JPH0738701B2 - Electronic still camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention forms a pure electronic still image of a subject by forming an image of the subject on an image sensor, which is a photoelectric conversion device, via an optical system. The present invention relates to an electronic still camera configured to record a still image signal read from the image sensor on a recording medium such as a rotating magnetic disk.

[Prior Art] FIG. 4 shows an example of a conventional electronic still camera of this type.

Incident light from a subject (not shown) has a front lens 1, an iris (aperture) 2, and a rear lens 3 arranged on the same optical axis.
And the optical system such as the shutter 4 and the image sensor 5
Image on. As the image sensor 5, a solid-state image pickup device using a MOS, CPD, CCD or the like, or an image pickup device such as an image pickup tube, of which one having a relatively long charge retention time is preferable. The aperture value of the iris 2 and the amount of light received by the photometric unit 6 are sent to the exposure control circuit 7, and the exposure control circuit 7 controls the opening / closing operation of the shutter 4.

The image sensor 5 is controlled by the image sensor drive circuit 8. The still image signal for one frame converted into an electric signal by the image sensor 5 is sent to the signal recording circuit 9 and is modulated by the signal recording circuit 9 into a time-series video signal for displaying the luminance and hue corresponding to the pixel ( For example, FM modulation). The operation of this circuit 9 is controlled by the reference signal generation circuit 10 and the recording timing control signal 508. The modulated video signal output from the signal recording circuit 9 is amplified by the recording amplifier 11 and input to the recording head 12. At this point, the magnetic disk 13 driven by the DC motor 14 is written at a predetermined steady speed. , And the state of the specified rotation phase must be reached.

With the activation of the DC motor 14, a frequency signal corresponding to the rotation speed of the motor 14 is output from the frequency generator 15,
Taken into the servo circuit 16. The servo circuit 16 performs speed control using the frequency signal and at the same time compares the reference signal VP with the phase detection signal PG to perform phase control on the DC motor 14 and regulate the magnetic disk 13 at a predetermined constant speed rotation. Lock to rotation phase. Reference numeral 18 denotes a pickup coil, which is a PG implanted at a predetermined position on the rotating magnetic disk 13.
A (phase generator) pin (not shown) is electromagnetically detected. The detection signal is amplified by the PG amplifier 19,
The phase detection signal PG is supplied to the servo circuit 16 and the like.

When the release button 20, which is the first release operation, is first pressed, the relay lever integrated with the release button 20 enters shallowly and closes the power switch to supply power to each circuit block (power supply circuit to each circuit block. (Not shown), and further sets the signal S1 to H (high) level. Also,
When the release button 20 which is the second release operation is pressed next time, the release lever is pushed deeply and the shutter release switch is closed to set the signal S2 to the H level. The signal S1 which has become H level by the first release operation is sent to the servo circuit 16, and the DC motor 14 is started by the circuit 16. Next, the signal S2 which has become H level by the second release operation is sent to the exposure control circuit 7, and the circuit 7 opens and closes the shutter 4.

Reference numeral 21 is a servo determination circuit that determines whether or not the rotation of the magnetic disk 13 has reached a servo target value of a prescribed circuit phase at a predetermined speed. Reference numeral 30 is a read / write timing control circuit.

[Problems to be Solved by the Invention] However, in the conventional electronic still camera, since the operation time of the solid-state imaging device such as CCD is constant, the slow motion of the conventional ordinary still camera (for example, a single-lens reflex camera) is slowed down. I couldn't get the same effect as the panning shot with the shutter. Also, for the same reason, it was not possible to take a picture such as obtaining a landscape photograph with a close-up perspective by narrowing down the aperture.

Therefore, the present invention eliminates the above-mentioned drawbacks and adds a unit for operating the image pickup unit twice or more continuously and a unit for combining a plurality of images from the image pickup unit to the conventional mechanism. An object of the present invention is to provide an electronic still camera capable of obtaining a shooting effect such as a follow shot similar to that of a slow shutter of a camera, widening a range of focusing by narrowing down, and combining a plurality of images.

[Means for Solving the Problems] In order to achieve the above object, an electronic still camera according to the present invention includes an image pickup means for converting a subject image formed via an image pickup optical system into an electric signal by photoelectric conversion. , Setting means for setting the storage time in the image pickup means, and if the storage time set by the setting means is longer than a predetermined time, the image pickup means is operated twice or more in succession to obtain two or more sheets. The control means for outputting the image of 1) and the image combining means for adding and combining the plurality of images supplied from the imaging means in the memory to output one image are output.

[Operation] According to the present invention, with the above-described configuration, it is possible to capture an image for a substantially long time without performing a long-time accumulation operation in the image sensor, and it is possible to obtain a still image with an extremely high image quality.

