JPH0738700B2 - Electronic still camera - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electronic still camera, more specifically, an image pickup device such as a solid-state image pickup device, which picks up an image of a subject and outputs a video signal of the image signal to a rotary recording medium such as a magnetic disk. The present invention relates to an electronic still camera for recording.

[Background of the Invention]

Recently, an image pickup device such as a solid-state image pickup device or a pickup tube is combined with a recording device using a rotary magnetic recording medium such as a magnetic disk which is inexpensive and has a relatively large storage capacity as a recording medium.
An electronic still camera system has been developed in which a subject is photographed electronically as a still image, recorded on a rotating magnetic recording medium, and an image is reproduced by a separate television system or printer.

In such an electronic still camera, an optical finder is used as the finder. When shooting while checking the subject with an optical viewfinder in an electronic still camera, recording on a recording medium such as a magnetic disk due to the characteristics of the solid-state image sensor such as CCD or the number of pixels of the image sensor is limited. The image information of the subject that is formed does not actually match the subject information that is visually recognized through the optical viewfinder. Therefore, it is normal for the photographer to have some discomfort when viewing the reproduced image.

On the other hand, there is an electronic viewfinder for the optical viewfinder, which uses the image information of the subject recorded on the recording medium to display the subject image on the display screen via an electronic viewfinder adapter as another interface. The signal is processed and displayed.

Therefore, the subject image confirmed by the electronic viewfinder is the same as the image reproduced from the image information actually recorded on the recording medium, and the recorded subject image can be confirmed as it is by the finder.

In the current electronic still cameras, an electronic viewfinder (this is not an electronic viewfinder adapter as an interface but an adapter mainly composed of a display section) can be attached as an adapter.

On the other hand, a system has been proposed in which an electronic still camera can be used as a movie camera by mounting an adapter on the electronic still camera. By attaching a movie adapter as an interface to the camera body, it is possible to switch the shooting mode from the normal mode for still shooting using the optical viewfinder provided on the camera body to the movie camera mode for shooting as a movie camera. It was made possible.

As described above, there are some conventional electronic still cameras that can be photographed by the normal mode and the movie camera,
There is no one that can switch between normal mode and movie still mode in which a movie adapter is attached and the video signal is output to the outside.

By the way, there is a conventional electronic still camera to which a so-called auto focus control for driving a focus adjusting mechanism of a photographing lens system to automatically focus on a subject is applied. Only the autofocus control is continuously performed for each shooting mode.

In this case, in the shooting mode such as the EVF mode or the movie still mode, the distance from the camera body to the subject frequently changes, so that there is a problem that power consumption by the autofocus control increases.

[Object of the Invention]

The present invention has been made in view of such circumstances,
An object of the present invention is to provide an electronic still camera in which the power consumption resulting from the autofocus control is reduced without lowering the control accuracy in the autofocus control.

[Outline of Invention]

In order to achieve the above-mentioned object, the present invention has a normal mode and an EV.
Mode switching means for switching between the F mode, an optical shutter that exposes a subject image to the image capturing means, and the image capturing means that photoelectrically converts the subject image exposed through the optical shutter and reads out a video signal corresponding to the subject image. Then, by driving the focus adjusting mechanism of the image pickup lens system to once focus on the subject, a focusing means for stopping the focusing operation thereafter and one frame read from the image pickup means on one track of the rotating rotary recording medium. Recording means for recording minute video signals, driving means for rotating the rotary recording medium, frequency signal generating means for generating a frequency signal indicating the rotation speed of the rotary recording medium, and the rotary recording medium. By detecting the phase generating member, 1 is generated for each rotation of the rotating recording medium.
Phase pulse generating means for generating one phase pulse, servo means for controlling the driving means so that the frequency signal matches a preset steady frequency, and a lock detection signal when the frequency signal matches the steady frequency A lock detection means for outputting a sync signal including a vertical sync signal to the imaging means and the recording means, and a synchronization signal generation means for outputting the first phase pulse after inputting the lock detection signal, Sync signal generating means for resetting and starting the sync signal at the time of inputting the phase pulse,
An electronic viewfinder that displays a subject image by inputting a video signal, and a control unit that controls the driving unit, the optical shutter, the imaging unit, the focusing unit, and the recording unit,
When the activation instruction is input in the normal mode, the control means activates the driving means and activates the focusing means only once, and inputs the exposure instruction,
While opening and closing the optical shutter, at least after inputting a lock detection signal from the lock detecting means, operate the image pickup means and the recording means, and in the EVF mode, open the optical shutter and operate the image pickup means. When a video signal is output to the electronic viewfinder and an activation instruction is input, the driving means is operated and the focusing means is repeatedly activated until an exposure instruction is input. When an exposure instruction is input, the optical shutter is activated. The optical shutter is closed for a time required for exposure, and the recording means is operated at least after the lock detection signal is input from the lock detection means.

