JPH0437620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic still camera equipped with a mechanical shutter.

Conventionally known CCD, CPD or MOS
Solid-state image sensing devices such as 3D type and other solid-state image sensors were developed and designed with the main aim of replacing existing image pickup tubes such as vidicon, and their structure was naturally designed to facilitate interlaced scanning suitable for normal television images. It is becoming something. Therefore, if you try to use this for still photography, various inconveniences will occur. One of them is the shutter function. CCD is the only device that has a shutter function in itself; CPD, MOS,
The element itself does not have a shutter function. CCD is structurally interline transfer type CCD (ILT-CCD)
It is broadly divided into two types: FT-CCD and frame transfer type CCD (FT-CCD), and proposals have been made for shutter functions for both. However, when the shutter function of the element itself is used, the only image that can be recorded is a field image, and the performance of the element is not fully utilized. In order to obtain an image that fully utilizes the performance of the element, that is, a frame image, it is possible to solve this problem by providing a shutter in front of the element. Now, considering installing a shutter that is reliable and sufficiently durable for practical use, it seems likely that a mechanical shutter will be installed. By equipping a camera with a mechanical shutter, not only CCDs but also elements such as CPDs and MOSs can be used for still photography, making it possible to record high-resolution frame images. However, it is not only convenient;
Inconveniences also arise. This is the vibration generated by mechanical shutters. For example, in the case of a focal plane shutter, the leading curtain moves and the shutter opens, then the rear curtain moves and the shutter closes, but when the shutter curtain stops moving, all of the running energy goes to the stopper. Rather than being absorbed by the camera, some of the vibrations are transmitted throughout the camera as vibrations. When a recording system that forms a recording track on a recording medium that is displaced (for example, a recording device such as a magnetic disk, magneto-optical disk, or magnetic tape) is used, this vibration may have a negative effect on recording. . This disturbs the displacement of the recording medium and makes normal recording impossible.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an electronic still camera which has a simple configuration, reduces the adverse effects of vibrations on a recording system, and improves recording conditions.

FIG. 1 shows a schematic block diagram of an embodiment. The recording format is assumed to be magnetic recording using a highly practical magnetic disk. As shown in the figure, the signals input to the recording system are a recording video signal 19,
There are five lines: a recording control signal 20, a frame and field recording switching signal 21, a synchronization signal 22, and a disk rotation start signal 23. Each block and each signal will be explained. First, light from the subject is input through lens 1, and optical system 2 uses silicon for photometry.
It is guided to a photodiode (hereinafter abbreviated as SPD) 8 and a shutter 3. Although not shown in the diagram, it goes without saying that light is also guided to the finder. The shutter is a mechanical focal plane shutter. The light passing through the shutter is converted into a time-series electrical signal by the image sensor 4,
Via the preamplifier 5, the color signal separation circuit 6 converts the red (R), green (G), and blue (B) signals into red (R), green (G), and blue (B) signals, which are then subjected to various necessary processing by the process circuit 7 and converted into recorded video signals. Input to the recording circuit. Further, the light input to the photometry SPD 8 is converted into an electrical signal, a photometry, arithmetic and control circuit 11 calculates the appropriate exposure, and the shutter is controlled through the shutter drive circuit 9 to achieve the appropriate exposure. It is also possible to control the shutter time manually. Sequence generation, control circuit 1
3 is a circuit that controls the sequence of the entire system, and outputs drive timing to each block.
The image sensor 4 is driven by a sensor drive circuit 10, and a drive pulse generation circuit 12 and a synchronization signal generation circuit 14 control detailed timing during driving.
This occurs in response to a synchronization signal. flame,
Field recording selection is a circuit that selects whether to record as a frame image or as a field image during recording, and the selection can be input manually.
Next is the release signal generation circuit, switch 1
7 and 18 are connected, and switch 17 is a ready switch, and by turning it on before switch 18, it generates a signal so that only the photometry system circuit and the synchronization signal system circuit operate, and also the disk The rotation start signal 23 starts the rotation of the magnetic disk of the recording system. The switch 18 is a release switch, and when turned on, still image recording is started. In Figure 1B, 24
The entire recording system circuit is simplified and shown as one block. 25 is a recording head, and 26 and 27 are a magnetic disk and a motor, respectively, and the whole constitutes a recording system.

