JP3139048B2 - Electronic still camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Called CCD. ) Relates to an electronic still camera configured to record a still image signal electronically captured in the electronic still camera.

[0002]

2. Description of the Related Art Recently, various electronic still cameras have been developed in which a still image signal electronically captured by using a CCD is recorded in a recording unit such as a magnetic disk or a semiconductor memory.

In such an electronic still camera, a still image signal electronically picked up by a CCD through an optical lens system is input to a video processor, and after performing predetermined signal processing such as Y / C separation, the signal is then processed. The data compression means performs predetermined data compression and records the data in the recording unit. And the still image recorded in this recording unit is
For example, reproduction can be performed using a television receiver.

In this case, the CCD used in the electronic still camera can be externally driven and controlled in a field mode and a frame mode, so that a characteristic image can be obtained depending on the purpose of use.

When photographing is performed by an electronic still camera, the photographer generally decides the combination of the shutter speed and the aperture value according to the subject conditions. In some cases, a combination of a shutter speed and an aperture value is automatically determined according to the brightness of a subject.

The combination of the shutter speed and the aperture value greatly affects the quality of a captured image.
For this reason, it is desired that the photographer can easily confirm the image state under the same conditions as at the time of photographing.

[0007] In response to such a request, conventionally, an image reproducing function is provided, and an image is reproduced after photographing so that the state can be confirmed. However, since this method only checks the image after shooting and does not check the image state at the time when the user wants to shoot, if formal shooting is to be performed again, a chance to miss a photo opportunity may be missed. In addition, there was a disadvantage that the photographing was performed twice and the handling was troublesome.

On the other hand, an optical still camera is widely used as an optical viewfinder. Recently, when an image pickup output by a CCD is used for the viewfinder, an optical viewfinder is separately provided. There is no need to provide it, and it has been put to practical use for reasons such as cost reduction.

However, the quality of the reproduced image of the viewfinder using the image pickup output of the CCD is affected by the surrounding brightness, and especially in a dark place, the exposure time of the CCD is 1 / the field frequency of the video signal. 60) In the case of extending over N fields, CCD
Is output only once in N fields, so that it may not be possible to secure sufficient brightness as a reproduced image of the viewfinder. Also, for example,
When an exposure time as long as several seconds is set, an image pickup output from the CCD cannot be obtained during this time, so that the viewfinder has a drawback that a subject to be photographed cannot be seen at all.

[0010]

[Problems that the Invention is to Solve] In this manner, in the conventional electronic still camera, is to utilize an imaging output by the CCD in bi-menu finder, etc. in a dark place, the brightness of sufficient reconstructed image of the viewfinder Can not secure
Or if you set an exposure time that can be several seconds,
There is a disadvantage that the subject to be photographed in the viewfinder has a time in which nothing can be seen. The purpose of the present invention is
Exposure time can be set to a long time, which is sufficient for the viewfinder
An object of the present invention is to provide an electronic still camera capable of ensuring display of brightness .

[0011]

According to the present invention, an image is formed on an imaging surface.
A solid-state imaging device that outputs an image signal of a subject image to be
Set the exposure time and aperture for this solid-state image sensor
Exposure time and aperture setting means, and the solid-state imaging device
Storage means for storing an image signal output from the child,
When the exposure time for the solid-state image sensor is within the specified time
The image signals output from the solid-state imaging device are sequentially displayed.
The exposure time for the solid-state imaging device
If the time is exceeded, the image signal stored in the storage means
And an image signal output from the solid-state imaging device
And display means for displaying the display in combination with
It is configured to be.

[0012]

[0013]

As a result, according to the present invention, the state of an image under the same conditions as during shooting can be displayed on the display means in real time, and the optimum state can be selected as the shooting condition.

Further, according to the present invention, since a pseudo image signal can be output even if the exposure time is long, sufficient brightness can be ensured in the reproduced image displayed on the display means.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of the embodiment. In the figure, reference numeral 11 denotes an optical lens system which forms a subject image on an image pickup surface of a CCD 12. In this case, the optical lens system 11 enables, for example, focus adjustment (focusing control) on a subject image formed on the imaging surface of the CCD 12 by an optical system driving unit (not shown). This optical lens system 1
The control 1 is performed by appropriately adopting a control method of an electronic still camera that has been proposed variously. An aperture 13 for controlling the exposure amount of the CCD 12 is disposed between the optical lens system 11 and the CCD 12.

In this case, the exposure time of the CCD 12 is controlled by an electronic shutter control circuit 14, and the aperture of the aperture 13 is controlled by an aperture control circuit 15. In the electronic shutter control circuit 14 and the aperture control circuit 15, the exposure time and the aperture are determined by the output of the program AE control circuit 16.

The program AE control circuit 16 includes, for example,
The exposure time and the aperture are determined in accordance with the program chart shown in FIG. 2. In the program chart shown in FIG. 2, the relationship between the exposure time T, the aperture F and the brightness EV of the subject is set for each of the modes 1 to 5. For example, if EV7 is given as the brightness of the subject in a state where mode 1 is set, the exposure time T
Is set to 1/8, and the aperture F is determined to be F4, and these are output to the electronic shutter control circuit 14 and the aperture control circuit 15.

