JPH0650907B2 - Still video camera with continuous shooting mode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In continuous shooting mode imaging, since the time allowed for one frame shooting is determined, the shutter speed and aperture value are determined so as to keep the shutter speed above a certain speed.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a still video camera (electronic still camera) for shooting a subject with an electronic image pickup device and recording the still video signal on a magnetic disk, and particularly a still video camera having a continuous shooting mode. Regarding

The operation of the still video camera in continuous shooting mode is
While the shutter release button is being pressed, the subject is imaged at regular intervals and the still video signal is sequentially recorded on each track of the magnetic disk. For example, in continuous shooting of 10 frames / second (continuous shooting), a subject is picked up and recorded every 1/10 second. Recording a still video signal onto a magnetic disk is one of the relatively time-consuming main operations performed by a still video camera when shooting one frame (time required: 1 /
60 seconds, the same below), check processing of the recorded video signal (1/60 seconds), and transfer of the magnetic head to the next unrecorded track (about 3/60 seconds). About 5/60 only with these actions
Since it takes seconds, in order to complete the shooting operation for one frame in 1/10 seconds (= 6/60 seconds), the time left for other operations is about 1/60 seconds. The shutter opening / closing operation is an operation that takes a relatively long time and the required time is variable according to the situation.
Cannot be less than a second.

In general, the exposure amount control in a program EE camera often employs a method of fixing the aperture value and determining the shutter speed, but in this case, the shutter speed is 1/60 when shooting in a relatively dark place. Seconds or less (eg 1
/ 10 seconds). Such a conventional exposure amount control method cannot be directly applied to the still video camera having the continuous shooting mode described above.

SUMMARY OF THE INVENTION An object of the present invention is to enable high-speed continuous shooting (continuous shooting) of 10 frames / second by performing exposure amount control which keeps a shutter speed above a predetermined value in any case.

To achieve this object, the present invention measures an imaging device that outputs a video signal of a subject, a diaphragm and a shutter for controlling the exposure amount to the imaging device, and the illuminance of incident light for controlling the exposure amount. In a still video camera equipped with a photometric element, a continuous shooting mode setting means, a means for determining whether or not the measured illuminance is below a predetermined value when the continuous shooting mode is set, and a measured illuminance below a predetermined value In this case, a means for setting the shutter speed and the aperture value by giving priority to the shutter speed is provided so as to maintain the shutter speed equal to or higher than a predetermined speed.

According to the present invention, in the continuous shooting mode, it is determined whether or not the measured illuminance is less than or equal to a predetermined value, and if the measured illuminance is less than or equal to the predetermined value, the shutter speed and aperture value are set with priority to the shutter speed, and the shutter speed is set to a predetermined speed (for example, It is controlled to maintain a value of 1/60 seconds or more. Therefore, since the shutter operation time within the time required for one frame shooting during the continuous shooting operation is never less than the predetermined lower limit value, it is possible to perform a preset relatively high-speed continuous shooting.

Description of Embodiments FIG. 1 schematically shows a part of the electrical configuration of a still video camera having a continuous shooting mode.

The magnetic disk 11 is built in a disk pack that houses it in a rotatable state. The still video camera is provided with a bucket that can be opened and closed. When the disk pack is inserted into the opened bucket and the bucket is then closed, the magnetic disk 11 becomes the spindle of the disk motor 33. Be chucked.

The magnetic disk 11 is provided with a plurality of tracks (for example, 50 tracks) (for example, a track pitch of 100 μm) in a concentric pattern, and each track has an FM of one field or one frame (one frame) depending on the photographing process. The modulated color video signal (including a luminance signal, a color difference signal, etc.) is magnetically recorded. The 50 tracks arranged concentrically on the magnetic recording surface of the magnetic disk 11 are arranged in order from the outer one.
Track numbers from No. 1 to No. 50 Is attached. Home position HP (origin position or standby position) is N
Outside the o.1 track. Home position HP
Is detected by the home position switch.

The operation of each part of the still video camera and the overall operation are summarized by the control device 30. This controller 30
Is composed of a central processing unit, preferably a microprocessor (hereinafter referred to as CPU), a memory for storing its program and necessary data, and an interface with peripheral elements, circuits, devices and the like.

A magnetic head 31 for writing a still video signal of an imaged subject on a predetermined track of the magnetic disk 11 is movably supported in the radial direction of the magnetic disk 11 by its transfer drive control device 35 and is transfer-controlled in the same direction. To be done. The control device 30 gives an instruction to the device 35 about the transfer direction and the transfer amount of the magnetic head 31. The device 35 includes a step motor, and the magnetic head 31 is moved in proportion to the rotation angle of the step motor. For example, each stepping pulse of the stepping motor causes the motor to rotate about 15 °, thereby moving the magnetic head 31 about 4.2 μm. Therefore, the transfer of the magnetic head 31 is performed very accurately.

