JPH118801A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive image pickup device and an electronic camera to photograph the still image and the moving images of high resolution by providing a function to eliminate the electric charge stored in a horizontal CCD and quickly eliminating the unnecessary electric charge that is supplied to a horizontal transfer means. SOLUTION: In a general, the electric charge moves to a low potential position from a high potential position and accordingly the electric charge stored in a horizontal CCD 103 never moves to a horizontal CCD drain 105 over a horizontal CCD drain gate 104. However, the electric charge flows into the drain 105 over the gate 104 from the CCD 103 since the potential of the gate 104 has a low level. The drain 105 has a function to eliminate the electric charge flowing into it and can eliminate all unnecessary electric charge supplied from a vertical CCD 102 out of the CCD 103. In other words, even the time when the electric charge is read out of the CCD 103 can be allocated to a fast operation of the CCD 102. As a result, a larger number of signals of unnecessary vertical images can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly, to a structure of a moving image and a still image pickup device and a driving method thereof.

[0002]

2. Description of the Related Art In recent years, the advance of image compression technology and the increase in capacity of recording media have progressed, and so-called electronic cameras for recording image information as digital signals have been commercialized. Current,
Electronic cameras are broadly classified according to the resolution of captured images, for consumer use and for business use. Currently, electronic cameras generally regarded as consumer use have a so-called VGA size with an image resolution of about 640 pixels in the horizontal and 480 pixels in the vertical direction. It has an image resolution of about 1,200 horizontal pixels and about 1,000 vertical pixels using the above image sensor.
At present, the above image resolution is generally used for consumer use, but there is a great need for higher resolution.

An electronic camera, unlike a photograph using a so-called silver halide film, can generate digital image data immediately after taking an image. In the consumer electronic camera, there is a high market need for an electronic camera having a function of displaying a captured image by using a display means such as a liquid crystal display taking advantage of the above characteristics.

Further, the liquid crystal display is often used also as a viewfinder at the time of image pickup.

[0005] In order to realize the above-mentioned market needs, the number of pixels of an image pickup device in a consumer electronic camera is also increasing, and the pixel of the image pickup device generally included in a so-called video camera such as the Hi8 system. Electronic cameras with more than a few pixels are becoming commercially available.

In order to realize a viewfinder using a liquid crystal display, which is another market need, a signal picked up by an image pickup device is supplied to a liquid crystal display as a video signal of, for example, an NTSC system which is a standard TV system. ,it's shown.

[0007]

As described above, in consideration of market needs and the like, the electronic camera is (1) to increase the resolution (to increase the number of pixels of the image sensor) and (2) to immediately reproduce a captured still image. A liquid crystal display is provided for this purpose. (3) The liquid crystal display is also used as a viewfinder. It is desirable to have the above three functions.

However, in order to realize the above function, an increase in the signal charge readout time accompanying an increase in the number of pixels of the image pickup device,
There is a problem. In a video camera or an electronic camera, an image pickup device generally uses a CCD image pickup device.
The configuration and operation of the CCD image sensor will not be described because they are not described further. However, when the charge photoelectrically converted by the photodiode is output from the image sensor, all the pixels must be read. That is, the electric charge transferred in the vertical direction by the vertical CCD is supplied to the horizontal CCD, and the electric charge supplied to the horizontal CCD must be output from the image sensor by driving the horizontal CCD. When the number increases, the time required to output a signal for one line from the image sensor increases, and in order to obtain a signal that can be supplied to the viewfinder (for example, a video signal of a scanning timing conforming to the NTSC system), the driving of the horizontal CCD is performed. The frequency increases, and the transfer of electric charges cannot be made in a conventional horizontal CCD.

[0009]

According to the present invention, in order to solve the above-mentioned problems, (1) a function of sweeping out charges of the horizontal CCD is provided. The electric charge supplied to the horizontal CCD has conventionally been output from the image sensor by driving the horizontal CCD.
In the present invention, unnecessary charges can be discarded at high speed by providing a function of discarding charges in the horizontal CCD. That is, unnecessary signal portions among all the effective pixels of the image sensor are collectively discarded.

(2) Two horizontal CCDs are provided. Conventionally, an image sensor having a plurality of horizontal CCDs reduces the driving frequency of each horizontal CCD by transferring charges in a time-division manner. And the other is used for signal output.