〔Example〕

Hereinafter, preferred embodiments of an 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 includes a photographing lens system 10 for forming a subject image and an aperture 12.
And an imaging optical system 24 including the optical shutter 14. The taking lens system 10 of the image pickup optical system 24 is connected via the AF motor 11,
Further, the diaphragm 12 is connected to the control circuit 20 via a diaphragm motor 13. The photometric element 16 is arranged in the optical path of the image pickup optical system 24, and the detection output from the photometric element 16 is taken into the control circuit 20 as the luminance information of the subject. The mirror 15 is a mirror for guiding the reflected light from the subject to an optical finder (not shown), and is normally at the position shown by the solid line, but at the time of exposure, it is jumped up to the position shown by the dotted line.
More controlled. Regarding the exposure control, the control circuit 20 responds to the photometric element 16, the switch SW2 that operates in response to the shutter release button 22, and the synchronization signal generation circuit 18, and operates the shutter 1
4 and diaphragm 12 are controlled.

In the present embodiment, the shutter release button 22 operates in a two-step stroke, and the switch SW1 is closed in the first stroke of the shutter release button 22 so that the circuit system power supply 76 responds to turn on the power to each part of the apparatus. As a result, the motor 44 that drives the magnetic disk 42 as a rotary recording medium is activated by a drive signal from the servo circuit 50 described later, and the AF lens 11 that receives the control signal from the control circuit 20 causes the taking lens system 10 to operate. Driven along the optical axis for automatic focusing (auto focus control)
Is done.

Further, the control circuit 20 operates so as to perform shutter release, photographing, and recording in the next stroke of the button 22. With such a configuration, it is configured to avoid power consumption of a power source such as a battery.

The control circuit 20 is supplied with mode switching signals MCS1 and MCS2 for switching shooting modes.The mode switching signals MCS1 and MCS2 are electronic viewfinder adapters (hereinafter referred to as EVF adapters) as described later. It is also configured to occur when the movie adapter is attached to the camera body.

When shooting stills using the optical viewfinder of the electronic still camera body, it is in normal mode.When the EVF adapter is attached to the camera body, the mode is switched to EVF mode, and when the movie adapter is attached, the movie mode is set. It can be switched to (including movie still mode and movie camera mode).

At the focal plane of the optical system 24, a solid-state image pickup device 26 having a two-dimensional image pickup cell array such as CCD is arranged.
In response to a drive signal including a vertical synchronizing signal and a horizontal synchronizing signal sent from the synchronizing signal generating circuit 18 through a control line 30, a video signal corresponding to a subject image formed on the image pickup surface 28 is accumulated, and Is output to the output line 32 as a serial signal.

The output line 32 of the image pickup device 26 is connected to the recording signal processing circuit 34. The recording signal processing 34 responds to a drive signal including a vertical synchronizing signal and a horizontal synchronizing signal sent from the synchronizing signal generating circuit 18 through a control line 36 and a phase pulse PG described later, and further sends from the control circuit 20 through a control line 35. A circuit for frequency-modulating the video signal output from the solid-state imaging device 26 by raster scanning in response to the recording instruction signal to be output, and outputting it to the output line 37 as a modulated video signal of a predetermined format. The output line 37 is connected to a magnetic recording head 40 via a recording amplifier 38.

The magnetic recording head 40 is a magnetic conversion element which is carried by a head phase mechanism conceptually shown by a dotted line 92 and which is transferred onto an empty track of the magnetic disk 42 by the head transfer circuit 90 and records a video signal on the empty track. The head transfer circuit 90 is controlled by the control circuit 20. The magnetic disk 42 has a core 48, and the core 48 is detachably attached to a rotary shaft 46 driven by a spindle motor 44, and is stationary in a predetermined direction by a motor 44, a frequency generator (FG) 54 and a servo circuit 50. Rotate.

The magnetic disk 42 has a track pitch of about 100 μm, that is, a track width of about 50 to 60 μm and a guard band width of 50 to 40 μm on a magnetic recording sheet having a small diameter of about 47 mm, for example.
About 50 tracks are recorded. The motor 44 drives the magnetic disk 42 at a predetermined rotation speed N of, for example, 3,600 rotations per minute.
It rotates at a constant speed, which enables recording of a video signal at a field or frame speed.