In order to improve the touching between the magnetic head 31 and the rotating magnetic disk 11, a regulation plate 28 is provided on the opposite side of the magnetic head 31 with the magnetic disk 11 interposed therebetween. In addition, a phase detector 32 that generates one pulse for each rotation of the magnetic disk 11 is close to the core of the magnetic disk 11. The detection pulse from the phase detector 32 is input to the control device 30.

The disk motor 33 is feed-back controlled by the servo control circuit 34 so as to rotate at a constant rotation speed, for example, at a constant speed of 3,600 rpm. The servo control circuit 34 also
The motor 33 is started and stopped according to commands from the control device 30.

The image pickup optical system 8 is composed of an image pickup lens system 41 for forming a subject image, a diaphragm 42, and an optical shutter 43. The diaphragm 42 has its aperture value controlled by the control device 30 together with the shutter speed of the shutter 43, as will be described later, based on the received light signal level representing the detected illuminance of the incident light of the photometric element 9 arranged in the optical path. Reference numeral 43 denotes a setting mode (single shot, single shot, in response to an input by the switch 56 which is turned on by pressing the shutter release button 6).
It is controlled by the controller 30 according to the continuous shooting mode).

At the focal plane of the optical system 8, a solid-state image pickup device 44 including a two-dimensional image pickup cell array is arranged in a CCD, for example. The video data accumulated in the image pickup device 44 is read out and recorded as a serial video signal in synchronization with the vertical and horizontal synchronization signals output from the control device 30 in synchronization with the phase detection pulse from the phase detector 32. The signal processing circuit 45 FM-modulates the luminance signal component and the color-difference signal component, synthesizes these modulated signals, and sends them to the drive circuit 46. While the magnetic disk 11 is rotating at the above-mentioned constant number of rotations, an FM-modulated still video signal is written on the predetermined track by the magnetic head 31.

In track search processing and check processing,
The read signal of the magnetic head 31 is sent to the envelope detection circuit 37 via the preamplifier 36. Envelope detection circuit 37
Is a read signal of the magnetic head 31, that is, the magnetic disk 11
Is a detection circuit that detects the envelope (envelope) of the FM-modulated video signal recorded on the track and outputs a voltage signal corresponding to it. The voltage signal representing the envelope is sent to an analog / digital converter (A / D converter) 38, converted into an 8-bit digital signal representing, for example, a quantization level of 256, and input to the controller 30.

The envelope detection signal is used to determine whether the track on the magnetic disk 11 is unrecorded or recorded. If the level of the detection signal does not reach the predetermined threshold level when the magnetic head 31 is transported across the track, the track is unrecorded, and if the level has reached the threshold level. Has recorded the track. The envelope detection signal is also used in the recording check process. The recording check process is performed by using the captured still video signal with the magnetic head 31
After recording on a predetermined track, it is checked whether or not this recording is actually performed. If the envelope detection signal is above a predetermined threshold level, it is judged that recording has been performed.

This still video camera has a single-shot mode in which a still image for one frame is recorded on the magnetic disk 11 every time the shutter release button 6 is pressed, and while the shutter release button 6 is pressed. , Fixed time (eg 1 /
There is a continuous shooting mode in which one frame is taken every 10 seconds and the still images are sequentially recorded on the magnetic disk 11. A single shooting mode switch 51 and a continuous shooting mode switch 52 are provided to select these modes. It is also possible to provide only the continuous shooting mode selection switch and automatically set the single shooting mode when there is no switch input.

The control device 30 controls the rotation of the magnetic disk 11, the recording control of the video signal, the track search control, the reading of various switches, the aperture value of the aperture 42 based on the illuminance detection signal from the photometric element 9, and the The shutter speed of the shutter 43 is controlled, that is, the exposure amount is controlled.

There are basically two methods for controlling the aperture value and shutter speed based on the detection of the illuminance of incident light. One of them is to store a table in which the optimum aperture value and the optimum shutter speed are predetermined for the illuminance in the memory in the control device 30, and use the detected illuminance as a key to obtain the optimum aperture value and the optimum shutter speed from this table. It is read and performed. The other is to incorporate a calculation formula for obtaining the optimum aperture value and the optimum shutter speed into the program of the control device 30, and substitute the detected illuminance value into this calculation formula to calculate the optimum aperture value and the optimum shutter speed. It is what you want.
At this time, generally, the optimum aperture value is first obtained by the detected illuminance, and then the shutter speed is calculated using the obtained aperture value. However, as will be described later, in continuous shooting mode, the illuminance is below a certain value. Sometimes the shutter speed is fixed first.

