JP2773787B2 - 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.

By the way, at the time of monitoring before capturing a still image (including a movie mode for capturing a moving image), it is necessary to take image information over a period of 4 V and to perform signal processing to reproduce the image. Is not preferred in terms of dynamic resolution and processing time. Therefore, in order to perform image reproduction in a short period of time, it is desired to perform NTSC system image reproduction during monitoring.

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.

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. In the monitor mode, it is desired to monitor in the NTSC system in order to easily and quickly reproduce an image.

FIG. 3A illustrates a case where the monitor of the NTSC system is performed by 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 image 105a based on the photodiodes A1 and A2 and the image 105b based on the photodiodes B1 and B2 are different in position in the vertical direction 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. In order to use a 1000-line imaging device and reproduce a 500-line NTSC image, FIG.
A system as shown in (D) has been proposed.

In the method shown in FIG. 3C, the stored charges are read out in the same manner as in the case of still image capturing, but only half of the charges from the photodiodes A1 and A2 are used for forming a reproduced image. That is, the output of the CCD is A
1, A2, B1, and B2 are supplied in this order, and writing to the memory is performed by directly writing the read image signal.

However, the monitor signal is performed by repeatedly reading out only the signals from the photodiodes A1 and A2 without using all the written image signals.
That is, when an image signal is read out from the photodiode A1 and written in the memory, the image information A2 stored previously is used.
Is read from the memory, and when writing the signal of the photodiode A2 to the memory next, the information of A1 written immediately before is read from the memory.

Next, even during the period in which the image signals B1 and B2 are to be read, the image signals A2 and A1 are read from the memory to reproduce a 500-line monitor image in which the vertical jitter is prevented.

When the image signal from the photodiode A1 is being written into the memory, the signal of A2 is read out,
The case where A1 is read when the image signal A2 is written has been described. When the image signal is read from the photodiodes A1 and A2, the signal is supplied to a monitor as it is and the image signal is read from the photodiodes B1 and B2. Alternatively, the previously stored image signals A1 and A2 may be read from the memory.

In this system, vertical jitter can be prevented, but it is difficult to increase the dynamic resolution.

FIG. 3D 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 the pixel mixing. Therefore, the obtained charge amount is the image information from each pixel during the 4 V period (accumulation period 4 V). It is the same as when taking out.

When image information is read out by performing pixel mixing, the charges accumulated in the two photodiodes are transferred together by the HCCD, so that the drive voltage of the HCCD does not correspond to twice the saturated charge. Not be.

That is, when light of high intensity is irradiated, electric charges close to saturated electric charges are accumulated in each photodiode. When these charges are mixed, it is necessary to transfer charges twice as high as the saturated charges by the HCCD. If the HCCD is driven at a drive voltage capable of transferring the saturated charge of one photodiode, charge transfer leakage will occur.

Therefore, the swing voltage of the drive voltage of the HCCD needs to be doubled, for example. C
Since the CD structure has a capacitance C that cannot be ignored, power loss is not negligible when doubling the swing voltage and transferring charges at high speed.

[0040]

As described above,
In the conventional 1000-line imaging apparatus, if the 500-line monitor is to be operated by the NTSC system, problems such as a vertical jitter, a decrease in dynamic resolution, a prolonged processing time, and a power loss will occur.

An object of the present invention is to enable an image pickup apparatus capable of reproducing a high-resolution still image to reproduce an image having a high dynamic resolution and a low power loss without generating vertical jitter during monitoring. is there.

[0042]

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. A plurality of columns of vertical CCDs arranged in parallel, sequentially transferring the charges in the vertical CCDs to a horizontal CCD commonly connected to the vertical CCDs, sequentially transferring the charges in the horizontal CCDs, and reading out signal charges. A method of driving an imaging device, wherein during monitoring, a step of adjusting the saturated charge amount of the photoelectric conversion element to approximately half and storing the charge, and at the time of monitoring, a step of simultaneously transferring charges of the two types of photoelectric conversion elements to the vertical CCD. When monitoring, the charge of the vertical CCD is transferred in the vertical direction, and the charges of the two types of photoelectric conversion elements are mixed to mix the horizontal CCD.
Transferring the mixed charges to the horizontal CCD during monitoring, transferring the transferred charges in the horizontal direction and reading them out as signals, and transferring the charges of the four types of photoelectric conversion elements to the vertical CCD one by one during still imaging. And a step.

[0043]

Since the charges from the two types of photoelectric conversion elements are simultaneously read during monitoring, all the charges can be read in a 2 V period, so that the dynamic resolution is high.

In monitoring, the sensitivity is halved due to the charge accumulation period and the like. Therefore, by mixing the read charges from the two types of photoelectric conversion elements into pixels, the sensitivity becomes equal to that in the still mode.

Since the amount of the saturated charge is halved, the charge transferred by the HCCD after pixel mixing has the same amount of the saturated charge as when the still image was captured. For this reason,
There is no need to increase the CCD drive voltage, and power loss can be prevented.

Since two types of mixed signals are used alternately for image reproduction, no vertical jitter occurs.

[0047]

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 saturated charge amount setting means 6 can set different saturated charge amounts in the monitor mode (including the movie mode) and the still mode with respect to the charge stored in the photodiode 3, and in the monitor mode, set it to half of the still mode. .

FIGS. 1B and 1C schematically show such a charge readout system. That is, in the reading from the photodiode to the VCCD in the monitor mode, the charges from the photodiodes A1 and A2 are read in the first V period, and the photodiode B is read in the next V period.
The charges from 1 and B2 are read.

