JPH08171120A - Image pickup device - Google Patents

Abstract

PURPOSE: To prevent aperture blades constituting a diaphragm device for an image pickup device from colliding against a stopper, bouncing back and opening again, at the time of closing. CONSTITUTION: The image pickup device provided with a diaphragm device having aperture blades 3, a driving means 5 driving the aperture blades 3 in closing/opening directions with a rotary driving plate 53 and the stopper 56a holding the rotary driving plate 53 for regulating a movement exceeding a specific amount or more in the closing directions of the aperture blades 3, in a closing position and starting the opening of the aperture blades 3, after the rotary driving plate 53 is driven in the opening direction from the closing position by a specific amount θ2 is constituted so that when the closing of the aperture blades 3 from a maximum aperture diameter is completed, the specific amount θ2 becomes larger than the bouncing amount of the rotary driving plate 53 after colliding against the stopper 56a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus and, more particularly, to an image pickup apparatus as a diaphragm apparatus which holds diaphragm blades in a closed position by a stopper like an IG meter.

[0002]

2. Description of the Related Art Conventionally, an IG has been used as a diaphragm device for video cameras.
Meter is being used.

First, the configuration of the IG meter will be described with reference to FIG. In the diaphragm driving means 5 shown in FIG. 7, 51 is a driving coil, and 52 is a rotor integrally formed with a permanent magnet. The rotor 52 is rotatable about a shaft 52a supported by a bearing (not shown). Reference numeral 53 is a diaphragm blade drive plate which rotates integrally with the rotor 52, and the pin 53
a and 53b are provided. The blade drive plate 53 is rotatable between the stoppers 56a and 56b. 54
Is a spring for urging the diaphragm blade drive plate 53 counterclockwise in the drawing. The diaphragm blades 3a and 3b are locked to the pins 53a and 53b by locking means (not shown), and the diaphragm blade drive plate 5
They are held by a mechanism (not shown) so as to move closer to or further away from each other in parallel with the rotation of 3, and move in parallel in the direction of the arrow in the drawing.

When no current is flowing through the drive coil 51, the diaphragm blade drive plate 53 is biased counterclockwise in the figure by the spring 54, and is positioned at the closed position by the stopper 56a. At this time, the diaphragm blades 3a and 3b are shown in FIG.
The opening is closed.

When a current is passed through the drive coil 51, an electromagnetic force is generated by the interaction between the current and the permanent magnet of the rotor 52, and the rotor 52 is urged clockwise in the drawing to rotate. Then, the aperture blades 3a and 3b start to open when the rotor 52 rotates by θ1 [deg]. At this time, the relationship between the rotation angle of the rotor 52 and the aperture diameter of the diaphragm is as shown in the graph of FIG. That is, the aperture of the diaphragm starts from the position where the rotor 52 in FIG. 7 is rotated clockwise from the stopper 56a by θ1 [deg], and the aperture is further rotated by more than θ1 [deg], so that the aperture diameter becomes larger. Eventually, the urging force of the spring 54 increases with the rotation of the rotor 52, and the rotation of the rotor 52 stops at a position where the two are in balance. At this time, the diaphragm blades 3a and 3b are as shown in FIG. 7B, and the opening is open.

As shown in FIGS. 7A and 7B, the aperture diameter of the aperture blades 3a and 3b changes with the rotation angle of the rotor 52. At this time, the hall element 55 detects the amount of rotation of the permanent magnet provided integrally with the rotor 52 as a voltage. Since the electromagnetic force is proportional to the current of the coil, it is possible to control the balanced position, that is, the rotation angle of the rotor 52 and the aperture diameter of the rotor 52 by controlling the current flowing through the coil.

Next, the control method for controlling the opening diameter of the diaphragm blade 3 by passing a current through the drive coil 51 will be described with reference to FIG. In FIG. 4, reference numeral 1 is a taking lens composed of 1a and 1b, 2 is a CCD, 3 is diaphragm blades, 5 is diaphragm driving means, and 6
Is a drive circuit, and 9 is a CPU. Reference numeral 4 is a signal processing circuit, and 8 is a recording unit.

