JP2000032318A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input device capable of simultaneously providing entire image information based on thinning scanning and high-resolution partial image information based on full pixel scanning from the same frame. SOLUTION: This image input device is composed of a pixel array 1, vertical and horizontal scanning circuits 2 and 3 a timing pulse generating circuit 4 for driving and controlling the vertical and horizontal scanning circuits so as to scan only the prescribed area of the pixel array in a full pixel scanning mode and to scan remaining areas while thinning them, a first buffer memory 6 for storing a thinning scan video signal separately from thinning scan and full pixel scan mixed video signals read out of the pixel array, a second buffer memory 7 for storing a full pixel scan video signal separately from the thinning scan and full pixel scan mixed video signals, a video synchronizing signal generating circuit 8 for reading the stored thinned video signal synchronously with a video monitor 10, and a CPU 11 for performing focal point discriminating processing or the like while using the full pixel scan video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image input apparatus, and more particularly to an image input apparatus using a solid-state image sensor capable of thinning-out scanning.

[0002]

2. Description of the Related Art Generally, in an image pickup apparatus using a solid-state image pickup device, when the number of pixels of the solid-state image pickup device is increased in order to increase the definition of a captured image, the frame rate for reading out all pixels is reduced. . Therefore, thinning-out reading is performed by thinning out pixels to increase the frame rate and use it for angle-of-view adjustment or the like. On the other hand, all pixels in a partial area are read out and used for focus adjustment or the like.

An image pickup apparatus using an image pickup device capable of performing such thinning-out reading is disclosed in Japanese Patent Application Laid-Open No. 9-2148.
Japanese Patent Publication No. 36 discloses the following configuration. That is, as shown in FIG. 5, an image sensor 104 capable of reading data of a predetermined pixel among all pixels formed on the photoelectric conversion surface, and a predetermined block among all the pixels in the image sensor 104 It is possible to control the driving of the image sensor 104 by switching between a block scanning mode for scanning pixels within the pixel and a thinning scanning mode for thinning and scanning a specific pixel at a predetermined thinning rate for all pixels. A driving unit 103, an overall display memory 107 for storing data read from the image sensor 104 in the thinning-out scanning mode and A / D converted by the A / D converter 105 via a switch 106; A partially enlarged display memory 108 for storing the data read and A / D converted in the block scanning mode via a switch 106, and each data stored in the two memories 107, 108 One monitor 11
0, a display output unit 109 that converts and outputs data so that it can be displayed as separate images on the display unit, and a controller 102 that controls each unit in response to an instruction from the input device 101,
When the controller 102 is instructed to perform angle of view or focus adjustment, that is, a process for monitoring a photographer, the controller 102 controls the drive unit 103 and the switch 106 so that the image data obtained by the thinning scan from the image sensor 104 is output. Image data by block scanning alternately in the entire display memory 10
7 and the partial enlarged display memory 108 for storage, and the image data stored in the two memories 107, 108 are alternately read out for each horizontal line and sent to the display output unit 109, and are output to the standard television. The signal is converted into a version signal and displayed on the display screen of one monitor 110.
When the controller 102 is instructed to perform processing for photographing, image data is sent out by scanning all pixels, and image data of one screen is recorded and stored on the hard disk 112 via the buffer memory 111. It has become.

[0004]

In the imaging apparatus disclosed in the above publication, when obtaining an entire image by thinning-out scanning for adjusting the angle of view or the like and a partially fine image by block scanning for focusing or the like, Since drive scanning is not performed in a mode in which the thinning scanning mode and the block scanning mode are mixed, it is impossible to obtain the entire image information and the high-resolution information for focusing from the same frame by the thinning scanning. Therefore, the conventional imaging apparatus disclosed in the above-mentioned publication has a problem in that it is not possible to output video for angle-of-view adjustment during focusing processing. In order to improve this, even when the thinned-out image input for angle-of-view adjustment and the high-definition image input for focusing are alternately read out for each frame, the effective frame of the video output for focusing is effective. There was a problem that the rate dropped.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional imaging apparatus, and is intended to obtain the whole image information by thinning-out scanning and the high-resolution partial image information by all-pixel scanning from the same frame. It is an object of the present invention to provide an image input device having the above configuration.