(3) The last stage of the vertical CCD is provided with a charge sweeping function. By providing a charge sweeping function at the last stage of the vertical CCD, the supply of charges to the horizontal CCD is prevented, and unnecessary charges are discarded.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically illustrating a configuration of an image sensor according to a first embodiment of the present invention. In the figure, 10
1 is a photodiode generally called a pixel, 10
2 is a vertical CCD, 103 is a horizontal CCD, 104 is a horizontal C
A CD drain gate 105 is a horizontal CCD drain. FIG. 2 is a diagram schematically showing a configuration of a conventional general imaging element.

In a conventional image sensor, a continuous image,
That is, in order to obtain a moving image, all the electric charges that have been photoelectrically converted by the photodiode 101 and transferred to the vertical CCD 102 must be transferred to the horizontal CCD 103 during the field period. Also, the signal for one line transferred to the horizontal CCD 103 must be output from the image sensor within one horizontal period. In the present embodiment,
The description will be given on the assumption that a moving image with horizontal and vertical scanning timings conforming to NTSC is obtained, but the scanning timing is not limited to this.

FIG. 3 shows a state in which the light receiving surface of the imaging element surface is viewed from above. In the figure, a white portion is a portion where effective pixels of the image sensor are arranged, and a hatched portion is a desired image cut-out region. CCD image sensor,
In reading out the signal photoelectrically converted by the photodiode 101, it is impossible to output a signal of only a desired cut-out image area from the image sensor as shown in FIG. That is, the electric charge photoelectrically converted by the photodiode 101 cannot be output from the image sensor by selecting only the desired image cutout region. Therefore, signals other than the desired image cut-out area are output from the image sensor by the following method.

First, the method of discarding the vertical charges shown in FIGS. 3A and 3B will be described. FIG.
FIG. 5 is a simplified diagram of a driving pulse for performing vertical charge transfer in FIG. In a general CCD image pickup device, charges are transferred in the vertical direction by a method like a so-called bucket brigade with four vertical transfer pulses. However, the method of transferring charges is well-known and will not be described. The portions indicated by A and B in FIG. 4 indicate portions that perform vertical transfer at high speed. The transfer of the electric charge from the photodiode 101 to the vertical CCD 102 is performed by the vertical CCD 102.
At a higher voltage than the charge transfer pulse. Normally, the transfer in the vertical direction is performed once per horizontal period. In the present embodiment, however, at least during the vertical blanking period (vertical retrace period), the number of lines indicated by A in FIG. The driving pulse is moved at a high speed so that electric charges can be transferred in the vertical direction by the number corresponding to. By the above operation, unnecessary charges corresponding to the upper part of the screen in the vertical CCD 102 can be discarded from the vertical CCD 102. It is to be noted that unnecessary charges at the upper part of the screen are discarded in the portion A in FIG. Unnecessary charges corresponding to the lower part of the screen shown in FIG. 3B are also discarded from inside the vertical CCD 102 in the same manner as described above.
The unnecessary charges at this time are discarded in a portion shown in FIG. 4B.

By the way, the vertical CCD 1 is operated by the above operation.
Unnecessary charges discarded from 02 do not disappear and disappear, but are stored in the horizontal CCD 103. Horizontal CCD
Unnecessary charges stored in the memory 103 are conventionally output from the image sensor by driving the horizontal CCD 103 at high speed during the vertical blanking period. However, the period of the vertical blanking period is limited, and when the number of pixels in the vertical direction of the image sensor increases, or when the lengths of A and B shown in FIG. Is extremely shifted above or below the area where the effective pixels of the image sensor are disposed), the vertical charge transfer in the vertical CCD 102 must be performed at a higher speed. However, there is a limit to the charge transfer speed.

In this embodiment, as shown in FIG. 1, a horizontal CCD 10 is used to discard more unnecessary charges in the vertical CCD 102 for a limited time.
3 and the horizontal CCD drain gate 104 and horizontal CC
D drain 105 was provided.

Next, the operation of the horizontal CCD drain gate 104 and horizontal CCD drain 105 will be described.