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, the photodiode A1 is read in the first V period, the photodiode A2 is read in the next V period, the photodiode B1 is read in the next V period, and the photodiode A1 is read in the fourth V period. The photodiode B2 is read.

In the monitor mode, the VCCD
Since the two kinds of charges read out in No. 4 have half the amount of saturated charges as compared with the still mode, the amount of saturated charges when mixed is the same as in the still mode.

For this reason, the saturated charge amount of the electric charge to be transferred by the HCCD becomes equal between the time of capturing a still image and the time of monitoring. Therefore, it is not necessary to increase the drive voltage of the HCCD 5 and power loss can be prevented. VCC
In the case where charge mixing is performed in D, the same is true for VCCD.

Although the sensitivity at the time of monitoring is half of the sensitivity at the time of capturing a still image, the sensitivity becomes equal due to pixel mixing.

Further, since a monitor image is formed by using two types of mixed charges, no vertical jitter occurs. Also, 2
Since one frame of image is composed in the V period, the dynamic resolution can be kept high.

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 outputting a signal from the preamplifier 12 as a signal. 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
, A control unit 16 for generating a horizontal drive pulse, a vertical drive pulse, and a shift gate signal, a horizontal drive circuit for receiving a horizontal drive pulse and generating a horizontal drive signal for HCCD drive 17,
It includes 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 a substrate bias by a mode signal.

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 an A / D conversion circuit 23 through a gamma processing circuit 22 to be converted into a digital signal,
Supplied to

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 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 for the main CPU 28 and the gamma processing circuit 22.

The main CPU 28 receives a switch signal from the external switch 32 and sends a mode signal to the memory controller 2.
7 and the camera head. Memory control unit 27
Receives the mode signal and changes the bank switching mode when the image signal is stored in the memory unit 24. Main CPU2
8 supplies a gain control signal to the gain control amplifier 21 for giving a predetermined gain according to the mode.

The power supply 30 supplies a power supply voltage to various circuits in the camera control unit 2. 4 and 5, the image signal accumulated by the CCD device 11 at the time of capturing a still image is read in a 4 V period,
Is accumulated in 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. 31 is displayed.

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 at one end to the HCCD 37. 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 a 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 control signals 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 mode signal 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.

In the monitor mode, since the charges of all the pixels are read out during the 2V period, the camera drive signal switches between field I and field II alternately. 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 capturing 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 waveform 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 1V period, and sequentially transferred in the vertical direction through the VCCD 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.

At time t2, drive voltage φVB1 attains a high level, so that charges from photodiode B1 are taken into 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 φVA
1 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 charges spreads over three transfer cells, and a barrier for one cell is formed between the 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 mode switching for converting the camera driving signal is performed in the next field after the signal rise. This mode switching is
It ends in V period. At the same time as the start of mode switching,
The mode signal rises to indicate the still mode.

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 amount becomes half as it is in the monitor mode in which two types of photodiodes are read at the same time. 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) is cleared in order to sweep out the charge in the CCD. In the case shown, the recording mode has been started after the clear operation of 4V. In the recording mode, the photodiodes A1 and A1
2, B1, and B2 are sequentially read out during a period of 4 V,
Recorded in memory.

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 goes high, 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 4 V period to form a high-resolution image, and in the monitor mode, the amount of saturated charges is set to about half and two times at a time. Each kind of charge is taken in 2V period, VCCD is transferred, HCCD is mixed and transferred, preventing power loss,
A monitor image with high dynamic resolution can be obtained 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.

[0094]

As described above, according to the present invention,
In the monitor mode, the sensitivity of each photoelectric conversion element is half that of the still mode, but the same sensitivity as in the still mode is obtained by performing pixel mixing. In the monitor mode, the maximum charge to be transferred by the HCCD can be the same by setting the saturation charge of the photoelectric conversion element to about half.

For this reason, the HCCD drive signal has the same condition in the still mode and the monitor mode. Therefore, power loss can be prevented.

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 types 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 and 2C 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.
Is a conceptual diagram for explaining double reading, and FIG. 3D is a conceptual diagram for explaining pixel mixed 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]

 Reference Signs List 1 camera head unit 2 camera control unit 3 photodiode 4 VCCD 5 HCCD 6 saturated charge setting means 8 amplifier 11 CCD device 12 preamplifier 13 drive circuit 15 PLL circuit 16 control unit 17, 18 drive circuit 19 substrate voltage control circuit 20 power supply 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

Claims (3)

(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. A method for driving a solid-state imaging device in which charges in a CCD are sequentially transferred to a horizontal CCD commonly connected to a vertical CCD, and charges in the horizontal CCD are sequentially transferred to read out signal charges. Adjusting the saturated charge amount to about half and accumulating the charge; transferring the charge of the two types of photoelectric conversion elements to the vertical CCD at the time of monitoring; and transferring the charge of the vertical CCD in the vertical direction at the time of monitoring. ,
Mixing the charges of the two types of photoelectric conversion elements and transferring the mixed charges to the horizontal CCD; monitoring, transferring the charges mixed and transferred to the horizontal CCD in the horizontal direction, and reading them out as a signal; Transferring a charge of each type of photoelectric conversion element to the vertical CCD one by one. 2. 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. 1 commonly connected to each end
In the horizontal CCD in the row and in the monitor mode in which charges of two types of photoelectric conversion elements among the four types of photoelectric conversion elements are mixed and read, the amount of saturation charge of the four types of photoelectric conversion elements is reduced by one. A solid-state imaging device including: a saturation charge amount setting unit that sets the saturation charge amount to about half of the saturation charge amount in the still mode in which each type is read. 3. The solid-state imaging device according to claim 2, wherein said saturation charge amount setting unit includes a substrate bias changing unit.