The signal processing circuit 4 integrates the image signal to generate a signal (a) representing the brightness of the photographic screen. Then, the voltage (b) obtained from the Hall element 55 (FIG. 7) is read by the CPU 9 and converted into an aperture diameter of a diaphragm according to a voltage-aperture diameter relationship table which is measured and recorded in advance. A value (c) obtained by comparing the signal representing brightness (a) with a reference signal representing the brightness of the screen at the time of proper exposure and multiplying the difference by a predetermined coefficient on the premise of the aperture opening diameter.
Is added to the current drive current to control the aperture opening diameter. Therefore, the brightness of the shooting screen is fed back so that the brightness is always close to the proper exposure.

The above is the configuration and control method of the IG meter used in the video camera.

In recent years, there has been proposed an imaging device capable of shooting a field rate movie and a frame rate still image. In such an image pickup apparatus, a diaphragm function shutter is required when shooting a movie, and a diaphragm function + shutter that functions as a rear curtain of a shutter when shooting a still image.

Therefore, it has been proposed to use the above IG meter to perform an aperture function during movie shooting and an aperture + shutter rear curtain function during still image shooting. That is, when shooting a movie, the same method as that of the above-described video camera is used. When shooting a still image, after the aperture is narrowed down to a fixed aperture with an IG meter, the front curtain uses the electronic shutter function of the CCD 2 and the rear curtain uses the IG meter as a mechanical shutter.

As described above, when the IG meter is used as the shutter that also serves as the diaphragm, the closing control of the rear curtain is as follows.
When the current flow to the drive coil 51 is stopped, the diaphragm blade moving plate 53 is biased by the spring 54 in the counterclockwise direction in the figure, so that the diaphragm blades 3a and 3b are closed by the biasing force of the spring 54. However, it is not enough power to release the high-speed shutter. Therefore, a method of applying a negative voltage to the driving coil 51 so that the diaphragm blades 3a and 3b move in the closing direction is considered.

FIG. 9 shows an example of a program diagram of exposure for photographing a still image in the image pickup apparatus. In the example shown in FIG. 9, the shutter speed is 1/250 to 1/4 second and the aperture is F.
2.8 to F22, and the photometric interlocking range is EV5 to 17. First, as a provisional initial setting, the aperture value is F = 2.8,
The shutter speed is set to 1/250 seconds, that is, Ev = 11, the CCD 2 is exposed once, and the shutter speed and aperture to be actually adopted are determined based on the photometric level and a predetermined appropriate level of the CCD.

[0014]

However, the IG meter was originally developed as a diaphragm device for a video camera,
It is not supposed to be used as a shutter for taking still images. Therefore, as shown in FIGS. 7 and 8, the diaphragm blades 3a and 3b are in a fully closed state (no current is flowing in the drive coil 51, and the urging force of the spring 54 causes the diaphragm blade drive plate 53 to move to the stopper 56a. From the time when the current is applied to the drive coil 51, a current is passed through the drive coil 51 and the drive coil 51 is actually opened and exposure is started (play), the rotation angle of the rotor 52 is only θ1 [deg]. That is, the amount of overlap (overlap amount) of the diaphragm blades 3a and 3b in the closed state.
There is not much.

Therefore, if an attempt is made to use a high-speed shutter near the open position, the diaphragm blade drive plate 53 rotates at a high speed, so that it violently collides with the stopper 56a, and the rotation angle of the rotor 52 becomes θ1 + α [deg] (α> 0). ) There is a problem in that the diaphragm blades 3a and 3b bounce back, and accordingly, the diaphragm blades 3a and 3b are once closed and then opened again, resulting in extra exposure.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide an image pickup apparatus having a diaphragm device which can prevent the diaphragm blades from re-opening due to collision with a stopper. To aim.

[0017]

In order to achieve the above-mentioned object, the invention of claim 1 relates to diaphragm blades, driving means for driving the diaphragm blades in a closing direction and an opening direction, and a closing direction of the diaphragm blades. A stopper device for restricting the movement of the diaphragm blades above a certain amount and holding the diaphragm blades in the closed position, and after the driving means drives the diaphragm blades in the opening direction from the closed position by a certain amount, the diaphragm device starts to open. In the image pickup apparatus having the above, when the diaphragm blade is closed from a maximum diaphragm aperture diameter, the fixed amount is larger than the recoiled amount with respect to the amount of the diaphragm blade colliding with the stopper and bouncing. It is characterized by

Further, the invention of claim 2 further comprises means capable of forming a plurality of diaphragm aperture diameters by the diaphragm blades, and controls the closing speed of the diaphragm blades according to the size of the diaphragm aperture diameters by the diaphragm blades. It is characterized by doing.