Unnecessary charges stored in the horizontal CCD 103 by the above operation are output from the image sensor by driving the horizontal CCD in the case of a conventional general CCD image sensor. However, horizontal CC
The driving speed of the D103 is determined by the transfer efficiency of the CCD.
There is a limit to the driving operation speed. Therefore, as shown in FIG. 1, a horizontal CCD drain gate 104 is arranged beside the horizontal CCD 103. 5 and 6 show a vertical CCD 102.
, Horizontal CCD 103, horizontal CCD drain gate 1
The relationship of the potential of No. 04 is schematically shown. The hatched portions above the horizontal CCD 103 in both figures represent electric charges.
Note that the potential decreases as the applied voltage increases. FIG. 5 shows the state of the horizontal CCD drain gate 104.
Is in a state of high potential, and the state of FIG.
The potential of the CD drain gate is low.
Since the electric charge moves from a high potential to a low potential, in the state shown in FIG. 5, the electric charge in the horizontal CCD 103 passes over the horizontal CCD drain gate 104 and the horizontal CCD.
Does not move to the drain. However, in the state of FIG. 6, since the potential of the horizontal CCD drain gate 104 is low, the charges in the horizontal CCD 103 flow into the horizontal CCD drain 105 beyond the horizontal CCD drain gate 104. The horizontal CCD drain 105 has a function of discarding the flowing charge into the substrate. When the vertical CCD 102 is driven at a high speed as shown in FIG. 6, all unnecessary charges supplied from the vertical CCD 102 are transferred to the horizontal CCD.
It can be discarded from the CD 103. In other words, horizontal CCD
The time for reading out the charges in the memory 103 can also be allocated to the high-speed operation of the vertical CCD 102, and more signals of unnecessary pixels in the vertical direction can be discarded. FIG. 7 shows an example of the driving waveform of the horizontal CCD drain gate 104 during the high-speed operation of the vertical CCD 102.

Next, how to discard unnecessary charges in the portions (horizontal direction) shown in FIGS. 3C and 3D will be described. As mentioned above,
The reading speed of the image sensor is NTSC for both horizontal and vertical
Must be performed in accordance with the timing of the method. N
One horizontal period of the TSC system is approximately 63.5 μS (microsecond), and the effective period excluding the retrace period is approximately 5 seconds.
Since it is 3 μS, the horizontal CCD 104 must be driven at a frequency determined by the following equation.

Horizontal CCD driving frequency = 1 / (53 μS / 1280) = approximately 24 MHz However, when the driving frequency of the horizontal CCD in the conventional imaging device is operated at the high speed of about 24 MHz,
Charge transfer is not in time. In view of the above, horizontal CC
The driving frequency of D103 must be reduced. Therefore, first, as shown in FIG.
The signal for one line is read from the vertical CCD 102. The electric charge in the horizontal CCD 103 is output from the image sensor by driving the horizontal CCD 103. FIG. 8B shows the state of FIG. 4C and the completion of the transfer of the electric charges in the desired pixel cutout area. At this time, the horizontal CCD 103
Since the electric charge of the D part remains, the horizontal CCD described above is used.
The horizontal CCD drain 10 is operated by the operation of the drain gate 104.
Discard to 5. That is, the number of times of charge transfer of the horizontal CCD 103 can be reduced by several pixels corresponding to the portion indicated by D in FIG. At this time, the number of pixels of C and D is equal, and the number of pixels in the horizontal direction of a desired image cut-out portion is 72.
Assuming that the number of pixels is 0, the driving frequency of the horizontal CCD 103 is as follows. (From the above conditions, the number of each of C and D is 280.) Horizontal CCD drive frequency = 1 / (53 μS / (1280-280)) = about 19 MHz By the above operation, the charge of the C portion is obtained from the image sensor. The electric charge in the desired image cut-out area is output. In addition,
As for the electric charge of the C portion, an image signal may be generated by a signal excluding the C portion using a so-called digital zoom for electrically enlarging the signal by an interpolation method using a line memory, for example. The above method is effective for capturing a continuous image, that is, a moving image, when the number of pixels in the horizontal direction of the image sensor is larger than the number of pixels in the horizontal direction of the image sensor used in a conventional video camera or the like. It is.

Next, the operation of capturing a still image will be described. In the case of a still image, there is no need to continuously capture images.
Transfer (readout) of pixels in the vertical direction can be performed. Therefore, in reading out the charges of the image pickup device, signals for all effective pixels of the image pickup device can be read out by a method generally used conventionally, and a high-resolution still image can be obtained.

The moving image obtained by the above operation is displayed on a liquid crystal display and used as a view finder.
It can be used as a guide for the photographed image of the user.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a diagram schematically illustrating a configuration of an image sensor according to the embodiment of the present invention. Note that the components in FIG. 9 have common points with the components illustrated in FIG. 1, and descriptions of components having the same operation will be omitted. In FIG. 9, 90
1 is a horizontal CCD drain gate, 902 is a horizontal CCD drain, and is different from each part of FIG.
CD drain gate 901 and horizontal CCD drain 90
2 are different in length.

