JP2000013686A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device which obtains an image signal having a lot of numer of frames per unit time from an image pickup element with low power consumption without using a high driving frequency. SOLUTION: This image pickup which has an image pickup element that can read a pixel signal has a read controlling means which controls a reading mode in which effective signal charge accumulated in the image pickup element is subjected to vertical transfer into an effective horizontal scanning period in such a timing as to transfer in a relatively rough frequency and is read and a sweeping mode in which unnecessary signal charge accumulated in the image pickup element is subjected to vertical transfer into the effective horizontal scanning period in such a timing as to transfer in a relatively dense frequency and is swept away. And, the read controlling means simultaneously sweeps away at least one part of an unnecessary part where unneeded signal charge of one frame is accumulated and at least one part of an unnecessary part where unneeded signal charge of the next frame is accumulated in the sweeping mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus that extracts a pixel signal from an image pickup device to record a still image or performs a moving image process.

[0002]

2. Description of the Related Art Conventionally, various types of image pickup devices used in this type of image pickup apparatus have been proposed.
As schematically shown in FIG. 1, there is known an interline CCD solid-state imaging device having a vertical overflow drain structure. The CCD is two-dimensionally arranged in a horizontal direction and a vertical direction, and receives a charge accumulated in the photodiode 21 via a transfer gate 22 after receiving a charge through a photodiode 21. , A vertical shift register 23 for sequentially transferring the charges in the vertical direction, and a horizontal shift register 2 for sequentially transferring the charges transferred by the vertical shift register 23 in the horizontal direction.
4 and a signal detector 25 for amplifying and outputting the output signal of the horizontal shift register 24.

[0003] Since the number of pixels of such a CCD has been increasing in accordance with recent advances in microfabrication technology, various image pickup devices incorporating a CCD having a high number of pixels have recently been proposed. However, for example, in a portable imaging device such as an electronic still camera, a high pixel count CC
Even if D is used, from the viewpoint of power consumption and cost, CCD
Drive frequency can not be too high, generally 20MHz
It is driven below. So, for example,
When a CCD equivalent to 1 million pixels is used, 10
Only about 15 frames can be obtained.

However, with this number of frames, for example,
When an image pickup device is provided with a liquid crystal display device for displaying a moving image picked up by a CCD, an auto focus control (AF), an automatic exposure control (A
E), when processing such as automatic white balance control (AWB) is performed, inconvenience occurs.

That is, when a moving image is displayed on a liquid crystal display device, a good moving image cannot be displayed unless image data of about 60 frames per second is supplied. Therefore,
Conventionally, a memory for storing image data from a CCD is provided, and data of the same frame stored in this memory is
For example, the data is repeatedly read out a plurality of times in a 1/60 second cycle and supplied to the liquid crystal display device for display. Therefore, in this case, if image data is obtained from the CCD at a rate of 10 frames per second, an image of the same frame is repeatedly displayed six times. However, providing an expensive memory only for adjusting the number of frames for display in this way is disadvantageous in terms of cost.

[0006] When taking a still image as in an electronic still camera, it is important not to miss a photo opportunity. For that purpose, the AF, AE,
Processing such as AWB needs to be performed at high speed. However, if only about 10 frames of image data can be obtained per second, for example,
In AF, focusing cannot always be performed using image data for one frame, and AF is performed using a plurality of frames.
Since the F operation is performed, if the processes such as AF, AE, and AWB are sequentially performed, a long time is required for the process, and control may not be performed in time. Therefore, conventionally, these processes are performed simultaneously in parallel, or by providing the above-described memory and storing image data,
These processes are sequentially performed. However, when the processes such as AF, AE, and AWB are performed simultaneously in parallel as in the former, the circuit scale becomes large and the cost becomes disadvantageous, and a memory is provided for the processing as in the latter. This is disadvantageous in terms of cost.