Any of the above approaches can be used with the present invention. FIG. 2 shows a so-called program diagram.
This may be considered as a graph of the above table or a graph of the calculation result of the above-described calculation formula.

In the second diagram, the horizontal axis represents the aperture value (the so-called f value), A _V values are also shown together in parentheses. The vertical axis called shutter speed (in seconds) indicates, T _V values are also shown together in parentheses. The graph indicated by the broken line is the illuminance L
With V as a parameter, all combinations of the aperture value and the shutter speed that give an appropriate exposure amount at each illuminance are shown. Typical illuminance LV6, LV6.5, LV
7, LV8, LV9, ... LV16, LV17, LV17.5, L
Only shown for V18.

The solid line A shows an example of the aperture value and the shutter speed that give the optimum exposure amount for the detected illuminance among the above combinations. A solid line B shows an example of an aperture value and a shutter speed which are adopted when the illuminance is LV11 or less in the continuous shooting mode as described later.

FIG. 3 shows a method of determining the aperture value and the shutter speed using such a program diagram, that is, a processing procedure by the CPU of the control device 30.

The received light level signal of the photometric element 9 is read and the illuminance of the incident light is measured (step 61). Next, it is determined whether the measured illuminance is LV11 or less (step 62). This is because, as can be seen from the solid line A in FIG. 2, when the illuminance is LV11 or less, the shutter speed may be 1/60 seconds or less.

If the measured illuminance exceeds LV11, the aperture value and shutter speed corresponding to the measured illuminance are determined according to the straight line A in FIG. 2 (step 63).

When the measured illuminance is LV11 or less, it is determined whether the continuous shooting mode is set (step 64). If it is not the continuous shooting mode (single shooting mode), there is no particular problem even if the shutter speed is slow, so the aperture value and the shutter speed are determined according to the line A. (Step 63).

When the measured illuminance is LV 11 or less and the continuous shooting mode is set, the shutter speed is prioritized so that the aperture value and the shutter speed corresponding to the measured illuminance are set so that the shutter speed does not fall below a predetermined speed (1/60 second in this embodiment). Determined (step 6
Five). That is, in this embodiment, the shutter speed is fixed to 1/125 seconds as indicated by the straight line B, and the aperture value that gives the exposure amount that matches the measured illuminance under this shutter speed condition is determined. The determination of the aperture value may be performed by calling the corresponding aperture value from the table as described above, or may be calculated according to a calculation formula.

In this embodiment, the shutter speed is fixed to 1/125 second in the case of LV 11 or less and the continuous shooting mode, but it may be set to 1/60 second, for example, and it can be changed according to the measured illuminance at that time. Good. In any case, the shutter speed may be determined to be equal to or higher than the predetermined speed. Needless to say, the above-mentioned predetermined speed is not limited to 1/60 seconds. Further, the illuminance that is determined by giving priority to the shutter speed is not always LV11 or less. It may be determined according to the specifications of the still camera, particularly how many frames / second continuous shooting, the sensitivity of the imaging device, and the like.

It goes without saying that the present invention can be applied to a still video camera having a continuous shooting mode of, for example, 8 frames / second, 6 frames / second, etc. other than 10 frames / second continuous shooting.

[Brief description of drawings]

FIG. 1 is a block diagram showing a part of the electrical structure of a still video camera, FIG. 2 is a graph showing a program diagram for determining the shutter speed and aperture value according to the measured illuminance, and FIG. The figure is a flow chart showing the process of determining the shutter speed and the aperture value. 8 ... Imaging optical system, 9 ... Photometric element, 11 ... Magnetic disk, 30 ... Control device, 31 ... Magnetic head, 42 ... Aperture, 43 ... Shutter, 44 ... Solid-state imaging device, 52 ... … Continuous shooting mode switch.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Kazuya Oda 2-26-30 Nishiazabu, Minato-ku, Tokyo Fuji Shashin Film Co., Ltd. (56) Reference JP-A-63-61565 (JP, A)

Claims (1)

[Claims] 1. A still comprising an imaging device for outputting a video signal of a subject, a diaphragm and a shutter for controlling the exposure amount to the imaging device, and a photometric element for measuring the illuminance of incident light for controlling the exposure amount.・ In a video camera, continuous shooting mode setting means, means for determining whether the measured illuminance is below a predetermined value when the continuous shooting mode is set, and a predetermined speed when the measured illuminance is below a predetermined value A still video camera having a continuous shooting mode, characterized in that means for setting a shutter speed and an aperture value with priority given to the shutter speed is provided so as to maintain the above shutter speed.