JP2001024930A - Image pickup unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate an animation and a still image by means of same driving and to avoid the deterioration of image quality by reading a pixel signal from an imaging device at every two line. SOLUTION: A read pixel signal is converted into a digital signal by an A/D converting circuit 3. RGB signals are generated by a matrix processing from signals which are read by a signal processing circuit 5. The RGB signals are processed by white-balance and processed by gamma processing and, moreover, a luminance signal Y and color difference signals U and V are generated. Read 480 lines are made to be 240 lines through the use of a line memory or the like in the signal processing circuit 5 to generate the animation. When the still image is photographed, the signals with 480 lines, which are read at every two line in a certain field, are successively and temporarily written in a memory such as DRAM in a converting circuit 4. Then the 480 lines which are read to fill the gap of two preceding lines in the succeeding field are written in the memory in the same way so that the still image is generated in the driving system being the same as that of the animation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus such as a video camera and an electronic still camera which can handle both moving images and still images.

[0002]

2. Description of the Related Art A conventional imaging apparatus that performs photoelectric conversion using an imaging element such as a CCD (Charge Coupled Device) and performs digital signal processing on the photoelectric conversion to obtain a predetermined digital image signal is a video camera that captures a moving image. And an electronic still camera that captures a still image. However, an imaging device that can support both moving image capturing and still image capturing has also been proposed. For such a device, for example, Japanese Patent Application Laid-Open No. 2-280496, 1995, Photographic Society of Japan, Fine Image Symposium Proceedings, It is described on pages 59 to 62.

In the above-mentioned prior art, the image pickup device generally uses a CCD for a moving image, that is, a video camera. FIG. 3A shows an example of a color filter array used in such an image sensor. In this example, Mg (magenta), G
(Green), Cy (cyan) and Ye (yellow) complementary color filters are used. When a moving image is generated using an image pickup device having this color filter, signals of two pixels adjacent in the vertical direction are mixed and output. In addition, analog T such as NTSC
A video signal in the V signal standard is an interlace signal. To generate such an interlace signal, pseudo interlace scanning is performed by changing a combination of rows to be mixed for each field.

When a still image is photographed using such an image sensor, signals of pixels are read out independently without mixing signals between vertically adjacent pixels. On this occasion,
First, the signals of the pixels in the odd rows are read in the first field, the signals in the even rows are read in the second field, and the signals of the first and second fields are sequentially converted into signals to generate a still image.

On the other hand, there has been proposed an image sensor in which the number of pixels of the image sensor is increased as compared with the image sensor for a video camera in order to increase the resolution of a still image. The number of vertical pixels of such an image sensor is larger than the number of scanning lines in the current television system. For example, when the number of effective pixels in the vertical direction is 960, the number of scanning lines in the television system is two.
Double. FIG. 3B shows an example of such a color filter arrangement of a still image pickup device. This filter uses three primary colors RGB.

[0006]

However, if the number of pixels of the CCD is increased in order to obtain a high resolution, there is a problem that it is difficult to generate a moving image. For example, when a CDD with 500 pixels in the horizontal and vertical directions and 250,000 pixels in total is used, it is possible to output 30 frame images per second at a driving frequency of about 10 Mhz.
A moving image such as an SC can be generated in real time.
However, if the number of pixels is increased to twice the resolution both horizontally and vertically, the number of pixels is quadrupled, and for example, the number of vertical pixels is 960.
In the case of (1), it is necessary to output a signal of 240 lines in one field (here, 1/60 second) by thinning out pixels at a ratio of one pixel to four pixels. However, when thinning out by 4 pixels,
As shown in (a), the rows of the same color light set are fetched and the color cannot be reproduced in one field. Therefore, in order to reproduce the color in one field, for example, FIG. The thinning interval is 5, 3, 5, as in b)
3, 5, 3 ... However, the resolution of the reproduced image falls because the interval of the thinning is irregular.

