JP2002330347A - Imaging device, drive method for the imaging device and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device that can ensure an ultrahigh speed shutter operation and suppress deterioration in the image quality due to decrease in a dynamic range and to provide its drive method or the like. SOLUTION: The imaging device of this invention employs the imaging device which has vertical transfer lines 13 capable of individually and simultaneously transferring electric charges of all pixels 11 corresponding to one frame and a drive means which performs interlace reading by dividing the electric charges of all the pixels corresponding to one frame into a plurality of fields and transferring the electric charges through the vertical transfer lines to field- sequentially read all pixel information corresponding to one frame. The drive means is preferably so configured that consecutive number of exciting phases to store the electric charges on the vertical transfer lines in the case of interlace reading is to be selected greater than consecutive number of exciting phases to store the electric charges on the vertical transfer lines in the case of progressive reading capable of individually and simultaneously transferring electric charges of all pixels corresponding to one frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image pickup device and a method of driving the same.

[0002]

2. Description of the Related Art As an image pickup device used in a digital camera or the like, in addition to an interlaced readout (interlaced scan) type CCD imager having a vertical transfer stage having half the number of vertical pixels (vertical lines), a CCD imager for the number of vertical pixels is used. 2. Description of the Related Art A progressive readout (sequential scanning) -compatible CCD imager in which electric charges of all pixels can be transferred simultaneously by providing a vertical transfer stage is known.

In an interlaced imager, it is possible to obtain a still image by a pure electronic shutter (element shutter) by performing field accumulation driving, but since the vertical resolution is reduced to half of the original, a high resolution is obtained. Can not get a still image. On the other hand, with a progressive imager, a high-resolution still image for one frame can be obtained by a pure electronic shutter, and an ultra-high-speed shutter that cannot be achieved by a mechanical shutter can be realized.

However, the progressive imager requires twice as many transfer stages as the interlaced imager, so that the amount of charge that can be handled during transfer, that is, the saturation level of the amount of charge, is smaller than that of the interlaced imager. Problem.

[0005] For example, when compared under the condition that the configuration of the pixel portion where the photoelectric conversion and the charge accumulation are performed is the same and therefore the area allocated to the vertical transfer path is the same, the progressive type imager uses the vertical transfer path. Since twice the number of transfer stages of the interlaced imager is assigned to the assigned area, the area assigned to each transfer electrode is １ ／ of that of the interlaced imager. Accordingly, the amount of handled charges, that is, the saturation level of the amount of charges is also reduced to about 、, and the dynamic range is reduced to cause deterioration of image quality.

In practice, since the amount of charge stored in the pixel portion becomes large as the amount of charge handled in the vertical transfer path decreases, the area allocated to the pixel portion is reduced and the portion is allocated to the transfer path. However, even in this case, it is impossible to make the allocated area of the transfer electrodes equal to that of the interlaced imager. Further, reducing the area of the pixel portion also causes a decrease in light receiving sensitivity, and is not an essential solution to the problem.

[0007]

As described above, in the progressive imager, a high-resolution still image of one frame can be obtained by an ultra-high-speed pure electronic shutter (element shutter). However, there is a problem that the dynamic range is reduced and the image quality is degraded because the amount of charge handled in the method is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an image sensor capable of securing an ultra-high-speed shutter operation and suppressing image quality deterioration due to a decrease in a dynamic range, and a driving method thereof. It aims to provide methods and the like.

[0009]

A method of driving an image sensor according to the present invention uses an image sensor having a vertical transfer path capable of individually and simultaneously transferring charges of all pixels corresponding to one frame, and using the image sensor for one frame. Interlaced reading is performed, in which the electric charges of all the corresponding pixels are divided into a plurality of fields and transferred by the vertical transfer path, so that all the pixel information corresponding to one frame is read out in a field sequence.

In the driving method of the image pickup device, the number of continuous excitation phases for retaining charges in the vertical transfer path at the time of the interlaced reading can be transferred individually and simultaneously for all pixels corresponding to one frame. It is preferable that the number of continuous excitation phases for retaining charges in the vertical transfer path at the time of progressive reading be larger than that.

In the driving method of the image pickup device, the number of driving phases of the vertical transfer path in the interlaced reading is smaller than the number of driving phases in the progressive reading which can individually and simultaneously transfer charges of all pixels corresponding to one frame. , Multiplied by an interlace ratio N (N is an integer of 2 or more).