A still image signal corresponding to a subject image formed on the image pickup surface of the CCD 12 is supplied to an A / D converter via an amplifier 17.
It is sent to the converter 18. Here, the amplifier 17 amplifies the still image signal to a predetermined signal processing level.
The A / D converter 18 digitizes an image signal output from the CCD 12 as, for example, an 8-bit signal.

The image signal digitized by the A / D converter 18 is sent to a field memory 19. The field memory 19 temporarily stores an image signal for one field, and its writing and reading are controlled by the output WE of the timing generator 21.

Output from Field Memory 19 and A / D
The output from the converter 18 is sent to a changeover switch 20. The changeover switch 20 includes a timing generator 21
Is “1” when the output WE is “= 1” and the output WE is “=
When it is "0", it can be switched to the "0" side.

The output from the changeover switch 20 is sent to a line interpolation unit 22. The line interpolating unit 22 interpolates a line with respect to the image signal for one field temporarily stored in the field memory 19, thereby obtaining Odd.
This is for pseudo-conversion of an image signal of an (odd) field into an image signal of an even (even) field, and conversely, an image signal of an even field to an image signal of an odd field.

The output from the line interpolation section 22 and the output through the changeover switch 20 are sent to a changeover switch 23. The changeover switch 23 is connected to the timing generator 21.
Is switched to the "1" side when the output SEL is "= 1", and to the "0" side when the output SEL is "= 0".

The output from the changeover switch 23 is sent to a D / A converter 24, converted into an analog signal, output to a viewfinder 25, and output as a video signal. .

The timing generator 21 also outputs a signal for controlling the operation timing of the electronic shutter control circuit 14 and the aperture control circuit 15 described above. When a shutter button (not shown) is pressed, the image signal written to the field memory 19 is transferred to the memory card 26 and stored therein. Next, the operation of the embodiment configured as described above will be described. First, a case in which an image state under the same condition as that at the time of shooting can be confirmed will be described.

When a subject image captured by the optical lens system 11 via the aperture 13 is formed on the image pickup surface of the CCD 12, an image signal corresponding to the subject image is output from the CCD 12.

In this case, the exposure time of the CCD 12 is controlled by an electronic shutter control circuit 14, and the aperture of the aperture 13 is controlled by an aperture control circuit 15. The exposure time and the aperture are controlled by a program. It is determined according to the program chart of the AE control circuit 16.
For example, assuming that a program chart as shown in FIG. 2 is set in the program AE control circuit 16, the brightness of the subject becomes E in a state where the mode 1 is set.
In the case of V7, the exposure time T is 1/8 and the aperture F is F
4, the exposure time "1/8" and the aperture "F"
4 ", the CCD 12 and the aperture 13 are controlled.

The image signal output from the CCD 12 is amplified by the amplifier 17 to a predetermined signal processing level.
The signal is sent to an A / D converter 18, where it is digitized as an 8-bit signal, for example, and sent to a field memory 19. In this case, the timing generator 21 matches the operation timing of the electronic shutter control circuit 14 and the aperture control circuit 15 with the write timing of the field memory 19 so that the image signal of the subject image to be photographed is written to the field memory 19 one by one. To

In this case, WE is output from the timing generator 21.
"0" and SEL "1" are output to switch the changeover switch 20 to the "0" side and the changeover switch 23 to the "1" side so that the image signal written in the field memory 19 is always read out. . As a result, the image signal read from the field memory 19 becomes D / A
The signal is converted into an analog signal by the converter 24 and displayed on the viewfinder 25.
The photographer looking into the camera can check the state of the image to be photographed in real time.

Then, after waiting for a photo opportunity from this state, pressing a shutter button (not shown) causes
The writing to the field memory 19 is interrupted, and the image signal written to the field memory 19 at this point is transferred to the memory card 26 and stored. Next, a case will be described in which a sufficient brightness can be ensured in the reproduced image of the viewfinder even when the exposure time is long.

When a subject image captured by the optical lens system 11 via the aperture 13 is formed on the image pickup surface of the CCD 12, an image signal corresponding to the subject image is output from the CCD 12.

In this case as well, the exposure time of the CCD 12 is controlled by the electronic shutter control circuit 14 and the aperture amount of the aperture 13 is controlled by the aperture control circuit 15.
When shooting in a dark place, the CCD 12
Exposure time may extend over N fields of the field frequency of the video signal.

FIG. 3 shows a case where the exposure time of the CCD 12 becomes N = 2 as shown in FIG. In this case, the output from the CCD 12 is effective only in the Odd field as shown in FIG.
At the timing of the Odd field, a write instruction is given to the field memory 19 by the timing generator 21, and at the same time, as shown in FIGS.
SEL “1” is output, and the changeover switches 20 and 23 are each switched to the “1” side. Then, the image signal of the Odd field of the CCD 12 digitized by the A / D converter 18 is written to the field memory 19, and at the same time, is sent to the D / A converter 24 through the changeover switches 20 and 23 to be converted into an analog signal. It is output to the viewfinder 25.

