JP2791999B2 - Driving method of solid-state imaging device and solid-state imaging device - 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,
In particular, the present invention relates to a driving method of a high-resolution solid-state imaging device having a large number of photoelectric conversion elements and a solid-state imaging device for implementing the method.

[0002]

2. Description of the Related Art In recent years, solid-state imaging devices have been remarkably developed mainly in video cameras. Higher resolution is one of the directions. For applications such as high-definition television (HD-TV), mechanical measurement, and astronomical observation, 2 million pixels to 4
A million-pixel solid-state imaging device has been developed.

At present, however, only an image pickup device having 400,000 pixels or less has been put into practical use for a color camera having 525 vertical scanning lines, which is the mainstream for consumer use.

In consideration of applications such as a still (still image) video camera, an image input device, and an electronic overhead projector (OHP), a device having a larger number of pixels is required in a system of 525 vertical scanning lines.

The present applicant has studied the optimum number of pixels based on theoretical calculations and image simulations.
It has been concluded that the number of pixels of about 100,000 can be adequately used for the above-mentioned applications. Based on this conclusion, various proposals have been made for a CCD color sensor having about 800,000 pixels.

It has been clarified that a preferable mode of arranging 800,000 pixels in an image having an aspect ratio of about 3: 4 is about 1000 in the vertical direction and about 800 in the horizontal direction.

That is, the photodiodes are arranged in a matrix of about 1000 in the vertical direction and about 800 in the horizontal direction, and the vertical C for transferring charges in the vertical direction adjacent to each column.
CD (VCCD) columns are provided, and horizontal CCDs (H) for transferring charges in the horizontal direction to the output terminals of these VCCD columns.
CCD) row.

In order to read out electric charges from about 1000 pixels arranged vertically, for example, a VCCD including two transfer cells per row is arranged.

In order to read out image information in a short time, it has been proposed to classify the photodiodes in the vertical direction into four types and read out charges from two types of photodiodes at a time. That is, assuming that the vertical scanning period is V, information from all pixels can be read in the period of 2V. In this case, two HCCDs are provided and two types of charges are simultaneously transferred by the two HCCDs due to the limitation of charge transfer in the horizontal direction.

According to the system using two HCCDs, the intensity of the image signal differs depending on which HCCD is used to transfer the image signal. In particular, in a color image pickup apparatus having a three-plate configuration, a level difference between image signals appears as a flicker phenomenon.

In order to prevent such a phenomenon, the present applicant uses one HCCD and sets a period 4 which is four times the vertical scanning period V.
A method of reading all image information with V was proposed. According to this method, a high-precision still screen can be reproduced.

When monitoring a still image before capturing a still image (including a movie mode for capturing a moving image),
In order to perform image reproduction in a short period of time, image reproduction of the NTSC system is performed.

FIG. 2 shows a conventional high-resolution solid-state imaging device. FIG. 2A schematically illustrates a configuration of the imaging device. A large number of photodiodes 3 are arranged in a matrix. For example, about 800 photodiodes in one row are arranged in about 1000 rows. The photodiodes 3 in each column are
From the top, they are classified into four types, A1, B1, A2, and B2.

A VCCD 4 is formed adjacent to the photodiodes 3 in each column. The VCCD 4 has two transfer cells per row, and eight cells in four rows constitute one unit. The transfer cell is configured by arranging an insulating electrode on a semiconductor transfer path. V1, V2, V3, V4, V5, V2, V
6, the control signal of V4 is given.

The electric charge stored in each photodiode is transferred from the photodiode to the VCCD 4 by applying a high voltage to a corresponding cell of the adjacent VCCD 4. The electric charge transferred to the VCCD 4 is applied to the electrodes of the VCCD 4 by selectively applying a predetermined voltage to the VCDC 4 sequentially.
It is transferred vertically downward in the CCD 4.

At the lower end of each VCCD 4, an HCCD 101 is commonly arranged adjacently. The electric charge transferred downward through each VCCD 4 is transferred to the HCCD 10 according to a control signal.
Transferred to 1.

Adjacent to the HCCD 101, a shift gate SG103 capable of selectively transferring charges is arranged, and another HCCD 102 is further disposed below the shift gate SG103.
Are arranged.

