JP2001024935A - Video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the still picture of high vertical resolution and satisfactory reproducibility by reading image signals for one frame of a CCD imaging device with one time of photographing when complementary color type color filter arrays are overlapped and the CCD imaging device capable of double pixel mixed reading is provided. SOLUTION: When a still picture button 12 is pressed by a photographer, a single pixel independent reading mode is selected by a reading mode selecting circuit 13. Synchronously with a first vertical synchronizing signal VS, an odd- numbered line read signal is outputted by a CCD driving circuit 23 and the image signals of odd-numbered fields are outputted from a CCD imaging device 22. Synchronously with the next vertical synchronizing signal VS, an even- numbered line read signal is outputted by the CCD driving circuit 23 and the image signals of even-numbered fields are outputted from the CCD imaging device 22. The CCD driving circuit 23 is controlled by a read order control circuit 15 so that the odd-numbered line read signal can be first outputted at all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts an image of a subject input through a complementary color filter array into an electric signal, accumulates the signal, and reads out the accumulated signal by a so-called two-pixel mixed reading method. The present invention relates to a video camera provided with a solid-state imaging device.

[0002]

2. Description of the Related Art Conventionally, video cameras, such as digital cameras and electronic still cameras, capable of taking still images in addition to moving images are known. Strobe lighting is effective for shooting still images. While one frame of the video camera is shot every (1/30) sec, the flash emission time is extremely short, about several μsec, so that even if the subject is moving, a clear image with almost no blurring can be obtained. Obtainable.

[0003] A consumer video camera is a single-plate CC with a complementary color filter array.
A D imaging device is used. The single-chip type CCD image pickup device obtains a luminance signal and a color signal from one image pickup device. Since there is one CCD image sensor, the configuration of the optical system can be made simple and compact, and a compact and inexpensive video camera can be provided.

A complementary color filter array is used to obtain an image with high resolution and sensitivity of a luminance signal. On the other hand, in a digital camera, an image having better color tone than resolution and sensitivity is prioritized, and a primary color type color filter array is often used.

There are various types of color filter arrays, and a field color difference sequential system is often used for a complementary color filter array. The field color difference sequential method is a method of obtaining color signals in the form of color difference signals line by line for each scanning line. When the complementary color filter array having this arrangement is used, the CCD image sensor performs interlacing by the two-pixel mixed readout method.

[0006] In the two-pixel mixed readout method, a process of adding or averaging the signals of two pixels adjacent in the vertical direction and mixing them is alternately shifted by one line to obtain two field images. Since the two field images are formed by reading out the signals of all the pixels of the CCD image sensor, the signal accumulation time of each pixel is one field period. For this reason, it is also called a field storage method or a field reading method. The mixing process of the two pixels in the vertical direction is generally performed by a vertical transfer register. By subjecting the obtained two field image signals to signal processing such as filtering, for example, a luminance signal and a chrominance signal are separated and extracted.

FIG. 6 is a block diagram showing a configuration of a conventional video camera having a still image shooting mode. As shown in FIG. 6, this video camera comprises a lens 1, a CCD image pickup device 2, a CCD drive circuit 3, a synchronization signal generation circuit 4, a first
A signal processing circuit 5, a second signal processing circuit 6, and a strobe lighting device 10 are provided.

The strobe lighting device 10 is used when a still image is taken by the video camera. When a strobe light emission signal STR is input, the strobe lighting device 10 emits a strobe to illuminate a subject. Lens 1
Forms an image of a subject on the CCD image sensor 2. The synchronization signal generation circuit 4 outputs the vertical synchronization signal V every one field period.
Generate S.

The CCD driving circuit 3 drives the CCD image pickup device 2. The CCD drive circuit 3 reads an odd line read signal for reading a signal of an odd line pixel among all the pixels of the CCD image pickup device 2, and an even line read signal for reading a signal of an even line pixel among all the pixels of the CCD drive circuit 2. A line read signal is output to the CCD image sensor 2 in synchronization with the vertical synchronization signal VS of the synchronization signal generation circuit 4.

The CCD image pickup device 2 photoelectrically converts an image of a subject input through a complementary color filter array into an electric signal by a plurality of pixels arranged in a matrix and accumulates the electric signals. The signal is output through a plurality of vertical transfer registers and horizontal transfer registers. C
In an image for one frame composed of each pixel of the CD imaging device 2, signals of two pixels that are adjacent in the vertical direction are:
Each vertical transfer register is mixed to form an image for one field. The mixing of these two pixels is performed by shifting one line alternately in each field period.

The first signal processing circuit 5 includes a CCD image pickup device 2
Amplifies the image signal output from the
Signal processing such as (correlated double sampling) processing is performed. The CDS process is a process for removing reset noise of accumulated charges of each pixel of the CCD image sensor 2 mixed in an image signal. Second signal processing circuit 6
Separates and extracts a luminance signal and a chrominance signal from the image signal output from the first signal processing circuit 5, performs signal processing such as gamma correction, and outputs a video signal.