As a method of solving such a problem,
Displaying a moving image on the liquid crystal display device as described above,
In the moving image processing mode for performing processing such as F, AE, and AWB,
It has been proposed to read out by thinning out horizontal pixel lines of a CCD. However, in the case of a CCD in which all pixels are read to obtain a color image signal, generally, as shown in FIG. 11, an odd line has a repeating pattern of red (R) and green (G), and an even line has For example, since a color filter of a Bayer array color difference line sequential format composed of a repeating pattern of G and blue (B) is used, if only odd lines are read out by thinning-out reading, for example, B
Is missing, and if only even lines are read out, R
Will be lost. For this reason, especially when displaying on a liquid crystal display device, there arises a problem that an accurate color image cannot be displayed.

Therefore, the present applicant has solved the above-mentioned various problems, and can obtain an image signal of a large number of frames per unit time from a solid-state image sensor in a moving image processing mode without using a high driving frequency. An imaging device has already been proposed (Japanese Patent Application No. 9-7831). In this imaging device,
FIG. 1 shows a screen of the solid-state imaging device in the moving image processing mode.
As shown in FIG. 2, the k-th line from the (j + 1) -th line to the (j + k) -th line, which is partially continuous in the vertical direction at the center of the screen, is the effective output area, and the first and j-th lines before and after that are the sweeping areas A, From the j + k + 1 line to the last line, each is defined as a sweep area B. As shown in FIG. 13, for each frame, in the effective output area, the signal charges accumulated in the effective output area are swept within the effective horizontal scanning period. The vertical transfer is performed at a timing such that the transfer is performed at a coarser frequency than in the areas A and B, and the readout is performed. In the sweeping areas A and B, the signal charges accumulated in the sweeping areas A and B are transferred within the effective horizontal scanning period. By performing vertical transfer at a high speed at a timing such that data is transferred more densely than in the effective output area, Of period T, for example, 1/60 second period, so as to obtain the video data of the effective output areas. Therefore, in this case, the sweep areas A and B
Assuming that the number of lines is the same and that the unnecessary charge sweeping time is ta and the effective output area read time is tb, T = 2 · ta + tb.

FIG. 14 is a timing chart showing the operation of reading and sweeping out charges of the solid-state imaging device in the moving image processing mode. Here, an interline CCD having a vertical overflow drain structure shown in FIG. 10 is used as the solid-state imaging device. In FIG. 14, the vertical synchronization signal VD is a pulse train that defines a predetermined unit period T for obtaining a signal (here, one frame) representing one image, for example, 1/60 second. The transfer gate pulse TGP is a pulse that determines the timing for transferring the charge accumulated in the photodiode 21 to the vertical shift register 23, and is applied to the transfer gate 22 in synchronization with the vertical synchronization signal VD.

The sub-pulse SUB is a pulse for discharging the charges generated in the photodiode 21 in the vertical direction of the substrate. The discharge of the charges is performed while the sub-pulse SUB is being output. . Therefore, the electric charge is accumulated in the photodiode 21 during the period when the sub-pulse SUB is stopped, and by controlling the accumulation period, a so-called element shutter for controlling the effective exposure time is realized. Note that this accumulation time is determined by AE control using moving image data,
The time is measured by counting the sub-pulses SUB.

The vertical shift register transfer pulse VT is used to transfer the charges in the vertical shift register 23 to the horizontal shift register 2.
This is a pulse for sequentially transferring data to the fourth side. In the imaging device previously proposed by the present applicant, the vertical shift register transfer pulse VT is used to transfer the charges in the sweeping areas A and B shown in FIG. 12 and FIG. Are applied in different forms. That is, during the period corresponding to the effective area, after applying a transfer pulse of a predetermined pulse width at a predetermined repetition frequency for a predetermined period, the application of the transfer pulse and the pause period are stopped so that the application of the transfer pulse is paused for a predetermined period. Are alternately repeated, and during a period corresponding to the sweep areas A and B, a transfer pulse having the same pulse width and repetition frequency is constantly applied without the above-mentioned pause period. Thus, unnecessary charges are swept out at high speed and discarded. Note that this vertical shift register transfer pulse VT needs to be synchronized with a horizontal blanking period (not shown) in the horizontal shift register 24 in the transfer of charges in the effective output area. Are unnecessary charges that are not used as information, and therefore need not necessarily be synchronized with the horizontal blanking period.