Incidentally, in a device for reading out the electric charge accumulated in the photodiode 3 in a period of 4 V, the shift gate SG103 and the HCCD 102 arranged below are omitted.

FIG. 2B shows a mode in which charges accumulated in all the photodiodes 3 are read out during a period of 2V. Of all the photodiodes 3, the charges of the photodiodes A1 and A2 are read out in the same V period, and B1 is read in the next V period.
And the charge on B2. By performing such reading, the charges of all the photodiodes 3 can be read during the 2 V period.

However, in the case of this mode, the electric charges accumulated in the photodiodes A2 and B2 are equal to those of the photodiodes A1 and B2.
And the charge stored in B1 and the shift gate SG1
03 is attenuated as a result of the transfer loss at the time of transfer.
Further, when the characteristics of the HCCDs 101 and 102 are different or when the amplifier characteristics of the output amplifiers FDA1 and FDA2 are different, the difference between the characteristics is further superimposed.

FIG. 2C illustrates a mode in which all charges of the photodiode are read during a period of 4V. In the first V period, the charge of the photodiode A1 is read, and in the next V period, the charge of the photodiode A2 is read.
The charge of the photodiode B1 is read during the period, and the charge of the photodiode B2 is read during the fourth V period.

According to such a charge reading mode,
Since all charges are read out through the HCCD 101 and the FDA 1, it is easy to maintain uniform charge readout characteristics.

In the case of instantaneous exposure, smear charge is also generated in the CCD of the solid-state imaging device because strong light is applied to the solid-state imaging device. If the signal charge is taken in ignoring the smear charge, the first field will take in an extra error signal for the smear charge compared to the other fields.

FIG. 2D shows a 4V read mode performed in the case of instantaneous exposure. Subsequent to the instantaneous exposure by operation of a strobe, a mechanical shutter, or the like, in the next V period, the smear charge in the CCD is swept out. In the subsequent 4 V period, signal charge is taken in from the photodiode in the same manner as in FIG.

As described above, in the case of the instantaneous exposure, first, the smear charge is swept out, and then the signal charge of 4 V is read out. As a result, the signal charge in the continuous exposure and the instantaneous exposure is obtained. Will be different. In a head-separated solid-state imaging device, information on whether continuous exposure or instantaneous exposure is performed is transmitted by a single cable that connects a camera head unit and a camera control unit.

When a still image is captured, the HD-T
In an apparatus for reading out an image by the V method, a simple and quick imaging method is desired at the time of monitoring for determining a composition or at the time of a movie for picking up a moving image.

FIG. 3 is a diagram for explaining a monitor mode (including a movie mode) in the 4V read system.

FIG. 3A illustrates a case where the monitor of the NTSC system is performed using a 500-line monitor. When signals from the photodiodes A1 and A2 are supplied as image signals during the first 2V period, the formed image corresponds to the photodiodes A1 and A2. In the next 2V period, charges are supplied from the photodiodes B1 and B2, and a corresponding image is formed.

The vertical position of the image 105a based on the photodiodes A1 and A2 and the image 105b based on the photodiodes B1 and B2 are different by one scanning line. For this reason, when a 500-system monitor is used to reproduce an image by the 4V readout method similar to that used when capturing a still image, vertical jitter occurs.

FIG. 3B shows a case where an image is monitored by a 1000-system monitor. If a signal of the 4V readout method is supplied as it is to the 1000 monitors,
Electric charges from the photodiodes A1, A2, B1, and B2 are supplied to form an image 106 of one screen.

In order to collect this image signal, a period of 4 V is required, and when all the image signals are reproduced by the HD-TV system, a time for temporarily storing the signal and further processing is required. Therefore, in the case of using 1000 monitors, there arises a problem that the dynamic resolution is low and the processing time is long.

At the time of monitoring, it is desirable to use the 500 NTSC system in order to easily and quickly reproduce an image. A system as shown in FIG. 3C has been proposed in order to reproduce a 500-system NTSC image using a 1000-system imaging device.