FIG. 7 is a time chart showing the operation of the conventional video camera shown in FIG. 6 in a still image shooting mode. The synchronizing signal generation circuit 4 generates a vertical synchronizing signal VS every field period, and the CCD driving circuit 3
An odd line read signal and an even line read signal are output in synchronization with the vertical synchronization signal VS.

When the strobe light emission signal STL rises to the H level, during this H level, strobe lighting is performed by the strobe lighting device 10, an image of the subject is formed on the CCD image pickup device 2 by the lens 1, and an image of the subject is formed. Is converted into an electric signal and stored. Then, in synchronism with the next vertical synchronizing signal, the odd-numbered line and even-numbered line read signals are output from the CCD driving circuit 3.

In the CCD image pickup device 2, when an odd-line read signal and an even-line read signal are input, signals accumulated in all pixels are output to respective vertical transfer registers, and two pixels adjacent in the vertical direction are read. The signals are mixed,
An image for one field is formed from an image for one frame of the CCD image sensor 2. The image signals for one field are vertically transferred line by line by a plurality of vertical transfer registers and transferred to a horizontal transfer register. The image signal for one line transferred to the horizontal transfer register is transferred in the horizontal direction, and a one-dimensional field image signal is output.

An image signal for one field output from the CCD image sensor 2 is subjected to respective signal processing by a first signal processing circuit 5 and a second signal processing circuit 6, and is output as a video signal. The video signal for one field is stored in an internal image memory or the like or output to an external device.

[0016]

However, in a conventional video camera having a still image shooting mode, one video camera is required.
The still image captured by the strobe illumination twice is an image for one field of the CCD image sensor 2, so that the vertical resolution is reduced to half of the image for one frame of the CCD image sensor 2. For this reason, there is a problem that an image lacks sharpness.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. When a moving image is shot, an image signal is read from a solid-state image pickup device by a two-pixel mixed readout method as in the conventional art, while a still image is shot. Sometimes, an object of the present invention is to provide a video camera which can obtain a still image of one frame of the solid-state imaging device by one-time shooting by reading an image signal from the solid-state imaging device by a so-called one-pixel independent reading method. .

Further, the present invention pays attention to the fact that two pixels adjacent to each other in the vertical direction have different colors of the color filters, so that the signal saturation conditions of these pixels are different, and each pixel is read out by the one-pixel independent reading method. A video camera capable of capturing a still image with high reproducibility by always reading out one of the same field image signal of the odd field image signal and the even field image signal of the solid-state imaging device. The purpose is to provide.

[0019]

A video camera according to the present invention comprises: a plurality of pixels arranged in a matrix for photoelectrically converting light incident through a complementary color filter array and accumulating the light; A plurality of vertical transfer registers provided in each of the columns and receiving signals accumulated in the pixels of the corresponding column and transferring the input signals in the vertical direction, and vertically transferring the signals by the plurality of vertical transfer registers And a horizontal transfer register for inputting the input signal for one line, transferring the input signal for one line in the horizontal direction, and outputting the signal. The vertical transfer register includes two pixels which are vertically adjacent to each other. Are alternately shifted by one line every one field period and added or averaged and mixed.
A solid-state imaging device having pixel mixing means and signals of two vertically adjacent pixels in an image of one frame composed of the plurality of pixels are alternately shifted by one line every one field period and mixed. A two-pixel mixed reading mode for reading a mixed one-field image, and a one-frame image composed of the plurality of pixels.
A read mode selecting means for selecting one of the one pixel independent read modes for alternately reading a field image of an odd line and a field image of an even line every one field period; and the read mode selecting means. When the two-pixel mixed read mode is selected, an odd line read signal for reading a signal of an odd line pixel among the plurality of pixels and an even line for reading a signal of an even line pixel among the plurality of pixels. A read signal is output every one field period, and when the one pixel independent read mode is selected by the read mode selection means, the odd line read signal and the even line read signal are alternately output every one field period. A drive circuit for driving the solid-state imaging device, and a one-pixel independent read mode by the read mode selecting means. When selected, image storage means for storing field images of odd lines and even lines alternately read from the solid-state imaging device according to the odd line and even line read signals alternately output by the drive circuit; The one-frame still image is formed by combining the odd-line and even-line field images stored in the image storage means, and signals of two pixels that are vertically adjacent to the formed one-frame still image are obtained. 1
Image mixing means for mixing two lines by shifting the lines alternately, wherein the drive circuit is adapted to output an odd-numbered line read signal and an even-numbered read signal when the one-pixel independent readout mode is selected by the readout mode selecting means. It is characterized in that one of the line read signals is always output first from the same read signal.

