JPH0795831B2 - Imaging device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an image pickup apparatus, and particularly to drive control of a photoelectric conversion unit suitable for both still image recording operation and normal video camera operation. The present invention relates to an image pickup apparatus including means.

[Background of the Invention]

FIG. 1 is a plan view showing an example of a color filter arrangement used in a conventional color image pickup apparatus. An arrangement in which primary color filters R (red), G (green), and B (blue) are arranged as shown in the figure is called a Bayer array, and each forms one pixel.

For signal reading, the pixels in the first row are sequentially read at a certain field, then the third row, the fifth row, ..., And the odd rows are sequentially read, and then the second row, the fourth row, ... Even rows are read in the next field. It is read and interlaced.

FIG. 2 is a block diagram showing the configuration of an electronic camera which is one of the image pickup devices using the photoelectric conversion unit 1 having the color filter arrangement shown in FIG. Reference numerals 11, 12, and 13 in FIG. 2 denote output terminals of the photoelectric conversion unit 1 to which the signals g, r, and b corresponding to the color filters G, R, and B are output. 2 is a 1H delay line, 3 is a normal signal processing circuit such as matrix circuit and process circuit, and 4 is for recording on a recording medium such as a magnetic sheet (not shown).
Recording circuit for modulating image signals, 5 is recording head, 6
Is a monitor of a captured image, 7 is a control circuit for controlling a still image recording operation by controlling a shutter, an aperture, driving of the photoelectric conversion unit 1, a recording circuit 4 and the like, which are not shown by a recording button, This is a drive circuit that drives the photoelectric conversion unit 1.

The above-mentioned 1H delay line is necessary because the r signal or the b signal is missing in either the nth row of the pixel shown in FIG. 1 or the (n + 2) row to be read next.

That is, the g and r signals in the (n-2) th row, the g and b signals in the nth row, and the g and r signals in the (n + 2) th row are sequentially read by the drive circuit 8 in FIG.

Therefore, in the horizontal scanning period in which the g and b signals of the nth row are read out, the r signal of the (n−2) th row is combined to form a luminance signal and a chrominance signal.
It is necessary to read the g and r signals of the +2) th row and combine them with the b signal of the nth row to generate the luminance and chrominance signals.

In this way, a frame image (still image) can be obtained by using the pixels obtained by the conventional color filter array and skipping each row and reading.

Based on this, the operation of recording a frame image on a recording medium (not shown) in the block diagram of FIG. 2 will be described.

First, when a recording button (not shown) is pressed, the shutter (not shown) is closed, and after the reading of all the pixels of the photoelectric conversion unit 1 is completed, the read operation is stopped by the drive circuit 8. After the reading operation is stopped, the diaphragm and the shutter (not shown) are controlled by the control circuit 7 to appropriately expose the photoelectric conversion unit 1.

After that, the driving circuit 8 is driven to perform the above-mentioned pixel reading operation, the frame image signal is taken out, and the signal processing circuit 3 and the recording circuit 4 are moved to the recording head 5 and recorded on a recording medium (not shown).

After the reading of the frame image, no image signal remains in the photoelectric conversion unit 1, and all information is recorded in a recording medium (not shown).

By the way, even an electronic camera, which is one of the image pickup devices, is basically the same as a video camera, so that it can have a function as a video camera and continuously pick up images. Then, the captured signal can be displayed on the monitor 6 as a moving image.

However, this video camera mode has the following drawbacks. That is, the screen flicker appears as if the image is flickering due to frame afterimages that occur when the camera pans, and the image quality deteriorates significantly.

This is because a moving image captured by an image pickup tube such as an ordinary broadcast camera for picking up a frame image has a large beam width of the image pickup tube. Therefore, if one field is read, all information on the image pickup surface is lost. That is, for example, 1/60 in the NTSC system
This is because the image signal accumulated for 2 seconds is generated, whereas the image signal accumulated for 1/30 seconds is obtained in the frame reading of the electronic camera.

