarily selecting the predetermined field equivalent period in which the generation of the read pulses 71 and 72 is stopped in multiple stages. .

According to the above solid-state image pickup device, when the photographing mode is set to the high sensitivity mode by the switching means 30, the read pulse 71 is applied in the odd field o and the read pulse 71 is applied in the even field e. The application interval of the read pulse 72 can be an integral multiple of the normal mode. Then, it becomes possible to increase the charge accumulation time in each light receiving unit 11 of the solid-state imaging device 10. Therefore, in shooting in the high sensitivity mode, the sensitivity of each light receiving unit 11 can be artificially improved. On the other hand, when the shooting mode is set to the normal mode by the switching unit 30, shooting can be performed in the normal charge accumulation time.

Next, in the second embodiment, an example of the driving method of the solid-state image pickup device will be described with reference to FIG. This driving method is applied to the case where the solid-state imaging device 1 described with reference to FIG. Here, a description will be given mainly about generation and stop of the read pulses 71 and 72 in the timing generator. First, the photographing mode of the solid-state imaging device is selected by the switching means. Then, when the normal mode is selected, driving is performed by the same frame reading method as the conventional one. On the other hand, when the high sensitivity mode is selected, the timing generator generates the read pulses 71 and 72 as follows.

First, in the odd field o of the mo-th frame (for example, the first frame here) 21, a read pulse 71 and a transfer pulse 70 subsequent thereto are generated. Next, in the even field e of the me-th frame (for example, the first frame here) 21, the read pulse 72 and the transfer pulse 70 subsequent thereto are generated.

After that, the odd fields o in the (mo + 1) th frame to the (mo + n-1) th frame (n is an integer of 2 or more), that is, in the second frame 22 and the third frame 23 in the case of n = 3, for example, Then, the generation of the read pulse 71 is stopped. Similarly to this
The generation of the read pulse 72 is also stopped in the even-numbered field e in the + 1st frame to the (me + n-1) th frame, that is, in the second frame 22 and the third frame 23.

Next, in the odd field o in the mo + nth frame, that is, the fourth frame 24, the read pulse 71 is generated as in the first frame 21. Then, the charge accumulated in each light receiving unit 11 is generated between the generation of the read pulse 71 in the odd field o of the first frame 21 and the generation of the next read pulse 71 in the odd field o of the fourth frame 24. read out. Also,
The (me + n) th frame, that is, the fourth frame 24
The read pulse 72 is generated in the even field e in, and the charge accumulated in each light receiving portion 11 is read in the same manner as above.

According to the above driving method, an output waveform having a field in which the output signals 81, 82, 91 and 92 do not appear can be obtained as shown in FIG. Then, the output signals 82 and 92 output in the odd field o and the even field e of the fourth frame 24 are output by the frame read method in the normal mode in which the read pulse is generated at each time interval corresponding to the field. The charge accumulating time in each light receiving portion becomes longer by the amount corresponding to the second frame 22 and the third frame 23. Therefore, shooting is performed with a sensitivity three times higher than that in the normal mode.

In the second embodiment, the case where the read pulses 71 and 72 are generated in the odd field o and the even field e in the same frame has been described. However, the present invention is not limited to the above as long as the interval between the read pulses 71 generated in the odd field o and the interval between the read pulses 72 generated in the even field e are equal. Therefore, as shown in FIG. 4, the frame in which the read pulse 71 is generated in the odd field o and the frame in which the read pulse 72 is generated in the even field e may be shifted.

Next, in the third embodiment, another example of the driving method of the solid-state image pickup device will be described with reference to FIG. This driving method is applied to the case where the solid-state imaging device 1 described with reference to FIG. 1 is used to perform driving by the field reading method, and the generation of the reading pulses 71 and 72 in the timing generator is performed as in the second embodiment. And the explanation will be centered on the stop. Then, first, similarly to the second embodiment, the switching means selects the shooting mode in the solid-state imaging device. Then, when the normal mode is selected, driving is performed by the field reading method similar to the conventional one. On the other hand, when the high sensitivity mode is selected, the timing generator generates the read pulses 71 and 72 as follows.

First, in the odd field o of the first frame 21, the read pulse 71 and the transfer pulse 70 subsequent thereto are generated. Next, in the odd field o of each frame from the second frame 22 to the third frame 23, the generation of the read pulse 71 is temporarily stopped. Then, the read pulse 71 and the transfer pulse 70 are generated in the odd field o of the fourth frame 24 as in the first frame 21.

On the other hand, the read pulse 7 in the even field e
2 is generated in a frame located near the center of the application interval of the read pulse 71 in the odd field o. That is, here, in the even field e of the second frame 22, the read pulse 72 and the transfer pulse 70 subsequent thereto are generated. As a result, the read pulse 71 and the read pulse 72 are generated alternately and at equal intervals.