The core 48 is provided with a phase generator 52 for generating one phase pulse PG at a predetermined reference rotation phase (angle) per one rotation of the disk 42. A detection coil 56 is arranged near the core 48, and this is a detector that outputs a phase pulse PG to the signal line 58 when the phase generator 52 passes near the coil 56. This signal line 58 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 signal FG generated by the frequency generator 54 on the signal line 64.
And the reference clock received from the reference generation circuit 68 on the signal line 66.
It is a motor control circuit having a phase locked loop (PLL) that controls the rotation speed and rotation phase of the motor 44 according to CLK1. As a PLL control circuit, for example, Toshiba model TC9142P
Advantageously, integrated circuits for motor control such as

In the frequency generator 54, in this embodiment, the repetition frequency of the signal FG is an integer fraction of the frequency of the color subcarrier of the video signal,
Well higher than that of the phase pulse PG. For example, it is set to take a value about 20 times higher.

The reference generation circuit 68 has a crystal oscillation element 70 that generates a clock with a stable frequency, and divides it down to a reference clock CLK2 of 14.3 MHz, and further divides this to generate a frequency corresponding to a color subcarrier. Outputs (3.58MHz) CLK1 respectively 7
This is the circuit generated in 2 and 66.

The servo circuit 50 has a lock detection circuit 100. The lock detection circuit 100 counts the cycle or frequency of the frequency signal FG by the reference clock CLK1, and the motor 44 maintains a predetermined rotation speed N within a predetermined allowable range. There is. That is, it is a circuit that detects whether or not it is in the "locked" state. An example of the configuration is shown in FIG.

In FIG. 2, the lock detection circuit 100 is configured by connecting flip-flops (FF) 102 and 114, AND gates 104 and 106, a binary counter 108, and comparators 110 and 112 as shown in the figure. ing.

The lock detection circuit 100 has a third
As can be seen, the frequency signal FG received on signal line 64
(When the cycle of the frequency signal FG is counted by using the output 116 obtained by dividing the frequency in FIG. 3 (a) by 1/2 by the flip-flop 102, and it is included in the predetermined range L (FIG. 4). Is a circuit that sets the output 74 to a high level.

More specifically, one input 116 of the AND gate 104 is energized by the frequency signal FG divided by 1/2 (FIG. 3 (b)), while the other input 116 is at the high level. input
The 66 reference clock CLK1 appears at its output 120 (the same (c)). The counter 108 counts this and outputs the count data to the output 118 (the same (d)). Counter 108
It is reset when the flip-flop 102 is reset.

The two comparators 110 and 112 are circuits for comparing the count data 118 with reference values L1 and L2, respectively, and a weighted logical comparison circuit such as Toshiba model TC4063BP / BF is used. These reference values L1 and L2 are set around a predetermined steady rotation speed N, for example 360 rpm, so as to define a predetermined lock range L of rotation of the motor 44 as shown in FIG. It is appropriate to set the range L to, for example, about 2H period.

Since the value of the output data 118 of the counter 108 has an inverse relationship with the rotation speed of the motor 44, the relationship between the two is a straight line 200 in FIG.
Is plotted. Therefore, when the output data 118 is in the range L, the outputs 120 and 122 of both comparators 110 and 112 are high level, and the output of the AND gate 106 is high level. Therefore, flip-flop 114 is set and its output 74 goes high. This is a lock detect signal 75 which indicates that the rotation of the motor 44 is "locked" at a predetermined rotational speed.

The output 74 of the lock detection circuit 100 is fed through the set input S of the flip-flop 76 and the inverter 78 to the monostable circuit (M
M) 80 is connected. The output 82 of the latter is connected to an audible signal generator 84 such as a piezoelectric element, and the lock detection circuit 100
Output 74 goes from high to low for a certain period of time,
The generator 84 is energized and these audible alarms are output. Instead of or in addition to the audible alarm, a visual display device that outputs a visual display may be used.

