JPH0430233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging device that reads a video signal from an imaging device in synchronization with an external synchronization signal, and particularly to an imaging device that is capable of high-speed shutter.

Generally used in this type of imaging device,
For example, a solid-state image sensor such as a CCD (Charge Coupled Device) is composed of a light receiving section and a transfer section, and the video signal that is photoelectrically converted in the light receiving section that receives light from the subject is sent from a synchronization signal generation circuit. Almost during the synchronization pulse period of the vertical synchronization signal, it is transferred to the transfer section, and from this transfer section, one field is transmitted in a time period of 1/60 seconds, which is 1 V during one vertical scanning period, similar to a general television video signal. I am trying to read out the video signal for 1 minute. In this way, the readout of the video signal from the solid-state image sensor is 1/60 seconds.
Therefore, it can be said that the solid-state image sensor itself has a shutter function that blocks the imaging light to the solid-state image sensor every 1/60 seconds.

However, it is not possible to achieve a shutter operation faster than 1/60 second, and some kind of ingenuity is required to achieve a shutter function faster than 1/60 second.

The present invention was developed in view of these points.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall appearance of an imaging device 1 to which the present invention is applied. As schematically shown in Figure 2,
Like a normal photosensitive film camera, it has a built-in lens system 3, iris mechanism 4, first and second shutter elements 5a, 5b, mirrors 6, 7, viewfinder 8, shutter operation member 9, etc. . Moreover, in the camera body 2, instead of a photosensitive film, a solid-state image sensor (for example, a charge-coupled device) 10 is provided for converting image information of a subject image from the lens system 3 into an electrical signal and recording it.
and a magnetic recording section 13 for magnetically recording electrical signals from the solid-state image sensor 10 onto a rotating magnetic sheet 11 serving as a magnetic recording medium using a magnetic head 12.
is built-in.

On the other hand, each of the first and second shutter elements 5
The shutter drive circuit 14 that drives the shutters a and 5b, the image sensor drive circuit 15 that drives the solid-state image sensor 10, and the motor drive circuit 17 that rotationally drives the motor 16 are controlled by a control circuit 18 in an interlocking relationship with each other. , this control circuit 18 is
The shutter operation member 9 is brought into operation by pressing the shutter operation member 9 described above. This shutter operating member 9 is
It is configured to be mechanically pressed in two stages. First, in the first stage pressing operation,
The rotational drive of the motor 16 is started, synchronized with the imaging operation by the solid-state image sensor 10, and the magnetic sheet 11 is placed on standby at the rotational phase and rotational speed state that can be recorded on the magnetic sheet 11 by the recording unit 13, and then In the second stage pressing operation, the video signal from the solid-state image sensor 10 is recorded on the magnetic sheet 11 in the rotational phase and rotational speed state of the magnetic sheet 11. In addition, magnetic sheet 1
1 is rotatably housed in a housing-like jacket 19, and this jacket 19 is detachably attached to the camera body 2. Further, image information of one still image is magnetically recorded on the magnetic sheet 11 by the magnetic head 12 so as to form an annular track for each recording track.

Next, the first and second shutter elements 5a, 5b
I will explain about it.

The first shutter element 5a and the second shutter element 5b are arranged between a first position where the optical optical path of the imaging light to the solid-state image sensor 10 is blocked and a second position where the optical optical path is not blocked. They are movably arranged and block and release the imaging light at predetermined time intervals in a leading and trailing relationship. That is, the first
The shutter element 5a changes from the state of blocking the imaging light to the open state before the second shutter element 5b, and then the second shutter element 5b
b is for changing the imaging light from the open state to the light-blocking state after a predetermined time has elapsed.

Next, the specific structure of the electronic circuit used in this embodiment will be explained along with its operation with reference to FIG.

First, the synchronization signal generator 20 outputs a vertical synchronization signal Vsync and a horizontal synchronization signal Hsync, and based on these synchronization signals, the drive circuit 21 outputs transfer clock pulses φ _H and φ _V.
The solid-state imaging device 10 is driven to perform an imaging operation using the transfer clock pulse. As described above, in the vicinity of the optical path of the imaging light irradiated to the solid-state image sensor 10, there are first and second shutter elements 5 for blocking the optical path.
a and 5b are provided.

The video signal read from the solid-state image sensor 10 is supplied to a recording system circuit 23 via an amplifier circuit 22 and also to an average value detection circuit 24 . The average value detection circuit 24 includes the solid-state image sensor 10
The average DC level L _A of the video signal from is supplied to the level comparator 25 as a detection output. In this case, the DC level of the detection output from the detection circuit 24 decreases when the subject image captured by the solid-state image sensor 10 is bright, and conversely, the DC level increases when the subject image is dark.