In the present embodiment, as in the first embodiment, a method for efficiently reading the signals in the hatched portions shown in FIG. 3 will be described. First, how to discard the electric charges in the vertical direction shown in FIGS. 3A and 3B will be described. In this embodiment, the electric charges in the portions A and B in FIG. 3 are transferred from the vertical CCD 102 to the horizontal CCD 10 in the same manner as in the first embodiment.
3. High-speed transfer. At this time, unlike the first embodiment, since all the charges in the horizontal CCD 103 cannot be discarded, the horizontal CCD 103 is driven to output the charges from the image sensor when the vertical high-speed transfer is completed. All the above operations are performed during the vertical blanking period.
In the present embodiment, the time of the vertical high-speed transfer, which was possible in the first embodiment, is the same as that of the horizontal CCD 103.
Since the charge sweeping time is required, each of the upper and lower portions of the screen is shortened by one horizontal period.

Next, a description will be given of a method of discarding the electric charges in the portions C and D in FIG. 3 corresponding to the line which is a desired image cut-out region. First, as shown in FIG.
A signal for one line is read from the vertical CCD 102 into the memory 103. The charge in the horizontal CCD 103 is
And outputs the same from the image sensor. FIG. 8B shows a state in which the transfer of the electric charges in the portion C of FIG. 3 and the portion of the desired pixel cutout region has been completed. At this time, since the electric charge of the portion D in FIG. 3 remains in the horizontal CCD 103, it is discarded to the horizontal CCD drain 902 by the operation of the horizontal CCD drain gate 901 described above. That is, similarly to the first embodiment, the number of times of charge transfer of the horizontal CCD 103 is set to D in FIG.
Can be reduced by several pixels corresponding to the portion indicated by. That is, similarly to the first embodiment, the drive frequency of the horizontal CCD 103 can be reduced.

Hereinafter, also in the present embodiment, the first
In the same manner as in the embodiment, the electric charge in the portion C in FIG. 3 is converted into a signal using a so-called digital zoom in which a signal is electrically enlarged by an interpolation method using, for example, a line memory.
What is necessary is just to generate an image signal by the signal except the part.

As shown in FIG. 10, a horizontal CCD drain gate 901 and a horizontal CCD drain 902 are arranged, and the horizontal CCD 103 is supplied with electric charge for one line from the vertical CCD 102 to the horizontal CCD 103 immediately after the horizontal CCD 103 is supplied. The charge may be discharged to the horizontal CCD drain 902 by operation.

In the methods shown in the first and second embodiments, the angle of view of the moving image displayed on the viewfinder differs from the angle of view of the captured still image. Therefore, of the charges stored in the photodiode 101, only charges on a specific line are selected, and the vertical CCD 10
Second, the vertical CCD 102
, A preliminary scan may be performed before attempting to capture a still image so that the angle of view can be easily determined.

The pre-scanning is a driving method of an image pickup device which thins out predetermined lines in all effective pixels of the image pickup device, transfers electric charges to the vertical CCD 102, and outputs only a predetermined number of lines from the image pickup device. is there. At this time, horizontal C
Since the CD 103 cannot output all the pixels in the effective image area during one horizontal period of the NTSC system for the above reason, the CD 103 takes a longer time than the time of the effective image area during one horizontal period of the NTSC system. To output electric charges. Although the image cannot be displayed on an NTSC monitor as it is, for example, the liquid crystal display used for display has a long afterimage time. Therefore, by adjusting the horizontal and vertical drive timing of the liquid crystal display to the drive timing of the image sensor, the screen display is performed. Becomes possible. Further, the same image may be displayed a plurality of times by using the memory to record the entire one screen until the next displayable image is generated, thereby generating a video signal having a timing conforming to the NTSC system. .

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a diagram schematically illustrating a configuration of an image sensor according to the third embodiment of the present invention. In the figure, 1101 is a horizontal CCD (1), 1102 is a horizontal CCD (1).
CD gate, 1103 is a horizontal CCD (2), 1104 is a horizontal CCD drain gate, 1105 is a horizontal CCD drain, and the parts having the same operations as those in FIG. 1 are given the same numbers as in FIG. I do. In this embodiment, as in the first embodiment, NT
The description will be given on the assumption that a moving image with horizontal and vertical scanning timings conforming to the SC is obtained, but the scanning timing is not limited to this. Also, the relationship between the effective pixels of the entire image sensor and the desired image cutout area will be described as being the same as in the first embodiment.

