JPH0481385B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an electronic still camera, more specifically,
Image the subject with an imaging device such as a solid-state image sensor,
The present invention relates to an electronic still camera that records obtained video signals in a field on a rotating recording medium such as a magnetic disk.

(Prior Art) Conventionally, on the screen of a television receiver, an odd field and an even field form a pair to form one frame, and two-to-one interlacing is performed to construct a complete frame still image. It is well known.

Therefore, even in electronic still camera systems in which images captured by the electronic still camera are reproduced using a separate television receiver, some cameras are capable of recording fields and frames.

Among these, in electronic still cameras capable of field recording, image information of a subject imaged by one shutter release is recorded as a field on one track of a rotating magnetic disk, and is reproduced after field-frame conversion.

Now, as a special use of this electronic still camera that can record fields, for example, when trying to create a composite image using multiple exposures that could be done with a conventional silver halide film camera, for example, you can record the images you want to composite on individual tracks in the field. This can be achieved by recording and simultaneously reproducing (frame reproduction) the video information of these two tracks using a two-channel reproducing magnetic head.

(Problems to be Solved by the Invention) However, in conventional field recordable electronic still cameras, the recorded information recorded on each track of a magnetic disk is either an odd field or an even field depending on the timing of the shutter release. Because these signals are recorded irregularly, for example, even if you try to overlap the video information of the first track and the second track to form a composite image,
Odd fields and even fields are not always paired, so frame playback is not possible.

Furthermore, when continuous shooting is performed using such a camera, there is no signal periodicity (odd fields and even fields are repeated alternately) between the continuously shot video information, as described above. It was not possible to ``freeze'' individual images and obtain frame reproduction images similar to decomposed photographs.

An object of the present invention has been made in view of the above circumstances, and the object of the present invention is to manage individual video information sequentially recorded on each track by constantly repeating odd-numbered fields and even-numbered fields, thereby producing composite images and continuous shooting by multiple exposure. To provide an electronic still camera capable of field recording, which enables special playback at times.

(Means for Solving the Problems) That is, the above object of the present invention is to provide an optical shutter that responds to an exposure instruction, and an imaging system that images a subject by opening the optical shutter and accumulates a video signal corresponding to the subject image. means, and recording control means and recording means for field-recording the video signal on a rotating recording medium, and the video signal is recorded in an odd field and in each of the video signals stored in the imaging means in response to a plurality of shutter releases. This is achieved by an electronic still camera characterized in that even fields are managed to be read out alternately.

(Example) Next, an example of the electronic still camera according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, an electronic still camera according to an embodiment of the present invention has an imaging optical system 24 including a photographic lens system 10 for forming a subject image, an aperture 12, and an optical shutter 14. This imaging optical system 24
is connected to a control circuit 20, and this control circuit 20 responds to a photometric element 16 disposed in its optical path, a switch SW2 that responds to a shutter release button 22, and a synchronization signal generation circuit 18 for exposure control. This is a control circuit that controls the shutter 14 and the diaphragm 12.

In this embodiment, the shutter release button 22 operates in two strokes, and in the first stroke, the switch SW1 closes, the circuit power supply 76 responds, and power is turned on to each part of the apparatus. As a result, the servo circuit 50, which will be described later, starts the drive motor 44 for the magnetic disk 42 as a rotating recording medium.
Furthermore, in the next step of the button 22, the control circuit 20
operates to release the shutter, take pictures, and record. This configuration avoids wasting power from a power source such as a battery.

At the focal plane of the optical system 24, a solid-state imaging device 2 having a two-dimensional imaging cell array such as a CCD is mounted.
6 is arranged, which responds to drive signals including vertical synchronization signals and horizontal synchronization signals sent from the synchronization signal generation circuit 18 through the control line 30 to generate a subject image formed on the imaging surface 28. The corresponding video signal is accumulated and output as a serial signal to the output 32.