In other words, when a sensor frame image reading method that is most suitable for an electronic camera is used, the decrease in spatial frequency due to panning doubles, and the size of the afterimage that looks like a tail is doubled. The image deterioration is very noticeable to the viewer. Furthermore, the difference in image storage time between 1/60 second and 1/30 second is double, but like Flicka, from the detection limit, it feels more than double the deterioration, and the moving image displayed on the monitor is remarkable. It has the drawback of getting worse.

By the way, there is an "imaging device" described in Japanese Patent Laid-Open No. 58-220577 as an idea for obtaining an imaging signal suitable for each of the video camera mode and the electronic camera mode. In the invention shown in the same document, the frame lancer type sensor and its driving method are changed so that in the video camera mode (“Movie image pickup” in the same document), an image pickup output reproducible by a television receiver is output from the sensor. I took it out. However, according to the present embodiment, in the electronic camera mode (“still image pickup” in the same document), there is a drawback that only an output that cannot be reproduced by the television receiver is obtained in the image output order and the like. That is, even with still image pickup, it is desirable that the signal processing system can be simplified by obtaining a signal similar to the signal for the television receiver, as in the case of movie image pickup. There is a drawback that it becomes an imaging output.

[Object of the Invention]

The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide an image pickup apparatus which outputs monitor information of higher image quality.

[Outline of Invention]

In order to achieve the above object, the present invention is divided into an electronic camera mode and a video camera mode, and in the video camera mode, the same pixel of the photoelectric conversion unit is divided by the field frequency, that is, the minimum vertical scanning period of the sensor. The feature is that the frame afterimage is eliminated by scanning once every (one field period).

As an example of scanning the same pixel of the photoelectric conversion unit once in each field period, No. 1 to No. 5 shown in Table 1 are used.
There is a street. In the electronic camera mode, the interlace scanning is the same as the conventional one.

Embodiments of the Invention Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a block diagram of an embodiment of the present invention.

In the figure, the same reference numerals as those in FIG. 2 represent the same or equivalent parts.

Reference numeral 71 is a control circuit, 701 is an electronic switch, 81 is a still image drive circuit for driving the photoelectric conversion unit 1 in the electronic camera mode, 8
Reference numeral 2 is a moving picture drive circuit for driving the photoelectric conversion unit 1 in the video camera mode, 91 is a lens having an aperture and a shutter mechanism, 92 is a shutter switch of an electronic camera, 31 is the 1H delay line 2 and signal processing shown in FIG. This is a signal processing circuit including all of the circuit 3 and the like.

The signal processing circuit 31 can be easily configured by those skilled in the art to which the present invention belongs by knowing the pixel arrangement of the photoelectric conversion unit 1 and the reading order thereof, and therefore the details thereof will be omitted here.

The embodiment of the present invention has the above-mentioned configuration, and its operation will be described below with reference to the signal waveform diagrams of the respective parts shown in FIG. Fourth
In the figure, (a) is a shutter pulse generated when the shutter switch 92 is pressed, (b) is a switching pulse for switching between the moving image drive circuit 82 and the still image drive circuit 81, and (c) is the shutter operation of the lens 91. A shutter operation pulse representing (4) is a recording pulse for recording the read signal of the photoelectric conversion unit 1 on a recording medium such as a disc (not shown).

Normally, the circuit of FIG. 3 performs the monitor operation in the video camera mode before the shutter switch 92 is pressed. That is, the moving picture drive circuit 82 drives the photoelectric conversion unit 1 according to any one of the five scanning examples shown in the above-mentioned table, and the photoelectric conversion unit 1 continuously outputs an image pickup signal. The signal processing circuit 31 extracts this image pickup signal.
Output to the monitor 6 as a video signal, and the monitor 6
A moving image is displayed on the top.

When the shutter switch 92 is pressed in the above video camera mode, the control circuit 71 which receives the shutter pulse (a) in FIG. 4 generates the switching pulse (b) in FIG. 4 to turn on the electronic switch 701. Driving circuit for still images 8
Switch to 1. That is, the electronic camera mode is set.

At this time, at the same time, the shutter operation pulse (c) in FIG. 4 stops the operation of the lens 91 in the video camera mode, for example, the automatic diaphragm, and operates the shutter mechanism to close the shutter to close the photoelectric conversion unit of the external light. Irradiation to the light receiving part is interrupted.