The video camera according to the present invention has a moving image photographing operation means for inputting an operation command for photographing a moving image and a still image photographing operation means for inputting an operation command for photographing a still image. And the read mode selection means comprises:
When the operation command is input by the moving image shooting operation means, the two-pixel mixed reading mode is selected, and when the operation command is input by the still image shooting operation means, the one-pixel independent reading mode is selected. It is a feature.

Further, the video camera according to the present invention is
When an operation command is input by the still image photographing operation means and the one-pixel independent read mode is selected by the read mode selection means, a read signal to be output next by the drive circuit is a line read signal to be output first. A read signal discriminating circuit for discriminating whether or not a read signal to be output next is not a line read signal to be output first by the read signal discriminating circuit; and a mask for stopping the output of the read signal. And a mask signal output circuit for outputting a signal, wherein the drive circuit stops outputting the next line read signal when the mask signal output by the mask signal output circuit is input. Things.

Also, the video camera according to the present invention is characterized in that, when an operation command is input by the still image photographing operation means, a strobe lighting means which emits a strobe light once at a predetermined timing, and the readout signal discriminating circuit. When the determined read signal is not the read signal of the line to be output first, the light emission timing of the strobe lighting means is determined by the read signal of the line to be output first by the read signal determined by the read signal determining circuit. And a delay circuit for delaying by one field period.

Also, in the video camera according to the present invention, the solid-state imaging device may be a CCD (charge coupled device).
It is characterized by being an image sensor.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a video camera according to the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of a video camera according to an embodiment of the present invention. This video camera has a function of shooting a still image in addition to a moving image. As shown in FIG. 1, a moving image button 11, a still image button 12, a reading mode selection circuit 13, a strobe signal generation circuit 14, a reading order control, Circuit 15, lens 21, CCD image pickup device 22, CCD drive circuit 23, synchronization signal generation circuit 2
4, first signal processing circuit 25, second signal processing circuit 26, switch 31, memory control operation circuit 32, and image memory 3
3 is provided.

The moving image button 11 is an operation button for photographing a moving image by the video camera. When the moving image button 11 is pressed by the photographer, shooting of a moving image is started. The still image button 12 is an operation button for taking a still image with the video camera. When the photographer presses the still image button 12, a still image is shot once.

The read mode selection circuit 13 is provided with a CC
The read mode of the D drive circuit 23 is selected. When the moving image button 11 is pressed by the photographer, the read mode selection signal MSEL for selecting the two-pixel mixed read mode is set to C.
When the still image button 12 is pressed by the photographer, a read mode selection signal MSEL for selecting the one-pixel independent read mode is output to the CCD drive circuit 23.

The strobe signal generating circuit 14 emits a strobe light emission signal STR for emitting a strobe by the strobe lighting device 20 at a predetermined timing when the photographer presses the still image button 12. The strobe light emission signal STR generated by the strobe signal generation circuit 14
Is the strobe lighting device 2 via the readout sequence control circuit 15.
0, CCD drive circuit 23 and memory control operation circuit 32
Is output to

The strobe lighting device 20 is used when a still image is taken by the video camera. When a strobe light emission signal STR is input, the strobe lighting device 20 emits a strobe to illuminate a subject. The light emission time of the strobe is about 3 μsec. The lens 21 forms an image of the subject on the CCD image sensor 22. Lens 21
The aperture amount that is optimal for each of the moving image shooting and the still image shooting is set in advance for the aperture.

The synchronization signal generation circuit 24 generates a vertical synchronization signal VS every field period. CCD drive circuit 2
Reference numeral 3 drives the CCD image pickup device 22. When the two-pixel mixed reading mode (moving image shooting mode) is selected by the reading mode selection circuit 13, the CCD driving circuit 23 synchronizes with the vertical synchronizing signal VS generated by the synchronizing signal generation circuit 24 and outputs the odd-numbered line reading signal and Outputs an even line read signal.

The CCD drive circuit 23 selects the one-pixel independent readout mode (still image shooting mode) by the readout mode selection circuit 13 and, when the strobe light emission signal STR is input, the vertical synchronization signal generated by the synchronization signal generation circuit 24. The odd line read signal and the even line read signal are alternately output in synchronization with the signal VS. Further, in the still image shooting mode, the CCD drive circuit 23 is controlled by a read order control circuit 15 described later so as to always output an odd line read signal first and then output an even line read signal.

The odd line read signal is a signal for reading a signal of an odd line pixel among all the pixels of the CCD image pickup device 22, and the even line read signal is a CCD signal.
This is a signal for reading a signal of an even line among all the pixels of the image sensor 22.