An image pickup device according to the present invention comprises a photoelectric conversion pixel section in which a plurality of pixels each having a photoelectric conversion element are two-dimensionally arranged; and reading out and accumulating each electric charge generated and accumulated in the photoelectric conversion pixel section. An image pickup device comprising: a vertical transfer path for transferring a signal; and a horizontal transfer path for transferring charges transferred by the vertical transfer path in a horizontal direction, wherein the vertical transfer path includes M rows (M rows per horizontal pixel row). Is an integer of 3 or more)
The vertical transfer electrode has an interlace ratio of N (where N is an integer of 2 or more) in an interlace read operation for reading all pixel information corresponding to one frame in a field sequence, where M × N. It is characterized in that the rows are connected in common with the minimum repetition period. In this case, it is preferable that M is 4 and N is 2.

Further, in the method of driving an image pickup device according to the present invention, a progressive drive using the image pickup device to excite vertical transfer electrodes of the vertical transfer path at a common timing for every M rows; And interlaced drive in which adjacent vertical transfer electrodes are excited at a common timing.

Further, the method of driving an image pickup device according to the present invention is characterized in that, using the image pickup device, a progressive drive for driving the vertical transfer path in the M phase and an interlace drive for driving the vertical transfer path in the M × N phase. It is selectively used.

An image pickup apparatus according to the present invention comprises an image pickup device having a vertical transfer path capable of individually and simultaneously transferring charges of all pixels corresponding to one frame, and a plurality of fields for transferring charges of all pixels corresponding to one frame. And a transfer unit for performing interlaced readout in which all pixel information corresponding to one frame is field-sequentially transferred by dividing the image data by the vertical transfer path.

In the imaging device, the driving means includes:
It is possible to execute progressive readout in which charges of all pixels corresponding to one frame can be transferred individually and simultaneously,
It is preferable that the image pickup device further includes a readout selection unit that selects either the interlaced readout or the progressive readout at the time of imaging by the imaging device.

In the above-mentioned imaging apparatus, the driving means includes:
The number of continuous excitation phases for retaining charges in the vertical transfer path during the interlaced readout is such that the charges of all the pixels corresponding to one frame can be transferred individually and simultaneously in the vertical transfer path during the progressive readout. Is preferably configured to be larger than the number of continuous excitation phases for

In the imaging device, the driving means includes:
The number of driving phases of the vertical transfer path in the interlaced reading is an interlace ratio N (where N is an integer of 2 or more) with respect to the number of driving phases in the progressive reading which can individually and simultaneously transfer charges of all pixels corresponding to one frame. ) Is preferably multiplied. In this case, the interlace ratio N is preferably 2.

In the image pickup apparatus, an optical shutter means for controlling input and cutoff of a subject image to the image pickup element is provided, and when the read-out selecting means selects the interlaced read-out, It is preferable that the exposure of the element be completed by the optical shutter means.

In the image pickup apparatus, there is provided exposure control means for controlling exposure when the image pickup device performs image pickup, and the readout selection means includes an exposure time applied by the exposure control means for a predetermined time when image pickup is performed. If it is shorter, it is preferable to select the progressive readout.

In the image pickup apparatus, a photographing mode selecting means for selecting a photographing mode is provided, and the reading selecting means selects the progressive reading when the continuous photographing mode is selected by the photographing mode selecting means. Is preferred.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

(Configuration of Image Sensor) FIG. 1 is a view schematically showing a basic configuration example of an image sensor (CCD imager) according to an embodiment of the present invention.

Similar to a normal CCD imager, a plurality of pixels 11 having photoelectric conversion elements are two-dimensionally arranged, and each pixel 11 generates and accumulates electric charge according to the amount of incident light. A vertical transfer path (vertical CCD) 13 is connected to each pixel 11 via a transfer gate 12, and the charges accumulated in each pixel 11 are read out to the vertical transfer path 13 and transferred in the vertical direction. A horizontal transfer path (horizontal CCD) 14 is connected to each vertical transfer path 13, and charges transferred from the vertical transfer path 13 are transferred in the horizontal direction by the horizontal transfer path 14. An output buffer 15 is connected to the horizontal transfer path 14, and the charges transferred through the horizontal transfer path 14 are sequentially output via the output buffer 15.

FIG. 2 is a diagram schematically showing a main part of the image pickup device shown in FIG.

