JPH05336452A - Solid-state image pickup device - Google Patents

Abstract

(57) [Abstract] [Purpose] When an excessive amount of light is input, unnecessary charges generated in the photoelectric conversion element are prevented from overflowing in the horizontal transfer register, and a solid-state imaging device capable of obtaining an imaging output with good image quality can be obtained. I will provide a. [Structure] The CCD driving circuit 6 variably controls the maximum accumulated charge amount of the photoelectric conversion elements S _O and S _E of the frame interline transfer type CCD image sensor 2,
The photoelectric conversion elements S _O, to reduce the maximum charge accumulation amount to the operation-mode of sweeping through the horizontal transfer register H _{RE G} unnecessary charges generated in S _E.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a charge coupled device (CCD:
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device using a solid-state image sensor such as a CCD image sensor formed by a Charge Coupled Device, and in particular, an image pickup unit having a vertical transfer register from which image pickup charges obtained by photoelectric conversion elements arranged in a matrix are read out. And a storage unit having a vertical transfer register in which the image pickup charges are transferred at high speed from the vertical transfer register of the image pickup unit, and a horizontal transfer register in which the image pickup charges are transferred line-sequentially from the vertical transfer register in the storage unit. The present invention relates to a solid-state image pickup device having an interline transfer type solid-state image sensor and having an operation mode in which unnecessary charges generated in the photoelectric conversion element are read into a vertical transfer register of the storage section and swept away through the horizontal transfer register.

[0002]

2. Description of the Related Art Generally, a solid-state image sensor such as a CCD image sensor is classified into a frame transfer type, an interline transfer type, and a frame interface type, which are classified according to a structure for reading out imaging charges obtained by photoelectric conversion elements arranged in a matrix. Various structures such as a line transfer type are known. In a solid-state image pickup device using such a solid-state image sensor, the solid-state image sensor is driven in a frame accumulation mode or a field accumulation mode to obtain NTSC (National Televis
Ion System Commitee) system and so on to obtain the image pickup output signal conforming to the standard television system.

That is, in the standard television system such as the NTSC system, interlaced scanning is adopted in which the scanning lines of the odd fields and the scanning lines of the even fields are positioned between the scanning lines.

In a solid-state image pickup device for picking up an image of a subject by a solid-state image sensor such as a CCD image sensor in which photoelectric conversion elements are arranged in a matrix, an operation mode called field reading (field storage mode) or frame reading is performed. The solid-state image sensor is operated in a so-called operation mode (frame accumulation mode) to obtain an image output corresponding to interlaced scanning.

For example, an interline transfer type C
In the CD image sensor, in the field read mode
In the case of operation, as shown in FIG. 6, every vertical blanking period
The read pulse of the
Imaging charge A by child_iAnd an even number of photoelectric conversion elements
Image charge B_iChange the upper and lower combinations for each field
Transfer to the vertical transfer register, and the imaging charge of each field
A_i+ B_i, B_i+ A _{i + 1}The above vertical transfer during the video period
Line-sequential read from register via horizontal transfer register
Image output corresponding to interlaced scanning
Is getting Also, when operating in the frame read mode,
In this case, as shown in FIG. 7, reading for each vertical blankin period
Pulsed by adjacent photoelectric conversion elements in odd columns
Imaging charge A_iAnd the image-capturing charge B by the photoelectric conversion elements in the even columns
_iAre alternately transferred to the vertical transfer register for each field
Then, the imaging charge A of each field_i, B_iDuring the video period
Line from the above vertical transfer register through the horizontal transfer register
Supports interlaced scanning by reading sequentially
The obtained imaging output is obtained.

Further, each photoelectric conversion element in a solid-state image sensor such as a CCD image sensor generates an imaging charge proportional to the amount of incident light, but the maximum charge storage amount is determined by, for example, an overflow drain potential, and this overflow drain potential is It can be controlled by changing the voltage applied to the substrate substrate. Then, by applying a shutter pulse to the substrate substrate so that the imaging charges generated in the photoelectric conversion element are swept away via the overflow drain potential, the effective charge accumulation period of the photoelectric conversion element is changed. The electronic shutter function is realized.

Further, in the hood interline transfer type CCD image sensor, unnecessary charges generated in the photoelectric conversion element are read out to the vertical transfer register of the image pickup section,
The effective charge accumulation period is controlled by high-speed transfer through a horizontal transfer register to sweep away the unnecessary charges.