[0006]

According to a first aspect of the present invention, there is provided a pixel array having a plurality of pixels arranged two-dimensionally, and the pixels of the pixel array are thinned out. In an image input apparatus provided with a solid-state imaging device capable of performing scanning in a plurality of scanning modes including thinning scanning, scanning is performed on all pixels of only a pixel group in a continuous predetermined region of a pixel array of the solid-state imaging device. A scan control unit that performs a thinning scan for a pixel group in a remaining area of the pixel array, and a video signal separating unit that separates a video signal from the all pixel scan region and a video signal from the thinned scan region from each other. The video signal from the pixel scanning area is used for exposure control or focus detection.

By providing such scanning control means and video signal separating means, all pixel scanning is performed for a pixel group in a specific area of a pixel array, and thinning scanning is performed for a pixel group in another area. A mixed signal of a video signal obtained by thinning scanning and a video signal obtained by scanning all pixels is obtained. These mixed signals are separated by a video signal separating unit, and the whole image information obtained by the thinning scanning and the whole image obtained by scanning all pixels are extracted from the same frame. High resolution partial image information is obtained.

[0008]

Next, an embodiment will be described. FIG. 1 is a block diagram showing an embodiment of the image input apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a pixel array in which a plurality of pixels each formed of a photoelectric conversion element are arranged two-dimensionally in an m × n arrangement; 2, 3 a vertical scanning circuit for scanning the pixel array 1 to read out pixel signals; The horizontal scanning circuit has a plurality of operation modes including a thinning operation. Reference numeral 4 denotes a timing pulse generation circuit for generating a timing pulse for controlling the driving of the vertical scanning circuit 2 and the horizontal scanning circuit 3, and these components constitute a solid-state imaging device. Reference numeral 5 denotes an A / D converter for amplifying and A / D converting the video signal read by the scanning of the vertical scanning circuit 2 and the horizontal scanning circuit 3, and 6, 7 control signals from the timing pulse generation circuit 4, respectively. A /
A first buffer memory for storing a decimated image signal from the D-converted digital video signal and a second buffer memory for storing only an image necessary for automatic focusing, 8 is a decimated memory stored in a first buffer memory 6 A video synchronizing signal generating circuit 9 for synchronizing and reading the signal with the video monitor 10; 9 a D / A converter for converting a digital signal stored in the first buffer memory 6 into an analog signal;
Is a CPU for performing automatic focusing processing.

As a configuration example of a scanning circuit capable of thinning-out scanning, for example, as shown in FIG. 2, in a shift register composed of a D-type flip-flop circuit (DFF),
A switch 21 for transferring the output signal of the FF to the next-stage DFF, and a switch 22 for inverting the control logic of the switch 21 and transferring the signal to the next-stage DFF by skipping one stage between each DFF. And a skip enable signal from the timing generation circuit 4 is input to the control terminals of the switches 21 and 22.

FIG. 3 is a diagram showing the operation timing of the scanning circuit capable of thinning-out scanning shown in FIG. 2, in which CK is a basic scanning clock, φIN is a scanning input signal, and φ1 to φ12 are scanning circuits. The output timing of the stage is shown. When Skip Enable is L, the connection switch 21 between the adjacent DFFs is turned on, and the scanning signal shifts by one step with respect to the period of CK. When Skip Enable becomes H, switch
While the switch 21 is turned on while the switch 21 is turned off, the scanning signal is transferred to the DFF of the next next stage, and by repeating this, the scanning signal moves while skipping every other stage. Therefore, by adopting such a scanning circuit for the vertical scanning circuit 2 and the horizontal scanning circuit 3, a configuration of an imaging device capable of thinning-out scanning becomes possible. Although the circuit configuration of the scanning circuit shown in FIG. 2 is capable of skipping scanning by skipping one pixel, the number of skipping pixels can be easily changed by changing the connection destination of the jumping switch 22.