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

The Q output 85 of the flip-flop 76 is connected to another input of the AND gate 60, and the output 86 of the latter is connected to the reset input R of the flip-flop 76 and the reset input of the synchronizing signal generating circuit 18. As can be seen from this configuration, when the output 74 of the lock detection circuit 100 becomes high level, that is, when the lock detection signal 75 is output, the flip-flop 76 is set and one input 85 of the AND gate 60 is activated. It Therefore, the first phase pulse detected by coil 52 thereafter.
PG passes through the gate 60 and is input as a reset pulse 88 to the synchronization signal generation circuit 18, which resets the circuit 18.
Further, the analog switches 150 and 152 can be switched by a control signal from the switch control circuit 20 for switching the phase input information of the servo circuit 50 for performing servo control of the spindle motor 44 and the phase reference signal between the normal mode and the movie still mode. It has become. In the normal mode, the switches 150 and 152 are in the positions indicated by solid lines, and the signal FG is selected as the phase input information and the internal reference signal is selected as the phase reference signal. Further, in the movie still mode, the switches 150 and 152 are switched to the dotted line side, the signal PG is selected as the phase input information, and the sync signal output from the sync signal generating circuit is selected as the phase reference signal. As described above, in the normal mode, the synchronizing signal generating circuit 18 is reset by the reset pulse 88 based on the signal FG, and the vertical synchronizing signal output from the synchronizing signal generating circuit 18 is synchronized with the signal FG by this reset operation. . On the other hand, in the movie still mode, the vertical synchronizing signal can be synchronized with the rotation of the servo circuit 50 and eventually the spindle motor 44.

The sync signal generation circuit 18 is a reference clock of the clock input 72.
It is a circuit that self-generates various synchronous control signals from CLK2 and outputs them to the output lines 30 and 36. For example, the output line
A sensor drive signal including a 15.7 KHz pixel clock for driving each image pickup cell of the image pickup device 26 to output accumulated charges and a synchronization signal are output to 30. A recording control signal for controlling the recording signal processing circuit 34 and synchronizing signals such as a 60 Hz vertical synchronizing signal and a horizontal synchronizing signal are output to the output line 36.

The synchronization signal generation circuit 18 is reset to the initial state by the reset pulse 88. Therefore, after confirming the reset time, various control signals can be output in a predetermined cycle with the confirmed phase. In the present embodiment, these control signals and sync signals are vertical sync signals located after a predetermined period, for example, 7H period, from the phase pulse PG, from which one unit, for example, one field (1V) still image signal It is output to the control lines 30 and 36 so as to be recorded on one track of the disc 42. Therefore, unless there is a large fluctuation in the rotation of the magnetic disk 42, the subsequent vertical synchronizing signal is generated in synchronization with the pulse PG with a delay of substantially 7H. As the synchronizing signal generating circuit 18, for example, a model MN6064 manufactured by Matsushita Electric Industrial Co., Ltd. is used.

Next, as an interface to the electronic still camera body
A mode switching signal generating circuit for generating mode switching signals MCS1 and MCS2 for switching the shooting mode from the normal mode to the EVF mode or the movie mode when the EVF adapter or the movie adapter is attached will be described with reference to FIG. In the figure, a mode switching signal generation circuit 310 is provided in the camera body 300, and the circuit 310 includes comparators 312, 314, inverters 316, 318, and gate 32.
0 and resistors R1 to R4. For the sake of convenience, the resistance values of the resistors R1 to R4 are represented by the same symbols, and R1 = R2 = R3 and R4> R1 + R2 + R3. Comparator 312, 314
Inverting input terminal of which is grounded through a high resistance R4, the non-inverting input terminal is in a voltage V _2, V ₁ to the power supply voltage Vcc is divided by the resistors R1-R3. The terminal 322a of the female connector 322 provided in the camera body 300 is connected to the inverting input terminals of the comparators 312 and 314, and the terminal 322b is grounded.

On the other hand, the EVF adapter 400 is provided with a female connector 410 to be attached to the connector 322, and the connector pin 410
b is grounded, and the power supply voltage Vcc is
The voltage V ₂ 'is supplied divided by R5 to R7. The movie adapter 500 is also provided with a female connector 510 to be attached to the connector 322, the connector pin 510b of the connector 510 is grounded, and the power supply voltage Vcc is divided by the resistors R5 to R7 to the connector pin 510a. Voltage V ₁ 'is supplied.

The voltages V ₁ , V ₁ ′, V ₂ and V ₂ ′ thus set are V ₁
<V ₁ ′ <V ₂ <V ₂ ′ <Vcc. Therefore, the outputs of the comparators 312 and 314 are in a high level state when the EVF adapter 400 or the movie adapter 500 is not connected to the camera body 300. Therefore, the outputs of the inverter 316 and the AND gate 320 are both low level,
The mode switching signals MCS1 and MCS2 are not output to the control circuit 20.

Next, when the EVF adapter 400 is attached to the camera body 300,
The voltage at the inverting input terminals of the comparators 312 and 314 becomes V ₂ ′, and V ₂ ′> V ₂ > V ₁ , and therefore the outputs of the comparators 312 and 314 are inverted.