Further, the invention according to claim 3 is further characterized in that the closing speed is controlled to be faster as the small aperture has a smaller aperture diameter.

[0020]

According to the invention of claim 1, 2 or 3, even if the diaphragm blade collides with the closing stopper from the maximum diaphragm aperture diameter and bounces back, the fixed amount of play of the diaphragm blade is larger than the bounced amount. Therefore, the diaphragm blade does not open again.

According to the second aspect of the present invention, a certain amount of play of the diaphragm blades is made larger than the amount of bounce, so that there is a margin for bounce when closing from an aperture diameter smaller than the maximum aperture diameter. Therefore, the speed of closing the diaphragm blades is controlled according to the size of the diaphragm aperture.

According to the third aspect of the invention, since there is a margin for the rebound as described above, the smaller the aperture diameter is, the faster the closing speed is controlled. As a result, it is possible to shoot an image without blur even for a moving subject.

[0023]

FIG. 1 shows an embodiment of claim 1 of the present invention. Among the configurations shown in the figure, those having the same numbers as those described in the conventional example of FIG. 7 are the same. That is, in FIG. 1, 51 in the drive means 5 is a drive coil, and 52 is a rotor integrally configured with a permanent magnet. Rotor 52
Can be centered on a shaft 52a supported by a bearing (not shown). Reference numeral 53 is a diaphragm blade drive plate which rotates integrally with the rotor 52, and is provided with pins 53a and 53b. The blade drive plate 53 is rotatable between the stoppers 56a and 56b. Reference numeral 54 is a spring for urging the diaphragm blade drive plate 53 counterclockwise in the drawing.

When no current is flowing through the drive coil 51, the diaphragm blade drive plate 53 is biased counterclockwise in the figure by the spring 54, and is positioned and held in the closed position by the stopper 56a. At this time, the diaphragm blades 3a and 3b have an overlap amount (θ2 [deg] at the rotation angle of the rotor 52) in which the diaphragm aperture diameter does not reopen due to bouncing even if the shutter is released at the fastest shutter speed from the opening.

When a current is passed through the drive coil 51, an electromagnetic force is generated by the interaction between the current and the permanent magnet of the rotor 52, and the rotor 52 is urged clockwise in the drawing to rotate. Eventually, as the rotor 52 rotates, the urging force of the spring 54 also increases, and the rotor 52 moves at a position where the two are in balance.
Stops rotating. Since the diaphragm blades 3a and 3b are locked to the pins 53a and 53b by locking means (not shown), the diaphragm blades 3a and 3b move toward each other or away from each other in parallel with the rotation of the diaphragm blade drive plate 53 in the direction of the arrow in the figure. Thus, it is held by a mechanism (not shown) and the opening diameter is changed. At this time, the hall element 55 detects the rotation amount of the permanent magnet integrally provided in the rotor as a voltage.

Since the electromagnetic force is proportional to the coil current, it is possible to control the balanced position, that is, the rotation angle of the rotor 52, and further the aperture diameter by controlling the current flowing through the coil. At this time, the relationship between the rotation angle of the rotor 52 and the aperture diameter of the diaphragm is as shown in the graph of FIG. That is,
In FIG. 2, the rotor 52 moves from the stopper 56a to θ2 [de
g] The aperture of the diaphragm starts from the position rotated clockwise,
By rotating further than θ2 [deg], the aperture diameter becomes larger. The overlap amount of the diaphragm blades 3a and 3b indicated by the rotation angle θ2 [deg] indicates, so to speak, the play of the diaphragm blades. That is, the aperture blades actually start to open only after the drive means has been driven in the opening direction by a certain amount indicated by the overlap amount.

Next, a control method when the IG meter is used as a diaphragm / shutter will be described with reference to FIG.
The shutter button (not shown) constitutes a two-step switch. First, the first switch sw1 is pressed with a shallow stroke, and the next switch sw2 is pressed with a deeper stroke.

