JPH0591417A - Solid state image pickup device and its driving method - Google Patents

Abstract

PURPOSE:To provide a solid state image pickup device which can reproduce the still images of high resolution and also can reproduce the images of low power loss with high dynamic image resolution and without producing any vertical jitter in a monitoring mode. CONSTITUTION:The electric charge stored in four types of many photoelectric conversion elements 3 arranged in a matrix form are fetched into plural columns of vertical VCCDs 4 arranged corresponding to each column of conversion elements 3 by an output terminal. This terminal transfers successively the electric charge stored in each VCCD to a horizontal HCCD 5 connected in common to the VCCDs 4 and is connected to an amplifier 8. In a monitoring mode, a saturated charge amount setting means 6 sets the amount of charge stored by the photoelectric conversion elements 3 at half as much as that set in a still mode. The electric charge is read out from conversion elements 2 of A1 and A2 in a first V period and then read out from the transducers 3 of B1 and B2 in the next V period respectively in the monitoring mode. Thus the electric charge are read out from all conversion elements 3 and sent to the VCCDs 4 in a cycle of 2V. In a still mode, the electric charge of four types of conversion elements 3 are transferred to the VCCDs 4 for each type. In other words, the mixed image signals are taken out from a fixed position in each cycle of 2V in the still and monitoring modes respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device,
In particular, the present invention relates to a method for driving 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 image pickup devices have been remarkably developed mainly for video cameras. High resolution is one of the directions, and 2 million pixels to 4 million for high-definition television (HD-TV), mechanical measurement, astronomical observation, etc.
A solid-state image sensor with, 000,000 pixels has been developed.

However, at present, only an image pickup device having 400,000 pixels or less is put to practical use for a color camera having 525 vertical scanning lines which is a 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 the 525 vertical scanning line system.

The applicant has studied the optimum number of pixels based on theoretical calculation and image simulation.
It was concluded that the number of pixels of about 0,000 pixels is sufficient for the above 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 for an image having an aspect ratio of about 3: 4 in the vertical and horizontal directions, a preferred form of arranging 800,000 pixels 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 advancing the charges in the vertical direction is adjacent to each column.
CD (VCCD) columns are provided, and horizontal CCDs (H) for horizontally transferring charges to the output terminals of these VCCD columns are provided.
CCD) rows are provided.

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

In order to read image information in a short time, it has been proposed to classify vertical photodiodes into four types and read 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, due to the limitation of horizontal charge transfer, two HCCDs are provided, and two kinds of charges are simultaneously transferred by the two HCCDs.

By the way, in a system using two HCCDs, the intensity of the image signal varies depending on which HCCD is used for transfer. Particularly in a color image pickup device having a three-plate structure, the level difference between image signals appears as a flicker phenomenon.

In order to prevent such a phenomenon, the applicant of the present invention uses one HCCD and uses a period 4 which is four times the vertical scanning period V.
A method of reading all image information by V was proposed. According to this method, it is possible to reproduce a highly accurate still screen.

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

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

A VCCD 4 is formed adjacent to the photodiode 3 in each column. The VCCD 4 has two transfer cells per row, and 4 rows and 8 cells are one unit. The transfer cell is configured by disposing an insulating electrode on the semiconductor transfer path. One unit cell has V1, V2, V3, V4, V5, V2, V from the top.
6, the control signal of V4 is given.

The charge accumulated in each photodiode is transferred from the photodiode to the VCCD 4 by applying a high voltage to the corresponding cell of the adjacent VCCD 4. The charges transferred to the VCCD 4 are Vc by selectively applying a predetermined voltage to the electrodes of the VCCD 4 sequentially.
It is transferred vertically downward in the CCD 4.

An HCCD 101 is commonly and adjacently arranged at the lower end of each VCCD 4. The charges transferred downward through each VCCD 4 are transferred to the HCCD 10 according to a control signal.
Forwarded to 1.

A shift gate SG103 capable of selectively transferring charges is arranged adjacent to the HCCD 101, and another HCCD 102 is provided below the shift gate SG103.
Are arranged.

The shift gate SG103 and the HCCD 102 arranged below the shift gate SG103 are omitted in the device for reading out the charges accumulated in the photodiode 3 in the period of 4V.

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

However, in this mode, the charges accumulated in the photodiodes A2 and B2 are the same as those of the photodiode A1.
And the charge accumulated in B1 are compared to shift gate SG1
As a result of the transfer loss when 03 is transferred, it is subject to attenuation.
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, this difference in characteristics is further superimposed.