[0008]

By the way, the unnecessary charges generated in the photoelectric conversion element are read out to the vertical transfer register of the image pickup section and transferred at high speed through the horizontal transfer register to sweep out the unnecessary charges. In this case, the maximum charge transfer capability of the horizontal transfer register becomes a problem, and unnecessary charges generated in the photoelectric conversion element overflow into the horizontal transfer register when an excessive amount of light is input, and enter the image portion to deteriorate the image quality. There is fear.

In view of the problems of the conventional solid-state image pickup device as described above, the present invention is provided with a frame interline transfer type solid-state image sensor, and vertically transfers unnecessary charges generated in the photoelectric conversion element to the storage section. In a solid-state imaging device having an operation mode of reading out to a register and sweeping out through a horizontal transfer register, when an excessive light amount is input,
It is an object of the present invention to prevent unnecessary charges generated in the photoelectric conversion element from overflowing in the horizontal transfer register so that an image pickup output with good image quality can be obtained.

[0010]

In order to solve the above problems, the present invention provides an image pickup section having a vertical transfer register from which image pickup charges obtained by photoelectric conversion elements arranged in a matrix are read out, and A frame interline transfer including a storage unit having a vertical transfer register to which the image pickup charges are transferred at high speed from the vertical transfer register of the image pickup unit, and a horizontal transfer register to which the image pickup charges are transferred line-sequentially from the vertical transfer register of the storage unit. Type solid-state image sensor, wherein the photoelectric conversion element has an operation mode in which unnecessary charges generated in the photoelectric conversion element are read out to the vertical transfer register of the storage section and swept away through the horizontal transfer register. The accumulated charge amount control means for variably controlling the maximum accumulated charge amount of The operation mode of sweeping the load via the horizontal transfer register by the accumulated charge amount control means is characterized in that to reduce the maximum accumulated charge amount of the photoelectric conversion element. The accumulated charge amount control means includes a changeover switch for changing the maximum accumulated charge amount of the photoelectric conversion element.

Further, in the solid-state image pickup device according to the present invention, the effective charge storage period of each photoelectric conversion element of the solid-state image sensor is independently changed between the photoelectric conversion elements in the odd-numbered columns and the photoelectric conversion elements in the even-numbered columns, and they are adjacent to each other. The image sensor drive control means for controlling the addition and mixing of the image-capturing charges obtained by the photoelectric conversion elements in the odd-numbered columns and the photoelectric conversion elements in the even-numbered columns for each field to read out.

Further, in the solid-state image pickup device according to the present invention, the image-pickup charges obtained by the photoelectric conversion elements in the odd-numbered columns and the image-charges obtained by the photoelectric conversion elements in the even-numbered columns of the solid-state image sensor are set to 1 during the video period. The data is read alternately into the vertical transfer register of the image pickup unit for each field, and is transferred at high speed from the vertical transfer register of the image pickup unit to the vertical transfer register of the storage unit during the vertical blanking period for each field, Control is performed to transfer the image-capturing charges from the vertical transfer register via the horizontal transfer register at high speed in a line-sequential manner and to sweep the image-capturing charges, and the image-capturing charges obtained by the photoelectric conversion elements in the odd-numbered columns and the photoelectric conversion elements in the even-numbered columns adjacent to each other are set to 1 During the vertical blanking period for each field, the signals are added and mixed, read out to the vertical transfer register of the image pickup unit, and read out from the vertical transfer register of the storage unit. High speed transfer data, in the video period, and a image sensor drive control means for line-sequentially read out controls the imaging charge from the vertical transfer registers of the storage section via the horizontal transfer register.

[0013]

In the solid-state image pickup device according to the present invention, the accumulated charge amount control means variably controls the maximum accumulated charge amount of the photoelectric conversion element of the frame interline transfer type solid-state image sensor to eliminate the unnecessary charge generated in the photoelectric conversion element. The maximum accumulated charge amount of the photoelectric conversion element is reduced in an operation mode in which charges are swept away via the horizontal transfer register. The accumulated charge amount control means switches the maximum accumulated charge amount of the photoelectric conversion element by a changeover switch.

Further, in the solid-state image pickup device according to the present invention, the image sensor drive control means causes the effective charge storage period of each photoelectric conversion element of the solid-state image sensor to be divided between the photoelectric conversion elements of odd columns and the photoelectric conversion elements of even columns. Independently, the control is performed such that the image pickup charges obtained by the photoelectric conversion elements in the odd-numbered columns and the photoelectric conversion elements in the even-numbered columns adjacent to each other are added and mixed for each field and read.