FIG. 3C is a diagram for explaining a pixel-mixing type reading method. In the first field, which is the first V period, image signals from the photodiodes A1 and B1 are read and mixed to form a monitor signal. Next V
In the second field, which is a period, image information from the photodiodes A2 and B2 is read and mixed to form a monitor signal. Thus, information of all pixels is read out during the 2V period.

According to this method, there is no vertical jitter,
A monitor image with a high moving resolution can be obtained. Also,
Since all the accumulated charges are read out during the 2 V period, the charge accumulation period is 2 V, and the charge amount is doubled due to pixel mixing.
This is the same as in the case of extracting image information from each pixel in V).

[0035]

As described above,
According to the related art, when capturing a still image, the period required for image reading changes between 4 V and 5 V depending on whether the exposure is continuous exposure or instantaneous exposure. In order to identify this exposure mode, it is necessary to transmit an identification signal. In a solid-state image pickup device separated from a camera head, this signal transmission requires one cable.

An object of the present invention is to provide a method of driving a solid-state imaging device capable of driving a solid-state imaging device at the same timing regardless of whether continuous exposure or instantaneous exposure is performed when capturing a still image. To provide.

Another object of the present invention is to provide a solid-state imaging device which enables such a driving method.

[0038]

According to a method of driving a solid-state imaging device of the present invention, electric charges accumulated in a large number of four types of photoelectric conversion elements arranged in a matrix correspond to each column of the photoelectric conversion elements. The charge in each vertical CCD is taken into a plurality of columns of vertical CCDs arranged as
, And sequentially transfers the charges in the horizontal CCD to read out the signal charges. When a still image pickup instruction is given, 4n (n
Is a positive integer) times the clearing operation, followed by
Irrespective of continuous exposure or instantaneous exposure, a step of sweeping out smear charges of the vertical CCD for a period of 1 V;
Subsequently, a step of capturing an image signal for a 4 V period and a step of amplifying the captured image signal by a factor of 4/5 in the case of continuous exposure are included.

[0039]

In the still mode, the solid-state imaging device can be driven at the same timing by clearing the smear charge of the CCD following the clear operation regardless of whether the exposure is continuous exposure or instantaneous exposure. Becomes

In the case of continuous exposure, generation of smear charges on the CCD is not a problematic amount, but there is no problem even if smear charges are swept out. By making the timing the same between the continuous exposure and the instantaneous exposure, signal transmission between the camera head unit and the camera control unit can be omitted. Therefore, in the head-separated solid-state imaging device, the number of cables can be reduced.

In monitoring, if the charges from the two types of photoelectric conversion elements are simultaneously read, all the charges can be read in a 2 V period, and the dynamic resolution is high.

In monitoring, the sensitivity is reduced to about 1/2, but the read charges from the two types of photoelectric conversion elements are mixed to double the charge amount, so that the sensitivity can be substantially equal to the sensitivity in still imaging. .

If the amount of the saturated charge is reduced by half during monitoring, the charge transferred by the HCCD after pixel mixing has the same amount of the saturated charge as when the still image was captured.
Therefore, there is no need to increase the CCD drive voltage, and power loss can be prevented.

Since two types of mixed signals can be used alternately for image reproduction, vertical jitter can be prevented.

[0045]

FIG. 1 shows a basic embodiment of the present invention. FIG.
(A) schematically shows a configuration of a solid-state imaging device. A large number of photodiodes 3 are arranged in a matrix, and the photodiodes 3 arranged in each column are classified into four types, A1, B1, A2, and B2. A corresponding VCCD 4 is arranged adjacent to each column of the photodiodes 3. VCCD
In FIG. 4, two transfer cells are formed per row of photodiodes.

An HCCD 5 is connected to the lower end of the VCCD 4 so that charges transferred vertically in the VCCD can be transferred horizontally. An amplifier 8 is connected to an output terminal of the HCCD 5.

The sensitivity adjusting means 6 includes an amplifier 6a having a magnification of 1, an amplifier 6b having a magnification of 4/5, and a changeover switch 6c. The changeover switch 6c switches whether to connect the input signal to the amplifier 6a or to the amplifier 6b according to information on whether the still image is captured by continuous exposure or by instantaneous exposure.

The smear detecting means 7 detects the amount of electric charge swept out of the CCD when the smear electric charge is swept out, judges whether the exposure is performed by continuous exposure or instantaneous exposure, and adjusts the sensitivity of the identification signal. To the means 6.