As described above, each pixel 11 (P1,
P2,...) Have transfer gates 12 (G1, G
2,...) Are connected to the vertical transfer path 13,
The vertical transfer path 13 is provided with four vertical transfer electrodes 16 (Ea to Ed, Ee to Eh) per pixel. Wirings 17 (Wa to Wh) are connected to the vertical transfer electrodes 16, and the vertical transfer electrodes Ea to Eh can be independently driven by the corresponding wirings Wa to Wh. That is, the wirings Wa to Wh are commonly connected with eight vertical transfer electrodes as the repetition period. In other words, the wirings Wa to Wh are commonly connected with a repetition period of two pixels adjacent in the vertical direction. In a conventional progressive CCD imager (in the case of four-phase driving), each wiring is commonly connected with one pixel as a repetition cycle, that is, with four vertical transfer electrodes as a repetition cycle. ,
The configuration is basically different from that of the conventional CCD imager in terms of the repetition period of each wiring.

Using the above-described configuration, each of the wirings Wa to
Wh, that is, each vertical transfer electrode Ea-E
By switching the signal supplied to h, the present imaging element can switch between progressive drive (progressive readout) and interlace drive (interlace readout).

(Operation of Image Sensor) Next, the operation of the image sensor shown in FIGS. 1 and 2 will be described with reference to a timing chart.

FIG. 3 is a timing chart showing an example of the vertical transfer operation when progressive reading is performed using the image pickup device. FIGS. 7A to 7H show control signals (drive signals) supplied from the wirings Wa to Wh to the vertical transfer electrodes Ea to Eh, respectively.

When performing progressive reading,
The electric charges accumulated in all the pixels 11 for one frame are individually and simultaneously read out to the vertical transfer path 13 via the transfer gate 12, and a predetermined drive signal (drive voltage) is applied to each of the vertical transfer electrodes Ea to Eh. As a result, the charge read from each pixel is transferred through the vertical transfer path 13. Specifically, a transfer gate pulse TGP1, which is a pulse for gate excitation of the vertical transfer electrode Ea and also used as G1, G3, G5,... These two TGs of TGP2 for the vertical transfer electrode Eb also used as G2, G4,.
By simultaneously applying P, the vertical transfer path 1 for all charges
3 are read simultaneously, and then the vertical transfer electrodes E
By supplying the same drive signals to a and Ee, Eb and Ef, Ec and Eg, and Ed and Eh, electric charges are transferred in the vertical transfer path 13 by four-phase driving.

First, in the period t1, the vertical transfer electrodes Ea,
A low (L) level drive signal is applied to Eb, Ee, and Ef, and a high (H) level drive signal is applied to the vertical transfer electrodes Ec, Ed, Eg, and Eh, and the vertical transfer electrodes Ea, Eb, E
The regions corresponding to e and Ef function as potential wells, and the regions corresponding to the vertical transfer electrodes Ec, Ed, Eg and Eh function as potential barriers. As a result, charges are held in regions corresponding to the vertical transfer electrodes Ea, Eb, Ee, and Ef.

In the period t2, the vertical transfer electrodes Ea, Eb,
In addition to Ee and Ef, an L-level drive signal is applied to the vertical transfer electrodes Ec and Eg, and a transition to a transition state of charge transfer occurs.

In the period t3, the vertical transfer electrodes Eb, Ec,
Lf drive signal and vertical transfer electrode E are applied to Ef and Eg.
A drive signal of H level is applied to a, Ed, Ee, and Eh, and regions corresponding to the vertical transfer electrodes Eb, Ec, Ef, and Eg are potential wells, and the vertical transfer electrodes Ea, Ed, E
The region corresponding to e and Eh functions as a potential barrier. As a result, the transferred charges are held in regions corresponding to the vertical transfer electrodes Eb, Ec, Ef, and Eg.

Thereafter, similarly, the portions to which the L-level and H-level drive signals are applied are sequentially shifted, and the charges are transferred in the vertical transfer path 13.

As described above, in the progressive readout, a drive equivalent to the conventionally known four-phase drive is used. In other words, two successive phases are held while electric charges are held by two continuous (adjacent) vertical transfer electrodes. Charges are sequentially transferred while in the excited state.