Immediately after that, the still image drive circuit 81 reads out all the charges accumulated in the photoelectric conversion unit 1, then stops the readout, and enters a state in which the image formed by the lens 91 is accumulated.

After this state is reached, the shutter is opened by the shutter mechanism of the lens 91 and the light receiving portion of the photoelectric conversion portion 1 is exposed. After closing the shutter and ending the exposure, drive circuit 81 for still images
Performs the interlaced scanning of the photoelectric conversion unit 1 to read out 2n-1 (odd column) pixel columns at odd fields and even field 2n (even column) pixel columns as shown in the table above. , Perform normal frame reading.

At the same time, the recording circuit 4 is operated by the recording pulse (d) in FIG. 4 to record the frame signal on the recording medium (not shown) through the recording head 5. After recording, the control circuit 71 inverts the switching pulse (b) shown in FIG.
Is switched to the drive circuit 82 at the time of moving picture, and the video camera mode for generating a normal video signal is set.

The above series of operations are all performed with time. In this case, detailed signal processing methods and operations, for example, when the shutter is closed and the exposure device (not shown) opens the shutter for a certain period of time according to the illuminance of the subject, simultaneously controls the aperture, and prioritizes the shutter speed. It is the same as the normal series of operations of the camera, and the operation control of the photoelectric conversion unit 1 can be easily configured by those in the field to which the present invention belongs, and thus the description thereof is omitted. did.

Five scanning examples in the video camera mode shown in the above table will be described below.

The scanning example of No. 1 is a case in which a pixel afterimage of 2n-1 (odd) columns is read out and an even column is skipped to prevent a frame afterimage.

In the scanning example of No. 2, pixels in the 2n (even) columns are read out and the odd columns are skipped to prevent frame afterimages.

In the two scanning examples of No. 1 and No. 2, since the same light receiving element is read out for each field, the output of the photoelectric conversion unit 1 is half of that during frame reading.
Correct it with 31.

In the scan example of No. 3, the adjacent pixel columns 1 and 2, 3, 4, 5 and 6 ...
In the order of, and in the scanning example of No. 4,
Read out in the order of 3,4 and 5,6 and 7 ... That is, the scanning examples of No. 3 and No. 4 show a case where two pixel columns are read simultaneously and all the pixels are read in one field period.

The signal processing in this case varies depending on the type and arrangement of the pixel filters. This will be described by taking the color filter arrangement shown in FIG. 1 as an example.

First, the pixel information output obtained in the scan example of No. 3 is the sum of the pixel information output of the photoelectric conversion unit 1 obtained in the scan examples of No. 1 and No. 2, as is clear from the above table. Same as
Signals r, g, r, g, ... in the first scan, but signals in the second scan
g, b, g, b ... Are output, and signals are output in the same order.

Since two lines are read simultaneously, the size of the signal output is 2
It is only doubled (however, it is the same as when reading the frame), and the signal processing is the same as the previous example.

In the case of No. 4, the two-line simultaneous read signal itself has the signals r, g, b as can be seen from the second and third columns of the color filter arrangement of FIG. Therefore, the luminance signal and the chrominance signal can be generated from the two columns themselves, and it is desirable to generate the luminance signal and the chrominance signal using the signals themselves from the viewpoint of vertical resolution.

FIG. 5 is a block diagram of the main part of the electronic camera that implements the scanning example of No. 4. 5, the same reference numerals as those in FIG. 3 represent the same or equivalent portions.
31a is a signal processing circuit in the electronic camera mode, 31b is a signal processing circuit in the video camera mode, 702 is the above signal processing circuit
Electronic switch for switching 31a and 31b, 703 is a terminal,
As shown in FIG. 3, the recording circuit 4 and the monitor 6 are connected.

In the electronic camera mode, the drive circuit 81 and the signal processing circuit 31a are connected by the electronic switches 701 and 702. Conversely, in the video camera mode, the drive circuit 82 and the signal processing circuit 31b are connected to perform field reading.

In the above reading, the pixel columns read are the same in every field and interlaced scanning is not performed, so the resolution in the vertical direction is reduced.