Further, in the solid-state image pickup device according to the present invention,
By the image sensor drive control means, the image-capturing charges obtained by the photoelectric conversion elements in the odd-numbered columns and the image-capturing charges obtained by the photoelectric conversion elements in the even-numbered columns of the frame interline transfer type solid-state image sensor are set to 1 during the video period.
The data is read alternately into the vertical transfer register of the image pickup section for each field, and is transferred at high speed from the vertical transfer register of the image pickup section to the vertical transfer register of the storage section during the vertical blanking period for each field, and Control is performed to transfer the image-capturing charges from the vertical transfer register via the horizontal transfer register at high speed in a line-sequential manner and to sweep the image-capturing charges, and the image-capturing charges obtained by the photoelectric conversion elements in the odd columns and the even columns adjacent to each other are set to 1 During the vertical blanking period for each field, the signals are added and mixed, read out to the vertical transfer register of the image pickup unit and transferred at high speed to the vertical transfer register of the storage unit, and during the video period, the horizontal transfer is performed from the vertical transfer register of the storage unit. Control is performed to read out the imaging charges line-sequentially via the transfer register.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the solid-state image pickup device according to the present invention will be described below in detail with reference to the drawings. The solid-state imaging device according to the present invention is configured, for example, as shown in FIG.

The solid-state image pickup device shown in FIG.
CCD of the image pickup unit 3 in which _i is incident through the image pickup optical system 1.
(Charge Coupled Device) Image sensor 2 captures the three primary color images of the subject image, and the NTSC (National T
The present invention is applied to a color television camera device that outputs a color television signal conforming to the Elevation System Commitee system, and a signal processing unit 4 to which an image pickup signal is supplied from the image pickup unit 3 and the signal processing unit 4 An encoder 5 to which an image pickup signal subjected to signal processing is supplied, a CCD drive circuit 6 for driving the CCD image sensor 2, a control unit 7 for controlling the operation of these various circuit blocks, and the like.

In this solid-state image pickup device, the image pickup section 3 is used.
As shown in FIG. 2, in the CCD image sensor 2 constituting the above, photoelectric conversion elements S _O and S _E such as photodiodes corresponding to respective pixels of an odd field image and an even field image are arranged in a matrix on the imaging surface. Of a so-called frame interline transfer (FIT) type having an image pickup section IM that has been captured and an accumulation section ST to which the accumulated charges obtained by each photoelectric conversion element S of the image pickup section IM are transferred via the vertical transfer register IMV _REG . A CCD image sensor, which is driven by the CCD driving circuit 6 and arranged in a matrix in the photoelectric conversion elements S _O ,
The imaging charge obtained by S _E is transferred from the vertical transfer register IMV _REG of the imaging unit IM to the vertical transfer register ST of the storage unit ST via the transfer gate SG for each vertical blanking.
₁ is transferred to the _REG through the vertical transfer register ST _REG horizontal transfer register H _REG of the storage unit ST during the video period.
The lines are read line by line.

The signal processing unit 4 forms an image pickup signal obtained by subjecting the image pickup signal read from the CCD image sensor 2 to process processing such as gamma correction. Then, this image pickup signal is supplied to the encoder 5. Further, the encoder 5 forms a television signal conforming to the NTSC system from the image pickup signal supplied from the signal processing unit 4 and outputs the television signal from the output terminal 8.

Further, the CCD drive circuit 6 applies the image pickup charges obtained by the photoelectric conversion elements S _O and S _E in the image pickup section IM to the vertical transfer register IMV on the basis of the timing signal given by the control section 7. Sensor gate pulses φSG ₁ and φSG ₂ to be transferred to _REG , a vertical transfer pulse vertical transfer pulse φIM to vertically transfer the signal charge in the vertical transfer register IMV _REG of the image pickup section IM,
Vertical transfer pulse vertical transfer pulse φ for vertically transferring the signal charge in the vertical transfer register STV _REG of the storage section ST
ST, a transfer pulse φVH for transferring signal charges from the vertical transfer register STV _REG of the storage unit ST to the horizontal transfer register H _REG , a horizontal transfer pulse φH for horizontally transferring signal charges in the horizontal transfer register H _REG , and the like. It is applied to the CCD image sensor 2.