FIG. 2C illustrates a mode in which all the charges of the photodiode are read during the period of 4V. The charge of the photodiode A1 is read during the first V period, the charge of the photodiode A2 is read during the next V period, and the next V
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 the charges are read out via the HCCD 101 and the FDA 1, it becomes easy to keep the charge reading characteristics uniform.

By the way, when capturing a still image, the HD-T
Even in an apparatus for reading an image by the V method, a simple and quick imaging method is desired at the time of monitoring when determining the composition or at the time of movie shooting of a moving image.

FIG. 3 is a diagram for explaining a monitor mode (including a movie mode) in the 4V read method. In the monitor mode, it is desired to perform the NTSC system monitor in order to simply and quickly reproduce the image.

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

By the way, 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 for one scanning line. Therefore, when an image by the 4V reading method similar to that at the time of capturing a still image is reproduced using a 500-line monitor, jitter occurs in the vertical direction.

FIG. 3B shows a case where an image is monitored by a 1000-line system monitor. If the signal of 4V read method is directly supplied to the 1000-line monitor,
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 4V period is required, and when all the image signals are reproduced by the HD-TV system, it is necessary to temporarily store the signal and further process it. Therefore, the 1000-line monitor causes a problem that the dynamic resolution is low and the processing time is long.

At the time of monitoring, it is desired to use the NTSC system of 500 lines in order to reproduce images easily and quickly. In order to reproduce the NTSC system image of 500 lines by using the imaging device of 1000 lines, FIG.
A method as shown in (D) has been proposed.

In the system shown in FIG. 3C, the accumulated charges are read out in the same manner as in the still image pickup, but only the charges from the half photodiodes A1 and A2 are used for reproducing image formation. That is, the output of the CCD is A
1, A2, B1, B2 are supplied in this order, and writing to the memory is also performed by directly writing the read image signal.

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

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

When the image signal from the photodiode A1 is written in the memory, the signal of A2 is read out,
The case of reading A1 while writing the image signal A2 has been described. However, when reading the image signal from the photodiodes A1 and A2, the signal is directly supplied to the monitor 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 the pixel-mixing type readout method. In the first field, which is the first V period, the 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 the period, the image information from the photodiodes A2 and B2 is read and mixed to form a monitor signal. In this way, the information of all pixels is read during the 2V period.

According to this method, there is no vertical jitter,
A monitor image with high dynamic resolution can be obtained. Also,
Since all the accumulated charges are read during the 2V period, the charge accumulation period is 2V, and the charge amount is doubled due to pixel mixing. Therefore, the obtained charge amount is the image information from each pixel during the 4V period (accumulation period 4V). It becomes the same as the case of taking out.

By the way, when pixel information is read out by performing pixel mixing, the charges accumulated in the two photodiodes are combined and transferred by the HCCD. Therefore, the driving voltage of the HCCD does not correspond to twice the saturated charge. Don't

That is, when light of strong intensity is applied, charges close to saturation charge are accumulated in each photodiode. When these charges are mixed, it is necessary to transfer twice the saturated charge by the HCCD. If the HCCD is driven with a drive voltage that can transfer the saturated charge of one photodiode, charge transfer leakage occurs.

Therefore, it is necessary to double the swing voltage of the drive voltage of the HCCD. C
Since the CD structure has a capacitance C that cannot be ignored, power loss cannot be ignored when the swing voltage is doubled and charges are transferred at high speed.

[0040]

As described above,
In the conventional 1000-line image pickup apparatus, if an attempt is made to perform 500-line monitor by the NTSC system, problems such as vertical jitter, lower dynamic resolution, longer processing time, and power loss will occur.

An object of the present invention is to provide an image pickup apparatus capable of reproducing a high-resolution still image, by which it is possible to reproduce an image with high dynamic resolution and low power loss without causing vertical jitter during monitoring. is there.