FIG. 2 shows the CCD image pickup device 2 shown in FIG.
FIG. 2 is a diagram illustrating a configuration of a second embodiment. As shown in FIG. 2, the CCD image pickup device 22 converts an image of a subject input through a complementary color filter array into an electric signal and stores the electric signal.
It includes a plurality of pixels 50 arranged in a matrix. Further, the CCD image pickup device 22 is provided in each column of the plurality of pixels 50, inputs image signals accumulated in the pixels 50 of the corresponding column, and transfers the input image signals in the vertical direction. A vertical transfer register 60 and a horizontal transfer register 70 for inputting an image signal for one line vertically transferred by the vertical transfer register 60, transferring the input image signal in the horizontal direction, and outputting the image signal. .

The complementary color filter array is composed of, for example, a field color difference sequential color filter array. The field color difference sequential method is a method of obtaining color signals in the form of color difference signals line by line for each scanning line. In the complementary color filter array, 4 × 2 pixels in which Ye, Mg, Cy, and Mg color filters are arranged in the first column and Cy, G, Ye, and G color filters are arranged in the second column. The pattern of the basic unit is repeated.

Incidentally, Ye (yellow), Mg (magenta)
), Cy (cyan), R (red), G (green) B (blu
e). The arrangement of the complementary color filter array is not limited to this, but may be any arrangement as long as two adjacent pixels in the vertical direction have different colors.

The signal of the subject image input through the complementary color filter array and stored in each pixel 50 requires interlacing by a two-pixel mixed readout system, as is well known in the art.

Of all the pixels 50, each pixel 5 on an odd line
0 outputs each signal to each vertical transfer register 60 when the odd line read signal output from the CCD drive circuit 23 is input to the CCD image sensor 22. Of all the pixels 50, each pixel 50 on the even line is C
When the even-numbered line read signal output from the CD drive circuit 23 is input to the CCD image sensor 22, each signal is output to each vertical transfer register 60.

As described above, when the two-pixel mixed read mode is selected by the read mode selection circuit 13,
An odd line read signal and an even line read signal are output by the D drive circuit 23 in synchronization with the vertical synchronization signal VS. Thus, the signals of all the pixels 50 of the CCD image sensor 22 are simultaneously output to the respective vertical transfer registers 60.

When the one-pixel independent read mode is selected by the read mode selection circuit 13 and the strobe light emission signal STR is input to the CCD drive circuit 23, the CCD drive circuit 23 synchronizes with the first vertical synchronization signal VS. An odd line read signal is output, and an even line read signal is output in synchronization with the next vertical synchronization signal VS. As a result, the signal of each pixel 50 on the odd line of the CCD drive circuit 23 is output first, and after one field period, the signal of each pixel on the even line is output.

Each vertical transfer register 60 performs a process of adding or averaging the signals of two pixels 50 adjacent in the vertical direction and mixing the signals by alternately shifting one line every one field period. 2 pixel mixing means.

In the two-pixel mixed reading mode, if n is an integer, the two-pixel mixing means (2
Pixel 5 on the (n + 1) th line and the (2n + 2) th line
0 to form a first field image, and (2n + 1) th line and (2
n) The processing of mixing the signals of the pixels 50 on the line and forming the second field image is alternately performed in synchronization with the vertical synchronization signal VS. As a result, the first field image and the second
The field image is alternately output from the CCD image sensor 22 in synchronization with the vertical synchronization signal VS.

In the one-pixel independent read mode,
Since the signals of two vertically adjacent pixels are not output at the same time, the signals of the two pixels are not mixed.
Therefore, the odd field image read out in response to the input of the odd line read signal and the even field image read out in response to the input of the even line read signal are respectively CC
It is output from the D image sensor 22.

Returning to FIG. 1, the first signal processing circuit 25 includes a CDS (correlated double sampling) circuit and an AGC (auto gain control) circuit (not shown).
It consists of a circuit and the like. The CDS circuit removes reset noise of accumulated charges of each pixel 50 of the CCD image sensor 22 mixed in the image signal output from the CCD image sensor 22. AG
The C circuit amplifies the image signal subjected to the CDS processing to an appropriate level.

The gain of the AGC circuit is set in advance to be optimal for each of moving image shooting and still image shooting. In the still image shooting mode, the gain is set so that an image signal of an appropriate level can be obtained according to the light emission of the strobe lighting device 20. Therefore, when the strobe lighting device 20 is turned off, the level of the luminance signal included in the image signal becomes almost zero.

The switch 31 is connected to the input terminal A connected to the first signal processing circuit 25, the output terminal B and the input terminal C connected to the memory control operation circuit 32, and to the second signal processing circuit 26. Output terminal D and an input terminal connected to the read mode selection circuit 13. The switch 31 connects the input terminal A to the output terminal D when the two-pixel mixed read mode is selected by the read mode selection circuit 13.
The switch 31 connects the input terminal A to the output terminal B and connects the input terminal C to the output terminal D when the one-pixel independent read mode is selected by the read mode selection circuit 13.