The CCD drive circuit 6 is shown in FIG.
As shown in FIG.
Pressure V-SUB₁, V-SUB₂Via the changeover switch 6B
To selectively output the output of the CCD image sensor 2.
It is designed to be applied to a bust substrate. Above
The exchange switch 6B is a control provided by the control unit 7.
According to the signal, the CCD image sensor 2
By switching the voltage V-SUB applied to the rate substrate,
Each photoelectric conversion element S of the CCD image sensor 2 _O, S_E
Maximum accumulated charge Q_MAXOverflow dray
Change the potential. CCD image sensor
S2 is each voltage V-SUB₁, V-SUB₂Is one of
Voltage V-SUB₁Is applied to the substrate substrate
Each photoelectric conversion element S_O, S_EMaximum accumulated charge Q_MAX1
Than the other voltage V-SUB₂Is the substrate board
Each photoelectric conversion element S when applied to the_O, S_EMaximum storage of
Product charge Q_MAX2Is set so that
It

Then, the control section 7 supplies a synchronizing signal, a blanking signal, etc. to the encoder 5 based on the system clock of the solid-state image pickup device, and various signals to the signal processing section 4 and the CCD drive circuit 6. It is designed to give timing signals. The control unit 7 operates in the first to third operation modes by a system controller (not shown).
The operation mode is switched to the three types of operation modes, and the following control operation is performed.

First, the first operation mode is the field read mode, and the control section 7 gives various timing signals in the field read mode to the CCD drive circuit 6.

In the first operation mode, the CC
The D drive circuit 6 applies the voltage V-SUB ₁ to the substrate substrate, and the sensor gate pulse φSG ₁ , during the vertical blanking period T _VBLK for each field.
By applying φSG ₂ to the image pickup section IM at the same time, the image pickup charges A _i obtained by the photoelectric conversion elements S _{O in} the odd columns and the image pickup charges B _i obtained by the photoelectric conversion elements S _{E in the} even columns are vertically changed for each field. By alternately changing the combination and transferring to the vertical transfer register IMV _REG , the imaging charges A _i + B _i , B _i + A _{i + 1} corresponding to the interline scanning in the field read mode are transferred to the vertical transfer register I.
_Read to MV _REG .

The sensor gate pulse φSG₁，
φSG₂Just before the timing of, high-speed vertical transfer pulse
φIM and φST are the vertical transfer registers I of the image pickup unit IM.
MV _REGAnd the vertical transfer register STV of the storage unit ST
_REGTo the vertical transfer register IM of the image pickup unit IM.
_REGUnnecessary charges such as smear components inside the storage unit ST
Vertical transfer register STV_REGTo transfer at high speed. This high
The vertical transfer register of the image pickup unit IM by the fast transfer operation.
IMV_REGThe inside is empty with unnecessary charges being swept out.
It

Then, the CCD drive circuit 6 gives sensor gate pulses φSG ₁ and φSG ₂ in a state where the vertical transfer register IMV _REG is emptied,
In the image pickup section IM, the image pickup charge A _i obtained by the odd-numbered photoelectric conversion elements S _O and the image pickup charge B _i obtained by the even-numbered photoelectric conversion elements S _E are alternately changed in the upper and lower portions for each field. The above vertical transfer register IMV
Transfer to _REG .

Furthermore, the sensor gate pulse φS
Immediately after the timing of G ₁ and φSG ₂ , high-speed vertical transfer pulses φIM ₁ and φST are given to the vertical transfer register IMV _REG of the image pickup unit IM and the vertical transfer register STV _REG of the storage unit ST to cause the image pickup unit IM. The charges A _i + B _i and B _i + A _{i + 1} in the vertical transfer register IMV _REG are transferred to the vertical transfer register STV _REG of the storage unit ST at high speed.

Then, the signal charges A _i + B _i , B transferred at high speed to the vertical transfer register STV _REG of the accumulating section ST.
_i + A _{i + 1} is, during the subsequent read period (video period),
It is read line-sequentially via the horizontal transfer register H _REG .

As described above, in the first operation mode, the CCD image sensor 2 performs the image pickup operation in the state of the maximum accumulated charge amount Q _MAX1 corresponding to the voltage V-SUB ₁ applied to the substrate substrate, The image-capturing charge A _i obtained by the photoelectric conversion elements S _{O in} the odd-numbered columns and the image-capturing charge B _i obtained by the photoelectric conversion elements S _{E in the} even-numbered columns of the image pickup unit IM are set to 1
The upper and lower combinations are alternately changed for each field and transferred to the vertical transfer register IMV _REG, and the imaging charges A _i + B _i , B _i + A _{i + 1} of each field are transferred to the vertical transfer register STV of the storage unit ST during the video period. By line-sequentially reading from _REG via the horizontal transfer register H _REG , an image pickup output corresponding to interlaced scanning is obtained in the field read mode. Then, the CCD image sensor 2
The image pickup signal read from is supplied to the encoder 5 through the signal processing unit 4, encoded into a television signal conforming to the NTSC system, and output from the output terminal 8.

