JPH0473344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an electronic still camera that records signals obtained by an imaging device such as a solid-state imaging device or an imaging tube on a magnetic disk.

Conventional technology and problems Recently, imaging devices such as solid-state image sensors and image pickup tubes,
In combination with a recording device that uses an inexpensive and relatively large-capacity magnetic disk as a recording medium, the subject is photographed purely electronically as a still photograph, and this is recorded on a rotating disk, and the images cannot be played back separately. An electronic still camera was devised that could be used with television systems and printers, and is attracting attention as a future replacement for the current cameras that use silver halide film, which require chemical processing.

Such an electronic still camera, like a conventional camera using silver halide film, stops the photoreceptor during photographing, moves the photoreceptor after photographing, and then
There is no need to stop the photoconductor again for recording the next time the photo is taken, and the optical signal input to the image sensor, which is essentially a fixed photoconductor, is recorded on a rotating magnetic disk. Therefore, for example, by performing photography while the magnetic disk is constantly rotating, there is a possibility of performing high-speed continuous photography. For example, such an electronic still camera can be applied as a high-speed camera useful for analyzing subjects, etc. Furthermore, it can be used for general photography at various continuous shooting speeds, and the images taken in this way can be Since it can be easily reproduced on a display device such as a television, by reproducing it at various reproduction speeds, it is possible to reproduce it more interestingly than with conventional photographs using silver halide film. It can be said that it is a technology.

On the other hand, such electronic still cameras, like video cameras commonly used today, read out the optical signals accumulated in the image sensor at the field rate, in other words, the optical signal accumulation time (exposure time) ) is constant and read out periodically at the field rate, it is possible to select various shutter speeds depending on the brightness of the subject, the movement speed of the subject, or the depth of field of the image you want to obtain. It is necessary to perform image formation, and the readout also needs to be performed after the above-described optical signal of indefinite length is accumulated.

Therefore, it is conceivable to read out the signals immediately after the accumulation of optical signals in the image sensor is completed, taking into consideration the signal retention time due to thermal noise of the image sensor, etc., but if this is done, each If the recording positions of the tracks are different and you want to switch the playback of each frame when playing back later on, for example on television, or when you want to play back each frame that has been shot consecutively as a moving image, it is necessary to erase the vertical blanking line of each track. This results in blurring of the image due to period mismatch, making it impossible to reproduce the image effectively as described above.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an electronic still camera that can perform recording suitable for playback in various modes.

Structure of the Invention It is an object of the present invention to provide an imaging optical system, an imaging element that converts an optical image incident from the imaging optical system into an electrical signal, and an electrical signal having different accumulation times due to the incident optical image. In an electronic still camera, the electronic still camera has an accumulation time control means for controlling the accumulation time so that it can be set, and a magnetic recording mechanism for recording electric signals converted and accumulated by the image sensor on a rotating magnetic disk. Controlling the start of accumulation of electrical signals in the accumulation time control means based on the detection of a fixed position on the circumference of the rotating magnetic disk, and sending an electric signal to the image sensor for the accumulation time set by the accumulation time control means. The first condition is that the electrical signal has been accumulated, and the second condition is to detect a certain position on the circumference of the rotating magnetic disk when the electric signal has been accumulated. This is achieved by an electronic still camera characterized by having a control circuit that controls the recording timing on a magnetic disk by satisfying the above conditions.

Embodiment of the Invention FIG. 1 is a block diagram of an embodiment of the invention. Incident light from a subject (not shown) passes through a lens 1, an aperture 2, and a shutter 3, and then enters an image sensor 4. The opening and closing of the shutter 3 is controlled by a shutter control circuit 5. The still image signal for one frame converted into an electric signal by the image sensor 4 is sent to a buffer circuit 7 via an image signal processing circuit 6 as a time-series image signal that displays brightness and hue corresponding to pixels.
recorded in The operations of these circuits 6 and 7 are controlled by a recording control circuit 8. The image signal for one frame recorded in the buffer circuit 7 is sent to a write head 10 installed on a magnetic disk 9. During such imaging and recording, when the mechanism control circuit 11 receives a shutter release operation signal from the shutter release 12, it issues a start signal to the motor 13. The rotation of the disk 9 reaches a steady speed several tens to hundreds of milliseconds after the motor 13 is started. This steady speed is set in consideration of the convenience of reading out image signals to a general-purpose television receiver.
For example, it is set to 60 revolutions per second (3600 rpm).