First, the operation of capturing a moving image will be described.
When capturing a moving image, as in the first embodiment,
Discard the charges other than the desired image cutout area shown in FIG.
A signal of a desired image cutout area is output from the image sensor. First, regarding the portions A and B in FIG. 3, for the unnecessary charges in the vertical direction, the vertical CCD 102 is driven at a high speed as in the first embodiment. Unnecessary charges transferred in the vertical direction by the vertical CCD 102 are transferred to the horizontal CCD (1) 1
It is transferred to 101. At this time, the horizontal CCD gate 110
2, the potential of the horizontal CCD drain gate 1104 is lowered, and the electric charge is discarded to the horizontal CCD drain 1105 via the horizontal CCD (2) 1103 as shown in FIG.

Next, a description will be given of a method of discarding the electric charges in the portions C and D in FIG. 3 corresponding to the line which is the desired image cutout region. First, as shown in FIG.
(1) A signal for one line is stored in a vertical CCD 10
Read from 2. The charges in the horizontal CCD (1) 1101 are shifted by driving the horizontal CCD (1) 1101. FIG. 1 shows a state in which the transfer of the charge corresponding to the portion C has been completed.
3 is shown. Note that the electric charge of the portion C in FIG. 3 may be output from the image sensor or may be discarded in the image sensor.
When the state shown in FIG.
(2) Transfer to 1103. This state is shown in FIG.
The horizontal CCD (1) 110 shown in FIG.
When the electric charges in 1 become empty, the horizontal CCD (1) 11
In step 01, signal charges for one line are read from the vertical CCD 102. The above state is shown in FIG. Horizontal CCD (2) 1
The signal charge transferred to 103 has a predetermined speed, ie, NT.
Approximately 50 μS if conforming to SC scan timing
Output from the image sensor. At this time, the horizontal CCD (1) 1
The signal charge corresponding to C shown in FIG. 3 in the signal charge in 101 is completed while the horizontal CCD (2) 1103 is being transferred. The horizontal CCD (2) 11
Unnecessary charges in the horizontal CCD drain gate 11
04 is discarded to the horizontal CCD drain 1105.
FIG. 16 shows an example of driving for performing the above operation. In the figure, the VCCD waveform is a vertical transfer pulse. When the pulse goes to the HI level, the signal charges in the vertical CCD 102 are transferred to the horizontal CCD (1) 1101, and the H1 waveform goes to the HI level. Horizontal CCD (1) 110
1, the signal charge in the horizontal CCD (2) 1103 is shifted by one by shifting the signal charge in the horizontal CCD (2) 1103 to the HI level, and the HD1 waveform is shifted in the horizontal direction by shifting to the HI level. The potential of the CCD gate 1102 is lowered, and all signal charges in the horizontal CCD (1) 1101 are transferred to the horizontal CCD (2).
The transition to the I level indicates that all the signal charges in the horizontal CCD (2) 1103 are discarded to the horizontal CCD drain (2) 1702.

When the lengths of the portions C and D shown in FIG. 3 are known in advance, as shown in FIG.
D gate 1102, horizontal CCD (2) 1103, horizontal C
CD drain gate 1104, horizontal CCD drain 11
05, horizontal CCD drain gate 1106 (2) and horizontal CCD drain (2) 1702
(2) The horizontal CCD (2) 1103 has a length corresponding to the length of a desired image cutout area, and the horizontal CCD (1103)
When the electric charge of only the desired image cutout portion is received from 1101 and the transfer of the electric charge of the desired image cutout region is completed, the potential of the horizontal CCD drain gate (2) 1701 is lowered to leave the horizontal CCD (2) 1103 in FIG. Of the horizontal CCD drain (2) 1702
In this case, unnecessary charges inside the horizontal CCD (2) 1103 can be omitted, and the horizontal CCD (2) 1103 can be omitted.
(2) The driving speed of 1103 can have more margin.

Next, the operation of capturing a still image will be described. In the case of a still image, continuous imaging is not necessary, and therefore, in this embodiment, as in the case of the first embodiment, the pixels in the horizontal and vertical directions are generated at the timing determined by the specifications of the imaging device. Can be transferred (read). Therefore, the reading of the charge of the image sensor is performed by using the horizontal CC.
D (2) 1103 without passing through horizontal CCD (1) 1101
Thus, signals for all effective pixels of the image sensor can be read out by a method generally used conventionally, and a high-resolution still image can be obtained. The moving image obtained by the above operation is displayed on a liquid crystal display, and can be used as a view finder and used as a guide for a photographed image of a user.

In the above method, the angle of view displayed on the viewfinder and the angle of view of the captured still image are different. The above problem is that, even when displaying a moving image, all pixels of the image sensor are read at a slow speed, an image is recorded in a memory, and a field rate is reduced to be displayed on a viewfinder. The image displayed on the viewfinder is
In addition to the above, the pre-scanning method described in the second embodiment may be used to make the angle of view of the still image coincide with the angle of view displayed on the viewfinder before capturing the still image.