FIG. 4 is a timing chart showing an example of the vertical transfer operation when interlaced reading is performed using the present image sensor. FIGS. 7A to 7H show control signals (drive signals) supplied from the wirings Wa to Wh to the vertical transfer electrodes Ea to Eh, respectively.

When performing interlace reading,
Each electric charge accumulated in all pixels 11 for one frame is divided into a plurality of fields, and the vertical
By applying a predetermined drive signal (drive voltage) to each of the vertical transfer electrodes Ea to Eh, the charge read from each pixel is transferred through the vertical transfer path 13. In particular,
First, a transfer gate pulse TGP1, which is a pulse for gate excitation, is applied to the vertical transfer electrode Ea which is also used as G1, G3, G5,... The pixel charges of the first field are read out to the vertical transfer path 13 and then the pixel charges of the first field are sequentially read out by transfer by the double electrode four-phase drive described later. Next, G2, G4,... Belonging to the second field
By applying TGP2 to the vertical transfer electrode Ee, which is also used for reading, the pixel charges of the second field are read out to the vertical transfer path 13, and then the pixel charges of the second field are also driven by the double electrode four-phase drive. Are sequentially read by transfer.

Here, the double electrode four-phase drive will be described. Two continuous (adjacent) electrodes are used as unit phases, that is, vertical transfer electrodes Ea and Eb, Ec and Ed, Ee and Ee.
f, Eg and Eh are supplied with the same drive signal, respectively, so that electric charges are substantially transferred by the four-phase drive to the vertical transfer path 1.
3 is transferred.

The vertical transfer shown in FIG. 4 is a double-electrode four-phase drive corresponding to the reading of the first field.
Then, a low (L) level drive signal and vertical transfer electrodes Ee, Ef, E are supplied to the vertical transfer electrodes Ea, Eb, Ec, and Ed.
A high (H) level drive signal is applied to g and Eh,
The regions corresponding to the vertical transfer electrodes Ea, Eb, Ec and Ed function as potential wells, and the regions corresponding to the vertical transfer electrodes Ee, Ef, Eg and Eh function as potential barriers. As a result, the vertical transfer electrodes Ea, Eb, Ec, and Ed
Are held in the region corresponding to.

In the period t2, the vertical transfer electrodes Ea, Eb,
In addition to Ec and Ed, an L-level drive signal is applied to the vertical transfer electrodes Ee and Ef, and the transition to the transient state of charge transfer occurs.

In the period t3, the vertical transfer electrodes Ec, Ed,
Le drive signal and vertical transfer electrode E are applied to Ee and Ef.
A drive signal of H level is applied to a, Eb, Eg, and Eh, and regions corresponding to the vertical transfer electrodes Ec, Ed, Ee, and Ef are potential wells and vertical transfer electrodes Ea, Eb, and Ef.
The region corresponding to g and Eh functions as a potential barrier. As a result, the transferred charges are held in regions corresponding to the vertical transfer electrodes Ec, Ed, Ee, and Ef.

Thereafter, similarly, portions to which the L-level and H-level drive signals are applied are sequentially shifted, and charges are transferred in the vertical transfer path 13.

Note that the vertical transfer in the second field is basically performed in the same manner. In this case, as described above, the electric charge in the pixel portion is transferred by the transfer gate pulse TGP.
2, the data is read out to the position of the vertical transfer electrode Ee, and the vertical transfer is executed with the state in which the potential well is formed at this position as the standby phase. That is, in the case of the second field, the transfer reading is performed with the period t5 in FIG.

As described above, in the interlaced readout, the double-electrode four-phase drive using two consecutive electrodes as a unit phase is applied, and the electric charge is held by four consecutive vertical transfer electrodes, in other words, four consecutive electrodes are used. While the two phases (two phases in terms of two electrodes) are in an excited state,
Charges are sequentially transferred.

As described above, in this embodiment, each wiring Wa is set such that two pixels adjacent in the vertical direction are set as the repetition period.
To Wh, that is, the respective vertical transfer electrodes Ea to Eh are commonly connected, and the signal supplied to each of the vertical transfer electrodes Ea to Eh is switched between progressive reading and interlaced reading. By doing so, the advantage of progressive reading that a high-resolution still image for one frame can be obtained by a pure electronic shutter (element shutter), and a reduction in the amount of charge handled in the vertical transfer path is suppressed. In addition, it is possible to obtain a CCD imager that has the advantage of interlaced reading that image quality deterioration due to a decrease in dynamic range can be prevented.