FIGS. 1B and 1C schematically show a charge readout method. In the reading from the photodiodes in the monitor mode, the charges from the photodiodes A1 and A2 are read during the first V period, and the charges from the photodiodes B1 and B2 are read during the next V period.

In this way, the charges from all the photodiodes are read out to the VCCD 4 at a cycle of 2V. Note that A1 and B1 may be read at the same time, and A2 and B2 may be read in the next V period.

In the still mode, prior to charge reading, first, smear charge sweeping of the CCD is performed using a 1V period. In the next V period, the photodiode A1
Are read, the photodiode A2 is read in the next V period, the photodiode B1 is read in the next V period, and the photodiode B2 is read in the fourth V period.

By the way, if a smear sweeping step is provided before the image signal reading even in the continuous exposure, the charge accumulation period in the photodiode becomes 5V. In the monitor mode, the charge accumulation period is 2 V, and the sensitivity is proportional to 2 V × 2 by performing charge mixing. In the still mode, a difference occurs because the sensitivity is proportional to 5V.

On the other hand, in the instantaneous exposure, even if an additional 1 V period due to smear sweeping is added in the middle, the accumulated charge does not increase, so that the sensitivity proportional to 4 V does not change. In the case of a dedicated strobe or the like, the sensitivity at the time of instantaneous exposure can be made proportional to 5 V to match the sensitivity at the time of continuous exposure.

The smear detecting means 7 and the sensitivity adjusting means 6 shown in FIG. 1A compensate for the difference in sensitivity in continuous exposure.
That is, in the case of continuous exposure, the detected charge signal
/ 5 times, the sensitivity is 5V × (4/5) = 4V
And the same as the sensitivity in the monitor mode and the sensitivity in the instantaneous exposure.

Since the sensitivity adjusting means 6 and the smear detecting means 7 can be provided in the camera control section, information on whether to select instantaneous exposure or continuous exposure in the camera head section is transmitted from the camera head section. There is no need to communicate to the camera control. Therefore, the number of cables for transmitting signals can be reduced.

Hereinafter, more specific embodiments of the present invention will be described. FIG. 4 is a block diagram showing a camera head unit of the imaging device according to the embodiment of the present invention.

The camera head unit 1 includes a CCD imaging device 11, a correlated double sampling preamplifier 12 for amplifying an output signal from the CCD imaging device while reducing noise, and a signal output from the preamplifier 12. 7 to be supplied to the camera control unit shown in FIG.
5 Ω drive circuit 13 is included.

The camera head unit 1 is provided with a horizontal drive signal HD and a vertical drive signal V from the camera control unit 2 shown in FIG.
PLL circuit 1 for receiving D and generating a synchronization signal
5. These synchronization signals HD and VD and the camera control unit 2
And a control unit 16 for generating a horizontal drive pulse, a vertical drive pulse, and a shift gate signal, and a horizontal drive circuit 17 for receiving a horizontal drive pulse and generating a horizontal drive signal for HCCD drive. , A vertical drive circuit 18 for receiving a vertical drive pulse and generating a vertical drive signal for driving the VCCD, and a substrate voltage control circuit 19 for changing and setting the substrate bias according to the mode signal. Further, a strobe 32 is connected to the timing generator of the control unit 16.

The control section 16 includes a timing generator, a control CPU, and the like. Further, the camera head unit 1 includes a power supply unit 20 for supplying power to each circuit included in the camera head unit 1.

FIG. 5 is a block diagram showing the camera control unit 2. The signal output supplied from the camera head unit 1 is
The gain is supplied to the gain control amplifier 21 to amplify the set gain. Gain control amplifier 21
Is supplied to the A / D conversion circuit 23 via the sensitivity adjusting means 6 and the gamma processing circuit 22, and is supplied as a digital signal to the memory unit 24.

The memory section 24 stores the supplied digital signal. The image signal read from the memory unit 24 is
The signal is converted to an analog signal via the D / A conversion circuit 25,
Is output.