Therefore, by performing the driving as shown in the scanning example of No. 5 in the above table and performing the pseudo interlaced scanning, it is possible to reduce the deterioration of the resolution in the vertical direction even in the video camera mode.

However, in this case, it is desirable to generate the luminance signal and the color signal by the two-line simultaneous read signal itself, and at the same time, the luminance signal and the color signal are generated only by the signal of one pixel column in order to suppress vertical deterioration even in the electronic camera mode. It is desired to do.
This is because when the video camera mode is used, the essence of the present invention is to use only the picture element signal that is scanned and reset for each field as shown in Table 1 as the output of the photoelectric conversion unit 1. There is a place to do it. That is, since the purpose is to obtain a captured image from which a frame afterimage is removed by using a signal that is reset once every field period,
When the driving method of the photoelectric conversion unit 1 that resets all the signals in one field period like the line simultaneous reading method is performed, the same object generation method as the signal generation in the electronic camera mode is performed. Although it is possible to obtain a picked-up image suitable for a moving image, it is desirable to perform the signal generation as described above for the purpose of obtaining a better picked-up image. This is certainly the same as in the electronic camera mode, but if the signal is generated using the signal of the line of 2n-1 line in the even field of the odd field in the odd field, the vertical resolution can be secured. This is because the resolution may become too good and the image quality may not be suitable for moving images. That is, in this case, since the vertical aperture ratio is about 50%, the vertical resolution is increased compared to the case of 100%, but moire in both directions also increases, and this moire also causes flicker due to interlaced scanning. Will end up. In the electronic camera mode, this interference is difficult to detect because it is a still image captured by the shutter, but in the video camera mode, the moire itself increases or decreases as the captured image moves, and the screen becomes unsightly in some cases. Therefore, it is desirable to prevent an increase in moire by performing signal generation by the two-line simultaneous read signal itself as described above so as to have an aperture ratio of about 100% like the signal generation of the imaging tube. Under such conditions, the Bayer array shown in the conventional example cannot be used, and another array is required.

FIG. 6 shows an example of color filter arrangement satisfying the above conditions.
Thereby, the respective requirements in the electronic camera mode and the video camera mode are satisfied. That is, it is caused by the filters arranged in the same row.

This is because the luminance signal and the color signal can be extracted by matrix-manipulating the signal of W (white) = g + r + b Cy (cyan) = g + b Ye (yellow) = g + r.

In these color filter arrangements, W, Cy, Ye are only 1
R, G, B and R, G, Cy and G, R, G, B
As shown by, etc., any arrangement is possible as long as the luminance signal and the color signal can be obtained in one line.

FIG. 7 shows another color filter arrangement example, for example, in the Δ arrangement in which the pixels in the even columns are positioned between the pixels in the odd columns. According to this arrangement, compared to the above examples,
Further, the horizontal resolution can be increased.

Although the single plate type has been described above, the similar drive can be applied to the multiple plate type to improve the image quality in the electronic camera mode and the video camera mode.

FIG. 8 shows a two-plate type embodiment. In FIG. 8, 92 is a lens, 10 is a spectroscopic system, 1001 is a G signal photoelectric conversion unit, 1002
Is a photoelectric conversion unit for R and B signals, and 101 is a half mirror or dichroic filter. If the 101 is a G-reflective dichroic filter, it is clear that
The G color filter of the G signal photoelectric conversion unit 1001 is not required.

FIGS. 9 (a) and 9 (b) show examples of color filter arrangements used in the embodiment of FIG. 8, but since the luminance signal and the color signal only have to be generated from two plates, this color filter arrangement is limited to this. It goes without saying that it is not limited. It is also clear that the half mirror may take the color signal from one of the photoelectric signals and the other from the photoelectric signals. This two-plate type pixel column scanning may use any of the scanning examples shown in the above table, but in particular,
The scan example of No. 5 is the best.

FIG. 10 shows a three-plate type embodiment. In FIG. 10, reference numeral 92 is a lens, 101 is a spectroscopic system, and an R, G, B decomposition system as shown is desirable. It is obvious that 1001, 1003 and 1004 are photoelectric conversion units for G, B and R signals, respectively, and the scanning of each photoelectric conversion unit may be the scanning example shown in the above table.