According to the driving method described above, an output waveform in which fields in which an output signal does not appear is evenly arranged can be obtained as shown in FIG. The output signal 91 output in the even field e of the second frame 22 and the output signal 82 output in the odd field o of the fourth frame 24 are normal field read signals that generate read pulses 71 and 72 in each frame. 2 than the driving method of the system
The charge accumulation time in each light receiving portion becomes longer by the amount corresponding to the field.

Next, FIG. 6 is a schematic configuration diagram showing a solid-state image pickup device according to a fourth embodiment of the present invention. The solid-state image pickup device will be described below with reference to this figure. This solid-state imaging device 6
Is connected to the solid-state imaging device 1 described with reference to FIG. 1, the storage unit 40 connected to an output unit (not shown) of the solid-state imaging device 1, and the storage unit 40 and the external output unit 4. The output control means 50 is provided.

The storage means 40 stores the output signal of the odd field and the output signal of the even field output from the solid-state image pickup device. Further, the output control means 50 stores in the storage means 40 immediately before that in a predetermined field-equivalent period from the output of each output signal from the solid-state imaging device to the output of each output signal next time. The output signal is controlled so that the generated output signal is repeatedly output.

According to the above-mentioned solid-state image pickup device 6, even when the solid-state image pickup device 1 takes an image in the high-sensitivity mode, even in a field where an output signal cannot be obtained because no read pulse is generated, immediately before that. The stored output signal is output, and an output waveform having the output signal in all fields is obtained.

Next, FIG. 7 is a diagram for explaining a driving method of the solid-state image pickup device according to the fourth embodiment, and an example of the driving method will be described below as a fifth embodiment with reference to this drawing. 7 (1) shows an output signal output from the solid-state image sensor and stored in the storage means (40).
(2) shows an output signal output from the output control means (50) and input to the external output means 4.

First, for example, a read pulse is generated in the timing generator of the solid-state image pickup device in the high sensitivity mode of the frame read system as described with reference to FIG. 2 in the second embodiment. Then, as shown in FIG. 7A, the output signal 8 is output in the odd field o of the first frame 21.
Get 1. Then, this output signal 81 is stored in the storage means (40) as an output signal of the odd field o. Thereafter, as shown in FIG. 7B, the output control means (50) outputs the stored output signal 81 to the odd field o of the first frame 21.

Next, as shown in FIG. 7A, the output signal 91 is obtained in the even field e of the first frame 21 in the same manner as described above. Then, this output signal 91 is stored in the storage means (40) as an output signal of the even field e.
Then, as shown in FIG. 7B, the output control means (5
In 0), the output signal 91 stored in the storage means (40) is output to the even field e of the first frame 21.

After that, as shown in FIG. 7A, in the second frame 22 and the third frame 23, the read pulse is not applied to the solid-state image pickup device, so that the output signal is not output.
Therefore, as shown in FIG. 7B, in the output control means (50), the second frame 22 and the third frame 23 are used.
Of the odd field o of
The output signal 81 stored in the storage means (40) is output. Further, the output signal 91 stored in the storage means (40) in the even field e immediately before the second frame 22 and the third frame 23 is output. Then, after the fourth frame 24 in which new output signals 82 and 92 are obtained from the solid-state image pickup device in the odd field o and the even field e, respectively, the above procedure is repeated.

By the above driving method, the output signals 81 and 91 are output to the field to which the read pulse is not applied. The output screen is prevented from becoming rough by temporarily stopping the generation of the read pulse.

Next, FIG. 8 is a diagram for explaining another example of the driving method of the solid-state image pickup device of the fourth embodiment described with reference to FIG. 6, and the driving method will be described below with reference to this figure. Another example will be described as a sixth embodiment. In addition, FIG. 8 (1)
Indicates an output signal output from the solid-state image sensor and stored in the storage means (40), and FIG. 8 (2) shows an output control means (5).
0) shows an output signal outputted from 0) and inputted to the output means (4).

First, a read pulse is applied to the solid-state image pickup device in the high-sensitivity mode of the field read system or the frame read system as described with reference to FIG. 4, for example, as shown in FIG. The output signal 81 is obtained in the odd field o of the frame 21. Then, the output signal 81 is stored in the storage means (40). afterwards,
As shown in FIG. 8B, in the output control means 50, the first
In the odd field o of the frame 21, the storage means 40
The output signal 81 stored in is output.

After that, as shown in FIG. 8A, since the read pulse is not generated in the odd field o of the second frame 22 and the third frame, the output signal is not output.
Therefore, as shown in FIG. 8B, the output control means (50) outputs the output signal 81 stored in the storage means 40 to the odd field o.