The output 32 of the image sensor 26 is sent to the recording signal processing circuit 3.
4, which responds to a drive signal including a vertical synchronization signal and a horizontal synchronization signal sent from the synchronization signal generation circuit 18 through a control line 36 and a phase pulse PG, which will be described later. This circuit frequency-modulates the video signal outputted from the solid-state image sensor 26 by raster scanning in response to a recording instruction signal sent through the recording instruction signal 35, and outputs it to an output 37 as a modulated video signal in a predetermined format. This output 37 is sent to magnetic recording heads 40, 4 via a switch 43 and recording amplifiers 38, 39.
Connected to 1.

The magnetic recording heads 40 and 41 have a two-channel head structure located on two adjacent tracks, and are integrally supported by a head transport mechanism conceptually indicated by a dotted line 92. 42 predetermined tracks and record video signals thereon. Head transfer circuit 90 is controlled by control circuit 20.

If the video signal to be recorded is an odd field, the switch 43 switches to the side of the magnetic head 40 located on the odd numbered track (first, third, fifth, . . . ) of the magnetic disk 42, for example. If it is an even field, the control circuit 20 will switch to the magnetic head 41 located on an even numbered track (second, fourth, sixth, . . . ). The magnetic disk 42 has a core 48 , which is removably attached to a rotating shaft 46 driven by a spindle motor 44 , and is driven at a predetermined level by the motor 44 , a frequency generator (FG) 54 , and a servo circuit 50 . Steady rotation in the direction of.

The magnetic disk 42 is, for example, a small magnetic recording sheet with a diameter of about 47 mm and a track pitch of 100 μm.
In other words, the track width is about 50 to 60 μm,
50 tracks are recorded with a guard band width of about 50 to 40 μm. The motor 44 is connected to the magnetic disk 4
2, it is rotated at a constant speed N of 3600 revolutions per minute, thereby making it possible to record video signals at field speed.

The core 48 has one phase pulse at a predetermined reference rotational phase (angle) per rotation of the disk 42.
A phase generator 52 is provided for generating PG. A detection coil 56 is disposed near the core 48, which sends a phase pulse to the signal line 58 when the phase generator 52 passes near the coil 56.
This is a detector that outputs PG. This signal line 58 is
It is connected to one input of the control circuit 20, the signal processing circuit 34, and the AND gate 60.

The servo circuit 50 supplies the drive current of the motor 44 to the connection line 62, and the frequency generator 54 supplies the drive current of the motor 44 to the connection line 62.
4, and the reference clock CLK1 received from the reference generation circuit 68 on the signal line 66.
This is a motor control circuit having a phase locked loop (PLL) that controls the rotational speed and rotational phase of the motor 44 according to the rotation speed and rotational phase of the motor 44. As the PLL control circuit, a motor control integrated circuit such as Toshiba model TC9142P is preferably used.

In this embodiment, the frequency generator 54 is configured such that the repetition frequency of the signal FG is an integer fraction of the frequency of the color subcarrier of the video signal and is sufficiently higher than that of the phase pulse PG, for example, about 20 times higher. is set to .

The reference generation circuit 68 has a crystal oscillation element 70 that generates a clock with a stable frequency, and steps down this to produce a 14.4MHz reference clock CLK2, and further divides this to produce a frequency corresponding to the color subcarrier. This circuit generates CLK1 (3.58MHz) at outputs 72 and 66, respectively.

The servo circuit 50 has a lock detection circuit 100, and the lock detection circuit 100 detects a reference clock.
This circuit counts the period or frequency of the frequency signal FG using CLK1 and detects whether the motor 44 is maintaining a predetermined rotational speed N within a predetermined tolerance range, that is, is in a "lock" state. .

When the lock detect circuit 100 is in the "lock" state, its output 74 goes high and outputs the lock detect signal 75.