Next, the operation of the thus configured image input apparatus will be described with reference to the pulse timing chart of FIG. For simplicity of description, a case will be described as an example in which all pixels are read from the Lth row to the Mth row of the pixel array 1 and pixels are read out every other pixel in every other row and column in other areas. Each pulse name in the pulse timing chart for explaining the operation of FIG. 4 is made to match the pulse name shown in FIG. φXi (φX1 to φXm)
Represents a row selection pulse, and when φXi is H, the pixel array 1
Indicates that only the pixel in the i-th row is selected. Also Skip
Enable is a pulse for controlling thinning-out scanning of the vertical scanning circuit 2 and the horizontal scanning circuit 3. When H is output to Skip Enable, both the vertical scanning circuit 2 and the horizontal scanning circuit 3 perform thinning-out scanning at every other pixel, and skip. When Enable is L, pixels are continuously scanned. Memory1 Write and Memory2 Wri
te is a first buffer memory 6 for each thinned image.
And a pulse for controlling the timing of inputting (writing) a signal to the second buffer memory 7 for focusing images. The column selection pulse φYj scans the column during the period when the row selection pulse φXi is at H, but is not shown in FIG. 4 to avoid complication.

Next, the details of the operation will be described with reference to the timing shown in FIG. In one frame period from time t _{0 to} t ₃ , Skip Enable is set to H during time t _{0 to} t ₁ , which is a period for scanning the pixels from the first row to the L-1st row.
Is output, thinning-out scanning is performed on both the vertical scanning circuit 2 and the horizontal scanning circuit 3, and both rows and columns are read out while thinning every other pixel. During this period, only Memory1 Write becomes H, and the A / D converter 5 Is written only in the first buffer memory 6 for the thinned image.

Next, during a period from time t _{1 to} time t _2, which is a period for scanning from the L-th row to the M-th row, L is output to SkipEnable, and both the vertical scanning circuit 2 and the horizontal scanning circuit 3 use all pixels. Scan. During this period, H is output to Memory2 Write, and the video signal is written to the second buffer memory 7 for the focused image. On the other hand, Memory1Write becomes H in synchronization with the timing at which the signal of the pixel at the position corresponding to the thinning scan is output from the A / D conversion unit 5, and the first buffer memory 6 for the thinned image is compatible with the thinning scan. Only the signal of the pixel at the corresponding position is written.

Between times t _{2 and} t _3, Skip Enable is set to H again.
By performing thinning-out scanning on both the row and the column from the (M + 1) th row to the (m) th row and setting Memory1 Write to H,
The digital video signal output from the A / D converter 5 is written only in the first buffer memory 6 for the thinned image.

By scanning one frame in this manner, the thinning signal of the entire image area is stored in the first buffer memory 6 for the thinned image, and all the pixels are stored in the second buffer memory 7 for the focused image. An image of the scanned area is stored. The video information for focusing recorded in the second buffer memory 7 is transferred to the CPU 11 for performing the focusing process (AF control), and the focus state is determined and fed back to the optical system.

On the other hand, the thinned-out video signal recorded in the first buffer memory 6 is read out in accordance with the video synchronization signal input from the video synchronization signal generation circuit 8, and the D / A
After the analog conversion by the conversion unit 9, the image is displayed as a moving image on the video monitor 10. At this time, the frame rate of the video output and the frame rate of the reading from the image sensor need to be matched, but the number of pixels read from the image sensor is larger than the number of pixels of the video output. There is a problem that the driving period at the data rate described above increases the readout period from the image sensor. If this time difference can be absorbed within the vertical retrace period of the video standard, there is no problem. However, if the time difference is exceeded, it can be solved by providing a slight difference between the two data rates.