As described above, in the moving image processing mode, unnecessary electric charges in the sweep-out areas A and B are swept out at high speed and discarded, so that moving image data (CCD signal in FIG. 14) of the effective output area can be obtained at a predetermined cycle T. I'm trying to get.

[0013]

As described above, according to the imaging apparatus according to the earlier proposal of the present applicant, in the moving image processing mode, all lines of the solid-state imaging device are sequentially scanned at a predetermined read cycle. Since the frame rate can be improved to (total number of lines) / k times as compared with the case where image signals are read out, a large number of frames per unit time can be obtained from the solid-state imaging device without using a high driving frequency. A signal can be obtained. Therefore, a favorable moving image can be displayed on the liquid crystal display device without using an expensive memory for display as in the related art, which is advantageous in cost. Further, even when processing such as AF, AE, and AWB is performed using moving image data, the processing can be sequentially performed without using a memory, which is advantageous in terms of circuit scale and cost. .

In a portable imaging device such as an electronic still camera, for example, a battery is used, so that low power consumption is particularly required. Here, when a pulse train with a constant amplitude is generated by the pulse generator,
In general, since the frequency of the generated pulse train and the peak consumption current flowing to the pulse generator at that time are in a proportional relationship, the higher the frequency of the generated pulse train, the higher the peak consumption current and the higher the power consumption. Become. Further, when the pulse train is continuous, the peak current continues to flow stably. Therefore, as described above, in order to increase the frame rate in the moving image processing mode, only the central portion (effective output area) in the screen is read out, and the electric charges in the unnecessary portions above and below it (sweep-out areas A and B) are swept at high speed. In this case, since the frequency of the vertical shift register transfer pulse VT needs to be increased to fo during the sweeping-out period ta, the peak consumption current Io increases as shown in FIG.

Therefore, a total of 2 · t in one frame
If the sweep period a is provided, power consumption may increase. Particularly, in a period in which the sweeping area B of one frame and the sweeping area A of the next frame are continuous, a large peak consumption current Io flows over 2 · ta. The voltage may drop and the system may go down.
Such a problem becomes more serious as the number of pixels of the image sensor increases, because the frame rate cannot be secured unless the sweeping frequency fo is increased.

The present invention has been made in view of such a point, and an image signal having a large number of frames per unit time can be obtained from an image pickup device without using a high driving frequency and with low power consumption. It is an object of the present invention to provide an imaging device appropriately configured as described above.

[0017]

In order to achieve the above object, the present invention relates to an image pickup apparatus having an image pickup device capable of reading out a pixel signal. A read mode in which vertical transfer is performed at a timing such that transfer is performed at a relatively coarse frequency within a period, and unnecessary signal charges accumulated in the image sensor are relatively densely stored within an effective horizontal scanning period. Read control means for controlling a sweep mode in which vertical transfer is performed at a timing such that transfer is performed in the sweep mode. The read control means includes an unnecessary portion in which unnecessary signal charges of one frame are accumulated in the sweep mode. At least a portion of the signal charges of the next frame and at least a portion of the unnecessary portions of the unnecessary portion where the unnecessary signal charges of the next frame are accumulated. It is characterized in that the configuration was.

In one embodiment of the present invention, the unnecessary portion of the one frame is a region before the last read pixel in the signal reading order of the frame, and the unnecessary portion of the next frame is the unnecessary portion of the next frame. In the signal readout order of the frame, it is a subsequent region including the first readout pixel.

Further, in one embodiment of the present invention, the read control means has a timing variable means for changing a vertical transfer timing of signal charges in the sweep mode.