The charge signal amplified by the gain control amplifier 21 is also supplied to the smear detecting means 7. The smear detecting means 7 receives a signal at a predetermined timing from a timing generator 29 described later, and detects smear charges.
It is possible to determine whether exposure is continuous exposure or instantaneous exposure based on the amount of smear charge. The smear signal detected by the smear detection means 7 is transmitted to a main CP described later.
It is supplied to U28.

The main CPU 28 determines whether the exposure is continuous exposure or instantaneous exposure from the smear signal, supplies a determination signal to the sensitivity adjusting means 6, and switches the changeover switch 6c of the sensitivity adjusting means 6.

As described above, the gain control amplifier 2
The output signal of 1 passes through the amplifier 6b or 6a of the sensitivity adjusting means depending on whether it is continuous exposure or instantaneous exposure, and is supplied to the gamma processing circuit 22. Therefore, the charge signal input to the gamma processing circuit 22 has been subjected to sensitivity adjustment.

The timing generator 29 generates a horizontal drive pulse HD, a vertical drive pulse VD and other control signals at predetermined timings, and also generates control signals to the main CPU 28 and the #processing circuit 22.

The main CPU 28 receives a switch signal from the external switch 32 and sends a trigger signal to the memory controller 2.
7 and the camera head. Still mode / monitor mode is indicated by ON / OFF of the trigger signal.

The memory control unit 27 receives the trigger signal,
The bank switching mode for storing the image signal in the memory unit 24 is changed. The main CPU 28 also supplies the gain control amplifier 21 with a gain switching signal for giving a predetermined gain depending on the mode. In addition, the power supply 30
A power supply voltage is supplied to various circuits in the camera control unit 2.

By the circuits shown in FIGS. 4 and 5, the image signal stored in the CCD device 11 at the time of capturing a still image is read in a 4 V period after a 1 V smear sweeping period, and is stored in the memory unit 24.

In the monitor mode, the substrate voltage is changed so that the amount of saturated charge of the photodiode is reduced to about half, and two kinds of charges stored in the CCD device 11 are simultaneously read out, mixed and supplied as a CCD output. Then, it is displayed on the monitor 31.

Hereinafter, each part of the imaging apparatus shown in FIGS. 4 and 5 will be described in more detail. FIG. 6 shows the configuration of the CCD device. FIG. 6A is a plan view, and FIG. 6B is a partial cross-sectional view. In FIG. 6A, the CCD device 1
Reference numeral 1 denotes a photodiode 35 arranged in a matrix and a VCCD 36 for taking in charges from the photodiodes 35 and transferring the charges in the vertical direction, and an HCCD 37 for transferring the charges transferred from the plurality of VCCDs 36 in the horizontal direction.

Each row of the photodiodes 35 is divided into four types of A1, B1, A2, and B2 in order from the top as shown, and each type of photodiode corresponds to an image of one field. VCCD adjacent to each photodiode row
The VCCD 36 has two transfer cells for one row of photodiodes. VCCD 36 is φVA
1. Charges are transferred by six-phase driving of φV2, φVB1, φV4, φVA2, φVB2.

The plurality of VCCDs 36 are connected to the HCCD 37 at one end. That is, the charge taken into the VCCD 36 from the photodiode 35 is
After the CD 36 is transferred in the vertical direction and transferred to the HCCD 37, the CD 36 is transferred in the HCCD 37 in the horizontal direction. HCCD
37 is a four-phase drive signal φH1, φH2, φH3, φH
4 driven. The output of the HCCD 37 is output via an amplifier 39.

FIG. 6B shows the structure of the photodiode formed on the surface of the substrate and the vertical overflow drain formed thereunder. A p-well 42 is formed on the surface of n-type semiconductor substrate 41. The p-well 42 has a first p-well 1pw having a small depth and a second p-well 42 having a large depth.
2pw of p wells are distributed.

On the first p well 1pw, an n-type region 43 is formed.
Are formed to form a photodiode. An n ⁻ -type region 44 is formed at a predetermined interval close to the n-type region 43 to form a charge transfer path of the VCCD. The p ⁺ type region 48 is a channel stop region. An insulating electrode 45 and a light-shielding mask 46 are formed on the n ⁻ -type region 44 forming the charge transfer path.