That is, when the image signal output from the first signal processing circuit 25 is in the two-pixel mixed read mode,
The signal is simply output to the second signal processing circuit 26 via the switch 31, and is output to the memory control operation circuit 32 via the switch 31 in the one-pixel independent reading mode. The second signal processing circuit 26 separates and extracts a luminance signal and a chrominance signal from the input image signal, performs signal processing such as gamma correction, and outputs a video signal.

When the one-pixel independent read mode is selected by the read mode selection circuit 13, the memory control operation circuit 32 outputs the odd field image and the even field image output from the first signal processing circuit 25 via the switch 31. The odd field image and the even field image are stored in the image memory 33.

The memory control arithmetic circuit 32 rearranges the odd field image and the even field image stored in the image memory 33 so as to correspond to the pixel array of the CCD image pickup device 22 to form an image for one frame. Further, the memory control operation circuit 32 calculates the CC in the two-pixel mixed read mode from the rearranged image for one frame.
As in the case of the vertical transfer register 60 of the D imaging device 22, the processing of adding or averaging and mixing the signals of the pixels 50 adjacent in the vertical direction is performed by shifting one line alternately, and
A field image and a second field image are configured.

The read order control circuit 15 receives the strobe light emission signal STR output from the strobe signal generation circuit 14 and outputs the input strobe light emission signal STR in accordance with the output state of the read signal of the CCD drive circuit 23. .

FIG. 3 is a block diagram showing a configuration of read order control circuit 15 shown in FIG. As shown in FIG. 3, the read order control circuit 15
1, a 1V delay circuit 42, a selector 43 and a mask signal output circuit 44 are provided.

The strobe light emission signal STR input to the read order control circuit 15 is input to a read line determination circuit 41, a 1V delay circuit 42, and a selector 43. When the strobe light emission signal STR is input, the read line discriminating circuit 41 outputs either the odd line read signal or the even line read signal by the CCD drive circuit 23 in synchronization with the immediately following vertical synchronizing signal VS. Is determined. When it is determined that the even line read signal is output, the read line determination circuit 41
A delay signal DLY for delaying TR
And a mask signal output circuit 44.

The 1V delay circuit 42 delays the input strobe light emission signal STR by one field period and outputs it. The selector 43 has an input terminal A, an input terminal B, and an output terminal C. When the delay signal DLY output from the read line determination circuit 41 is input, the selector 43 connects the input terminal A to the output terminal C, and
When Y is not input, the input terminal B and the output terminal C are connected.

That is, when it is determined by the read line discriminating circuit 41 that an even line read signal is to be output, the strobe light emission signal STR delayed by one field period by the 1V delay circuit 42 is output from the selector 43, and the read line discriminating is performed. When the circuit 41 determines that the odd line read signal is output, the strobe light emission signal STR is output from the selector 43 without delay.

The mask signal output circuit 44 outputs a mask signal MASK for stopping the output of the even line read signal of the CCD drive circuit 23 when the delay signal DLY output from the read line determination circuit 41 is input. . CC
When the mask signal MASK output from the mask signal output circuit 44 is input, the D drive circuit 23 stops outputting the next even line read signal.

The emission timing of the strobe of the strobe lighting device 20, that is, the timing of generation of the strobe light emission signal STR by the strobe signal generation circuit 14 is determined by the output of the odd line read signal and the even line read signal of the CCD drive circuit 23 and the time. Are set so that they do not overlap. CC
If the strobe light is emitted during the transfer of the image signal by the vertical transfer register 60 of the D imaging device 22, the signal is not stored in each pixel 50, but is transferred directly to the vertical transfer register 60, and the signal is lost. .

FIG. 4 is a time chart showing the operation of the video camera shown in FIGS. 1 to 3 in the still image shooting mode. The synchronizing signal generating circuit 24 generates a vertical synchronizing signal VS for each field period, and the CCD driving circuit 23 alternately outputs the odd line reading signal and the even line reading signal in synchronization with the vertical synchronizing signal VS.

When the still image button 12 is pressed by the photographer, the reading mode selection circuit 13
Readout mode selection signal MSEL for selecting pixel independent mode
Is output to the CCD drive circuit 23 and the switch 31.
At the same time, a strobe light emission signal STR is generated at a predetermined timing by the strobe signal generation circuit 14, and the read line discriminating circuit 41 and the 1V delay circuit 4
2 and the selector 43.

In the read line determination circuit 41, the next period B
The CCD drive circuit 23 determines which of the odd line read signal and the even line read signal is output in synchronization with the vertical synchronizing signal VS. As understood from FIG. 4, in the period A, the odd-numbered line read signal was output from the CCD driving circuit 23, and thus in the period B,
An even line read signal is output by the CCD drive circuit 23. Therefore, it is determined by the read line determination circuit 41 that an even line read signal is output, and the delay signal DLY is output.
Is output to the selector 43 and the mask signal output circuit 44.