In both the two-plate type and the three-plate type, an example in which light is dispersed by a prism is shown, but it goes without saying that a relay lens system may be used. The color filter arrangement may be any arrangement as long as it can generate a luminance signal and a color signal.

The above is clear from the fact that the present invention realizes the removal of the frame afterimage in the video camera mode by scanning the same pixel once in each field period,
The arrangement of the color filter, the spectroscopic system, and the photoelectric conversion unit is not limited to the examples.

Further, in the above description, it was explained that when the shutter button is pressed, the video camera mode is automatically changed to the electronic camera mode and the frame image is recorded, but the electronic camera mode is changed to the video camera mode by the operation of the switch (not shown). May be converted to the field image recording. Also, although not particularly shown in the figure, in the video camera mode, the shooting angle etc. may be determined by, for example, an electronic viewfinder, but since it is not normally used in the video camera mode, the lens such as TTL is used. Means may be added so that the electronic camera alone can be used without operating in the video camera mode.

〔The invention's effect〕

As is clear from the above description, according to the present invention, when the image pickup apparatus capable of recording a frame image is used as a video camera, the same pixel is scanned once in each field period, so that a frame afterimage disappears. The effect is that a good screen can be obtained on the monitor.

[Brief description of drawings]

FIG. 1 is a layout diagram of a color filter used in a conventional color image pickup device, FIG. 2 is a block diagram of a conventional electronic camera, and FIG.
FIG. 4 is a block diagram showing the first embodiment of the present invention, FIG. 4 is a waveform diagram for explaining the operation of the embodiment of FIG. 3, and FIG. 5 is a main part showing the second embodiment of the present invention. Block diagrams, FIGS. 6 and 7 are color filter layout diagrams suitable for carrying out the present invention,
Fig. 8 is a layout drawing showing a two-plate type embodiment Fig. 9 (a),
(B) is a layout view of a color filter suitable for use in the apparatus of FIG. 8, and FIG. 10 is a layout view showing a three-plate type embodiment. 1 ... Photoelectric conversion part, 2 ... 1H delay line 3 ... Signal processing circuit, 4 ... Recording circuit 5 ... Recording head, 6 ... Monitor 7 ... Control circuit, 8 ... Driving circuit 91 ... Lens , 92 …… Shutter switch 10 …… Spectral system, 81 …… Still image drive circuit 82 …… Video drive circuit 31 (31a, 31b) …… Signal processing circuit 1001, 1002, 1003, 1004 …… Photoelectric converter 701, 702 ...... Electronic switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Iwa Ayuzawa Inventor, Iwa Ayuzawa, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Home Appliances Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-57-178480 (JP, A) 58-181369 (JP, A)

Claims (2)

[Claims] 1. A photoelectric conversion unit having a plurality of pixel rows, a shutter for blocking a path of light reaching the photoelectric conversion unit, a shutter switch, and the photoelectric conversion unit in the first field. A first driving circuit for extracting a still image signal by performing interlaced scanning for reading out 2N rows and 2N + 1 rows of signals in the second field; and a moving image signal of the photoelectric conversion unit for each field period. A second driving circuit that scans all of the pixel rows required to generate the image signal once to extract a moving image signal, and a signal processing circuit that processes the image signal read from the photoelectric conversion unit, A switching circuit that switches between driving the photoelectric conversion unit by the first driving circuit and driving the photoelectric conversion unit by the second driving circuit; and, when the shutter switch is pressed, Switching the circuit to the first driving circuit, by performing exposure for a predetermined time by operating the shutter, said first
The driving circuit for extracting the still image signal, and when the shutter switch is not pressed, the switching circuit is switched to the second driving circuit to open the shutter, An image pickup device, comprising: a control circuit for causing the driving circuit of No. 2 to extract the moving image signal. 2. The signal processing circuit comprises a first signal processing circuit for processing the still image signal, and a second signal processing circuit for processing the moving image signal. The image pickup apparatus according to claim 1.