As described above, only a part of the pixel array is scanned with all pixels, and other areas are scanned with thinning, and the output video signal is subjected to a thinned image and an image of the area obtained by scanning all pixels through a plurality of buffer memories. The thinned image is output in accordance with the video synchronization signal, and the image of the area scanned by all pixels is used for focusing processing, so that the frame rate does not decrease even if the image input device is made high definition. In addition, information for angle of view alignment and information for focusing can be obtained at the same time.

In this embodiment, all pixels are read out from all the pixels in the L-th to M-th rows.
By changing the timing of ble, it is possible to arbitrarily set the area for reading out all pixels in the column direction. Further, the thinning-out is not limited to skipping by one pixel, and can be adapted to skipping by 3 pixels or 4 pixels by simply changing the scanning circuit. In addition, in this embodiment, a case has been described in which video information obtained by reading all pixels of a partial area of an image is used for focusing. However, local exposure time control and local white balance processing can be performed by adding the information to the processing contents of the CPU. It can also be used effectively.

[0019]

As described above, according to the present invention, according to the present invention, all pixels are scanned only in a pixel group in a predetermined continuous area of a pixel array of a solid-state imaging device.
Scanning control means for performing thinning scanning for the pixel group in the remaining area of the pixel array, and video signal separating means for separating video signals from all pixel scanning areas and video signals from the thinning scanning area from each other. Therefore, all pixel scanning is performed for a pixel group in a specific area of the pixel array, and thinning scanning is performed for pixel groups in other areas, and a video signal by thinning scanning and a video signal by all pixel scanning are mixed. Signals are obtained, and these mixed signals are separated by the video signal separating means, so that the whole image information by thinning scanning and the high-resolution partial image information by all pixel scanning can be simultaneously obtained from the same frame.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an embodiment of an image input device according to the present invention.

FIG. 2 is a block diagram showing a configuration example of a scanning circuit capable of thinning scanning in the embodiment shown in FIG. 1;

FIG. 3 is a timing chart for explaining the operation of the scanning circuit capable of thinning-out scanning shown in FIG. 2;

FIG. 4 is a timing chart for explaining the operation of the embodiment shown in FIG. 1;

FIG. 5 is a block diagram showing a configuration example of a conventional image input device.

[Explanation of symbols]

 Reference Signs List 1 pixel array 2 vertical scanning circuit 3 horizontal scanning circuit 4 timing pulse generation circuit 5 A / D conversion unit 6 first buffer memory 7 second buffer memory 8 video synchronization signal generation circuit 9 D / A conversion unit 10 video monitor 11 CPU 21, 22 switch

Claims (3)

[Claims] 1. A solid-state imaging device having a pixel array in which a plurality of pixels are arranged two-dimensionally, and capable of scanning in a plurality of scanning modes including a thinning scan for thinning out and scanning the pixels of the pixel array. A scanning control unit that performs all-pixel scanning only on a pixel group in a continuous predetermined area of the pixel array of the solid-state imaging device, and performs thinning scanning on a pixel group in the remaining area of the pixel array. Video signal separating means for separating a video signal from the all-pixel scanning area and a video signal from the thinning-out scanning area from each other, and using the video signal from the all-pixel scanning area for exposure control or focus detection. Characteristic image input device. 2. A plurality of frame buffer memories for storing video signals output from a pixel array under scanning control of the scanning control means, and all-pixel scanning images respectively corresponding to all-pixel scanning areas in the plurality of frame buffer memories. Memory control means for separating and storing a signal and a thinned-scanning video signal corresponding to the thinned-scanning area; 2. A thinning-out scanning video signal synthesizing means for forming a video signal, wherein the synthesized thinning-out scanning video signal output from the thinning-out scanning video signal synthesizing means is output as a video signal. Such an image input device. 3. The solid-state imaging device includes a timing generation circuit, the timing generation circuit comprising a timing pulse for a video signal separation operation in the memory control means and a video signal synthesis operation in the thinned-scanning video signal synthesis means. 3. An image input device according to claim 2, wherein the image input device is configured to supply a timing pulse for the operation.