[0042]

According to a method for driving a solid-state image pickup device of the present invention, charges accumulated in a large number of four types of photoelectric conversion elements arranged in a matrix are associated with each column of the photoelectric conversion elements. A solid state which takes in a plurality of columns of vertical CCDs arranged in parallel, sequentially transfers the charges in each vertical CCD to a horizontal CCD commonly connected to the vertical CCDs, and sequentially transfers the charges in the horizontal CCDs to read out signal charges. A method of driving an image pickup device, which comprises a step of adjusting a saturated charge amount of a photoelectric conversion element to about half at the time of monitoring and accumulating the charges, and a step of simultaneously transferring charges of two types of photoelectric conversion elements to a vertical CCD at the time of monitoring. During monitoring, the charges of the vertical CCD are transferred in the vertical direction, and the charges of the two types of photoelectric conversion elements are mixed to produce a horizontal CCD.
To the vertical CCD, and to transfer the charges mixed and transferred to the horizontal CCD in the horizontal direction at the time of monitoring and read out as a signal, and to transfer the charges of the four types of photoelectric conversion elements to the vertical CCD one by one at the time of still imaging. And a process.

[0043]

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

Further, since the sensitivity is halved at the time of monitoring due to the charge accumulation period and the like, 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.

Further, since the saturated charge amount is halved, the charge transferred by the HCCD after pixel mixing has the same saturated charge amount as at the time of still image pickup. For this reason,
It is not necessary to increase the CCD drive voltage, and power loss can be prevented.

Further, since two kinds of mixed signals are alternately used for image reproduction, vertical jitter does not occur.

[0047]

1 shows a basic embodiment of the present invention. Figure 1
FIG. 1A schematically shows the 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
Two transfer cells are formed in each row 4 of the photodiode.

The HCCD 5 is connected to the lower end of the VCCD 4, and the charges transferred in the vertical direction through the VCCD can be transferred in the horizontal direction. An amplifier 8 is connected to the output end 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 accumulated in the photodiode 3, and in the monitor mode, it is set to half of the still mode. ..

FIGS. 1B and 1C schematically show such a charge reading method. 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 during the first V period, and the photodiode B is read during 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 with a cycle of 2V. Note that A1 and B1 may be read at the same time and A2 and B2 may be read during the next V period.

In the still mode, the photodiode A1 is read during the first V period, the photodiode A2 is read during the next V period, the photodiode B1 is read during the next V period, and the fourth V period is reached. The photodiode B2 is read.

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

Therefore, the saturated charge amount of the charges to be transferred by the HCCD is the same when the still image is picked up and when the monitor is performed. Therefore, it is not necessary to increase the drive voltage of the HCCD 5, and power loss can be prevented. VCC
When charge mixing is performed in D, the same situation applies to VCCD.

Further, the sensitivity at the time of monitoring is half that at the time of picking up a still image, but the sensitivity becomes equal due to pixel mixing.

Further, since the monitor image is constructed by using the two kinds of mixed charges, the vertical jitter does not occur. Also, 2
Since one frame image is formed in the V period, the dynamic resolution can be kept high.

Hereinafter, more specific examples of the present invention will be described. FIG. 4 is a block diagram showing a camera head unit of the image pickup apparatus according to the embodiment of the present invention.

The camera head unit 1 outputs a signal from the CCD image pickup device 11 and a preamplifier 12 for correlated double sampling for amplifying the output signal from the CCD image pickup device while reducing noise. For supplying to the camera controller shown in FIG.
A 5Ω drive circuit 13 is included.

Further, the camera head unit 1 has 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 synchronizing signals HD, VD and the camera control unit 2
The horizontal drive circuit for receiving the mode selection signal MODE from the control unit 16 for producing the horizontal drive pulse, the vertical drive pulse, and the shift gate signal, and the horizontal drive pulse for receiving the horizontal drive pulse and generating the horizontal drive signal for driving the HCCD. 17,
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 according to a mode signal are included.

The control unit 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 electric 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
It is supplied to the gain control amplifier 21 and amplifies the set gain. Gain control amplifier 21
Is supplied to the A / D conversion circuit 23 via the gamma processing circuit 22, becomes a digital signal, and is output to the memory section 24.
Is supplied to.

The memory section 24 stores the supplied digital signal. The image signal read from the memory unit 24 is
Is converted into 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 a predetermined timing, and also generates control signals for the main CPU 28 and the gamma processing circuit 22.

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

The power supply 30 supplies a power supply voltage to various circuits in the camera control section 2. By the circuits shown in FIGS. 4 and 5, the image signal accumulated in the CCD device 11 at the time of capturing a still image is read in the 4V period, and the memory unit 24
Accumulated in. In the monitor mode, the substrate voltage is changed so that the saturation charge amount of the photodiode becomes about half, and two types of charges accumulated in the CCD device 11 are simultaneously read out, mixed, and supplied as a CCD output for monitoring. 31 is displayed.