Output 74 of lock detection circuit 100 is connected to set input S of flip-flop 76 and to inverter 78.
is connected to a monostable circuit (MM) 80 through. The latter output 82 is connected to an audible signal generator 84, such as a piezoelectric element, so that when the output 74 of the lock detection circuit 100 goes from a high level to a low level, the generator 84 is energized for a predetermined period of time, from which an audible alarm is output. be done. Note that instead of or in addition to the audible alarm, a visual indicator that outputs a visual indication may be used.

On the other hand, this lock signal 75 is also supplied to the control circuit 20 via a control line 91.

The Q output 85 of flip-flop 76 is connected to another input of AND gate 60, and the output 86 of the latter
is the reset input R of flip-flop 76, and
It is connected to the reset input of the synchronization signal generation circuit 18. As can be seen from this configuration, when the output 74 of the lock detection circuit 100 goes high, that is, when the lock detection signal 75 is output, the flip-flop 76 is set and the AND gate 60 is set.
One input 85 of is energized. Therefore, the first phase pulse detected by coil 52 after that
PG passes through gate 60 and reset pulse 88
The signal is input to the synchronizing signal generating circuit 18 as a signal, and the circuit 18 is reset.

The synchronizing signal generating circuit 18 is a circuit that freely generates various periodic control signals from the reference clock CLK2 of the clock input 72 and outputs them to the outputs 30 and 36. For example, the output 30 outputs a sensor drive signal including a 15.7 KHz pixel clock that drives each image sensor cell of the image sensor 26 to output accumulated charge, a synchronization signal, and the like. Furthermore, the output 30 is connected to a determination circuit 19, which determines the timing (odd field or even field) of the read video signal and controls the control circuit 20. Further, to the output 36, a recording control signal for controlling the recording signal processing circuit 34 and synchronization signals such as a 60 Hz vertical synchronization signal and a horizontal synchronization signal are output.

The synchronization signal generation circuit 18 generates a reset pulse 88
It is reset to the initial state by. Therefore, once the reset point is determined, various control signals can be outputted at predetermined cycles with the determined phase.

Next, special photography using multiple exposure using the electronic still camera of the present invention will be explained.

As an initial shooting operation, when the relay button 22 is operated and the switch SW1 is closed to turn on power to each circuit of this device, the motor 44 starts rotating and the synchronizing signal generating circuit 18 emits a drive signal. The residual charge of the photographing element 26 is discharged. When the rotation of the motor 44 stabilizes after a predetermined period of time has elapsed, the synchronization signal generation circuit 18 is reset by a reset pulse 88 issued based on the lock signal 75 output from the lock detection circuit 100 and the phase pulse PG, and photography is possible. set to state. Under these conditions, when the release button 22 is pressed into the second stroke, the control circuit 20 opens the shutter 14 in response to this, and imaging of the subject is executed for the first time. Note that the opening period of the shutter 14 depends on the illuminance of the incident light detected by the photometric element 16.

The synchronization signal generation circuit 18 generates a drive signal for alternately reading out the video signal connection timing, that is, odd-numbered fields and even-numbered fields, in synchronization with the phase pulse PG that arrives first after the shutter 14 is closed, and performs imaging using this signal. The element 26 is driven to output the accumulated charge.

Further, the determination circuit 19 detects the timing of the video signal (odd field, even field) based on the drive signal, and transmits the detected timing to the control circuit 20.