That is, if light is incident on the image sensor for a long time of 1 second and the accumulation operation is performed during that time, the S / N deteriorates due to an increase in dark current, resulting in an image that is unbearable for viewing. Will end up. However, according to the present invention, since the above-mentioned configuration is adopted in order to realize long-time storage, there is no adverse effect due to dark current.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a schematic circuit configuration of an electronic still camera according to an embodiment of the present invention. Here, 51 is an A / D (analog-type) for digitizing an analog video signal from the image sensor 5.
Digital) converter. Reference numeral 52 is a general image correction circuit that performs processing such as shading correction for correcting the digital video signal from the A / D converter 51 into a visually beautiful image. Actually, it is a ROM (read only memory) or logic. It consists of circuits. The A / D converter 51 and the image correction circuit 52 constitute the signal recording circuit 9 described above.

53 is an adder for synthesizing a plurality of images, and outputs the logical sum of two digital values. The adder 53 is actually composed of a ROM or the like. Reference numeral 54 is an image memory that temporarily stores the video data that has been image-processed by the image correction circuit 52 and is input via the adder 53, and is composed of, for example, a RAM (random access memory). Reference numeral 55 denotes an address counter for accessing the image memory 54, which may be a synchronous clock when the image memory 54 is a serial input / output type. Adder 53
Adds the old image stored in the image memory 54 and the new image sent from the image correction circuit 52, and stores again in the image memory 54.

Reference numeral 56 is a control circuit for performing overall control according to the present invention.
According to the control procedure as shown in FIG. 2 stored in advance in the OM (program ROM) 57, the control operation described later is performed. A general MPU (microprocessor) can be used as the control circuit 56. Reference numeral 58 is a key switch for setting the shutter speed and the like. Other configurations are similar to those of the conventional example shown in FIG. 4 described above, and thus detailed description thereof will be omitted.

Next, the operation of the embodiment of the present invention will be described with reference to the flowchart of FIG. Note that S1 to S14 indicate steps of the control procedure.

First, the operator (photographer) designates a desired photographing condition such as a shutter speed with the key switch 58 before pressing down the release button 20. When the power is turned on in response to the first step (shallow press) of the release button 20, the floppy disk 13 is started, and the control circuit 56 initializes the internal timer, registers and the image memory 54. (S1). Subsequently, shooting conditions such as shutter speed and aperture are set according to the key input state of the key switch 58. At this time, when the aperture is designated as the automatic aperture, the optimal aperture value is set based on the received light amount obtained by the photometry unit 6 and the designated shutter speed. For example, if the shutter speed is 1/250 seconds and the aperture is 4
Aperture at 5.6 / 125 seconds, aperture at 1/60 seconds, aperture at 1/30 seconds 1
Set the aperture value according to the shutter speed set with the key switch 58, such as 16 in 1/15 seconds,
The iris 2 is narrowed down through the exposure control circuit 7 (S2).

Next, the second-step depression (deep depression) of the release button 20 is detected (S3), and it is determined whether the shutter speed set in S2 is equal to or longer than a predetermined reference time (S4). The reference time is set to, for example, 1/250 seconds with reference to the shutter speed at the time of normal shooting that does not require image addition processing as described later. If the shutter speed is within the normal range, the shutter 4 is opened / closed (S6) as in the conventional case, and the image signal received by the image sensor 5 through the photographing optical systems 1 and 3 is photoelectrically converted to A /. After digitization by the D converter 51 and image correction processing by the image correction circuit 52 (S
6), via the recording amplifier 11 and the recording head 12, it is stored on the track of the floppy disk 13 which is rotating at high speed (S14).

On the other hand, when S4 is affirmative, that is, when the shutter speed is a slow shutter of the reference time or more, the internal timer is started and the shutter 4 is opened (S7).
Similar to S6, the video signal from the image sensor 5 is sequentially processed to obtain new image data (S8), and at the same time, the image sensor
Address counter for old image data of the same address from 54
It is read based on 55 (S9), and the new image data and the old image data are added by the adder 53 (S10). This addition is performed on a pixel basis or on a line basis, for example.

The result of addition as described above is stored again in the same address of the image memory 54 (S11).

During the first image processing, the image memory 54 is cleared by default and there is no previous image data.
The new image data does not change even after passing through the addition processing of 53, and the new image data is stored in the image memory 54 as it is.
Next, it is determined whether or not the value of the timer, that is, the total exposure time required for the image processing up to now exceeds the set shutter speed time (S12). If not, the process returns to S8 again, and S12 is affirmative. The processes of S8 to S12 are repeated until the determination is made.

As a result, two screens, new and old, are added in the second addition.
In the third addition, the image data obtained by adding the three screens is stored in the image memory 54. Assuming that the first addition process takes, for example, 1/250 seconds, two screens are displayed at a shutter speed of 1/250 seconds, and 4 screens at 1/60 seconds.
8 screens at 1/30 second and 16 screens at 1/15 second are overlapped and stored in the image memory 54.

If the above total time matches or exceeds the shutter speed, the shutter 4 is closed (S13) and the image memory 5
The image data stored in 4 is read out and output to the recording amplifier 11, and recorded on the track of the floppy disk 13 which is rotating at high speed via the recording amplifier 11 and the recording head 12,
The necessary ending operation is performed to end the series of processing (S14).
As a result, the contents of the image memory 54 are transferred and stored on the floppy disk 13, so that the floppy disk 13 can be taken out from the camera body and used for other recording / reproducing means such as a CRT display or a color projector.
Further, when set in various printers or the like, a follow shot or a photographic image having a perspective effect can be output on a screen, a display screen, or a recording medium such as plain paper or photographic paper.