Further, as shown in FIG. 8A, since no read pulse is generated in the even field e of the first frame 21, no output signal is output. Therefore, FIG.
As shown in (2), in the output control means (50),
The output signal 90 stored in the storage means (40) when the read pulse is generated in the immediately previous even field e is output to the even field e.

Hereinafter, as shown in FIG. 8A, the output signals 91 and 82 are sequentially stored in the storage means 40 each time the output signals 91 and 82 are output from the solid-state image pickup device.
Then, in each odd field o and even field e until a new output signal is output thereafter, the output signals 91 and 82 of the fields most recently stored in the storage means 40 are output control means ( Repeatedly output according to 50).

According to the driving method described above, similarly to the driving method of the fifth embodiment, the output signal is output to the field to which the read pulse is not applied, and the application of the read pulse is temporarily stopped so that the output screen becomes rough. Is prevented.

According to the solid-state image pickup device of the third embodiment and the driving methods of the fourth and fifth embodiments, by applying these to an image capturing device such as a personal computer and its driving method, the output to be stored. Since the information amount of the signal can be reduced, the storage capacity can be compressed. Further, in the above embodiments of the respective driving methods, the generation of the dark current can be suppressed by generating the transfer pulse without stopping even in the field to which the read pulse is not applied.

[0038]

As described above, according to the solid-state imaging device and the driving method thereof of the present invention, the switching means for selecting the normal mode and the high sensitivity mode is provided, and the timing generator is selected when the high sensitivity mode is selected. By stopping the generation of the read pulse in the period corresponding to a predetermined field, it is possible to switch the charge accumulation time in each light receiving portion of the solid-state imaging device between the normal accumulation time and an integral multiple thereof. Therefore, with one solid-state imaging device, it is possible to perform shooting with normal sensitivity and shooting with pseudo high sensitivity by extending the exposure time to an integral multiple of the normal when the exposure light intensity is insufficient. .

Further, it is provided with storage means for storing an output signal output from the solid-state image pickup device, and output control means for repeatedly outputting the output signal stored in the storage means immediately before the predetermined field period. As a result, the output signal can be output to all fields even when shooting is performed in the high sensitivity mode. Then, it becomes possible to prevent the output screen from becoming rough.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a solid-state imaging device according to a first embodiment.

FIG. 2 is a timing chart showing a driving method according to a second embodiment.

FIG. 3 is an output waveform according to the driving method of the second embodiment.

FIG. 4 is a timing chart showing a driving method according to second and third embodiments.

FIG. 5 is an output waveform according to the driving method of the second and third embodiments.

FIG. 6 is a schematic configuration diagram of a solid-state imaging device according to a fourth embodiment.

FIG. 7 is an output waveform for explaining a driving method according to a fifth embodiment.

FIG. 8 is an output waveform illustrating a driving method according to a sixth embodiment.

FIG. 9 is a schematic configuration diagram of a conventional solid-state imaging device.

FIG. 10 is a timing chart showing a conventional driving method.

FIG. 11 is an output waveform according to a conventional driving method.

[Explanation of symbols]

1, 6 Solid-state imaging device 10 Solid-state imaging device 11
Light receiving section 20 Timing generator 30 Switching means 40 Storage means 50 Output control means 71, 72 Read pulse e
Even field o odd field

Claims (4)

[Claims] 1. A solid-state imaging device comprising: a solid-state imaging device; and a timing generator that generates a read pulse for reading charges from a light-receiving portion of the solid-state imaging device, wherein a shooting mode is set to a normal mode or a high-sensitivity mode. The timing generator generates the read pulse at each time interval corresponding to each field in the normal mode, and stops the generation of the read pulse for a predetermined field equivalent period in the high sensitivity mode. A solid-state imaging device characterized by the above. 2. Storage means for storing an output signal output from the solid-state image pickup device, and output control means for repeatedly outputting the output signal stored in the storage means immediately before the predetermined field corresponding period. The solid-state imaging device according to claim 1, further comprising: 3. A normal mode or a high-sensitivity shooting mode is selected, and when the normal mode is selected, a read pulse for reading charges from each light receiving section of the solid-state image sensor is equivalent to a field. The method of driving a solid-state imaging device, wherein the generation of the read pulse is stopped for a period corresponding to a predetermined field when the high sensitivity mode is selected. 4. The solid-state imaging device driving method according to claim 3, wherein when the high-sensitivity mode is selected, an output signal output from the solid-state imaging device upon application of the read pulse is stored, A method of driving a solid-state image pickup device, characterized in that the stored output signal is repeatedly output over a period corresponding to a predetermined field.