On the other hand, in the 1V delay circuit 42, the input strobe light emission signal STR is delayed by one field period.
It is output to the selector 43. In the selector 43, the delay signal DLY output from the read line determination circuit 41 is input, and the input terminal A and the output terminal C are connected. As a result, the strobe light emission signal STR input to the read line determination circuit 41 is output from the read line determination circuit 41 after being delayed by one field period.

On the other hand, in the mask signal output circuit 44, when the delay signal DLY is input, the mask signal MA for stopping the output of the even line read signal of the CCD drive circuit 23 is output.
SK is output. As a result, in the CCD driving circuit 23, the output of the even-numbered line read signal indicated by the broken line in the drawing, which is synchronized with the vertical synchronization signal VS in the period B, is stopped.

In the period B, the read line determination circuit 41
Strobe light emission signal S delayed by one field period
TR is input to the strobe lighting device 20, the CCD drive circuit 23, and the memory control operation circuit 32. In the strobe lighting device 20, strobe light emission is performed, and an image of the illuminated subject is captured by each pixel 50 of the CCD image sensor 22.

In the period C, an odd line read signal is output by the CCD drive circuit 23 in synchronization with the vertical synchronizing signal VS, and each pixel 50 on the odd line of the CCD image sensor 22 is output.
Are output via the vertical transfer register 60 and the horizontal transfer register 70. CCD image sensor 2
The image signal of the odd field output from 2 is subjected to predetermined signal processing by the first signal processing circuit 25, and is stored in the image memory 33 via the memory control operation circuit 32.

In the period D, an even line read signal is output by the CCD drive circuit 23 in synchronization with the vertical synchronizing signal VS, and each pixel 50 of the even line of the CCD image sensor 22 is output.
Are output via the vertical transfer register 60 and the horizontal transfer register 70. CCD image sensor 2
The image signal of the even field output from 2 is subjected to predetermined signal processing by the first signal processing circuit 25, and is stored in the image memory 33 via the memory control operation circuit 32.

The image signals of the odd field and the even field stored in the image memory 33 are rearranged by the memory control arithmetic circuit 32 so as to correspond to the pixel arrangement of the CCD image pickup device 22 to form an image for one frame.
Further, a process of mixing signals of the pixels 50 adjacent in the vertical direction is alternately shifted by one line, thereby forming a first field image and a second field image. The first field image and the second field image are read out by the memory control operation circuit 32,
The signal is output to the signal processing circuit 26.

A luminance signal and a chrominance signal are separated and extracted from the first field image and the second field image by the second signal processing circuit 26, subjected to predetermined signal processing such as gamma correction, and output as a video signal. . The output video signal is stored in an internal image memory (not shown) or output to an external device.

When the strobe light emission signal STR is input to the read order control circuit 15 and the read line determination circuit 41 determines that the odd line read signal is output in the next period, the read line determination circuit 41 delays. Since the signal DLY is not output and the input terminal B and the output terminal C of the selector 43 are connected, the strobe light emission signal STR input to the read order control circuit 15 is not delayed and is output from the read order control circuit 15 as it is. Is output.

As a result, in the next period, the odd line readout signal is output by the CCD drive circuit 23 in synchronization with the vertical synchronizing signal VS, and the image signal of the odd field is output from the CCD image pickup device 22. , An even line read signal is output by the CCD driving circuit 23 in synchronization with the vertical synchronizing signal VS.
From 2 an image signal of an even field is output.

The operation of the video camera in the moving image shooting mode is the same as the operation of the conventional video camera, and the description thereof is omitted.

As described above, in the video camera of this embodiment, when the still image button 12 is pressed by the photographer, the one-pixel independent mode is selected by the read mode selection circuit 13. The odd line read signal and the even line read signal are alternately output by the CCD drive circuit 23 in synchronization with the vertical synchronization signal VS, and the odd field image signal and the even field image signal are alternately read from the CCD image pickup device 22. . From the image signals of the odd field and the even field, a first
And the image signal of the second field. Accordingly, an image signal for one frame of the CCD image sensor 22 can be obtained by one photographing operation, so that a still image with a high vertical resolution can be obtained.

In the video camera of this embodiment, the reading order control circuit 15 is provided and the CCD driving circuit 23 is provided.
Thus, the odd line read signal is always output first, and then the even line read signal is output.

In the complementary color filter array shown in FIG. 2, two pixels 5 adjacent in the vertical direction are used.
The color of each color filter of 0 is different. For this reason, two pixels adjacent to each other in the vertical direction also have different signal light intensity levels. Generally, in a CCD image sensor, in order to obtain an image having a good S / N ratio (signal-to-noise ratio),
Use up to the area near the upper limit of the dynamic range. For this reason, signal saturation occurs in each pixel of the CCD image sensor, and signal charges overflowing from each pixel often leak into adjacent pixels or signal lines.