Next, the second operation mode is the frame read mode, and the control section 7 gives various timing signals in the frame read mode to the CCD drive circuit 6.

In the second operation mode, the CC
The D drive circuit 6 uses the voltage V-SUB₁Substrate
The vertical blanking period T
_VBLKInside sensor gate pulse φSG₁, ΦSG₂1 hour
It is given to the image pickup section IM alternately for each field,
Photoelectric conversion element S_OImaging charge A obtained by_iAnd even columns
Photoelectric conversion element S_EImaging charge B obtained by_i1 hour
Alternate vertical transfer register IMV for each field_REGTransferred to
The frame reading mode.
Imaging charge A corresponding to line scanning_i, B_iThe above vertical
Transfer register IMV _REGRead to.

Even in this second operation mode,
Immediately before the timing of the sensor gate pulses φSG ₁ and φSG ₂ , high-speed vertical transfer pulses φIM and φST are applied to the vertical transfer register IMV _REG of the image pickup section IM and the vertical transfer register STV _REG of the storage section ST, The unnecessary charges such as smear components in the vertical transfer register IM _REG of the image pickup unit IM are transferred to the vertical transfer register S of the storage unit ST.
High speed transfer to TV _REG . By this high-speed transfer operation,
The vertical transfer register IMV _REG of the image pickup section IM is in an empty state in which unnecessary charges are swept out.

Then, the CCD driving circuit 6 gives sensor gate pulses φSG ₁ and φSG ₂ in a state where the vertical transfer register IMV _REG is emptied, and the photoelectric conversion elements S of odd columns in the image pickup section IM are given. _The image pickup charges A _i obtained by _O and the image pickup charges B _i obtained by the photoelectric conversion elements S _{E in the} even columns are alternately transferred to the vertical transfer register IMV _REG for each field.

Further, the sensor gate pulse φS
Immediately after the timing of G ₁ and φSG ₂ , high-speed vertical transfer pulses φIM and φST are supplied to the vertical transfer register IMV _REG of the image pickup section IM and the vertical transfer register S of the storage section ST.
The charges A _i and B _i in the vertical transfer register IMV _REG of the image pickup section IM are given to the TV _REG and transferred at high speed to the vertical transfer register STV _REG of the storage section ST.

The signal charges A _i and B _i transferred at high speed to the vertical transfer register STV _REG of the storage section ST are
During the subsequent read period, the horizontal transfer register H _REG
Read through.

As described above, in the second operation mode,
Voltage V-SUB applied to the bust substrate₁According to
Maximum charge accumulation Q_MAX1In the state of
The image pickup operation is performed by the sensor 2 and
Photoelectric conversion element S_OImaging charge A obtained by_iAnd even
Photoelectric conversion element S in a row_EImaging charge B obtained by_i1
Alternate vertical transfer register IMV for each field_REGTurn to
Image pickup charge A of each field_i, B_iThe video period
The vertical transfer register STV of the storage unit ST _REGFrom
Horizontal transfer register H_REGRead line-sequentially via
Allows interlaced scanning in frame read mode
An imaging output corresponding to is obtained. And the CCD image
The image pickup signal read from the di-sensor 2 is processed by the above signal processing.
It is supplied to the encoder 5 via the unit 4 and is in the NTSC system.
Encoded into a compliant television signal and output above
It is output from the terminal 8.

Furthermore, the third operation mode is the operation mode of the solid-state image pickup device according to the present invention, and the control unit 7 is
The CCD drive circuit 6 is operated as follows by giving various timing signals.

In the third operation mode, the CC
The D drive circuit 6 uses the voltage V-SUB₁Substrate
Applied to the substrate and, as shown in FIG.
Sensor field is alternated for each field during the field
Pulse pulse SG₁, ΦSG ₂Is given to the imaging unit IM
And the vertical blanking period T for each field.
_VBLKInside sensor gate pulse φSG₁, ΦSG₂The above
The photoelectric conversion elements S of odd columns are given to the image pickup section IM at the same time._O
Imaging charge A obtained by_iAnd even-numbered photoelectric conversion elements S
_EImaging charge B obtained by_iUp and down for each field
Alternately change the combination of the vertical transfer register IMV
_REGTo the field read mode.
Imaging charge A for interline scanning_i+
B_i, B_i+ A _{i + 1}The above vertical transfer register IMV_REG
Read to.