Hereinafter, each part of the image pickup device shown in FIGS. 4 and 5 will be described in more detail. FIG. 6 shows the structure of the CCD device. 6A is a plan view and FIG. 6B is a partial cross-sectional view. In FIG. 6A, the CCD device 1
Reference numeral 1 includes photodiodes 35 arranged in rows and columns, VCCDs 36 for taking in charges from the photodiodes 35 and transferring them in the vertical direction, and HCCDs 37 for transferring charges transferred from a plurality of VCCDs 36 in the horizontal direction.

Each row of the photodiodes 35 is divided into four types A1, B1, A2, B2 in order from the top as shown in the figure, and each type of photodiode corresponds to one field image. Adjacent to each photodiode row, VCCD
36 are arranged, and the VCCD 36 has two transfer cells for one row of photodiodes. VCCD 36 is φVA
Charges are transferred by 6-phase driving of 1, φV2, φVB1, φV4, φVA2, and φVB2.

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

FIG. 6B shows the structure of the photodiode formed on the surface of the substrate and the vertical overflow drain formed below the photodiode. A p well 42 is formed in the surface portion of the n-type semiconductor substrate 41. The p-well 42 has a shallow first p-well 1pw and a deep second p-well 1pw.
The p wells 2pw are distributed.

An n-type region 43 is formed on the first p-well 1pw.
Are formed to form a photodiode. An n ⁻ type region 44 is formed in the vicinity of the n type region 43 at a predetermined interval 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.

Incident light is incident on 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 the variable DC power supply 50 controlled by the substrate voltage control circuit 19.

When the charges are accumulated excessively by the incident light, n
Electrons from the mold region 43 overflow into the n-type substrate 41. When the substrate voltage is changed, the overflow potential changes and the saturation charge amount of the photodiode is changed. In the monitor mode, the substrate voltage is set so that the saturated charge amount is half the saturated charge amount in the still mode. The charge that overflows the photodiode is the substrate 41
Sucked into.

FIG. 7 shows a timing chart of the control signal in the monitor mode for monitoring the image to determine the composition. The field switching signal FI has a pulse-shaped 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 "1" in the still mode.

In the monitor mode, the charges of all the pixels are read out in 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 the waveform of the drive signal for capturing the image signal in the 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 for driving the VCCD. At time t2, drive signal φV
Since B1 becomes a high level, at this time the photodiode B
The accumulated charge is transferred from 1 to VCCD. Also, at time t
In 4, the drive signal φVA1 is at a high level, so 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 in the 1V period, sequentially transferred in the vertical direction in the VCCD in each horizontal blank period, the two types of charges are mixed, and the next horizontal scanning is performed. H during the period
It is transferred at high speed through the CCD.

FIG. 9 is an enlarged waveform diagram showing the portion indicated by the broken line in FIG. VCCD drive signals φVA1, φVA
2, φV2, φVB1, φVB2, φV4 change as shown to transfer charges in the vertical direction in the VCCD.

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

At time t2, the drive voltage φVB1 becomes a high level, so that the charge from the photodiode B1 is taken into the VCCD. At time t4, the taken-in charges are transferred to the right in the figure for one cell of the VCCD. At time t4, the drive voltage φVA
1 becomes a high level, and the charges of the photodiode A1 are taken into the same VCCD.

At the next time t5, each of the charges taken in spreads over three transfer cells, and a barrier for one cell is formed between the charges. After that, the charge taken in from the time t6 to t11 is contracted backward by 1 cell, then extended forward by 1 cell, and again contracted backward by 1 cell, and the same operation is repeated and transferred to the right side in the figure by the scale insect method. To be done.
In the HCCD, two types of charges are mixed.

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

FIG. 12 shows a signal waveform when the shutter is driven to pick up a still image and the external switch 32 shown in FIG. 5 is turned on. The external switch 32 generates an external switch signal which is "1" for a predetermined period. When the external switch signal changes from "0" to "1", mode switching for converting the camera drive signal is performed in the field next to the rising edge of the signal. This mode switching is 1
It ends in the V period. At the same time as the start of mode switching,
The mode signal rises and the still mode is displayed.

At the same time as the mode signal, the substrate voltage (SU
B) The switching signal also rises to adjust 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 two types of photodiodes are read at the same time, so that the saturated charge amount is half that of the monitor mode. This difference in saturated charge amount is adjusted by the substrate voltage.