FIG. 5 is a timing chart showing a modified example of the operation example in the case of performing interlaced reading using the present image sensor. FIGS. 7A to 7H respectively show the vertical transfer electrodes Ea to Eh from the wirings Wa to Wh.
It shows a control signal (drive signal) supplied to Eh.
Note that progressive reading is the same as in the example shown in FIG.

Also in the case of performing the interlaced readout according to this modification, each charge accumulated in all the pixels 11 for one frame is divided into a plurality of fields and read out to the vertical transfer path 13 in the field order, and each vertical transfer electrode is read out. Ea-E
By applying a predetermined drive signal (drive voltage) to h, the charge read from each pixel is transferred through the vertical transfer path 13. However, in this example, by supplying different drive signals to the vertical transfer electrodes Ea to Eh, charges are transferred in the vertical transfer path 13 by eight-phase driving.

First, in the period t1, the vertical transfer electrodes Ea to
Low (L) level drive signal and vertical transfer electrode Eg are applied to Ef.
And Eh, a high (H) level drive signal is applied, the regions corresponding to the vertical transfer electrodes Ea to Ef function as potential wells, and the regions corresponding to the vertical transfer electrodes Eg and Eh function as potential barriers. As a result, the vertical transfer electrode E
Charges are held in regions corresponding to a to Ef.

In the period t2, in addition to the vertical transfer electrodes Ea to Ef, an L-level drive signal is applied to the vertical transfer electrode Eg, and a transition is made to a transition state of charge transfer.

In the period t3, an L-level drive signal is applied to the vertical transfer electrodes Eb to Eg, and an H-level drive signal is applied to the vertical transfer electrodes Ea and Eh, so that regions corresponding to the vertical transfer electrodes Eb to Eg are potential wells. Regions corresponding to the vertical transfer electrodes Ea and Eh function as potential barriers. As a result, the transferred charges are held in regions corresponding to the vertical transfer electrodes Eb to Eg.

Thereafter, similarly, the portions to which the L-level and H-level drive signals are applied are sequentially shifted, and the electric charges are transferred in the vertical transfer path 13.

As described above, in the interlaced readout of the present modified example, the charges are sequentially transferred while holding the charges by the continuous six vertical transfer electrodes, in other words, while the continuous six phases are in the excited state.

In this modified example, the same operation and effect as those of the above-described example can be obtained. In addition, since the transfer is performed while holding the electric charges by the continuous six vertical transfer electrodes,
More charge can be transferred. Conversely,
Even if the area allocated to the vertical transfer path is reduced, it is possible to transfer a certain amount of charge or more, and the area of the pixel region can be increased accordingly, so that the light receiving sensitivity is increased by increasing the area of the pixel region. It is also possible.

In the period t1, a potential well including both positions of the vertical transfer electrodes Ea and Ee from which electric charges are read out in the first and second fields is formed. A common standby phase (initial state of transfer) independent of the field can be obtained, and the driving method can be simplified.

In the example shown in FIG. 2, the number of vertical transfer electrodes per pixel (the number of vertical transfer electrodes per horizontal pixel row) M is 4, the interlace ratio N is 2, and
Each wiring (each vertical transfer electrode) is commonly connected with eight vertical transfer electrodes (4 × 2) as a repetition cycle. However, the number of M and N can be changed as appropriate. The repetition period is generally M × N (M is an integer of 3 or more, N is an integer of 2 or more).

According to this generalization, the above-mentioned double electrode four-phase drive is replaced with the N-fold electrode M-phase drive, and the eight-phase electrode is driven by M × N.
Each is generalized to phase drive.

(Configuration of Imaging Apparatus) Next, a digital camera (electronic still camera) will be described as an imaging apparatus using the above-described imaging device and its driving method. FIG.
1 is a block diagram schematically illustrating a basic configuration example of a digital camera.

The basic structure of the image pickup system is the same as that of an ordinary digital camera, and the photographing lens system 101 and the exposure mechanism 1
02, the filter system 103, and the image sensor (C
CD imager) 104 and the like. That is, by subjecting the subject image formed by the photographing lens system 11 to photoelectric conversion by the CCD imager 104 and inputting the photoelectrically converted image signal to a pre-processing unit 105 for performing processing such as A / D conversion, digital conversion is performed. The obtained image signal is obtained. Exposure mechanism 10
Reference numeral 2 includes an optical shutter for controlling input and cutoff of a subject image to the CCD imager 104.
In this embodiment, a mechanical shutter will be described as an example of the optical shutter, but a liquid crystal shutter or the like may be used.