Even in the third operation mode,
Each vertical blanking period T_VBLKSensor gate pulse for each
φSG₁, ΦSG₂Just before the timing of the fast vertical
Vertical transfer of transfer pulses φIM and φST of the imaging unit IM
Register IMV_REGAnd the vertical transfer register of the storage unit ST
Data STV_REGTo the vertical transfer register of the image pickup unit IM.
IM_REGAccumulate unnecessary charges such as smear components inside
Vertical transfer register STV of section ST_REGFast transfer to
It By this high-speed transfer operation, the video of each field above
Sensor gate pulse φ alternately every 1 field during the period
SG₁, ΦSG₂Is given to the image pickup unit IM by
Vertical transfer register IMV of the imaging unit IM _REGRead to
The odd-numbered photoelectric conversion elements S_OImaging charge A_i’
And even-numbered photoelectric conversion elements S_EImaging charge B_i'Is unnecessary
The vertical transfer register of the image pickup unit IM, which is swept as a load.
IMV_REGInside is an empty state where unnecessary charges have been swept out.
Become.

Then, the CCD drive circuit 6 gives sensor gate pulses φSG ₁ and φSG ₂ in a state where the vertical transfer register IMV _REG is emptied,
In the image pickup section IM, the image pickup charge A _i obtained by the odd-numbered photoelectric conversion elements S _O and the image pickup charge B _i obtained by the even-numbered photoelectric conversion elements S _E are alternately changed in the upper and lower portions for each field. The above vertical transfer register IMV
Transfer to _REG .

Further, the sensor gate pulse φS
Immediately after the timing of G ₁ and φSG ₂ , high-speed vertical transfer pulses φIM and φST are supplied to the vertical transfer register IMV _REG of the image pickup section IM and the vertical transfer register S of the storage section ST.
The electric charges A _i + B _i and B _i + A _{i + 1} in the vertical transfer register IMV _REG of the image pickup section IM are given to the TV _REG and are transferred at high speed to the vertical transfer register STV _REG of the storage section ST.

Here, in the third operation mode, the sensor gate pulses φSG ₁ and φSG ₂ are alternately applied for each field during the video period of each field.
To the vertical transfer register IMV _REG of the image pickup section IM, the photoelectric conversion elements S of the odd-numbered columns are read.
_Since the image pickup charge A _i ′ of _{O and} the image pickup charge B _i ′ of the photoelectric conversion elements S _{E in} the even columns are swept out as unnecessary charges, a large amount of unnecessary charges are generated. Therefore, during the high-speed transfer period to the vertical transfer register STV _REG , the horizontal transfer pulse φH is also set to a high-speed pulse so that unnecessary charges are swept out through the horizontal transfer register H _REG by high-speed transfer. In the third operation mode, a large amount of unnecessary charges are generated as described above, but a large amount of unnecessary charges can be swept out through the horizontal transfer register H _REG by the high speed transfer. That is, the horizontal transfer register H _REG can sweep away a large amount of unnecessary charges by increasing the number of transfers at the high speed transfer even if the amount of charges transferred per transfer is small. Further, as described above, the voltage V-SUB ₁ is applied to the substrate substrate to reduce the maximum accumulated charge amount of each photoelectric conversion element S _O , S _E as Q _MAX2 , thereby _reducing the amount of unnecessary charge generated. Can be reduced. This prevents unnecessary charges generated in the photoelectric conversion elements S _O and S _{E from} overflowing in the horizontal transfer register STV _REG when an excessive amount of light is input, and an image pickup output with good image quality can be obtained. ..