Further, in a pixel-mixing type CCD used in a conventional video camera, a driving method differs between a moving image and a still image, so that the circuit has to correspond to it.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide
An object of the present invention is to provide an imaging device using a CCD, which can generate a moving image and a still image with the same drive.

[0009]

In order to achieve the above object, photoelectric conversion means for thinning out pixel signals accumulated in a plurality of pixels every two rows and outputting interlaced signals, and interlaced signals output by the photoelectric converting means are sequentially output. A sequential conversion unit for converting the video signal into a signal; a video signal sequentially converted by the sequential conversion unit into a predetermined image format to generate a video signal; and a video signal output from the photoelectric conversion unit to a predetermined format. Signal processing means, a video signal output by the signal processing means compresses data by an encoding method such as JPEG to generate image data, a recording medium for recording the image data output by the compression means, An image pickup apparatus is constituted by expansion means for expanding image data recorded on a recording medium and reproducing a video signal.

According to the present invention, both a moving image and a still image can be generated by a driving method in which pixel signals are thinned out every two rows from the image sensor and interlaced. Also, since signals are read out regularly every two rows,
Deterioration of image quality when generating a moving image can be avoided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of an imaging apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a lens, 2 denotes an image sensor such as a CCD, and 3 denotes an A / D conversion circuit. Reference numeral 4 denotes a sequential conversion circuit including a memory such as a DRAM, and reference numeral 5 denotes a signal processing circuit which converts an output signal of the A / D conversion circuit 3 into a YUV signal and generates a standard television signal such as NTSC or PAL. 7 is aperture,
Reference numeral 8 denotes a driving circuit for driving an image sensor, 9 denotes a recording medium for recording image data, and 10 denotes a JPEG (Joint Photographic Export).
Group), etc., for compressing and expanding images. As the recording medium 9, a semiconductor memory such as a flash memory or a magnetic disk such as a hard disk is used. A removable medium such as a PC card may be used. An output terminal 11 outputs the generated NTSC signal. 6 is
It is a control circuit that controls the operation timing of each block and controls input / output of image data. FIG. 2 illustrates the image sensor 2 in detail, wherein reference numeral 20 denotes a pixel, 21 denotes a vertical transfer unit, 22 denotes a horizontal transfer unit, and 23 denotes an output unit.

The operation of the imaging device according to the present embodiment will be described.

The light incident on the lens 1 forms an image on the image pickup surface of the image pickup device 2 via the stop 7. As shown in FIG. 2, the image pickup device 2 has a large number of pixels on its image pickup surface. At this time, a primary color RGB filter is used as a color filter as shown in FIG. The pixel signals generated by the photoelectric conversion in the pixel 20 are first transferred to the vertical transfer unit 21 as signals of two lines, such as 1, 2, 5, 6,..., And further transferred to the horizontal transfer unit 22. Then, it is read from the output unit 23. In the next field, 3 and 4, 7
, And the vertical transfer unit using two lines of signals such as
After being transferred to the horizontal transfer unit 22 and read out from the output unit 23. That is, the read signal of a certain field and the read signal of the next field have an interlaced relationship that fills a gap between each other. Next, a description will be given of how both a moving image and a still image can be generated by a driving method of reading out a signal every two lines as described above.

For example, assume that there are 1280 effective pixels in the horizontal direction and 960 effective pixels in the vertical direction.

First, generation of a moving image will be described.

As described above, in a certain field, 2
The pixel data of every other line is read from the output unit 23 of FIG. The read pixel signal is converted into a digital signal by the A / D conversion circuit 3 in FIG. Before A / D conversion, low noise processing such as CDS (Corelated Double Sampling) may be performed. The signal digitized by the A / D conversion circuit 3 is sent to the signal processing circuit 5. Signal processing circuit 5
A matrix process is performed on the (R / G) and (G / B) signals read in step (1) to generate RGB signals. A white balance process and a gamma process are performed on the generated RGB signal, and a luminance signal Y and color difference signals U and V are generated. Here, the signal processing circuit 5 reads 480 lines in one field.
As it is against the NTSC standard as it is, the 480
The line is processed by the signal processing circuit 5 using a line memory or the like.
Change to 240 lines. Similarly, in the next field, the read 480 lines are converted into 240 lines by the signal processing circuit 5. In this way, an interlaced signal of the NTSC standard is generated. By generating a moving image as described above, deterioration in image quality can be reduced as compared with the case where pixels are thinned out irregularly.