The lens of the taking lens system 101 is driven by a lens driving mechanism 107 under the control of a lens driving circuit 106. The CCD imager 104 is driven by the CCD driving circuit 108 according to the driving method described above. Also, the exposure mechanism 102 is an exposure mechanism control circuit 1
The exposure mechanism control circuit 109 also drives the strobe 110.

A system controller 111 constituted by a microcomputer or the like controls each part of the digital camera, such as drive control of the CCD imager 104, drive control of the exposure mechanism 102, and selection control of progressive drive or interlace drive of the CCD imager. The control program is stored in the EEPROM 112.

The digital processing section 113 constituted by a RAM or the like has a function as a work area for various digital processing such as image processing, in addition to a function of temporarily storing image data obtained by imaging. I have.

The memory interface 114 is an interface for transmitting and receiving information to and from the memory card 115 inserted into the card slot. Then, the image information is read from the memory card 115. Also, the LCD display unit 11
Numeral 6 is for displaying a photographed image or the like.

The operation switch section 117 is for giving various instructions to the digital camera, and includes a release button, a shooting mode selection switch for selecting a shooting mode, and the like. The operation display unit 118 displays a shooting mode and the like.

(Operation of Imaging Apparatus) Next, the operation of the imaging apparatus (digital camera) shown in FIG. 6 will be described with reference to a timing chart.

FIG. 7 is a timing chart showing an operation example when performing interlaced reading. 2A shows the timing of the release operation, FIG. 2B shows the timing of the charge discharge pulse (pulse for discharging the charges accumulated in the pixels 11 to the semiconductor substrate), and FIG. 2C shows the first field. (D) shows the timing of the transfer gate pulse TGP2 of the second field, (e) shows the timing of charge transfer, and (f) shows the opening / closing timing of the mechanical shutter. FIG.

When the interlace reading is selected, the exposure of the CCD imager 104 is terminated by a mechanical shutter included in the exposure mechanism 102. That is, after the release operation, the exposure period starts at the time when the charge discharging operation by the charge discharging pulse ends, and the substantial exposure period ends when the mechanical shutter shifts from the open state to the closed state.

After the exposure is completed, the first transfer gate (transfer gates G1, G3,... In FIG. 2) is opened to open the pixel (pixel P) connected to the transfer gate.
1, P3,...) Are read out to the vertical transfer path, and the charges read out to the vertical transfer path are sequentially transferred, so that the pixels in the first field from the output buffer 15 shown in FIG. Information is obtained. Then, the second transfer gates (G2, G4,...) Are opened to open the pixels (pixels P2, P4,...) Connected to the transfer gates.
By reading out only the charges accumulated in the vertical transfer path and sequentially transferring the charges read out to the vertical transfer path, pixel information of the second field can be obtained from the output buffer 15.
For the vertical transfer in each field in the case of interlaced reading, either the above-described double electrode four-phase drive or eight-phase drive is used.

FIG. 8 is a timing chart showing an example of the operation when performing the progressive reading. FIG.
Regarding the meaning of each timing of (a) to FIG.
This is the same as that shown in FIGS. 7A to 7F.

When progressive reading is selected, exposure by the CCD imager 104 is performed by a pure electronic shutter (element shutter). That is, after the release operation, the exposure period is started from the time when the charge discharging operation by the charge discharging pulse is completed, and the transfer gate pulses TGP1 and TGP2 are simultaneously output before the mechanical shutter closing operation is started. The exposure period ends. That is, in the progressive read, each transfer gate (G1, G2 in FIG. 2)
, G3, G4,...) Are all driven at the same time, and the electric charges accumulated in each pixel (P1, P2, P3, P4,...) Are all simultaneously read out to the vertical transfer path. Thereafter, by sequentially transferring the charges read to the vertical transfer path, all pixel information is obtained from the output buffer 15 shown in FIG. 1 within a single field (= frame). For the vertical transfer in the case of the progressive reading, a drive equivalent to the above-described conventionally known four-phase drive is used.

At this time, the mechanical shutter is used for the purpose of avoiding the occurrence of smear due to the incidence of light at the time of vertical transfer, and the charge transfer readout is performed after the mechanical shutter is closed. ing.