As a result, only the output of the inverter 316 becomes high level, and the mode switching signal MCS1 is output to the control circuit 20.

On the other hand, when the movie adapter 500 is attached to the camera body 300, the voltage at the inverting input terminals of the comparators 312 and 314 is V ₁ ′.
From the relationship of V ₁ <V ₁ ′ <V ₂ , the output of only the comparator 314 is inverted from the high level to the low level, and the output of the comparator 312 remains at the high level. As a result, only the mode switching signal MCS2 is output from the AND gate 320 to the control circuit 20.

In this way, in the control circuit 20, the mode switching signals MCS1 and MC
From the combination of the output states (high level or low level) of S2, it is determined which adapter is attached to the camera body 300, and various controls are performed according to the corresponding shooting mode. Here, when the movie adapter 500 is attached to the camera body 300, one of two shooting modes, movie still mode and movie camera mode, can be selected. This selection is the mode provided in the movie adapter 500. It is performed by operating a switch (not shown).

The movie adapter 500 converts the video signal output (luminance signal and color difference signals RY and BY) from the camera body 300 into a video signal, and also converts the power supply from the outside into a voltage of a predetermined level to the camera body. Power is supplied to each circuit in 300.

As a video signal output, a video signal for an electronic viewfinder is also output. Sixth
FIG. 1A is a front view and a side view showing a mounting state of the camera body 300 and the EVF adapter 400, and FIG.
FIG. 9 is a front view and a side view showing a mounting state of 0 and the movie adapter 500.

Next, the operation of the electronic still camera according to the present invention will be described based on the timing charts shown in FIGS.
FIG. 7 shows an operation example in the normal mode. In FIG. 7, when the release button 22 is operated at time t1, the switch SW1 is first closed (FIG. 7 (a)). At this point, power is supplied to each circuit section of the present apparatus, and the brightness information of the subject from the photometric element 16 is taken into the control circuit 20, and
The spindle motor 44 is driven by the drive signal from the servo circuit 50.
Also starts rotating ((k) in the same figure). At the same time AF motor
11 is continuously driven by receiving a control signal from the control circuit 20, moves the taking lens system 10 in the optical axis direction, and performs automatic focusing ((l) in the same figure). Here, the automatic focusing by the AF motor 11 is configured so that it can be continuously controlled from the time the spindle motor 44 is activated to the time it is locked, but once the subject is in focus, the shooting lens system will not move unless the subject moves. At that point, the driving of the AF motor 11 is stopped.

As the rotation speed of the spindle motor 44 increases, the coil 56 starts to output the phase pulse PG, and its repetitive synchronization becomes gradually shorter. At the same time, the frequency signal FG generated by the frequency generator 54 also has a shorter cycle, and eventually enters the “locked” state. That is, when the rotation speed of the motor 44 approaches the predetermined value N and the count value of the counter 108 falls within the predetermined lock range L, the lock signal 75 is output from the detection circuit 100, which sets the flip-flop 76. One of the inputs of gate 60 is activated. The lock signal 75 is also input to the control circuit 20 through the control line 91.

In this state, for example, when the phase pulse PG arrives from the coil 56 at time 12, the output of the gate 60 becomes high level, and the reset pulse 88 is output to the synchronization signal generation circuit 18. As a result, the vertical synchronization signal is reset at time t3 ((j) in the figure), and after time t3, the vertical synchronization signal is output substantially in synchronization with the phase pulse PG.

On the other hand, in the control circuit 20, in response to the input of the lock signal 75, the signal indicating the state of the switch SW ((b) in the figure) can be read.

Next, for example, as shown in FIG. 7 (b), when the release button 22 is further pressed at time t4 and the release switch SW2 is closed, the control circuit 20 rotationally drives the diaphragm motor 13 to open the diaphragm 12. The aperture control is started so that the aperture value becomes a predetermined aperture value based on the brightness information of the subject captured from the photometric element 16, and the mirror 15 is flipped up to complete the exposure preparation ((d) and (e) in the same figure). Further, when the driving of the aperture motor 13 is stopped at time t5, the shutter 14 is opened, the image pickup surface 28 of the solid-state image pickup device 26 is exposed, and a video signal corresponding to the subject image formed on the image pickup surface 28 is generated. The data is accumulated in the solid-state image sensor 26 and is read out in synchronization with the vertical synchronizing signal. The recording signal processing circuit 34 receives the control signal from the control circuit 20 in synchronization with the reading period of the solid-state image sensor 26, and the recording signal processing circuit 34 outputs the video signal read from the solid-state image sensor 26 to the magnetic disk 42.
After the recording, the content recorded on the magnetic disk 42 is checked at the time (time t8) when a period of 0.5 V has elapsed from the end of the recording (time (t8)). Further, at time t9, the head transfer circuit
The head 40 is fed forward by one track from 92 ((i) in the same figure).