Next, the operation will be explained with reference to FIG. 2 showing the time chart of each signal. Figure 2 shows an interline transfer type image sensor.
A timing chart of an embodiment in which a CCD (ILT-CCD) is used is shown. Lady switch 1
7 is turned ON and the timing from immediately before the release switch 18 is activated is shown. When the release switch 18 is turned on, the release signal generation circuit 1
6, a release signal is generated at time t21. In synchronization with the first vertical synchronization signal after generation, the overflow control gate changes from the M voltage to the H voltage after time t22, and the overflow drain drains the unnecessary charge that had been accumulated in the SPD in the CCD until then. . Here, the M voltage refers to a voltage for suppressing blooming during normal shooting.
In the example, the two-field period from time t22 to t24 is used for discharging unnecessary charges, but this period is used for aperture control and, if a quick return mirror is used, the time required for the mirror to rise, etc. It goes without saying that the shorter the time, the smaller the time lag from release to shooting, which is better. In synchronization with the overflow control gate dropping from H voltage to M voltage, the front curtain of the shutter starts running and the shutter opens. As of t24. Exposure, or charge accumulation, begins in the SPD within the CCD. Then, the shutter is controlled by the photometry, calculation, and control circuit 11.
It is controlled when the proper exposure is achieved, and the rear curtain begins to run and close. When it is completely closed, a close signal (second curtain signal) is transmitted to the sequence generation and control circuit 13 through the line 24. Exposure is completely completed at time t25. After this, all you have to do is output the recording video signal to the recording circuit in synchronization with the vertical synchronization signal and start recording, but in the case of a mechanical shutter, immediately after the trailing curtain runs, the running energy of the curtain is used as a buffer. However, not all of the vibrations can be removed, and some of the vibrations are transmitted to the entire camera as vibrations, which may have an adverse effect on the rotation of the magnetic disk in the recording system. In other words, there is a risk that the rotation of the magnetic disk will be disturbed, resulting in a state where recording is impossible. In order to avoid this risk as much as possible, even if the recording video signal can be output in synchronization with the vertical synchronization signal immediately after exposure ends, recording continues until the vibrations generated by the running energy of the trailing curtain are small or disappear. delay. t25~t26
The period of is the delay time. This time may be set in advance as the time required for the vibration to decay and become extremely small. A circuit diagram of this recording start delay circuit portion is shown in FIG. 3, and the operation timing is shown in FIG. 4. The trailing curtain signal 51 switches from H to L when the trailing curtain finishes running. Upon receiving this signal, the one-shot multivibrator 52 changes its output to L for a delay time set in advance by the timer circuit (52a). The trailing curtain signal 51 and the output of the one-shot multivibrator 52 are input to an exclusive OR 53, and the output is sampled by a D-type flip-flop 54 as a synchronizing signal 56. As a result, the output of the flip-flop 54, that is, the recording control signal becomes H in synchronization with the synchronization signal immediately after the delay time. The counter 55 is a frame
When the field switching SW 57 is set to the field recording side, the output of the flip-flop 54 is high.
The synchronization signal is counted from the time when the sync signal is reached, and at the rising edge of the second pulse, a clear signal is output to the D-type flip-flop 54, and the recording control signal 5 is output.
8 from H to L. When the switch SW 57 is set to the frame recording side, as shown in FIG. 4, the counter 55 counts the synchronization signal from the time when the output of the flip-flop 54 becomes H, and clears the flip-flop 54 at the rising edge of the third pulse. Then, the recording control signal 58 is set to H or L. The time during which the output of the one-shot multivibrator 52 is at L corresponds to the delay time.
This period is represented in FIG. 2 by the period from t25 to t26. The recording control signal changes from L to H in synchronization with the vertical synchronization signal immediately after this period, and in the example of FIG. 2, frame recording is performed. Here φV ₁ , ₂
indicates the drive waveform of the vertical CCD, and φH indicates the drive waveform of the horizontal CCD. This means that while the recording signal is H, the recording system is in the recording state. Recording completed (t28
The release signal is reset by
Complete the still shooting operation.

Next, Figure 5 shows MOS as an image sensor.
The timing chart of the embodiment assumes that the following is used. In synchronization with the vertical synchronization signal immediately after the release signal is generated, the sensor scanning clock operates in order to read out unnecessary charges in the sensor and bring it into a reset state. In the figure, 1 from t52 to t53
Although this is a field period, the clock must be operated at high speed in order to discharge unnecessary charges from all sensors and bring them into the reset state in one field period. Resetting all sensors within a period of two fields is possible at normal operating speed. Either method may be used to discharge unnecessary charges, but if other conditions are permitted, one-field high-speed reset is preferable because it can reduce the time lag from release to photographing. After resetting, the shutter begins to open in synchronization with the vertical sync signal. The period from t53 to t54 is the period during which the shutter is open, that is, the exposure period. As described above, this period is appropriately controlled by the photometry, calculation, and control circuit 11. The recording delay period from t54 to t55 is as described above. A recording control signal is output in synchronization with the vertical synchronization signal immediately after the delay period ends, and the recorded video signal is recorded on the magnetic disk. Again, frame recording is taken as an example.
Still shooting is completed with t57. As described above, with a very simple circuit configuration, it is possible to protect the recording system from vibrations caused by the rear curtain of the shutter, and because the recording operation is performed in better conditions, it is possible to record still images with less image distortion. Can be provided.

[Brief explanation of drawings]

Figure 1 is a circuit block diagram of this embodiment, and Figure 2 is an interline transfer type image sensor.
Rough timing chart when using CCD,
Figure 3 is a schematic example of a circuit for generating a recording delay period, Figure 4 is an operation timing chart of the circuit example in Figure 3, and Figure 5 is an example of an image sensor.
A rough timing chart when using MOS is shown. <Explanation of symbols of main parts>, 1...Photographing lens, 4-7...Imaging means, 3...Mechanical shutter, 24-27...Recording means, 52-55
... Recording start delay means.

Claims (1)

[Scope of Claims] 1. A photographic lens that forms an image of a subject; an imaging means that converts the image of the subject into a video signal; and an imaging means that is disposed between the photographic lens and the imaging means and that captures the image of the subject. An electronic still camera comprising: a mechanical shutter that controls the amount of exposure to the mechanical shutter by opening and closing operations; and a recording means that records a video signal from the imaging means while forming a recording track on a recording medium in which the mechanical shutter is placed.・Detecting means for detecting the closing operation of the shutter and outputting a closing signal; Timing means for measuring a predetermined time after the closing signal is input and outputting a elapsed signal when the predetermined time has elapsed; An electronic still camera comprising: control means for causing the recording means to start recording when the progress signal is input.