Further, in one embodiment of the present invention, an effective portion for reading out effective signal charges from each frame in the readout mode is a central portion of the frame, and the unnecessary portion is located before and after this central portion. It is assumed that.

Further, in one embodiment of the present invention, the image pickup device has a two-dimensional array of pixels that receive light and converts it into an electric signal, and a line that is partially continuous in the vertical direction of the image pickup device. Is an effective part, and the other lines are the unnecessary parts.

Further, in one embodiment of the present invention, the image pickup device has a vertical transfer path, and in the sweep mode, in the vertical transfer path, a signal charge of an unnecessary portion of the one frame and the next And then sweeps out after adding the signal charges of unnecessary portions of the frame.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a first embodiment of an imaging apparatus according to the present invention. This imaging apparatus is mainly intended to capture and record a still image, and includes a lens and an aperture 17.
CCD 1, which is a two-dimensional array of solid-state imaging devices for converting a subject image incident through the CCD into electric signals, a correlated double sampling circuit (CDS) 2 for removing reset noise and the like from the output of the CCD 1, and a CDS 2 Control amplifier (AMP) 3 for adjusting the output gain
An analog-to-digital converter (A / D) 4 for converting the output signal of the AMP 3 into a digital signal, a process processing circuit 5 for performing various processes on the image signal converted into the digital signal, and a drive for driving the CCD 1. A timing generator (TG) 6 that outputs drive signals such as various transfer pulses, outputs a pulse for sample and hold in the CDS, and outputs a timing pulse for performing A / D conversion in the A / D 4. And the TG 6 and a CP to be described later.
A signal generator (SG) 7 for generating a signal for synchronizing with the U8, a CPU 8 comprising a microcomputer, for example, which constitutes a reading control means of the CCD 1 and performs various controls including timing and the like for the whole image pickup apparatus; , C output from the process processing circuit 5
A DRAM 9 constituting a memory for storing pixel data of the CD 1 and image data supplied from a recording medium 16 to be described later via a compression / expansion circuit 15, and an autofocus circuit (AF) for controlling autofocus by a lens and an aperture 17. And 10) an automatic exposure control circuit (AE) 11 for performing photometry of a subject image formed on the CCD 1.
An automatic white balance circuit (AWB) 12 for automatically controlling the white balance, a liquid crystal display device 13 which is a monitor built in the imaging device, and an image signal or the like output to a display device such as an external monitor. External display terminal 14 and the image data for one frame stored in the DRAM 9 are compressed in order to reduce the amount of data to be recorded on a recording medium 16 to be described later, and the compressed data read from the recording medium 16 is compressed. It has a compression / expansion circuit 15 for expanding image data and a recording medium 16 for recording still image data.

In such an electronic image pickup apparatus, when an image is recorded on the recording medium 16, the CCD 1
2. The image data output via the AMP 3, the A / D 4 and the process processing circuit 5 is, for example, a liquid crystal display 13
Is supplied and displayed. Thus, the photographer can determine the composition and the like of the subject while looking at the liquid crystal display device 13. In this state, when a shooting button (not shown) is pressed, the image data supplied from the process processing circuit 5 to the compression / expansion circuit 15 via the DRAM 9 is compressed and recorded on the recording medium 16.

When reproducing the image data recorded on the recording medium 16, the compressed data read from the recording medium 16 is decompressed by the compression / decompression circuit 15 and is subjected to DR processing.
The image data written in the AM 9 and written in the DRAM 9 is transmitted to the liquid crystal display 1 via the process processing circuit 5.
3, and supplied to the external display device via the external display terminal 14 and reproduced as a still image.