Next, the operation in the EVF mode will be described with reference to the timing chart in FIG. In the figure, when the EVF adapter 400 is attached to the camera body 300 at time t1, the camera body 3
The mode switching signal generation circuit in 00 outputs the mode switching signal MCS1 to the control circuit 20, and power is supplied to each circuit section. As a result, the control circuit 20 starts taking in the brightness information of the subject from the photometric element 16, and the diaphragm motor 13 is rotationally driven by the control signal from the control circuit 20 to start diaphragm control ((c) in FIG. (D)). At the same time, the mirror 15 is jumped up in response to a control signal from the control circuit 20, the shutter 14 is opened, the driving of the solid-state image pickup device 26 is started, and a subject image is formed on the image pickup surface 28 of the device 26. It is imaged ((e), (f), (g) in the figure). From this time t _{1, the} solid-state imaging device is synchronized with the vertical synchronization signal ((k) in the figure) output from the synchronization signal generation circuit 18 to the solid-state imaging device 26.
A video signal is read from 26 in units of one field, and a subject image is displayed on a display screen of an electronic viewfinder (not shown) ((g) and (j) in the figure).

After the photographer confirms the subject image on the display screen of the electronic viewfinder, the release switch SW1 is closed by operating the release button 22 at the time t2 ((a) in the figure), and the spindle motor 44 rotates. Along with being driven, the AF motor 11 is also driven to rotate intermittently to take a lens system.
10 autofocus controls are performed ((l) in the figure,
(M)).

This autofocus control is always performed intermittently except during the period when the video signal is recorded on the magnetic disk 42. Even if the autofocus control is intermittently performed in this manner, the same control accuracy as that obtained by performing the autofocus control substantially continuously can be obtained.

Further, the rotation speed of the spindle motor 44 increases and approaches the predetermined value N as in the normal mode, and the counter 108
When the count value of is included in the predetermined lock range L, the lock signal 75 (not shown) is output from the detection circuit 100 at time t3.
, Which sets flip-flop 76 to energize one input of gate 60. In this state, the vertical synchronizing signal is reset at time t4 when the phase pulse PG is input to the gate 60 from the coil 56 ((l) in the figure,
(K)). After this time t4, the vertical synchronizing signal is output from the synchronizing signal generating circuit 18 substantially in synchronization with the phase pulse PG. After that, at time t5, the release button 22 is further pressed and the release switch SW2 is closed ((b) in the figure), and the aperture motor 13 is driven to perform the final aperture reduction, and at the same time, the shutter is released. 14 is closed ((c), (d), (f) in the figure).

Further, the reading of the video signal from the solid-state imaging device 26 is stopped (FIG. 9 (g)), and the input of the video signal to the EVF adapter 400 is stopped (muting) (FIG. 9 (g), (j)). )). And the final refinement is done,
When the diaphragm motor 13 is stopped at time t6 ((d) in the figure),
The shutter 14 is opened, and a subject image is formed on the image pickup surface 28 of the solid-state image pickup device 26 ((f) and (g) in the same figure). Then, at time t7, the shutter 14 is closed and the image pickup surface of the solid-state image pickup device 26 is
The exposure to 28 is completed ((f) and (g) in the same figure). After that, the signal charge is accumulated in the solid-state image sensor 26, and the video signal, that is, the accumulated charge is read out in 1-field units in synchronization with the vertical synchronization signal. The video signal read from the element 26 is recorded on a predetermined track of the magnetic disk by the magnetic head 40 via the recording signal processing circuit 34, and the time t9
After a lapse of a predetermined time (for example, 0.5 V), the recorded content is checked at time t10 ((h) in the figure).

On the other hand, at time t9 when the video signal recording is completed, the aperture motor 13
Is started, the aperture control is performed ((d) in the figure), the shutter 14 is opened ((f) in the figure), and the EVF
Input of a video signal is started in the adapter 400, and a subject image is displayed on the display screen of the electronic viewfinder ((g) in the figure).

Further, at time t11, the magnetic head 40 is moved forward by one track from the current track by the drive signal from the head transfer circuit 90 ((i) in the same figure) to prepare for the next photographing.