Next, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 18 is a diagram schematically illustrating a configuration of an imaging device according to the fourth embodiment of the present invention. In the figure, reference numeral 1801 denotes a vertical CCD drain gate;
Numeral 2 denotes a vertical CCD drain, and portions which operate in common with the above-described embodiment are given the same numbers.
Description is omitted. Further, the vertical CCD drain gate 1801 and the vertical CCD drain 1802 are provided in all the vertical CCDs 102 included in the imaging device, and the final stage of the vertical CCD 102, that is, the electric charge is transferred to the horizontal CCD 102.
D103 is arranged on the last vertical CCD 102 to be sent out.

First, the operation of capturing a moving image will be described.
Also in this embodiment, a desired image cut-out area shown in FIG. 3 is output from the image sensor as a moving image similarly to the first embodiment, and the moving image has a horizontal / vertical scanning timing conforming to the NTSC system. The still image is generated from all valid pixel information of the image sensor. As in the first embodiment, of the charges transferred to the vertical CCD 102, the vertical CCD 102 is driven at a high speed by the number of lines corresponding to the portion indicated by A in FIG. At this time,
Operate the vertical CCD drain gate to transfer charge to the vertical CCD.
Discard into drain 1801.

Next, the vertical CCD drain gate 1801
Will be described. 19 and 20 show vertical CCDs.
102, vertical CCD drain gate 1801, vertical C
The potential relationship of the CD drain 1802 is schematically shown. The hatched portions above the vertical CCD 102 in both figures represent electric charges. Note that the potential decreases as the applied voltage increases. 19 shows a state in which the potential of the vertical CCD drain gate 1801 is high, and FIG.
1 has a low potential. Since the electric charge moves from a high potential to a low potential, in the state shown in FIG. 19, the electric charge in the vertical CCD 102 passes through the vertical CCD drain gate 1801 and reaches the vertical CCD drain 16.
It does not move to 02. However, the state in FIG.
Since the potential of the vertical CCD drain gate 1801 is low, the electric charge in the vertical CCD 102 exceeds the vertical CCD drain gate 1801 and the vertical CCD drain 1802
Flow into The vertical CCD drain 1802 has a function of discarding the flowing charge into the substrate. The above vertical CCD 10
By setting the state shown in FIG. 20 during the period when 2 is driven at high speed, all unnecessary charges supplied to the last stage of the vertical CCD 102 can be discarded from the vertical CCD 102. In other words, the supply of charges to the horizontal CCD 103 is blocked,
The time to read the charge in the horizontal CCD 103 is also vertical CCD
102 can be assigned to the high-speed operation, and more unnecessary pixel signals in the vertical direction can be discarded. FIG. 21 shows an example of a driving waveform of the vertical CCD drain gate 1801 during the high-speed operation of the vertical CCD 102. The charge is also discarded in the portion shown in FIG. 3B as in the above operation.

Next, a description will be given of how to discard the unnecessary charges in the portions (horizontal direction) shown in FIGS. 3C and 3D. As mentioned above,
The reading speed of the image sensor is NTSC for both horizontal and vertical
It must be done according to the timing of the method,
As described in the first embodiment, there is a limit to the signals for one line that can be read during one horizontal period of the NTSC system. Therefore, the vertical CCD drain gate 1 to which a portion corresponding to the pixel of the portion shown in FIG.
The potential of only 801 is lowered to the state shown in FIG. 20, and the electric charge in the portion shown in FIG. 3D is discarded to the vertical CCD drain 1802. By the above operation, the horizontal CCD 10
3 is supplied with electric charge as shown in FIG. FIG.
Then, the horizontal CCD 103 is driven to output the electric charges of the portion shown in FIG. 3C and the portion corresponding to the desired image cut-out region from the image sensor. By the above operation, the horizontal CCD 103 is operated similarly to the first embodiment.
Can be reduced by the number of pixels corresponding to the portion indicated by D in FIG. In the same manner as in the first embodiment, the charge in the C portion is removed by using a so-called digital zoom in which a signal is electrically enlarged by, for example, a line memory using an interpolation method. What is necessary is just to generate an image signal with a signal. The above method is effective for capturing a continuous image, that is, a moving image, when the number of pixels in the horizontal direction of the image sensor is larger than the number of pixels in the horizontal direction of the image sensor used in a conventional video camera or the like. It is.