In the third operation mode as described above, the CCD image sensor 2 performs an image pickup operation in the state of the maximum charge storage amount Q _MAX2 corresponding to the voltage V-SUB ₂ applied to the substrate substrate, and Sensor gate pulse φ alternately every 1 field during the video period of each field
SG ₁ and φSG ₂ are given to the image pickup unit IM, and the image pickup charges A _i obtained by the odd-numbered photoelectric conversion elements S _O and the image pickup charges B _i obtained by the even-numbered photoelectric conversion elements S _E are field by field. By alternately reading the dummy, the imaging charges A _i + B _i , B _i + A for each field
_{The i + 1} additive mixing ratio can be changed from 1: 1 in the normal field read mode. Then, for example, with the addition mixture ratio set to 1: 2, the imaging charges A _i obtained by the photoelectric conversion elements S _{O in} the odd columns of the imaging unit IM.
And the imaging charges B obtained by the photoelectric conversion elements S _{E in the} even columns
_i is transferred to the vertical transfer register IMV _REG by alternately changing the upper and lower combinations for each field, and the image-capturing charges A _i + B _i of each field are horizontally transferred from the vertical transfer register STV _REG of the storage unit ST during the video period. Register H _RE
By line-sequentially reading through _G , an imaging output corresponding to interlaced scanning is obtained in the field reading mode. Then, the image pickup signal read from the CCD image sensor 2 is supplied to the encoder 5 via the signal processing unit 4, encoded into a television signal conforming to the NTSC system, and output from the output terminal 8. ..

As described above, by changing the mixing ratio of the image pickup charges A _i obtained by the odd-numbered photoelectric conversion elements S _O and the image pickup charges B _i obtained by the even-numbered photoelectric conversion elements S _{E, the} result shown in FIG. As shown, a vertical resolution (MTF) intermediate between the first or normal field read mode and the second or frame read mode can be obtained. Then, for example, the addition mixing ratio is set to 1: 2 to obtain an image output corresponding to the interlaced scanning in the field read mode, thereby improving the vertical resolution as compared with the first operation mode, that is, the normal field read mode. Further, the dynamic range and sensitivity can be maintained at 75%, and the dynamic range and sensitivity can be improved more than in the second operation mode, that is, the frame read mode.

In the above embodiment, the CCD image
Voltage V-SU applied to the substrate substrate of sensor 2
B₁, V-SUB₂Each photoelectric conversion element
S_O, S _EThe maximum charge storage amount of_MAX1To Q_MAX2Cut into
However, the CCD image sensor 2 support
The voltage V-SUB applied to the bust substrate is continuously applied.
By variably controlling each photoelectric conversion element S_O, S_Eof
Being able to continuously change the maximum charge storage amount
You can also

[0046]

As is apparent from the above description, in the solid-state image pickup device according to the present invention, the maximum accumulated charge amount of the photoelectric conversion element of the frame interline transfer type solid-state image sensor is changed by the accumulated charge amount control means. Control
Since the maximum accumulated charge amount of the photoelectric conversion element is reduced in the operation mode in which the unnecessary charge generated in the photoelectric conversion element is swept away through the horizontal transfer register, the unnecessary charge generated in the photoelectric conversion element is reduced to the vertical transfer register of the imaging unit. To prevent unnecessary charges generated in the photoelectric conversion element from overflowing in the horizontal transfer register when an excessive amount of light is input, when the unnecessary charges are swept away by high-speed transfer through the horizontal transfer register. Therefore, it is possible to obtain an imaging output with good image quality.

Further, the image sensor drive control means transfers the image-capturing charges obtained by the photoelectric conversion elements in the odd-numbered columns and the image-capturing charges obtained by the photoelectric conversion elements in the even-numbered columns of the frame interline transfer type solid-state image sensor in the middle of the video period. By performing control to alternately read out to the vertical transfer register of the image pickup unit every 1 field,
The effective charge storage period of each photoelectric conversion element can be changed independently for the photoelectric conversion elements in the odd-numbered columns and the photoelectric conversion elements in the even-numbered columns. During the video period, the image-capturing charges read alternately to the vertical transfer register of the image pickup unit for each field are transferred from the vertical transfer register of the image pickup unit to the storage unit during the vertical blanking period for each field. High-speed transfer to the vertical transfer registers of the storage section, line-sequential high-speed transfer from the vertical transfer registers of the accumulating section through the horizontal transfer registers, and swept as unnecessary charges. Then, by reducing the maximum accumulated charge amount of the photoelectric conversion element in the operation mode in which unnecessary charges generated in the photoelectric conversion element are swept away through the horizontal transfer register, unnecessary charges generated in the photoelectric conversion element when an excessive light amount is input. It is possible to prevent electric charges from overflowing in the horizontal transfer register, and it is possible to obtain an image pickup output with good image quality.