As can be seen from the above description, the shooting operation in the EVF mode is different from that in the normal mode. It is always performed from the time of supply, (3) Aperture control is almost always performed except at the time of recording, (4) The mirror 15 is placed in a state of being flipped up from the time of power supply, (5) The shutter 14 is temporarily controlled to perform the operations of open → close → open → close, and (6) the autofocus control is intermittently performed. This is an essential operation so that the subject image can always be confirmed on the display screen of the electronic viewfinder before shooting.

Next, the operation of the movie still mode will be described with reference to the timing chart of FIG. Time in the figure
At t1, the movie adapter 500 is attached to the camera body 300, the power switch of the movie adapter (not shown) is closed, and the movie still mode is selected by the mode switch provided on the movie adapter 500. Is switched to the dotted line side by the control signal from the control circuit 20, and the phase input information in the servo circuit 50 becomes
The FG reference is switched to the PG reference, and the phase reference signal is switched from the internal reference signal to the vertical sync signal output from the sync signal generator. Then, the mode switching signal generation circuit in the camera body 300 outputs the mode switching signal MCS2 to the control circuit 20, and the power is supplied to each circuit section. As a result, the control circuit 20 starts capturing the brightness information of the subject from the photometric element 16, and the diaphragm motor is driven by the control signal from the control circuit 20.
13 is rotationally driven to start aperture control ((c) and (d) in the same figure). This aperture control is continuously performed as long as the movie still mode is designated. At the same time, the mirror 15 is flipped up in response to a control signal from the control circuit 20, the shutter 14 is opened, the driving of the solid-state image pickup device 26 is started, and a subject image is formed on the image pickup surface 28 of the device 26. It is imaged ((e), (f), (g) in the figure).
From this time t ₁ , the synchronization signal generating circuit 18 to the solid-state image sensor 26
A video signal is read from the solid-state imaging device 26 in units of one field in synchronization with a vertical sync signal ((k) in the same figure) output to the video signal, and the video signal is converted into a video signal by the movie adapter 500 and externally output. The video signal is also output to an electronic viewfinder (not shown) mounted on the camera body 300 ((g), (j)).

In this way, the subject image is displayed on the electronic viewfinder. After the photographer confirms the subject image with the electronic viewfinder and operates the release button 22 at time t2 to close the release switch SW1 ((a) in the figure), the spindle motor 44 is rotationally driven. At the same time, the AF motor 11 is driven to rotate synchronously, and the shooting lens system
10 auto focus control is performed ((l) in the figure,
(M)). Similar to the EVF mode, this autofocus control is performed intermittently except during the period when the video signal is recorded on the magnetic disk 42, and the control accuracy is substantially the same as when the autofocus control is continuously performed. Is obtained.

Further, the rotation speed of the spindle motor 44 increases and approaches the predetermined value N as in the normal mode, and the counter 108
When the count value of is included in the predetermined lock range L, the lock signal 75 (not shown) is output from the detection circuit 100 at time t3.
, Which sets flip-flop 76 to energize one input of gate 60. In this state, the vertical synchronizing signal is reset at time t4 when the phase pulse PG is input to the gate 60 from the coil 56 ((l) in the figure,
(K)). After this time t4, the vertical synchronizing signal is output from the synchronizing signal generating circuit 18 substantially in synchronization with the phase pulse PG. After that, when the release button 22 is further pressed at time t5 and the release switch SW2 is closed ((b) in the figure), the time t5 to t6 is synchronized with the read cycle of the video signal from the solid-state image sensor 26. The video signal read from the image sensor 26 during the period of time is recorded on a predetermined track of the magnetic disk by the magnetic head 40 via the recording signal processing circuit 34, and a predetermined time (for example, 0.5 V) has elapsed from time t6. At t7, the recorded contents are checked ((h) in the same figure).

Further, when the release switch SW2 is opened at time t8, at the same time, the drive signal from the head transfer circuit 90 causes the magnetic head 40 to move forward by one track from the current track ((i) in the figure). It will prepare for the next shooting.

As can be seen from the above description, the shooting operation in the movie still mode is different from that in the normal mode. (1) When the power supply to each part of the circuit is performed at the time when the movie still mode is switched, (2) photometry for the subject is performed. Is always performed from the time of power supply, (3) The aperture control is always performed, (4) The mirror 15 is placed in a state of being flipped up from the time of power supply, and (5) the shutter 14 is the power source. Always be left open from the time of supply,
(6) The solid-state imaging device 26 is controlled so that the signal charge, that is, the video signal is always read out in synchronization with the vertical synchronizing signal from the time when power is supplied. (7) The autofocus control is intermittently performed. , (8) Spindle motor 44
Is to rotate in synchronization with the vertical synchronization signal output by the synchronization signal generation circuit 18.