Next, a read operation for driving the CCD 1 to obtain image data will be described with reference to FIG. In FIG. 2, a horizontal line of pixels of the two-dimensional array forming the CCD 1 is defined as a line, and this line is defined as a first line.
It is assumed that they are arranged vertically from the line to the L-th line. FIG. 2A shows a mode in which the CCD 1 is sequentially scanned from the first line to the L-th line, so that pixel signals relating to all pixels are sequentially read at a predetermined read frequency, and a still image is recorded. The reading in the still image recording mode is so-called progressive scanning. Since the full screen area as shown by the outer large rectangular frame in FIG. 12 is sequentially scanned to output information on all pixels, A high-resolution image can be obtained as an image.

FIG. 2B shows a moving image processing mode. In this moving image processing mode, moving image processing is performed by reading pixel signals on k (k is a positive integer) lines that are partially continuous in the vertical direction, that is, from the (j + 1) th line to the (j + k) th line (j is an integer of 0 or more). As described above, by reading the image data of only the effective output area of the continuous k lines, the frame rate can be improved by L / k times as compared with the case of reading all the L lines. Obtainable. Here, the effective output area of the continuous k lines is preferably the center of the full screen area of the CCD 1. That is, the image data of the effective output area read in this mode is displayed on the liquid crystal display device 13 and, as described later, for example, A
F10, AE11, and AWB12 are used in the respective processes. In these processes, center-weighted processing using the image data of the central portion of the full image area is often performed. By doing so, required processing can be easily performed. The image data in the effective output area read in this mode can be recorded as a still image.

Therefore, in this embodiment, as described with reference to FIG. 12, the k lines from the (j + 1) th line to the (j + k) th line which are partially continuous in the vertical direction at the center of the screen are set as the effective output area, A sweep area A is defined from the first line to the j-th line, and a sweep area B is defined from the j + k + 1 line to the last line. Also,
The sweeping cycle of the unnecessary charges in the sweeping areas A and B is two times the cycle of the sweeping frequency fo in FIG.
Double it. Here, the sweeping areas A and B
Are the same.

In this manner, as shown in FIG. 3, a schematic diagram of the charge reading and sweeping operation of the CCD 1 in the moving image processing mode, as shown in FIG.
After sweeping out unnecessary charges in the sweeping area A at a sweeping frequency of fo / 2 for a time of 2 · ta at a high speed, the signal charges in the effective output area are read out at a predetermined vertical transfer timing over a time tb, and the second frame is read. Thereafter, the unnecessary charges in the sweeping area A of the frame and the unnecessary charges in the sweeping area B of the immediately preceding frame are added and the high-speed sweeping is performed at the sweeping frequency fo / 2 for a time of 2 · ta, and then the signal of the frame is increased. The electric charges are read out at a predetermined vertical transfer timing over a time tb, and the moving image data in the effective output area of the sequential frames is read at a predetermined period T (T = 2 ·
ta + tb), for example, in a 1/60 second cycle.

FIG. 4 shows the CC in the moving image processing mode.
5 is a timing chart showing the operation of reading and sweeping out the charge of D1. Note that the vertical synchronization signal V shown in FIG.
D, transfer gate pulse TGP, sub-pulse S
The operations of the UB and the vertical shift register transfer pulse VT are the same as those described with reference to FIG. 14, and a description thereof will be omitted.

Hereinafter, the CC in the moving image processing mode shown in FIG.
The operation of reading and sweeping out the charge of D1 will be described in more detail with reference to FIG. FIG.
5 schematically shows how charges are transferred in the vertical shift register 23 of the CCD 1. First, in the first first frame, as shown in FIG. 5A, the charge of each photodiode 21 in the vertical direction is transferred to the corresponding vertical shift register 23 by the transfer gate pulse TGP.
, The unnecessary charges A ₁ ,
A _2, A _3, a, ..., a vertical shift register transfer pulse VT of the frequency sweep was continuous vertical transfer timing cycle of fo / 2, and sweep the fast time 2 · ta, FIG 5 (B) State. Next, the signal charges Y ₁ , Y ₂ , Y ₃ ,.
Is transferred by a vertical shift register transfer pulse VT at a predetermined timing in synchronization with the horizontal blanking period in the horizontal shift register 24, and is read out at time tb.
The state shown in FIG. The operations shown in FIGS. 5A to 5C are performed at a predetermined cycle T.