Further, the horizontal transfer register sweeps away a large amount of unnecessary charges during the vertical blanking period for each field by increasing the number of transfers by high-speed transfer even if the amount of charges transferred per transfer is small. You can

Then, the image-capturing charges obtained by the photoelectric conversion elements in the odd-numbered columns and the photoelectric conversion elements in the even-numbered columns which are adjacent to each other are added and mixed during the vertical blanking period for each field and read out to the vertical transfer register of the image-acquisition unit. By performing high-speed transfer to the vertical transfer register of the storage section and reading the imaging charges line-sequentially from the vertical transfer register of the storage section through the horizontal transfer register during the video period, as compared with the case of the field read mode. Vertical resolution (MTF)
Is less likely to occur, an afterimage is less than in the case of frame reading, and an imaging output with a wide dynamic range can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a solid-state imaging device according to the present invention.

FIG. 2 is a schematic plan view showing a configuration of a frame interline transfer type CCD image sensor used in the solid-state imaging device.

FIG. 3 is a diagram showing a means for generating a voltage applied to a substrate substrate of the CCD image sensor in the solid-state imaging device.

FIG. 4 is a timing chart showing the operation of the solid-state imaging device.

FIG. 5 is a characteristic diagram showing a vertical MTF characteristic of an image pickup signal obtained by the solid-state image pickup device.

FIG. 6 is a timing chart showing an operation in a field read mode.

FIG. 7 is a timing chart showing an operation in a frame read mode.

[Explanation of symbols]

1 ... Imaging optical system 2 ... CCD image sensor 3 ... Imaging unit 4 ... Signal processing unit 5 ...・ ・ ・ ・ ・ ・ Encoder 6 ・ ・ ・ ・ ・ ・ ・ ・ CCD drive circuit 6A ・ ・ ・ ・ ・ Voltage generator 6B ・ ・ ・ ・ ・ Switch 7 ・ ・ ・Section 8 ... Output terminal S ... Photoelectric conversion element IM ... Imaging section IMV _REG ... Vertical transfer register ST ... .... Storage unit STV _REG ... Vertical transfer register H _REG .... Horizontal transfer register

Claims (4)

[Claims] 1. An image pickup unit having a vertical transfer register for reading image pickup charges obtained by photoelectric conversion elements arranged in a matrix, and a vertical transfer register for high-speed transfer of image pickup charges from the vertical transfer register of the image pickup unit. And a frame interline transfer type solid-state image sensor including a horizontal transfer register in which imaging charges are line-sequentially transferred from a vertical transfer register of the storage unit, and unnecessary charges generated in the photoelectric conversion element are provided. In a solid-state imaging device having an operation mode of reading out to the vertical transfer register of the storage section and sweeping out through the horizontal transfer register, a stored charge amount control means for variably controlling the maximum stored charge amount of the photoelectric conversion element is provided, In operation mode in which unnecessary charges generated in the photoelectric conversion element are swept away via the horizontal transfer register The solid-state imaging apparatus characterized by reducing the maximum accumulated charge amount of the photoelectric conversion element by the accumulated charge amount control means. 2. The solid-state imaging device according to claim 1, wherein the accumulated charge amount control means includes a changeover switch for changing the maximum accumulated charge amount of the photoelectric conversion element. 3. The photoelectric conversion elements of the odd-numbered columns and the even-numbered photoelectric conversion elements are independently changed in the effective charge storage period of each photoelectric conversion element of the solid-state image sensor, and the photoelectric conversion elements of the odd-numbered columns adjacent to each other are even. The solid-state imaging device according to claim 1 or 2, further comprising: an image sensor drive control unit that controls the addition and mixing of the image pickup charges obtained by the photoelectric conversion elements of the columns for each field. 4. The imaging charges obtained by the photoelectric conversion elements in the odd-numbered columns and the imaging charges obtained by the photoelectric conversion elements in the even-numbered columns of the solid-state image sensor are alternated for each field in the middle of a video period. The data is read out to the vertical transfer register, and during the vertical blanking period for each field, high-speed transfer is performed from the vertical transfer register of the imaging unit to the vertical transfer register of the storage unit, and the horizontal transfer register is transferred from the vertical transfer register of the storage unit. The image-capturing charge is line-sequentially transferred at high speed via the sweeping control, and the image-capturing charge obtained by the adjacent odd-numbered photoelectric conversion elements and even-numbered photoelectric conversion elements during the vertical blanking period for each field. Add and mix, read to the vertical transfer register of the image pickup unit, and transfer at high speed to the vertical transfer register of the storage unit.
The solid-state image sensor according to claim 1 or 2, further comprising image sensor drive control means for controlling line-sequential reading of imaging charges from the vertical transfer register of the storage section through the horizontal transfer register during a video period. Imaging device.