After the mode switching is completed, at least 4V (or 4nV) is cleared to sweep away the charges in the CCD. In the illustrated case, the recording mode has started after the 4V clear operation. In the recording mode, the photodiodes A1 and A are set in accordance with the recording signal REC.
The charges of 2, B1, and B2 are sequentially read in the period of 4V,
Recorded in memory.

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

At time S1, the drive signal φA1 becomes high level, and the charge from the photodiode A1 becomes VCC.
VC in each subsequent horizontal blank period
It is transferred vertically through the CD.

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

FIG. 15 and FIG. 16 show the waveforms of drive signals in the fields for extracting charges from the photodiodes B1 and B2, respectively.

In FIG. 15, drive signal φB1 attains a high level at time S6, and the accumulated charge is taken in from photodiode B1. Further, in FIG. 16, the drive signal φB2 becomes high level at time S10, and the accumulated charge is taken in from the photodiode B2 to the VCCD.
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 B2 photodiodes, in the still mode, all charges are read in a 4V period to form a high-resolution image. It takes in all the electric charges in 2V period for each type, transfers VCCD, mixes and transfers HCCD, so power loss is prevented,
A monitor image with the same sensitivity and the same saturated charge amount and high dynamic resolution can be obtained.

The present invention has been described above with reference to the 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 1/2 of that in the still mode, but pixel mixing is performed to obtain the same sensitivity as in the still mode. Further, in the monitor mode, the maximum charge amount to be transferred by the HCCD can be made the same by setting the saturation charge amount of the photoelectric conversion element to about half.

Therefore, the signals for driving the HCCD have the same conditions in the still mode and the monitor mode. Therefore, power loss can be prevented.

Further, in the monitor mode, since the image signal is taken in at a cycle of 2V, 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 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 read state of accumulated charges in a monitor mode and a still mode.

FIG. 2 shows a conventional technique. FIG. 2A is a schematic plan view showing the 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 read method in a conventional technique. FIG. 3A is a schematic diagram for explaining a reproduced image on a 500-line monitor, and FIG.
FIG. 3C is a schematic diagram illustrating a reproduced image on the 0-line monitor.
FIG. 3 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 image pickup apparatus according to the embodiment of the present invention.

FIG. 5 is a block diagram showing a camera control unit of the image pickup 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 sectional view.

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

FIG. 8 is a waveform diagram for explaining image signal acquisition in the monitor mode.

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

FIG. 10 is a waveform diagram showing control signals of other fields in the monitor mode.

FIG. 11 is a potential diagram for explaining acquisition 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 a still mode.

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

[Explanation of symbols]

 1 Camera Head Section 2 Camera Control Section 3 Photodiode 4 VCCD 5 HCCD 6 Saturation Charge Setting Means 8 Amplifier 11 CCD Device 12 Preamplifier 13 Drive Circuit 15 PLL Circuit 16 Control Section 17, 18 Drive Circuit 19 Board 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)

[Claims] 1. The electric charges accumulated in a large number of four types of photoelectric conversion elements arranged in a matrix are taken into a plurality of columns of vertical CCDs arranged corresponding to each column of the photoelectric conversion elements, and each vertical CCD 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. The step of adjusting the saturation charge amount to about half and storing the charges, the step of simultaneously transferring the charges of two types of photoelectric conversion elements to the vertical CCD during monitoring, and the step of vertically transferring the charges of the vertical CCD during monitoring. ,
The process of mixing the charges of the two types of photoelectric conversion elements and transferring them to the horizontal CCD, the process of transferring the charges mixed and transferred to the horizontal CCD in the horizontal direction at the time of monitoring, and reading as a signal, A method for driving a solid-state image pickup device, which comprises a step of transferring charges of photoelectric conversion elements of one kind to a vertical CCD one by one. 2. A plurality of four kinds of photoelectric conversion elements arranged in a matrix, a plurality of columns of vertical CCDs arranged corresponding to each column of the photoelectric conversion elements, and a plurality of columns of vertical CCDs. 1 commonly connected to each end
A solid-state image pickup device comprising: a horizontal CCD of a row; and a saturation charge amount setting means for setting the saturation charge amount of the photoelectric conversion element in the monitor mode to about half the saturation charge amount in the still mode. 3. The solid-state imaging device according to claim 2, wherein the saturation charge amount setting means includes a substrate bias changing means.