A timing signal T is recorded at a predetermined position on the disk 9, and in order to read it,
A read head 15 is installed at a predetermined angle apart from the write head 10 in the direction of disk rotation. The timing signal read by the read head 15 is supplied to a timing detection circuit 16. The timing detection circuit 16 uses a timer circuit or other appropriate means to determine whether the interval between timing signals received from the reading head 15 has become less than a predetermined value, that is, whether the rotation of the disk 9 has reached a steady speed. The variable frequency divider circuit 17 and the trigger pulse generator circuit 2 detect the timing signal over the entire period of steady speed.
Output to 0.

Among the circuits to which this timing signal is input, the variable frequency divider circuit 17 divides the frequency of the periodic timing signal received from the detection circuit 16 and supplies it to the trigger pulse generation circuit 20, but this frequency division ratio is It is changed according to the output of the continuous shooting speed selection circuit 18. The continuous shooting speed selection circuit 18 selects the user's continuous shooting speed designation information received at the input terminal 19 and the received light amount sensor 14.
The continuous shooting speed to be output to the frequency dividing circuit 17 is selected based on the amount of light received from the frequency dividing circuit 17. That is, if the amount of light received is large enough to enable continuous shooting at the speed specified by the user, the continuous shooting speed selection circuit 18 selects the specified continuous shooting speed and notifies the user that the user's request has been accepted. The user is notified by a light emitting diode or the like (not shown). On the other hand, if the amount of received light is insufficient, the maximum continuous shooting speed that can be achieved under the amount of received light is selected, and the user is notified of this using a different color light emitting diode or the like. The frequency-divided timing pulse is supplied from the variable frequency divider circuit 17 to the trigger pulse generation circuit 20 in accordance with the continuous shooting speed selected in this manner.

On the other hand, the trigger pulse generation circuit 20 receives the timing pulse of the magnetic disk 9 from the timing detection circuit 16, and also receives the timing pulse from the variable frequency dividing circuit 1.
The frequency-divided timing pulse from 7 and the shutter status display signal from the shutter control circuit 5 are input,
The timing at which the accumulation of electrical signals in the image sensor 4 is completed is detected, and a certain position on the circumference of the rotating magnetic disk 9 is detected when the accumulation of electrical signals is completed, thereby generating a recording timing pulse. is output to the recording control circuit 8, and also generates various trigger pulses for controlling other circuit parts.

FIG. 2 is a waveform diagram for explaining the operation of the circuit shown in FIG. 1. When the shutter release signal input to the mechanism control circuit 11 is turned on, the motor 13 is started, and after a while, the disk rotation speed reaches a steady value, and the timing detection circuit 16 outputs a periodic signal to the variable frequency divider circuit 17. Supply of timing pulses is started. This timing pulse is transmitted to the continuous shooting speed selection circuit 18 in the variable frequency dividing circuit 17.
The frequency is divided by the frequency division ratio selected by (in the illustrated example, the frequency division ratio is 3), and as the frequency division timing pulse,
The signal is supplied to the shutter control circuit 5. Upon receiving this, the shutter control circuit 5 opens the shutter 3 for a period corresponding to the amount of light received from the received light amount sensor 14. Therefore, the shutter 3 is opened by the first frequency division timing pulse, and the first frame is transferred to the image element 4.
will be incorporated into.

On the other hand, a flip-flop 21 in the trigger pulse generating circuit 20 receives a frequency dividing timing signal from the variable frequency dividing circuit 17 at its set terminal S, and outputs "1" to its output terminal Q. That is, the flip-flop 21 is activated by the first frequency division timing pulse immediately after the disk 9 reaches the steady speed.
is set, and its output “1” is the NAND gate 2
2. A shutter state display signal indicating the open ("1") or closed ("0") state of the shutter is supplied from the shutter control circuit 5 to the inverting input terminal of the NAND gate 22. Therefore, when the shutter 3 is closed and imaging of the first frame on the image sensor 4 is completed, the "1" output of the NAND gate 22 is coupled to one input terminal of the AND gate 23. The output of this AND gate 23 is
It becomes "1" by the timing pulse supplied from the timing detection circuit 16 immediately after the completion of imaging. This is supplied to the recording control circuit 8 as a recording trigger pulse. Recording control circuit 8 that received this
causes the image signal processing circuit 6 and buffer circuit 7 to perform a series of operations consisting of reading, processing, buffering, and outputting the image signal in the image sensor 4 to the write head 10. This recording operation is performed at the timing indicated as recording operation in the bottom row of FIG. On the other hand, the recording trigger pulse is also supplied to the reset terminal R of the flip-flop 21, and the flip-flop is reset at the same time as the above-mentioned recording operation starts, preparing for the next shutter opening operation. Thereafter, the shutter opening/closing operation (imaging) and recording operation are performed alternately in the same manner.