On the other hand, the synchronization signal generator 20 supplies the above-mentioned vertical synchronization signal Vsync to the sawtooth wave signal generator 26, and based on this vertical synchronization signal Vsync, the sawtooth wave signal generator 26 generates a signal as shown in FIG. As shown in B, a sawtooth signal SW is formed. This sawtooth wave signal SW is supplied to the level comparator 25 described above. In this case, the inclination angle θ of the sawtooth wave signal SW is set according to the aperture setting state of the iris mechanism 4, and is set to a small angle as the optical path of the imaging light is narrowed down by the iris mechanism 4. be done.

In the level comparator 25, the sawtooth wave signal SW
The level comparator ₂₅ outputs a rectangular wave signal SQ as shown in FIG. 4C.
This rectangular wave signal SQ is generated during the exposure period shown in FIG. 4K.
The monostable multivibrator 27 is triggered at its falling edge, which has a pulse width τ corresponding to T ₁ . The triggered monostable multivibrator 27 outputs a shutter pulse SP as shown in FIG. 4D every 1 V during the vertical scanning period. This shutter pulse SP is supplied to the above-mentioned AND gate circuit 28 and output from there. This AND gate circuit is gate-controlled by ON/OFF operation of the release switch 29.

Next, an example of the configuration of a pulse generation circuit and a gate signal generation circuit for driving the first shutter element 5a will be described along with their functions.

First, when the shutter operating member 9 is pressed and the release switch 29 is turned on,
The first flip-flop 30 is triggered and the Q output goes high, as shown in FIG. 4E. That is, when the shutter operation member 9 is pressed, the control circuit 18 outputs an output signal as shown in FIG. 4E at a certain arbitrary timing _t0 of the vertical synchronization signal Vsync, as shown in FIG. 4A, for example. A shutter operation signal _{tS is supplied to the shutter operation signal tS} . in this case,
Reset terminal 30 of first flip-flop 30
Since PG (VD) output is supplied to a,
As shown in FIG. 4A, at the next PG output _t0 , the Q output of this first flip-flop becomes low level (FIG. 4E). In synchronization with the fall of this Q output, the first monostable multivibrator (hereinafter referred to as "first mono multi") 31 rises as shown in FIG. 4F. Here, this first
The mono/multi 31 is configured such that the first shutter element 5a in the closed state starts to open the light receiving surface 10a of the solid-state image sensor 10 at the generation timing of the VD (PG) pulse synchronized with the vertical synchronization signal Vsync. , is a delay mono-multi for adjusting the time point at which the first shutter element 5a starts moving.

Now, at the time when the first mono-multi 31 has stopped falling, the second mono-multi 32 has its first shutter element 5a as shown in FIG. 4G.
A first shutter drive pulse _P1 is obtained, which operates the first shutter element _5a , as shown by the solid line in FIG.
It is supplied to the plunger 33 which holds Oa in the open position. Therefore, due to the action of the plunger 33, the first shutter element 5a shields the light receiving surface 10a from the falling edge of the first shutter drive pulse _P1 . This light shielding dynamic state is shown by the rise of the waveform in FIG. 4H. Then, at the timing of generation of the next VD pulse t ₁ , the light-receiving portion surface 10a is shifted from the light-blocking state to the open state. This open operation state is shown by the falling waveform of H in the figure.

As shown by the broken line in FIG. 5, when the first shutter element 5a passes the light receiving surface 10a, the first
Since the first shutter element 5a is configured to stop its movement at the point where it passes the light receiving surface 10a, for example, by a stopper member, the first shutter element 5a stops at that point. Therefore, this first shutter element 5
a is held open. In this case,
The time when the first shutter element 5a starts opening the light receiving surface 10a is the time after the solid-state image sensor 10 clears the video signal of the previous field,
At this point, in this embodiment, for example, VD
(PG) This is the pulse generation timing position.