Therefore, when the same subject is photographed with the same illumination, images having different signal levels can be obtained due to the difference in the field image to be read first. Therefore, in the video camera according to the present embodiment, when a still image is captured, the same signal level is obtained when a still image of the same subject is repeatedly captured under the same illumination by always reading from an odd field image. Image was reproduced. Needless to say, the data may always be read from the even field image.

FIG. 5 is a diagram showing a comparative example of a luminance signal of a still image obtained by photographing a test chart. As shown in FIG. 5A, a still image of a test chart 80 in which a uniform red region 80R, a uniform blue region 80B, and a uniform yellow region 80Y are arranged in the horizontal direction is repeated with the same illumination. The still image shot twice and the first shot still image and the second shot still image are compared by the luminance signal of one line at the same position.

As shown in FIG. 5B, in the first photographing, the even field image of the CCD image sensor is read first, and in the second photographing, the odd field image of the CCD image sensor is read first. When the still image is photographed, a difference of ΔY occurs in the level of the luminance signal in the yellow portion of the test chart, and a bright image is obtained at the first time and a dark image is obtained at the second time.

As described above, the influence of the difference between the signal saturation levels of the two pixels due to the difference in the color of the color filter is, in particular,
It appears remarkably in an image signal containing a color component with a high luminance level such as yellow or cyan.

On the other hand, as shown in FIG.
In both the first and second shootings, if the odd field image is read first, a still image with no difference in the luminance signal of the yellow portion of the test chart is obtained. Therefore, a still image with good reproducibility can be taken.

In the video camera of this embodiment, the strobe is illuminated by the strobe lighting device 20 when the still image button 12 is pressed, but the strobe is emitted as needed. It may be configured as follows.

For example, a menu screen is displayed on a liquid crystal panel (not shown), and when the still image button 12 is pressed, a mode in which the strobe is forcibly emitted, a mode in which the strobe is not forcibly emitted, and the surrounding brightness are detected. When the detected brightness is equal to or less than a certain value, one of the automatic modes for emitting a strobe light may be set in advance.

In the video camera of this embodiment, when the still image button 12 is pressed, the one-pixel independent reading mode is selected. For example, a menu screen is displayed on a liquid crystal panel (not shown). It is also possible to adopt a configuration in which the display is performed and one of the two-pixel mixed read mode and the one-pixel independent read mode is selected in advance.

[0079]

According to the video camera of the present invention, when the one-pixel independent read mode is selected by the read mode selecting means, the odd-line read signal and the even-line read signal alternate by the drive circuit every one field period. Is output to At this time, the drive circuit always outputs the same read signal first. As a result, the image of the odd field and the image of the even field are always output in the same order from the solid-state imaging device and stored in the image storage means. The image of the odd field and the image of the even field are combined into a still image for one frame by the image mixing means, and two field images obtained by mixing signals of two pixels adjacent in the vertical direction alternately by one line are combined. Be composed.

Therefore, two field images can be obtained by one shooting, and an image signal for one frame can be taken out, so that an image with a high vertical resolution can be obtained. In addition, since the image of the odd field and the image of the even field can always be read out from the solid-state imaging device in the same order, when a still image of the same subject is repeatedly photographed, there is no change in the saturation level of the signal, and the reproducibility is low. Good images can be obtained.

According to the video camera of the present invention,
When an operation command is input by the moving image shooting operation means, the two-pixel mixed reading mode is selected, and when an operation command is input by the still image shooting operation means, the one-pixel independent reading mode is selected. Therefore, a moving image can be photographed by a conventional method, and when photographing a still image, a still image with high resolution and good reproducibility can always be obtained.

Further, according to the video camera of the present invention, when an operation command is input by the still image photographing operation means and the one-pixel independent reading mode is selected by the reading mode selection means, the driving circuit next outputs the signal. The read signal determination circuit determines whether the output read signal is a line read signal to be output first. When it is determined that the read signal is not a line read signal to be output first, the mask signal output circuit outputs a mask signal, and the drive circuit stops outputting the line read signal. Therefore, when an operation command is input by the still image photographing operation means and the one-pixel independent readout mode is selected by the readout mode selection means, a drive circuit reliably outputs a readout signal of a line to be output first. Can be.

According to the video camera of the present invention,
A strobe lighting unit that emits a strobe light once when an operation command is input by the still image photographing operation unit, wherein a read signal output next from the drive circuit is output first by the read signal determination circuit; When it is determined that the read signal is not a line read signal to be output, the delay circuit determines that the read signal output next from the drive circuit is a line read signal to be output first by the read signal determination circuit. Instead, the light emission timing of the strobe lighting means is delayed by one field period. Therefore, the strobe can emit light in accordance with the line read signal output earlier from the drive circuit, so that a still image with stable brightness can always be obtained.