By the way, when composing a plurality of screens as described above, if the shutters 4 are opened and closed one by one, the recorded image may be blurred due to mechanical shock. Therefore, in this embodiment, the aperture for adjusting the light amount is narrowed down as described above,
The shutter 4 is kept open for the time of the set shutter speed, and the rotary mirror (not shown) for the finder is also kept raised above the optical path. However, when an electronic shutter applying a Kerr battery, for example, is used as the shutter, there is no mechanical shock, and it goes without saying that the shutter may be opened and closed for each sheet.

Further, in the above-described embodiment, since the reading and writing of the image memory 54 are performed at the same time, time-division processing is necessary, and if the input speed of the digital image signal is high, it may not be used as it is. in this case,
For example, as shown in FIG. 3, a plurality of image memories 60, 6
1 is required, and the multiplexer 59 can switch between input and output to the image memories 60 and 61. here,
Reference numerals 62 and 63 are address counters for high-speed access to the image memories 60 and 61, respectively.

First, when inputting the first image, use the multiplexer
The line L1 and the line L4 are connected by the line 59, the line L2 and the line L3 are connected (hereinafter referred to as X-type connection), and the image is input to the first image memory 60 through the lines L0, L2, and L3. When inputting the second image, the multiplexer 59 connects the line L1 and the line L3 and the line L2 and the line L4 (hereinafter, referred to as type II connection).
As the first image (old image) read from the first image memory 60 through the lines L3 and L1 and the second image (new image) input from the input line L0 are added by the adder 53 and added. The result is passed through lines L2 and L4 to the second image memory 61.
Remember.

When inputting the third image, the above-mentioned X-type connection is switched again by the multiplexer 59, and the old image read from the second image memory 61 and the new image input from the input line L0 are added by the adder 53. , The addition result is first
Image memory 60.

In this way, since the multiplexer 59 is alternately switched between the X-type connection and the II-type connection and the addition processing is performed, it is possible to take out and put in an image at high speed. A floppy disk
Of course, when the image is transferred to 13, the image in any of the image memories 60 or 61 in which the image is finally stored is read and output to the recording amplifier 11.

The image synthesizing unit 70 (see FIG. 1) in the present embodiment described above is not limited to the electronic still camera body having the image pickup unit, but can be applied to an image reproducing unit such as a separate projector or printer. When the image synthesizing unit 70 is applied to the image reproducing unit, it is possible to simultaneously reproduce two or more photographs by image synthesizing, in addition to the same effect as the above.

Further, in the configuration of the embodiment shown in FIG. 1, when the adder 53 is replaced with a subtractor and two images are combined, one image captures a focused image and the other one receives. The effect of sharpening the image apparently by capturing it as an out-of-focus image and subtracting the image of the latter out-of-focus image by a predetermined coefficient from the former in-focus image (blurring mask) It is also possible to bring out the effect.

[Effects of the Invention] As described above, according to the present invention, when the storage time of the image pickup means set by the setting means is longer than the predetermined time, the control means causes the image pickup means to be operated twice consecutively. The above operation is performed to output two or more images, and the plurality of images are added and combined in the memory to be output as one image. Therefore, the image pickup device is allowed to perform a long-time accumulation operation. In this case, it is possible to perform imaging for a substantially long time, and it is possible to obtain a still image with extremely high image quality without being adversely affected by the dark current.

Further, the following effects can be obtained.

Similar to a normal camera, the slow shutter provides shooting effects such as panning.

 Since the focus can be narrowed down, the range of focus is expanded.

 It is also possible to easily combine completely different images.

A sharp image can be obtained by combining a focused image and an out-of-focus image.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of an electronic still camera of an embodiment of the present invention, FIG. 2 is a flow chart showing an operation example of a control circuit of FIG. 1, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a block diagram showing a main part of an example, and FIG. 4 is a block diagram showing a circuit configuration of a conventional electronic still camera. 1, 3 ...... Optical system, 2 ...... Aperture, 4 ...... Shutter, 5 ...... Image sensor (CCD), 13 ...... Floppy disk, 53 ...... Adder, 54 ...... Image memory, 55 ...... Address counter , 56 …… control circuit, 59 …… multiplexer, 60, 61 …… image memory, 62, 63 …… address counter.

Claims (1)

[Claims] 1. An image pickup means for converting a subject image formed through an image pickup optical system into an electric signal by photoelectric conversion, a setting means for setting a storage time in the image pickup means, and a setting means for setting the storage time. When the accumulation time is longer than a predetermined time, the image pickup means is operated continuously two or more times to output two or more images, and a plurality of images supplied from the image pickup means. An electronic still camera, comprising: an image synthesizing unit for adding and synthesizing in a memory to output a single image.