Thereafter, in the second frame, as shown in FIG.
As shown in FIG.
The charge of each photodiode 21 in the vertical direction is assigned to the corresponding vertical
The data is transferred to the shift register 23 and is transferred to the second frame.
Charge A in the sweep area A₁, A_Two, A_Three,
.. and the previous frame (in this case, the first frame)
Charge B in sweep area B₁, B_Two, B_Three,
.. Are added in the vertical shift register 23. Next
And the added unnecessary charge A₁+ B₁, A_Two+ B _Two, A
_Three+ B_Three,... Of the period of the sweep frequency fo / 2
The time 2 · t is obtained by the vertical shift register transfer pulse VT.
In FIG. 5A, the data is swept at a high speed to obtain the state shown in FIG.
Then, the signal power of the effective output area in the second frame is
Load Y₁, Y _Two, Y_Three,... In the horizontal shift register 2
In synchronization with the horizontal blanking period in
Transfer with the vertical shift register transfer pulse VT
Reading is performed at time tb, and the state shown in FIG. This
5 (D), 5 (B) and 5 (C) are predetermined.
In the cycle T. Thereafter, sequential frames after the third frame
Frame, as in the second frame,
The sequential operations shown in (D), (B) and (C) are performed at predetermined times.
Repeat at cycle T. In sweeping out unnecessary charges,
Is not necessarily the same as that described with reference to FIG.
Synchronize with horizontal blanking period in register 24
No need.

As described above, the unnecessary charges in the sweep area B in a certain frame and the unnecessary charges in the sweep area A in the next frame are added, and the sweep frequency f is calculated.
If high-speed sweeping is performed at o / 2, the same frame rate as in the case of FIG. 14, that is, 1 / T = 1 / (2 · ta +
At tb), as shown in FIG. 4, the peak current consumption Io 'at the sweep time 2 · ta can be made smaller than the peak current consumption Io in the case of FIG. Therefore, it is possible to reduce power consumption, effectively prevent a system down due to a decrease in power supply voltage, and easily cope with an increase in the number of pixels of the image sensor.

Next, FIG. 6 shows how the still image recording mode as shown in FIG. 2A and the moving image processing mode as shown in FIG. 2B are executed. FIG. 7 is a timing chart showing a read mode of the CCD 1;
Will be described with reference to a time chart showing the read mode and control data shown in FIG. Reading of image data from the CCD 1 is performed, for example, in synchronization with a vertical synchronizing signal VD having a period of 1/60 second. However, except for capturing a high-quality image for a still image, a moving image processing mode is executed.
With this moving image processing mode, the image data of the effective output area at the center in the sequential frames is converted into the vertical synchronization signal VD.
Is read out in synchronization with. The image data read in the moving image processing mode is supplied to the liquid crystal display device 13 via the CDS 2, the AMP 3, the A / D 4, and the process processing circuit 5 to be displayed as a moving image, and, as shown in FIG. In a process of calculating control data such as AF and AWB, the data is repeatedly used, for example, one frame at a time.
In the case where such different processing is repeatedly performed for each frame, control data may be stored, for example. In this case, the stored data is stored in the same format in accordance with each processing content. It is also possible to accumulate and process by the accumulation system.

When a trigger is generated as shown in FIG. 6 due to, for example, pressing of a shooting button (not shown) during the above-described moving image processing, exposure and focus are appropriately performed according to the moving image processing mode up to that time. Since the state is already controlled to match, the mode immediately shifts to the still image recording mode immediately after the frame at the time when the trigger is input.