According to the video camera of the present invention,
Since the solid-state imaging device is constituted by the CCD imaging device, M
An image having a high S / N ratio can be easily obtained as compared with an OS (metal oxide semiconductor) image sensor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video camera according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a CCD image sensor 22 shown in FIG.

FIG. 3 is a block diagram showing a configuration of a read order control circuit 15 shown in FIG.

FIG. 4 is a time chart showing an operation of the video camera shown in FIGS. 1 to 3 in a still image shooting mode.

FIG. 5 is a diagram illustrating a comparative example of a luminance signal of a still image obtained by capturing a test chart.

FIG. 6 is a block diagram showing a configuration of a conventional video camera having a still image shooting mode.

7 is a time chart showing an operation of the conventional video camera shown in FIG. 6 in a still image shooting mode.

[Explanation of symbols]

11 video button, 12 still image button, 13 read mode selection circuit, 14 strobe signal generation circuit, 1
5 reading order control circuit, 20 strobe lighting device,
21 lens, 22 CCD image sensor, 23 CC
D drive circuit, 24 synchronization signal generation circuit, 25 first signal processing circuit, 26 second signal processing circuit, 31 switch, 32 memory control operation circuit, 33 image memory, 41 read line discrimination circuit, 42 1 V delay circuit, 43 Selector, 44 mask signal output circuit,
50 pixels, 60 vertical transfer registers, 70 horizontal transfer registers, VS vertical synchronization signal, MSEL read mode selection signal, STR strobe light emission signal, DL
Y Delay signal, MASK mask signal.

Claims (5)

[Claims] 1. A plurality of pixels arranged in a matrix for photoelectrically converting and accumulating light incident through a complementary color filter array, and a plurality of pixels provided in each column of the plurality of pixels. A plurality of vertical transfer registers for inputting signals accumulated in the pixels and transferring the input signals in the vertical direction, and inputting a signal for one line vertically transferred by the plurality of vertical transfer registers; And a horizontal transfer register that transfers the output signal of one line in the horizontal direction and outputs the signal. The vertical transfer register alternately shifts the signal of two pixels adjacent in the vertical direction by one line every one field period. Solid-state imaging device having a two-pixel mixing unit for adding or averaging and mixing the two pixels; A two-pixel mixing readout mode in which pixel signals are alternately shifted by one line every one field period to mix and read an image for one mixed field, and an image for one frame composed of the plurality of pixels. Reading mode selection means for selecting one of the one-pixel independent reading modes for alternately reading the field image of the odd line and the field image of the even line every field period; When the two-pixel mixed read mode is selected by the means, an odd line read signal for reading a signal of an odd line pixel among the plurality of pixels and a signal for reading an even line pixel of the plurality of pixels are provided. An even line read signal is output for each one field period, and the read mode selecting means selects one pixel independent read mode. When selected, a drive circuit for alternately outputting the odd line read signal and the even line read signal every one field period to drive the solid-state imaging device; and a one-pixel independent read mode by the read mode selecting means. When is selected, image storage means for storing a field image of odd lines and even lines alternately read from the solid-state imaging device according to the odd line and even line read signals alternately output by the drive circuit, The one-frame still image is formed by combining the odd-line and even-line field images stored in the image storage means, and signals of two pixels that are vertically adjacent to the formed one-frame still image. And an image mixing unit that alternately mixes two lines by one line to form two field images. Wherein when the one-pixel independent read mode is selected by the read mode selecting means, one of the odd line read signal and the even line read signal is always output first from the same read signal. . 2. A moving image photographing operation means for inputting an operation command for photographing a moving image, and a still image photographing operation means for inputting an operation command for photographing a still image, wherein the read mode selection means is provided. Selecting the two-pixel mixed reading mode when an operation command is input by the moving image shooting operation means, and selecting the one-pixel independent reading mode when an operation command is input by the still image shooting operation means. Claim 1 characterized by the following:
A video camera according to claim 1. 3. When an operation command is input by the still image photographing operation means and the one-pixel independent read mode is selected by the read mode selection means, a read signal output next by the drive circuit is output first. A read signal discriminating circuit for discriminating whether the read signal is a line read signal to be output, and a read signal discriminating circuit for judging whether the next read signal is not a line read signal to be output first. And a mask signal output circuit for outputting a mask signal for stopping the output of the signal. The drive circuit stops outputting the next line read signal when the mask signal output by the mask signal output circuit is input. The video camera according to claim 2, wherein 4. A strobe lighting means for emitting a strobe light once at a predetermined timing when an operation command is inputted by said still image photographing operation means, and a line read signal outputted next by said read signal discriminating circuit. Is determined not to be the line read signal to be output first, the flash timing of the strobe lighting means is changed to the line read signal to be output next by the read signal determination circuit. The video camera according to claim 3, further comprising: a delay circuit that delays one field period more than when it is determined that 5. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is a CCD (charge c
The video camera according to claim 1, wherein the video camera is an image pickup device.