Note that the recording control circuit 8 sends a head feed signal to the mechanism control circuit 11 in synchronization with the output command to the buffer 7. The mechanism control circuit 11 receiving this,
Controls the advance of the write head 10. The recording area on the disk 9 may be continuous in a spiral shape,
It may also consist of a number of tracks separated in the radial direction. In the latter case, the length can be set so that an integral number of still pictures (frames) can be recorded per track, and the leading edge of one frame can be set at a predetermined position.

In the above description of the embodiments, the present invention has been described with respect to an electric still camera capable of continuous shooting.
The features of the present invention include a mechanism that detects the timing at which the accumulation of electrical signals in the image sensor is completed, and a mechanism that detects the position on the circumference of the rotating magnetic disk when the accumulation of electrical signals is completed. a mechanism for generating recording timing pulses by;
The invention is not necessarily limited to the electronic still camera capable of continuous shooting as long as it has a control circuit that controls recording on the magnetic disk based on this recording timing pulse. Furthermore, in the above embodiment, the shutter 3 was provided to control the accumulation time of the electrical signal to the image sensor, but the image sensor 4
Of course, it is also possible to provide a mechanism (so-called non-mechanical shutter mechanism) for controlling the charge accumulation time and control this time using the shutter control mechanism 5.

Effects of the Invention As explained in detail above, the present invention detects that the accumulation of charges in the image sensor is completed, detects a certain position on the circumference of the rotating magnetic disk in this accumulation completion state, and Since this signal is used as a reference for recording on the magnetic disk,
Since recording is performed on each track on the magnetic disk with recording positions aligned in the circumferential direction, there is no distortion in the reproduced image when switching tracks during playback, and therefore it is possible to reproduce continuously shot images as a moving image. It is also possible to perform playback in various modes.

In addition, all major operations can be performed in synchronization only with the rotational speed of the magnetic disk, so in this way, the functions of each part will change over time, or the rotational speed of the magnetic disk will change. There is an advantage that even if the value varies, there is essentially no deterioration in imaging and recording.

Furthermore, since the present invention uses a recording method in which recording of one frame is started from a predetermined position on the disk, playback is easy, and frame-drop playback, frame selection,
Another advantage is that highly flexible playback such as piece reversal can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.
FIG. 2 is a waveform diagram illustrating the operation of the embodiment shown in FIG. 1... Lens, 2... Aperture, 3... Shutter,
4...Image sensor, 5...Shutter control circuit, 6...
...Image signal processing circuit, 7...Buffer circuit, 8...
...recording control circuit, 9...magnetic disk, 10...
Write head, 11... Mechanism control circuit, 12... Shutter release, 13... Motor, 14... Light reception amount sensor, 15... Read head, 16... Timing detection circuit, 17... Variable frequency dividing circuit , 18...
...Continuous shooting speed selection circuit, 19...Continuous shooting speed specification input terminal, 20...Trigger pulse generation circuit, 21, 2
4...Flip flop, 22, 23, 25,
26...and gate.

Claims (1)

[Claims] 1. An imaging optical system, an imaging element that converts an optical image incident from the imaging optical system into an electrical signal, and an accumulation device that controls the accumulation time of the electrical signal due to the incidence of the optical image so that it can be set to a different accumulation time. In an electronic still camera having a time control means and a magnetic recording mechanism for recording electrical signals converted and accumulated by the image sensor on a rotating magnetic disk, controlling the start of accumulation of electrical signals in the accumulation time control means based on the detection of a certain position;
The first condition is that the accumulation of electrical signals in the image sensor for the accumulation time set by the accumulation time control means has been completed, and on the circumference of the rotating magnetic disk in a state where the accumulation of the electrical signals has been completed. 1. An electronic still camera, characterized in that it has a second condition of detecting a certain position of a magnetic disk, and has a control circuit that controls recording timing on a magnetic disk by satisfying these conditions.