Next, the operation of capturing a still image will be described. In the case of a still image, there is no need to continuously capture images.
Transfer (readout) of pixels in the vertical direction can be performed. Therefore, in reading out the charges of the image pickup device, signals for all effective pixels of the image pickup device can be read out by a method generally used conventionally, and a high-resolution still image can be obtained. The moving image obtained by the above operation is displayed on a liquid crystal display, and can be used as a viewfinder to be used as a guide for a photographed image of a user.

[0042]

As described above, according to the present invention, an inexpensive imaging device capable of capturing a high-resolution still image and a moving image even when using a CCD imaging device having a large number of pixels. And an electronic camera can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an imaging device according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing a general configuration of a conventional image sensor.

FIG. 3 is a diagram showing effective pixels and a desired image cut-out area of the image sensor according to the first, second, third, and fourth embodiments of the present invention.

FIG. 4 is an example of a drive timing chart of the imaging device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating potentials of the image sensor according to the first, second, and third embodiments of the present invention.

FIG. 6 is a diagram illustrating a potential of the image sensor according to the first, second, and third embodiments of the present invention.

FIG. 7 is an example of a drive timing chart of the image sensor according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a state of charges in a horizontal CCD according to the first, second and third embodiments of the present invention.

FIG. 9 is a diagram schematically illustrating a configuration of an imaging device according to a second embodiment of the present invention.

FIG. 10 is a diagram schematically illustrating a configuration of an imaging device according to a second embodiment of the present invention.

FIG. 11 is a diagram schematically illustrating a configuration of an imaging device according to a third embodiment of the present invention.

FIG. 12 is a diagram illustrating a potential of an imaging device according to a third embodiment of the present invention.

FIG. 13 is a horizontal CCD according to a third embodiment of the present invention.
FIG. 3 is a diagram showing a state of electric charges in the inside.

FIG. 14 is a horizontal CCD according to a third embodiment of the present invention.
FIG. 3 is a diagram showing a state of electric charges in the inside.

FIG. 15 is a horizontal CCD according to a third embodiment of the present invention.
FIG. 3 is a diagram showing a state of electric charges in the inside.

FIG. 16 is an example of a drive timing chart of an image sensor according to a third embodiment of the present invention.

FIG. 17 is a diagram schematically illustrating a configuration of an imaging device according to a third embodiment of the present invention.

FIG. 18 is a diagram schematically illustrating a configuration of an imaging device according to a fourth embodiment of the present invention.

FIG. 19 is a diagram illustrating a potential of an imaging device according to a fourth embodiment of the present invention.

FIG. 20 is a diagram illustrating a potential of an imaging device according to a fourth embodiment of the present invention.

FIG. 21 is an example of a drive timing chart of an imaging device according to a fourth embodiment of the present invention.

FIG. 22 is a horizontal CCD according to a fourth embodiment of the present invention.
FIG. 3 is a diagram showing a state of electric charges in the inside.

[Explanation of symbols]

 101: photodiode 102: vertical CCD 103: horizontal CCD 104: horizontal CCD drain gate 105: horizontal CCD drain 901: horizontal CCD drain gate 902: horizontal CCD drain 1101 ... Horizontal CCD (1) 1102 Horizontal CCD gate 1103 Horizontal CCD (2) 1104 Horizontal CCD drain gate 1105 Horizontal CCD drain 1701 Horizontal CCD drain gate (2) 1706 ..Horizontal CCD drain (2) 1801 ... Vertical CCD drain gate 1802 ... Vertical CCD drain

Claims (15)