The pulse for driving the first shutter element from the second mono-multi 32 (see FIG. 4G) is as follows:
It is also supplied to the clock input terminal 34a of the second flip-flop 34. Therefore, this second
The Q output of the third flip-flop 34 rises as shown in FIG.
The J input side of becomes high level. Therefore, on the clock input side of the third flip-flop 35,
When the next PG pulse is supplied, the Q output of the third flip-flop 35 becomes high level. The Q output of the third flip-flop 35 is connected to the reset terminal 34b of the second flip-flop 34.
At this point, the Q output of the second flip-flop 34 becomes low level. As a result, the second flip-flop 34 produces an output as shown in FIG. 4I. Furthermore, the next
When the PG pulse is supplied to the clock terminal 35a of the third flip-flop 2, the J input side is at a low level, so the Q output of the third flip-flop 35 is at a low level at this point, as shown in FIG. The output shown in J is obtained. Since this output is supplied to the AND gate circuit ₂₈ shown in FIG. ), a pulse for driving the second shutter element is supplied to the second shutter element plunger after the shutter opening time _T1 shown in FIG. 4K has elapsed.
Therefore, the second shutter element 5b starts to move due to this plunger (this is shown by the rising edge of the waveform in FIG. 4K), and begins to shield the light receiving surface 10a from light. This light shielding state by the second shutter element 5b is shown by the high level portion of the waveform in FIG. 4K. In this way, the second shutter element 5b is operated to block light, and the second shutter element 5b is stopped with the light receiving surface 10a closed.

Note that the first and second shutter elements 5a, 5b
As a mechanism for restoring the shutter element 5 to its original position, for example, each shutter element 5
A mechanism for operating the restoration plunger associated with a and 5b is used.

In this way, from the point in time when the first shutter element 5a, which has shielded the light-receiving surface 10a, starts opening its light-receiving surface 10a, that is, in response to the shutter operation signal _tS , the second external A predetermined period T ₁ from the time point t ₁ when the synchronization signal is generated (see Figure 4 K)
After the elapsed time (after the exposure time of the solid-state image sensor 10 has elapsed)
, the second shutter element 5b is connected to the light receiving surface 10a.
Since the first shutter element 5a operates to begin to block light and completely block it, the first shutter element 5a
The light receiving surface 10a can be continuously shielded from light by the second shutter element 5b from the opening start point (time point t ₁ of VD pulse generation). Therefore,
Exposure time can be shortened compared to the case where there is only one shutter element. Furthermore, the exposure time (the predetermined period T ₁ shown in FIG. 4K) can be changed by changing the light-shielding timing of the second shutter element 5b that follows the first shutter element 5a and shields the light-receiving surface 10a. can.

As described above, the present invention provides an imaging device that reads a video signal from an imaging device in synchronization with an external synchronization signal, and provides a first position that blocks an optical optical path of imaging light to the imaging device, and a first position that blocks the optical optical path of imaging light to the imaging device. first and second shutter elements, each of which is movable between a second position and a second position that does not obstruct the first and second shutter elements;
The first shutter element is moved from the first position to the second position at the time of generation of the external synchronization signal in response to a shutter operation signal, and the second shutter element is moved from the first position to the second position. After a predetermined period of time has elapsed since the shutter element moved to the second position, the shutter element moves from the second position to the first position.
and a shutter control means for controlling the camera to move the camera to the position of the camera and to cause the imaging light to enter the image sensor only for the predetermined period of time.
A high-speed shutter can be realized with a simple configuration.

In particular, when changing the exposure time, the time from when the first shutter element moves to the second position to when the second shutter element moves to the first position is electrically controlled. Therefore, the exposure time can be easily varied, and the exposure time can be quickly varied.

Furthermore, since it is possible to quickly change the exposure time, when continuously shooting a single subject to perform so-called panning shots, even when changing the exposure time to an appropriate exposure time for each captured image, it is possible to change the exposure time for each image. It becomes possible to set an appropriate exposure time for each image.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of an imaging device according to the present invention, FIG. 2 is a sectional view schematically showing the internal structure of the imaging device, and FIG. 3 is a circuit structure used in the device of the present invention. 4A to 4K are timing charts for explaining the operation of the device of the present invention, and FIG. 5 is a block diagram showing the state in which the first shutter element moves the light-receiving surface of the solid-state image sensor from an open state to a closed state. FIG. 2 is a schematic diagram for explaining the process of 1...imaging device, 5a, 5b...first and second
each shutter element, 9...shutter operating member, 10...imaging element.

Claims (1)

[Scope of Claims] 1. In an imaging device configured to read out a video signal from an imaging device in synchronization with an external synchronization signal, a first lens that blocks an optical optical path of imaging light to the imaging device is provided.
first and second shutter elements, each of which is movably arranged between a position of the first shutter element and a second position where the optical path is not obstructed; and the first shutter element is configured to respond to a shutter operation signal. and move the second shutter element from the first position to the second position at the time when the external synchronization signal is generated, and move the second shutter element after the first shutter element has moved to the second position. An imaging device comprising: shutter control means for controlling the shutter to move from the second position to the first position after a predetermined time has elapsed, and to cause imaging light to enter the image sensor only for the predetermined time.