The incident light enters the n-type region 43 forming the photodiode. A reverse bias voltage is applied between the p-well region 42 and the n-type substrate 41 by a variable DC power supply 50 controlled by the substrate voltage control circuit 19.

If the charge is excessively accumulated due to the incidence of light, n
Electrons from the mold region 43 overflow to the n-type substrate 41. When the substrate voltage is changed, the potential at which the overflow occurs changes, and the saturated charge amount of the photodiode changes. In the monitor mode, the substrate voltage is set so that the saturation charge is half the saturation charge in the still mode. The charge overflowing the photodiode is the substrate 41
It is sucked out.

FIG. 7 is a timing chart of a control signal in a monitor mode for monitoring an image to determine a composition. The field switching signal FI has a pulse-like waveform that changes alternately for each field. The external switch signal always keeps a value of “0” because the shutter is not pressed in the monitor mode.

The trigger signal TRG is "0" in the monitor mode and "1" in the still mode. The SUB switching signal has a value of “0” in the monitor mode and a value of “1” in the still mode. The strobe signal is "0" while the strobe is not operated.

In the monitor mode, the electric charges of all the pixels are read out during the 2V period, so that the camera drive signal alternately switches between field I and field II. In the monitor mode, since recording is not performed, the recording signal R
EC is “0”.

FIG. 8 shows a waveform of a drive signal for taking in an image signal in field I. When the voltage of the transfer cell adjacent to the photodiode of the VCCD is set to a predetermined height, the accumulated charge is taken into the VCCD from the photodiode.

The upper part of FIG. 8 shows the waveforms of the six-phase signal driven by the VCCD. At time t2, drive signal φV
At this time, the photodiode B
1 to the VCCD. Time t
In No. 4, since the drive signal φVA1 is at a high level, the accumulated charge is taken in from the photodiode A1.

That is, charges are taken into the VCCD from the two types of photodiodes A1 and B1 during the 1 V period, sequentially transferred in the VCCD in the vertical direction during each horizontal blank period, and the two types of charges are mixed to perform the next horizontal scan. H during the period
High-speed transfer through the CCD.

FIG. 9 is an enlarged waveform diagram showing a portion indicated by a broken line in FIG. VCCD drive signals φVA1, φVA
2, .phi.V2, .phi.VB1, .phi.VB2, and .phi.V4 change as shown to cause the charge to be transferred vertically in the VCCD.

Note that the times t1 to t1 shown in FIGS.
The potential in the VCCD at 0 is shown in FIG.

In FIG. 11, at time t2, drive voltage φV
Since B1 is at a high level, the charge from the photodiode B1 is taken into the VCCD. At time t4, the fetched charges are transferred rightward in the drawing for one cell of the VCCD. At this time t4, the drive voltage φVA1 becomes a high level, and the charge of the photodiode A1 is taken into the same VCCD.

At the next time t5, each of the captured electric charges spreads for three transfer cells, and a barrier for one cell is formed between the electric charges. Thereafter, the electric charge taken in from time t6 to time t11 is reduced by one cell at the rear, then extended by one cell at the front, reduced by one cell again at the rear, and the same operation is repeated and transferred to the right side in the drawing by the scale insect method. Is done.
In HCCD, two types of charges are mixed.

The driving of the field I for taking in electric charges from the photodiodes A1 and B1 has been described.
In field II, similar charge taking-in and transfer are performed. FIG. 10 shows a drive signal waveform for capturing image data in field II.

FIG. 12 shows a signal waveform when the shutter is driven to capture a still image and the external switch 32 shown in FIG. 5 is turned on. The external switch 32 generates an external switch signal that becomes “1” for a predetermined period. When the external switch signal changes from "0" to "1", the trigger signal TRG rises in the field next to the rise of the signal, and the mode switching for converting the camera driving signal is performed. This mode switching ends in the 1V period.

Also, at the same time as the mode signal, the substrate voltage (SU
B) The switching signal also rises, and adjusts the substrate voltage variable DC power supply 50 shown in FIG. 6B via the substrate voltage control circuit 19 shown in FIG. That is, in the still mode, one type of photodiode is read at a time, and the saturation charge is about half as it is in the monitor mode in which two types of photodiodes are simultaneously read.
This difference in the amount of saturated charge is adjusted by the substrate voltage.