[Claims] 1. A photoelectric conversion element for photoelectrically converting incident light, a vertical transfer means for vertically transferring charges photoelectrically converted by the photoelectric conversion element, and a charge transfer means for transferring charges supplied from the vertical transfer means in a horizontal direction. An image pickup device having a horizontal transfer means for transferring the electric charges supplied to the horizontal transfer means and a signal sweeping means for discarding the electric charges supplied to the horizontal transfer means. An imaging element characterized by the above-mentioned. 2. The signal sweeping means according to claim 1, wherein when the electric charge supplied to the horizontal transfer means is unnecessary, the electric charge supplied to the horizontal transfer means is continuously swept away.
An image sensor according to claim 1. 3. The image pickup device according to claim 1, wherein said signal sweeping means sweeps out all or a predetermined part of the charges of said horizontal transfer means. 4. The signal sweeping means according to claim 1, wherein said horizontal transfer means sweeps off the charge remaining in said horizontal transfer means when horizontal transfer of a desired charge is completed. An image sensor according to claim 1. 5. A photoelectric conversion element for photoelectrically converting incident light, vertical transfer means for vertically transferring a signal photoelectrically converted by the photoelectric conversion element, and a signal supplied from the vertical transfer means in a horizontal direction. A first horizontal transfer means for transferring the signal supplied from the first horizontal transfer means, a second horizontal transfer means for transferring the signal supplied from the first horizontal transfer means in the horizontal direction, and a signal supplied to the first horizontal transfer means. First to throw away
And a second signal sweeping means for discarding the signal supplied to the second horizontal transfer means. 6. A photoelectric conversion element for photoelectrically converting incident light, vertical transfer means for transferring a signal photoelectrically converted by the photoelectric conversion element in a vertical direction, and a signal supplied from the vertical transfer means in a horizontal direction. A first horizontal transfer means for transferring the signal supplied from the first horizontal transfer means, a second horizontal transfer means for transferring the signal supplied from the first horizontal transfer means in the horizontal direction, and a signal supplied to the first horizontal transfer means. The first horizontal transfer means has a function capable of transferring the number of charges supplied from the vertical transfer means, and the second horizontal transfer means has a function of transferring the electric charges supplied from the vertical transfer means. An image sensor, wherein the transfer means has a function of transferring at least a smaller number of charges than the transferable number of charges of the first horizontal transfer means. 7. A photoelectric conversion element for photoelectrically converting incident light, vertical transfer means for transferring a signal photoelectrically converted by the photoelectric conversion element in a vertical direction, and a signal supplied from the vertical transfer means in a horizontal direction. A first horizontal transfer means for transferring the signal supplied from the first horizontal transfer means, a second horizontal transfer means for transferring the signal supplied from the first horizontal transfer means in the horizontal direction, and a signal supplied to the first horizontal transfer means. In the imaging device having the signal sweeping means for discarding, when capturing a still image, the charge transferred by the first horizontal transfer means is output from the imaging device, and when capturing a moving image,
The charge transferred in the horizontal direction by a predetermined amount by the first horizontal transfer means is output to the second horizontal transfer means, and the charge transferred by the second horizontal transfer means is output from an image sensor. Imaging device. 8. A photoelectric conversion element for photoelectrically converting incident light, vertical transfer means for transferring a signal photoelectrically converted by the photoelectric conversion element in a vertical direction, and a signal supplied from the vertical transfer means in a horizontal direction. A first horizontal transfer means for transferring the signal supplied from the first horizontal transfer means, a second horizontal transfer means for transferring the signal supplied from the first horizontal transfer means in the horizontal direction, and a signal supplied to the first horizontal transfer means. First signal sweeping means for discarding;
A second step of discarding the charge supplied to the second horizontal transfer means;
An image pickup device comprising: a signal sweeping means; wherein the charges of the first horizontal transfer means and the second horizontal transfer means are independently transferred. 9. The method according to claim 8, wherein the charge in the first horizontal transfer means is transferred to the second horizontal transfer means after transferring the first horizontal transfer means by a predetermined number of stages. Image sensor. 10. The signal sweeping means, when the charge supplied to the first horizontal transfer means is unnecessary, continuously sweeps away the charge supplied to the first horizontal transfer means. The imaging device according to claim 5. 11. An image sensor according to claim 5, wherein said signal sweeping means sweeps away all or a predetermined part of the electric charge of said first horizontal transfer means. 12. The signal sweeping means, when the horizontal transfer of a desired charge is completed in the first horizontal transfer means, sweeps away the charge remaining in the first horizontal transfer means. 7. The image sensor according to 5 or 6. 13. Even when a moving image is picked up, the charge transferred by the first horizontal transfer means can be output from the image pickup device, and the charge can be output from the first horizontal transfer means or the second horizontal transfer means. 7. The imaging device according to claim 6, wherein any one of the transfer units can be switched. 14. A photoelectric conversion element for photoelectrically converting incident light, a vertical transfer means for vertically transferring a signal photoelectrically converted by the photoelectric conversion element, and a signal for horizontally transferring a signal supplied from the vertical transfer means. An image pickup device having a horizontal transfer means for transferring data to the horizontal transfer means and a signal sweeping means for discarding a signal transferred from the vertical transfer means to the horizontal transfer means, wherein the signal sweeping means changes from the vertical transfer means to the horizontal transfer means. An image pickup device characterized by discarding all signals transferred at a time among supplied signals. 15. The imaging device according to claim 14, wherein said signal sweeping means discards only a part of the signal transferred from the vertical transfer means to the horizontal transfer means.