These differences are due to the fact that it is necessary to always output a video signal to the outside in the movie still mode and that the distance between the camera body and the subject changes frequently.

As described above, according to this embodiment, it is possible to reduce the power consumption due to the autofocus control.

〔The invention's effect〕

As described above, according to the present invention, the autofocus control is intermittently performed in the EVF mode or the movie still mode in which the distance between the camera body and the subject is frequently changed. It is possible to reduce power consumption by the driving unit that drives the adjustment mechanism.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an electronic still camera according to the present invention, FIG. 2 is a block diagram showing a configuration example of a lock detection circuit of the embodiment shown in FIG. 1, and FIG. Two
Timing chart showing signal waveforms appearing in each part of the circuit shown in the figure, FIG. 4 is a bluff for explaining the operation of the circuit of FIG. 2, and FIG. 5 is mounting of an electronic still camera body and an EVF adapter or movie adapter. A circuit diagram showing a mode switching signal generating circuit for generating a mode switching signal at times.
Figures (A ₁ ) and (A ₂ ) are front and side views showing the mounting state of the electronic still camera body and the EVF adapter, respectively (B ₁ ),
(B ₂ ) is a front view and a side view showing the mounted state of the electronic still camera body and the movie adapter, FIG. 7 is a timing chart showing the operation of the electronic still camera in the normal mode, and FIG. 8 is an EVF mode of the electronic still camera. 9 is a timing chart showing the operation of the electronic still camera, and FIG. 9 is a timing chart showing the operation of the electronic still camera in the movie still mode. 11 ... AF motor, 12 ... Aperture, 13 ... Aperture motor, 14 ...
… Shutter, 15 …… Mirror, 18 …… Sync signal generator,
20 ... Control circuit, 22 ... Shutter release button, 26 ...
Image sensor, 34 Recording signal processing circuit, 40 Magnetic head, 42 Magnetic disk, 44 Spindle motor, 50
…… Servo circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Konishi Inventor Masahiro Konishi 2-26-30 Nishiazabu, Minato-ku, Tokyo Fuji Shashin Film Co., Ltd. Inside Photograph Co., Ltd. (72) Inventor Kazutsugu Ogata 1-324 Uetakecho, Omiya City, Saitama Prefecture Inside Fuji Photograph Co., Ltd.

Claims (1)

[Claims] 1. A mode switching means (310) for switching between a normal mode and an EVF mode, an optical shutter (14) for exposing a subject image to an image pickup means (26), and a subject image exposed through the optical shutter. Once the subject is focused by photoelectrically converting the image signal that reads out the video signal corresponding to the subject image and the focus adjustment mechanism (11) of the imaging lens system (10), the focusing operation is stopped after that. Focusing means, recording means (34, 38, 40) for recording a video signal for one frame read from the image pickup means on one track of a rotating rotating recording medium (42), and the rotating recording medium is rotated. By detecting a drive means (44) for causing, a frequency signal generating means (54) for generating a frequency signal indicating the rotation speed of the rotary recording medium, and a phase generating member (52) provided on the rotary recording medium. The rotation note Phase pulse generating means (56) for generating one phase pulse each time the recording medium makes one revolution, and servo means (50) for controlling the driving means so that the frequency signal matches a preset steady frequency. )
A lock detection means (100) for outputting a lock detection signal when the frequency signal matches a steady frequency, and a synchronization signal generation means for outputting a synchronization signal including a vertical synchronization signal to the imaging means and recording means, When the first phase pulse is input after the lock detection signal is input,
A synchronizing signal generating means (18) for resetting and starting the synchronizing signal at the time of inputting the phase pulse, an electronic viewfinder (400) for displaying a subject image by inputting a video signal, the driving means, an optical shutter, and an imaging device. And a control means (20) for controlling the focusing means and the recording means, wherein the control means activates the driving means and activates the focusing means only once when an activation instruction is input in the normal mode. When it is activated and an exposure instruction is input, the optical shutter is opened and closed, and at the same time, the image pickup means and the recording means are operated after the lock detection means is input from the lock detection means, and the optical shutter is opened in the EVF mode. And operate the image pickup means to output a video signal to the electronic viewfinder and input a start instruction. , The drive means is operated and the focusing means is repeatedly activated until an exposure instruction is input, and when the exposure instruction is input, the optical shutter is closed, and then the optical shutter is opened for a time required for exposure. An electronic still camera, wherein the recording means is operated at least after a lock detection signal is input from the lock detection means.