After the mode switching is completed, at least 4 V (or 4 nV, n
Is a positive integer). In the case shown, 4V
After the clear operation, the smear charge of 1 V is swept out, and then the recording mode is started. In the recording mode, the photodiodes A1,
The charges of A2, B1, and B2 are sequentially read in a period of 4 V and recorded in the memory.

That is, the charge signal capturing and storage is started at 7 V from the rising of the trigger signal TRG. When the clear operation is performed at 4 nV, the operation is started at (4n + 3) V.

When the strobe light is emitted or the shutter is operated, the light emission operation is performed immediately before the smear charge sweeping step.

FIG. 13 shows a drive signal waveform for reading out the charge of the photodiode A1 in the first V period.

At time S1, drive signal φA1 attains a high level, and the charge from photodiode A1 becomes VCC.
D during each subsequent horizontal blanking period.
It is transferred vertically in the CD.

FIG. 14 shows a field control signal for reading out the photodiode A2. At time S8, the drive signal φA2 goes to a high level, and takes in the charge from the photodiode A2. Photodiode A2 to VCCD
The electric charge taken into each horizontal blank period is VCCD
It is transferred vertically inside. Also, during the horizontal scanning period, V
The charge in the CCD is stopped, and the charge in the HCCD is transferred at high speed in the horizontal direction.

FIG. 15 and FIG. 16 show the waveforms of the driving signals in the fields for extracting the electric charges from the photodiodes B1 and B2, respectively. In FIG. 15, at time S6, the drive signal φB1 changes to a high level, and the accumulated charge is taken in from the photodiode B1. Further, in FIG. 16, at time S10, the drive signal φB2 becomes high level, and the accumulated charge is taken into the VCCD from the photodiode B2. The transfer of these charges is the same as described above.

As described above, A1, A2, B1,
In a CCD device including a large number of four types of photodiodes of B2, in the still mode, all charges are read out in a 4V period after smear charge sweeping out, regardless of whether the exposure is instantaneous exposure or continuous exposure. Form an image.

The driving timing of the CCD does not change depending on whether the exposure is instantaneous exposure or continuous exposure, and the imaging operation can be performed at a constant timing. For this reason, the number of cables between the camera head unit and the camera control unit can be reduced. Note that the charge accumulation period in the continuous exposure, which is increased by the smear charge sweeping step, can be compensated by sensitivity adjustment based on smear charge detection.

Further, in the monitor mode, the saturation charge is set to about half and the total charge is taken in two at a time in a 2 V period, the VCCD is transferred, and the HCCD is mixed and transferred to the HCCD, so that power loss is prevented. In addition, it is possible to obtain a monitor image having high dynamic resolution with the same sensitivity and the same saturation charge amount.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0101]

As described above, according to the present invention,
The solid-state imaging device can be driven under certain conditions regardless of whether it is instantaneous exposure or continuous exposure.

Therefore, it is not necessary to transmit information on whether the exposure is the instantaneous exposure or the continuous exposure from the camera head unit to the camera control unit in order to determine when to start storing. For this reason, the number of cables between the camera head unit and the camera control unit can be reduced.

In the monitor mode, the image signal is taken in at a cycle of 2 V, so that the dynamic resolution can be kept high.

Further, since the two kinds of mixed image signals to be read can be taken in from a fixed position, jitter can be prevented.

[Brief description of the drawings]

FIG. 1 shows a basic embodiment of the present invention. FIG. 1A is a schematic diagram showing a configuration, and FIGS. 1B and 1C are schematic diagrams for explaining a state of reading stored charges in a monitor mode and a still mode.

FIG. 2 shows a conventional technique. FIG. 2A is a schematic plan view showing a configuration, and FIGS. 2B, 2C, and 2D are conceptual diagrams for explaining charge reading.

FIG. 3 is a diagram illustrating a monitor mode of a 4V readout method according to the related art. FIG. 3A is a schematic diagram for explaining a reproduced image of a 500-line monitor, and FIG.
FIG. 3C is a schematic diagram for explaining a reproduced image of the zero-system monitor.
FIG. 4 is a conceptual diagram for explaining pixel mixture reading.