In the still image recording mode, as described with reference to FIG. 2A, the still image pixel signals of all the pixels from the first line to the L-th line of the CCD 1 are sequentially read at a predetermined read frequency. CDS2, AMP3, A /
The data is supplied to the compression / expansion circuit 15 via the D4, the process processing circuit 5, and the DRAM 9, where it is compressed and recorded on the recording medium 16. If it takes, for example, 1/10 second to scan all the lines of the CCD 1, it takes six frames to output all the data of the still image. It is controlled by counting the synchronization signal VD.

When the output of the still image data in the still image recording mode is completed, the imaging apparatus shifts again to the moving image processing mode, and the image data of the effective output area at the center in the sequential frames is synchronized with the vertical synchronizing signal VD. Then, a moving image is displayed on the liquid crystal display device 13 and a process of calculating control data such as AE, AF, and AWB is performed to prepare for the next photographing.

In the first embodiment described above, in the moving image processing mode, the unnecessary charges in the sweeping area B in a certain frame and the unnecessary charges in the sweeping area A in the next frame are added to each other, so that a predetermined reading period is obtained. In the second embodiment of the present invention, the unnecessary charge in the sweep area B in a certain frame in the moving image processing mode and the sweep area A in the next frame are used. Unnecessary charges are added, and sweeping is performed at high speed at the cycle of the sweeping frequency fo.

That is, FIG. 8 is a schematic diagram of the charge reading and sweeping operations of the CCD 1, and FIG. 9 is a timing chart. In the moving image processing mode according to the second embodiment, in the first frame from the start of the operation, After the unnecessary charges in the sweep area A are swept out at high speed over the time ta at the sweeping cycle of the frequency fo, the signal charges in the effective output area are read out at the predetermined vertical transfer timing over the time tb. Unnecessary charges in the sweeping area A of the frame and unnecessary charges in the sweeping area B of the immediately preceding frame are added to perform a high-speed sweeping over a time ta in a sweeping cycle of the frequency fo, and then, the signal charges of the frame are vertically transferred. Time tb at timing
Read over. In this manner, the moving image data in the effective output area of the successive frames is transmitted at a predetermined cycle T '(T' =
ta + tb).

As described above, by adding the unnecessary charges in the sweeping area B in a certain frame and the unnecessary charges in the sweeping area A in the next frame, and sweeping out at high speed with a sweeping cycle of the frequency fo, moving image processing can be performed. The frame rate in the mode is 1 / T '= 1 / (ta + t
b), which can be improved as compared with the first embodiment. Therefore, it is possible to easily cope with an increase in the number of pixels of the image sensor. Also, the sweep cycle is as short as 1 / fo, and therefore, as shown in FIG.
The peak current at the sweep time ta also becomes Io,
Although it is higher than in the case of the embodiment, the sweeping time in one frame is short as ta as a whole, and there is no continuation between successive frames, so that power consumption can be reduced and power supply voltage can be reduced. System down can also be effectively prevented.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified or changed. For example, in the above-described embodiment, the number of lines in the sweeping areas A and B has been described as being the same. However, the number of lines in the sweeping area A may be larger than the number of lines in the sweeping area B. Also, the vertical transfer timing of the signal charge in the sweep mode, that is, the sweep cycle can be set to 1 / fo, 2 / fo or any other cycle to obtain a desired frame rate. Can also. Further, the present invention can be effectively applied not only to the above-described interline CCD having the vertical overflow drain structure, but also to other CCDs and various solid-state imaging devices.

[0042]

According to the present invention, at least a part of the signal charge of the unnecessary part of one frame and the at least a part of the signal charge of the unnecessary part of the next frame are simultaneously swept at a high speed. An image signal with a large number of frames per unit time can be obtained from an image sensor without using a high driving frequency and with low power consumption.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining a read operation of the CCD according to the first embodiment.

FIG. 3 is a schematic diagram illustrating charge readout and sweeping operations of a CCD in a moving image processing mode according to the first embodiment.

FIG. 4 is a timing chart showing the operation of reading and sweeping out charges of a CCD in the moving image processing mode.