Next, when the timing has shifted to the Even field timing, a read instruction is given to the field memory 19 by the timing generator 21, and at the same time, FIG.
As shown in (d), WE “0” and SEL “0” are output, and the changeover switches 20 and 23 are each switched to the “0” side. Then, the image signal of the field memory 19 read in the Odd field is transferred to the changeover switch 20.
To the line interpolating unit 22, where the line is interpolated and pseudo-converted into an Even field image signal, sent to the D / A converter 24 through the changeover switch 23, converted to an analog signal, and converted into an analog signal
Is output to

Therefore, by repeating the same operation, the image signal output from the CCD 12 and the image signal simulated from the image signal read to the field memory 19 are alternately output to the viewfinder 25. So that the reproduced image of the viewfinder 25
Sufficient brightness can be secured.

Next, FIG. 4 shows a case where the exposure time of the CCD 12 becomes N = 3 as shown in FIG.
In this case, the output from the CCD 12 is valid in the Odd field and the Even field as shown in FIG. Also in this case, the timing generator 21 first sets the field memory 1 at the timing of the Odd field.
9, a WE "1" and a SEL "1" are output at the same time, and the changeover switches 20 and 23 are respectively switched to the "1" side as shown in FIGS.
As a result, the image signal of the Odd field of the CCD 12 is written to the field memory 19 and, at the same time, is output to the viewfinder 25 through the changeover switches 20 and 23 and the D / A converter 24. Next, when the timing has shifted to the even field timing, the timing generator 21 gives a reading instruction to the field memory 19, and at the same time, as shown in FIGS.
SEL “0” is output, and the changeover switches 20 and 23 are each switched to the “0” side. As a result, the image signal of the field memory 19 read in the Odd field is supplied to the line interpolation unit 22 through the changeover switch 20, where the line signal is interpolated and pseudo-converted into the image signal of the Even field. D /
It is output to the viewfinder 25 through the A converter 24. Next, when the operation again shifts to the timing of the Odd field, the reading instruction is continuously given to the field memory 19 by the timing generator 21, and at the same time, WE “0”, S
EL “1” is output, and the changeover switch 23 is switched to “1” while the changeover switch 20 remains at “0”.
The image signal of the field memory 19 is supplied to the switch 2
0 and 23 are output from the D / A converter 24 to the viewfinder 25.

Therefore, by repeating the same operation, the image signal from the CCD 12 and the field memory 19
The image signal simulated from the read image signal and the image signal read from the field memory 19 are sequentially output, so that the reproduced image of the viewfinder 25 has sufficient brightness. Can be secured.

Next, FIG. 5 shows a case where the exposure time of the CCD 12 becomes N = 4 as shown in FIG.
In this case, the image signal from the CCD 12, the image signal simulated from the image signal read from the field memory 19, the image signal read from the field memory 19, and the image read from the field memory 19 Image signals artificially generated from the signals are output in order, and sufficient brightness can be ensured in the reproduced image of the viewfinder 25.

In the above description, the exposure time of the CCD is N =
As described above, even when an exposure time of, for example, several seconds is set, it is possible to avoid a situation in which the subject to be photographed becomes invisible in the viewfinder by the same operation as described above.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented without changing the gist.
For example, in the above-described embodiment, the case where the exposure time of the CCD 12 and the aperture amount of the aperture 13 are obtained according to the program chart of the program AE control circuit has been described, but the exposure time and the aperture amount may be manually set. The present invention is applicable.

[0041]

According to the electronic still camera of the present invention, the exposure time
Can be set for a long time, so that a display with sufficient brightness can be secured for the display on the display means, so that shooting in dark places can be reliably performed while checking with the viewfinder,
In addition, even when an exposure time of several seconds is set, an image of the subject can be output to the display means, thereby avoiding a situation where the subject to be photographed cannot be seen on the display means. Can also.

[0042]

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an example of a program chart in a program AE control circuit used in the embodiment of FIG. 1;

FIG. 3 is a time chart for explaining the operation of the embodiment of FIG. 1;

FIG. 4 is a time chart for explaining the operation of the embodiment of FIG. 1;

FIG. 5 is a time chart for explaining the operation of the embodiment of FIG. 1;

[Explanation of symbols]

11: Optical lens system, 12: CCD, 13: Aperture, 14
... Electronic shutter control circuit, 15 ... Aperture control circuit, 16 ...
Program AE control circuit, 17 ... Amplifier, 18 ... A / D
Converter 19, field memory 20, 23 switch, 21 timing generator 22, line interpolator 24 D / A converter 25 viewfinder 2,
6 Memory card.

Claims (1)

(57) [Claims] An image signal of a subject image formed on an imaging surface.
And the solid-state image pickup element for outputting, setting the exposure time and the aperture amount for the solid-state imaging device
An exposure time and aperture amount setting means for storing the image signal output from the solid-state imaging device.
If the exposure time for the solid-state imaging device is within a predetermined time,
In this case, the image signals output from the solid-state
And the exposure time for the solid-state imaging device.
If it exceeds the predetermined time, the image stored in the storage means
Image read out from signal and output from the solid-state image sensor
Display means for displaying the signal mixed with the signal.
An electronic still camera.