FIG. 4 is a block diagram of a camera head unit of the imaging device according to the embodiment of the present invention.

FIG. 5 is a block diagram illustrating a camera control unit of the imaging apparatus according to the embodiment of the present invention.

FIG. 6 shows the configuration of the CCD device shown in FIG. 5 in more detail. FIG. 6A is a schematic plan view, and FIG. 6B is a partial cross-sectional view.

FIG. 7 is a waveform diagram showing a control signal waveform in a monitor mode.

FIG. 8 is a waveform chart for explaining image signal capture in a monitor mode.

FIG. 9 is a waveform chart for explaining image data transfer in a monitor mode.

FIG. 10 is a waveform chart showing a control signal of another field in the monitor mode.

FIG. 11 is a potential diagram for explaining capture and transfer of image data in the VCCD in the monitor mode.

FIG. 12 is a waveform diagram showing a control signal waveform in a still mode.

FIG. 13 is a drive signal waveform diagram of an A1 field in a still mode.

FIG. 14 is a drive signal waveform diagram of an A2 field in a still mode.

FIG. 15 is a drive signal waveform diagram of a B1 field in the still mode.

FIG. 16 is a drive signal waveform diagram of a B2 field in the still mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera head part 2 Camera control part 3 Photodiode 4 VCCD 5 HCCD 6 Sensitivity adjustment means 7 Smear detection means 8 Amplifier 11 CCD device 12 Preamplifier 13 Drive circuit 15 PLL circuit 16 Control parts 17, 18 Drive circuit 19 Substrate voltage control circuit 20 Power supply Reference Signs List 21 gain control amplifier 22 gamma processing circuit 23 A / D conversion circuit 24 memory unit 25 D / A conversion circuit 27 memory control unit 28 main CPU 29 timing generator 30 power supply 31 monitor 32 strobe

Claims (5)

(57) [Claims] An electric charge accumulated in a large number of four types of photoelectric conversion elements arranged in a matrix is taken into a plurality of columns of vertical CCDs arranged corresponding to each column of the photoelectric conversion elements, and each of the vertical CCDs is taken up. The charge in the CCD is transferred to the horizontal CC connected to the vertical CCD.
D is a method of driving a solid-state imaging device that sequentially transfers charges in a horizontal CCD and reads out signal charges by sequentially transferring charges in a horizontal CCD.
(N is a positive integer) times the step of performing a clear operation, and then, regardless of whether it is continuous exposure or instantaneous exposure,
A step of sweeping out smear charges of the vertical CCD for a period of 1 V, a step of taking in an image signal for a period of 4 V, and a step of amplifying the taken-in image signal by 4/5 in the case of continuous exposure. A method for driving a solid-state imaging device including: 2. The solid-state imaging device according to claim 1, further comprising a step of irradiating the photoelectric conversion element with light to accumulate charges within a period of 1 V before the smear charge sweeping step in the case of the instantaneous exposure. How to drive the device. 3. The method of driving a solid-state imaging device according to claim 1, further comprising a step of simultaneously taking in charges from two types of photoelectric conversion elements and mixing pixels during monitoring. 4. A plurality of four types of photoelectric conversion elements arranged in a matrix, a plurality of columns of vertical CCDs arranged corresponding to respective columns of the photoelectric conversion elements, and a plurality of columns of vertical CCDs. One row of horizontal CCD connected to each end, and in still mode, when a still image instruction is given,
A clear operation of 4n times (n is a positive integer) times the vertical scanning period V is performed, and then a smear charge sweep of the vertical CCD is performed in a 1V period regardless of continuous exposure or instantaneous exposure, Control driving means for taking in an image signal during a 4 V period; and means for detecting the amount of discharged charge when performing smear charge discharge of the vertical CCD and determining whether continuous exposure or instantaneous exposure is performed. Means for amplifying the captured signal charges at different amplification factors based on the determination of continuous exposure or instantaneous exposure. 5. Further, at the time of monitoring, charges from two types of photoelectric conversion elements are taken in, read out by mixing pixels.
5. The solid-state imaging device according to claim 4, further comprising a control circuit for controlling the vertical CCD so as to read out all charges in the V period.