The decision whether to drive the CCD imager 104 progressively or interlacely is made as follows. That is, if the exposure time T (shutter speed or the like) applied at the time of shooting is shorter than the predetermined time T0 (T <T0), the progressive drive is selected, and the exposure time T applied at the time of shooting is set to the predetermined time T0. In the above case (T ≧ T0), the interlace drive is selected. The predetermined time T0 is a value determined by the operation speed of the mechanical shutter and the like. Also, when the continuous shooting mode is selected by the shooting mode selection switch of the operation switch unit 117, the operation speed of the mechanical shutter often cannot catch up with the speed of continuous shooting.
Select progressive drive. When the mode is not the continuous shooting mode (single shooting mode), the interlace driving is selected on condition that T ≧ T0.

As described above, by switching between the progressive reading and the interlaced reading, the progressive reading is selected when photographing with an ultra-high-speed shutter using a pure electronic shutter, and a wide dynamic range in which the transfer charge amount is increased. In the case of shooting, the interlaced reading can be selected, and a digital camera having both the advantages of the progressive reading and the interlaced reading can be obtained.

In other words, in other words, if exposure time control by an optical shutter such as a mechanical shutter is effective (not necessarily limited to the parameter of shutter speed or the mode of continuous shooting), interlace reading is selected. By doing so, it is possible to perform shooting in a wide dynamic range with a large amount of transfer charge, and even when exposure time control by an optical shutter is not effective,
By selecting progressive reading, at least high-precision shooting with an ultra-high-speed shutter using a pure electronic shutter can be performed. In each case, information of all pixels is read out individually, resulting in degradation of resolution. Does not occur.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the gist thereof. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed constituent elements. For example, even if some constituent elements are deleted from the disclosed constituent elements, they can be extracted as an invention as long as a predetermined effect can be obtained.

[0075]

According to the present invention, progressive reading and interlaced reading can be performed by a single image pickup device. By using both of them, an ultra-high-speed shutter operation can be ensured and a wide dynamic range can be secured. Can also be secured.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a basic configuration example of an image sensor according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a main part of the imaging device illustrated in FIG. 1;

FIG. 3 is a timing chart showing an operation example when performing progressive reading using the image sensor according to the embodiment of the present invention.

FIG. 4 is a timing chart showing an operation example when performing interlaced reading using the image sensor according to the embodiment of the present invention.

FIG. 5 is a timing chart showing a modified example of the operation when interlaced reading is performed using the image sensor according to the embodiment of the present invention.

FIG. 6 is a block diagram schematically showing a basic configuration example of an imaging device according to an embodiment of the present invention.

FIG. 7 is a timing chart showing an operation example when interlaced reading is performed using the imaging device according to the embodiment of the present invention.

FIG. 8 is a timing chart showing an operation example when performing progressive reading using the imaging apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 11, P1 to P5: Pixel 12, G1 to G5: Transfer gate 13, Vertical transfer path 14, Horizontal transfer path 15, Output buffer 16, Ea to Eh, Vertical transfer electrode 17, Wa to Wh, Wiring 101: Photographic lens system 102 Exposure mechanism 103 Filter system 104 Image sensor (CCD imager) 105 Preprocessing unit 106 Lens drive circuit 107 Lens drive mechanism 108 CCD drive circuit 109 Exposure mechanism control circuit 110 Strobe 111 System controller 112 ... EEPROM 113 ... Digital process unit 114 ... Memory interface 115 ... Memory card 116 ... LCD display unit 117 ... Operation switch unit 118 ... Operation display unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M118 AA02 AB01 BA13 DB01 DB03 DB08 FA06 5C024 AX01 BX01 CX47 CX54 JX12 JX23 JX25

Claims (16)