On the other hand, after the shutter is closed, the control circuit 20 sends the video signal to the recording signal processing circuit 34 to the disc 42 at the timing of the desired field based on the signal from the determination circuit 19 and with the signal PG that arrives first. Instruct recording to. As a result, the charges accumulated in the image sensor 26 are read out, and are sequentially recorded on predetermined tracks of the magnetic disk 42 by the recording signal processing circuit 34 via the switch 43 and amplifiers 38 and 39. be done.
In this embodiment, video signals of odd fields are set to be recorded on odd-numbered tracks of the magnetic disk, and video signals of even-numbered fields are recorded on even-numbered tracks.
The switch 43 switches based on the command, and a predetermined magnetic head is set. In other words, the first
For example, the odd field video signal obtained by the second shutter release is switched to be recorded on the first track of the magnetic disk. Next, when another object is imaged using the same steps as described above, this video signal is read out as an even field by the drive signal and recorded on the second track. When the recording of the first and second tracks is completed, the control circuit 20 then controls the head transfer circuit 90 to move the heads 40 and 41 to the next track position.
Then, in response to the next imaging, the video signal of the odd field is recorded on the third track, and the video signal of the next even field is sequentially recorded on the fourth track.

Once a recorded magnetic disk on which video signals of odd and even fields are alternately recorded in this manner is provided, this recorded magnetic disk is loaded into a reproducing device. The playback device uses a frame playback device with a two-channel magnetic head structure, which plays back both the video signal of the odd field on the first track of the magnetic disk and the video signal of the even field of the second track, and transmits it to the television receiver. A composite image of these fields is played back in frames.

Furthermore, when the electronic still camera of the present invention is used in continuous shooting mode, the continuous shooting mode is generally used for decomposition photography in which individual images are "frozen", for example, to study golf or tennis swings; There is a strong correlation between the pictures. Therefore,
As shown in Figure 2, each track (n, n+1,
A picture in which odd fields and even fields are recorded alternately in field/frame conversion is reproduced as shown in Figure 2a, whereas when frame reproduction is performed, adjacent two fields are recorded alternately.
Since two tracks are played back simultaneously, an image similar to an exploded photograph as shown in FIG. 2b is obtained.

Additionally, when playing back a frame, conventionally, the corresponding track was fixed, for example, the first track, the second track, the third track, and the fourth track, but in continuous shooting mode, as mentioned above, the previous and next pictures are Since there is a correlation, the number of continuous shots can be ensured by sequentially playing back frames between the first track and the second track, the second track and the third track, the third track and the fourth track, etc. during frame playback. This is an effective playback method.

In the embodiment shown in FIG. 1, the recording of the video signal was described as being performed by switching between the two channel heads using the switch 43. It's okay.

Furthermore, it is also possible to obtain the same special photography as the object of the present invention by field-recording different pictures on each track using a frame-recordable camera using a switching means that selectively switches between two tracks to be recorded. I can do it.

(Effects of the Invention) As described above, according to the electronic still camera of the present invention, a video signal to be recorded in a field is sequentially recorded on a magnetic disk by reading the odd field and even field alternately. Therefore, it is possible to obtain special photography by multiple exposure, which could be done with conventional silver halide film cameras, or to obtain images similar to decomposition photographs in continuous shooting mode.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the electronic still camera according to the present invention, FIG. 2 is a diagram illustrating a reproduced image when the electronic still camera according to the present invention is taken in continuous shooting mode, and FIG. When each track is played back sequentially in the field, FIG. 2b shows the case where frames are played back using two adjacent tracks. 18... Synchronization signal generation circuit, 19... Judgment circuit, 20... Control circuit, 22... Shutter release button, 26... Image sensor, 34... Recording signal processing circuit, 40, 41... Magnetic recording head , 42
...Magnetic disk, 43...Switcher, 90...Head transfer circuit.

Claims (1)

[Scope of Claims] 1. An optical shutter that responds to an exposure instruction, an imaging means that images a subject by opening the optical shutter and stores a video signal corresponding to the subject image, and fields the video signal on a rotating recording medium. It has a recording control means and a recording means for recording, and is managed so that odd-numbered fields and even-numbered fields among the respective video signals accumulated in the imaging means are read out alternately in response to a plurality of shutter releases. An electronic still camera characterized by: 2. The electronic still camera according to claim 1, wherein the video signal is recorded by a recording means having a two-channel head structure via a switching means that switches alternately.