FIG. 5 is a schematic diagram showing how charges are transferred in the vertical shift register of the CCD in the moving image processing mode.

FIG. 6 is a timing chart illustrating a read mode of the CCD according to the first embodiment.

FIG. 7 is a timing chart showing a CCD read mode and control data.

FIG. 8 is a schematic diagram illustrating a charge reading and sweeping operation of a CCD in a moving image processing mode according to a second embodiment.

FIG. 9 is a timing chart showing the operation of reading and sweeping out the charge of the CCD in the moving image processing mode.

FIG. 10 is a diagram showing a configuration of an example of a CCD as an imaging device that can be used in the imaging device according to the present invention.

FIG. 11 is a diagram showing an example of a color filter used in the CCD shown in FIG.

FIG. 12 is a diagram showing an effective output area and a sweep-out area of a CCD screen in a moving image processing mode by the imaging device according to the earlier proposal of the present applicant.

FIG. 13 is a schematic diagram showing a charge reading and sweeping operation of the CCD in the moving image processing mode by the imaging device according to the earlier proposal of the present applicant.

FIG. 14 is a timing chart showing the operation of reading and sweeping out the charge of the CCD in the moving image processing mode.

[Explanation of symbols]

 Reference Signs List 1 CCD 2 correlated double sampling circuit (CDS) 3 gain control amplifier (AMP) 4 analog-to-digital converter (A / D) 5 process processing circuit 6 timing generator (TG) 7 signal generator (SG) 8 CPU 9 DRAM 10 auto Focus circuit (AF) 11 Automatic exposure control circuit (AE) 12 Auto white balance circuit (AWB) 13 Liquid crystal display device 14 External display terminal 15 Compression / expansion circuit 16 Recording medium 17 Lens and aperture 21 Photodiode 22 Transfer gate 23 Vertical shift Register 24 Horizontal shift register 25 Signal detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C024 AA01 BA01 CA16 CA24 DA05 FA01 FA11 GA11 GA45 GA48 HA07 HA14 JA10 JA21 JA32 JA35

Claims (6)

[Claims] 1. An image pickup apparatus having an image pickup device capable of reading out a pixel signal, wherein the effective signal charges accumulated in the image pickup device are transferred at a relatively coarse frequency within an effective horizontal scanning period. And a sweep mode in which unnecessary signal charges accumulated in the image sensor are vertically transferred at a timing such that the unnecessary signal charges are relatively densely transferred within an effective horizontal scanning period. Read control means, the read control means, in the sweep mode,
A structure in which at least a part of the unnecessary portion of the unnecessary signal charge in one frame and the unnecessary portion of the next frame in which the unnecessary signal charge is stored are simultaneously swept. An imaging device, comprising: 2. The imaging device according to claim 1, wherein the unnecessary portion of the one frame is a region before a last read pixel in a signal reading order of the frame, and an unnecessary portion of the next frame. Is an area including a first pixel to be read in a signal reading order of the frame. 3. The imaging apparatus according to claim 1, wherein the read control unit includes a timing variable unit that changes a vertical transfer timing of signal charges in the sweep mode. 4. The imaging device according to claim 1, wherein an effective portion for reading out effective signal charges from each frame in the readout mode is a central portion of the frame.
An image pickup apparatus, wherein the unnecessary part is located before and after the central part. 5. The image pickup device according to claim 1, wherein the image pickup device is configured by two-dimensionally arranging pixels that receive light and convert the light into an electric signal. An imaging apparatus characterized in that a line that is partially continuous in the vertical direction is an effective part, and other lines are the unnecessary parts. 6. The image pickup device according to claim 1, wherein the image pickup device has a vertical transfer path, and in the sweep mode, the one frame of the one frame is included in the vertical transfer path. An image pickup apparatus, wherein the signal charge of an unnecessary portion and the signal charge of an unnecessary portion of the next frame are added and then swept out.