[Claims] 1. An image pickup device having a vertical transfer path capable of individually and simultaneously transferring charges of all pixels corresponding to one frame, and dividing the charges of all pixels corresponding to one frame into a plurality of fields. By transferring via the vertical transfer path, 1
A method for driving an image sensor, wherein interlaced reading is performed to read all pixel information corresponding to a frame in a field sequence. 2. The method according to claim 1, wherein the number of continuous excitation phases for retaining charges in the vertical transfer path during the interlaced readout is one.
2. The number of continuous excitation phases for retaining charges in a vertical transfer path at the time of progressive readout in which charges of all pixels corresponding to a frame can be transferred individually and simultaneously is set larger. A method for driving an image sensor. 3. The number of driving phases of the vertical transfer path in the interlaced reading is set to an interlace ratio N with respect to the number of driving phases in the progressive reading capable of individually and simultaneously transferring charges of all pixels corresponding to one frame.
3. The method according to claim 1, wherein (N is an integer of 2 or more). 4. A photoelectric conversion pixel section in which a plurality of pixels each having a photoelectric conversion element are two-dimensionally arranged; and a vertical transfer path for reading out and accumulating each electric charge generated and accumulated in the photoelectric conversion pixel section and vertically transferring the electric charge. A horizontal transfer path for transferring the charges transferred by the vertical transfer path in a horizontal direction, wherein the vertical transfer path has M rows (M is an integer of 3 or more) per horizontal pixel row. The vertical transfer electrode has an interlace ratio of N (N is an integer of 2 or more) in an interlace readout in which all pixel information corresponding to one frame is read out in a field sequence. An imaging element, wherein the rows are connected in common with a minimum repetition period. 5. The imaging device according to claim 4, wherein said M is four, and said N is two. 6. An imaging device according to claim 4 or 5,
It is possible to selectively use progressive drive for exciting the vertical transfer electrodes of the vertical transfer path at a common timing for every M rows and interlaced drive for exciting adjacent vertical transfer electrodes of the vertical transfer path at a common timing. A method for driving an imaging device, which is a feature of the invention. 7. The interlaced drive, wherein N adjacent transfer electrodes corresponding to an interlace ratio N (N is an integer of 2 or more) is used as a unit phase, and the number of drive phases is the same as the number M of drive phases in the progressive drive. 7. The method for driving an image sensor according to claim 6, wherein the driving is performed by N-times electrode M-phase driving. 8. An imaging device according to claim 4 or 5,
A progressive drive for driving the vertical transfer path in the M phase;
A method of driving an image sensor, wherein interlaced driving for driving the vertical transfer path in an M × N phase is selectively used. 9. An image pickup device having a vertical transfer path capable of individually and simultaneously transferring charges of all pixels corresponding to one frame, and dividing the charges of all pixels corresponding to one frame into a plurality of fields. By transferring via the transfer path, 1
A driving unit for performing interlaced readout for reading out all pixel information corresponding to a frame in a field sequence. 10. The driving means is capable of executing progressive readout in which charges of all pixels corresponding to one frame can be individually and simultaneously transferred, and can perform either interlaced readout or progressive readout at the time of imaging by the image pickup device. The imaging apparatus according to claim 9, further comprising a readout selection unit that selects one of the following. 11. The driving unit according to claim 1, wherein the number of continuous excitation phases for retaining charges in the vertical transfer path at the time of the interlaced readout is such that the charges of all pixels corresponding to one frame can be transferred individually and simultaneously. The imaging apparatus according to claim 9, wherein the number of continuous excitation phases for retaining charges in a vertical transfer path at the time of reading is larger than the number of excitation phases. 12. The driving unit according to claim 1, wherein the number of driving phases of the vertical transfer path in the interlaced reading is smaller than the number of driving phases in the progressive reading which can individually and simultaneously transfer charges of all pixels corresponding to one frame. 11. An image processing apparatus according to claim 9, wherein said interlace ratio is multiplied by an interlace ratio N (N is an integer of 2 or more).
An imaging device according to claim 1. 13. The apparatus according to claim 12, wherein the interlace ratio N is 2. 14. An image pickup device comprising: an optical shutter means for controlling input and cutoff of a subject image to the image pickup element; and when the readout selection means selects the interlace readout, an exposure in the image pickup element. 14. The imaging apparatus according to claim 10, wherein the end of the image processing is performed by the optical shutter unit. 15. An image pickup device comprising: an exposure control unit configured to control an exposure when an image is captured by the imaging device; wherein the readout selection unit is configured to perform an exposure time shorter than a predetermined time when the exposure control unit performs the image capture. 15. The imaging apparatus according to claim 10, wherein the progressive reading is selected in the case. 16. A photographing mode selecting means for selecting a photographing mode, wherein the reading selecting means selects the progressive reading when the continuous photographing mode is selected by the photographing mode selecting means. Claim 1
The imaging device according to any one of 0 to 15.