Next, generation of a still picture will be described.

When a still image is captured, unlike the case of capturing a moving image, signals of 480 lines read out every two lines in a certain field are sequentially transferred to the DRAM in the conversion circuit 4 via the signal processing circuit 5. Etc. once. And
The 480 lines read so as to fill the gap between the previous two lines in the next field are similarly written in the memory. A 960-line signal written to the memory in the next field is read out in order of one line, two lines, and so on to generate one still image. As described above, a still image can be generated even with the same driving method as that for a moving image.

In this embodiment, the filter of the primary color of RGB is used. However, as shown in FIG.
A filter of complementary colors of (magenta), C (cyan), Ye (yellow), and G (green) or a 2 × 4 RGB filter shown in FIG. 3B may be used.

In addition, since the signal level (D range) of a pixel can be increased when pixels are read out independently of each other than when pixels are mixed, deterioration in image quality is reduced.

[0023]

As described above, a moving image and a still image can be generated by the same drive by reading out the pixel signals from the image sensor every two lines. Further, by reading out the signals regularly when generating a moving image, deterioration of the image quality can be avoided.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of a CCD.

FIG. 3 is a diagram showing a color filter array of a CCD.

FIG. 4 is a diagram showing timing for reading out pixels from a CCD.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lens, 2 ... Image sensor, 3 ... A / D conversion circuit, 4 ...
Sequential conversion circuit, 5 ... signal processing circuit, 6 ... control circuit, 7 ...
Aperture, 8: CCD drive circuit, 9: Recording medium, 10: Compression / expansion circuit, 11: Output terminal, 20: Pixel, 21: Vertical transfer unit, 22: Horizontal transfer unit, 23: Output unit.

Continued on front page (72) Inventor Kazuyuki Sato 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Digital Media System Division, Hitachi, Ltd.

Claims (7)

[Claims] A pixel array in which a plurality of pixels for converting an optical signal imaged by an optical system such as a lens into an electric signal is arranged in a horizontal direction and a vertical direction, and a pixel signal stored in the plurality of pixels is provided. Photoelectric conversion means for thinning out every two rows and outputting an interlaced output, a sequential conversion means for converting the first video signal interlaced output by the photoelectric conversion means to a sequential signal as necessary, and Signal processing means for converting the first video signal into a video signal of a predetermined image format, or converting the second video signal output by the photoelectric conversion means into a predetermined format, and output by the signal processing means Encoding means for compressing the video signal by various encoding methods to generate compressed data, recording means for recording the compressed data output by the encoding means, and recording means Imaging apparatus characterized by comprising a decoding means for reproducing video signals by decoding the recorded image data. 2. The imaging device according to claim 1, wherein the first video signal is a still image. 3. The imaging apparatus according to claim 2, wherein the second video signal is a moving image including a plurality of continuous images. 4. The pixel array according to claim 3, wherein the pixel array of the photoelectric conversion means has a repetition cycle having two vertical columns and two horizontal rows as a basic unit, and receives the first color light in the first row. The pixels and the pixels that are exposed to the second color light are alternately arranged, and the pixels that are exposed to the third color light and the pixels that are exposed to the fourth color light are alternately arranged in the second row. Imaging device. 5. The method according to claim 4, wherein the first color light is red,
An imaging apparatus, wherein the color light is green, the third color light is green, and the fourth color light is blue. 6. An imaging apparatus according to claim 4, wherein the first color light is magenta, the second color light is green, the third color light is cyan, and the fourth color light is yellow. 7. The imaging apparatus according to claim 5, wherein the number of effective pixels in the vertical direction in the photoelectric conversion means is about 960 or more.