First, when the switch sw1 is pressed (the left end in the lower part of FIG. 5), a voltage previously measured and recorded so that the aperture opening diameter is opened is applied to the drive coil 51 (FIG. 1) to open the aperture opening diameter ( F = 2.8 (FIG. 3)) (upper left end in FIG. 5), and a focusing operation and photometry are performed using a known method.
Then, wait for the focusing operation and photometry to finish, and then
Calculate the target aperture diameter and shutter speed for proper exposure from the photometric value.

Next, when the switch sw2 is pressed (see FIG. 5).
Lower right) Feedback control (Fig. 4) is applied to the difference between the target opening diameter calculated by calculation and the actual opening diameter.
And its description) to stabilize the target opening diameter. Then, after stabilization, the charge of the CCD as the front curtain of the shutter is cleared (right in the middle part of FIG. 5), and a constant negative voltage is applied to the drive coil 51 as the rear curtain after a certain time so that the calculated shutter speed is achieved. (Fig. 5, bottom right)
The diaphragm blades 3a and 3b are closed (upper right end in FIG. 5).

At this time, as in the conventional case, the diaphragm blade drive plate 5
3 collides with the mechanical stopper 56a and bounces and bounces, and the rotor 52 rotates by θ1 + α [deg]. However, as shown in FIG. 1 of the present embodiment, the overlapping amount of the diaphragm blades 3a and 3b is θ2 [deg]. Only (θ2 ≧ θ1 + α) is taken. That is, the fixed amount of play of the diaphragm blade 3, that is, the overlap amount (θ2) is made larger than the bounce amount (θ1 + α). This prevents the diaphragm blades 3a and 3b from opening again. Therefore, proper exposure can be obtained without extra exposure.

The embodiments of claims 2 and 3 of the present invention will be described with reference to FIGS. 3 and 6. FIG. 3 is an example of a program diagram of a shutter that also serves as an aperture using the image pickup apparatus of the present invention. FIG. 6 is a diagram showing a change with time of the rotation angle of the rotor 52 when the IG meter is closed from each constant aperture opening diameter at a constant speed. IG as shown in this figure
The meter bounces differently depending on the aperture size. The bounce amount is large when the maximum aperture opening diameter, that is, the opening side is closed, and the bounce amount is small when the small aperture opening diameter, that is, the small aperture side is closed.

The overlap amount of the present invention is such that even if the shutter is released at the fastest shutter speed and the shutter is released, the aperture does not open again due to bouncing. Therefore, when the aperture is small, a slightly higher negative voltage is applied to the drive coil 51. Do not open again. Therefore, when the diaphragm blades 3a and 3b are closed, the bound amount does not exceed the overlap amount of the diaphragm blades 3a and 3b from the relation table of the diaphragm opening diameter and the bound amount which is measured and recorded in advance according to the aperture opening diameter. To
By controlling the negative voltage applied to the drive coil 51,
For example, the faster the shutter can be released as the aperture diameter becomes smaller. That is, FIG.
As shown in the program diagram shown in,
A fast shutter can be released when the aperture is stopped (where F is large).

The shutter speed consists of the time until the negative voltage is applied after the charge of the CCD is cleared and the time required for closing the diaphragm blade 3 (right end in FIG. 5). Therefore, if you can release the shutter quickly, you can shorten the time required to close the diaphragm blades.
It is possible to shorten the entire shutter speed. Also, the brightness range linked with photometry is expanded. Therefore, high exposure accuracy can be obtained, and an image without blur can be captured even for a fast-moving subject.

In the above embodiment, the program mode is used, and the aperture diameter and the shutter speed are determined according to a predetermined program. However, in another embodiment, even when the shutter speed priority mode or the aperture priority mode is selected, if the shutter speed or the aperture is fixed and the other one is controlled so as to have an appropriate exposure, the present invention is similarly performed. It is clear that

In the above embodiment, the Hall element 55 is used to detect the aperture diameter of the aperture, but in other embodiments, the aperture blade drive plate 53 and the aperture blade 3 are provided with slits. It is possible to use a known method such as detecting the movement with a photoimpterer, and it is clear that the same effect can be obtained.

In the above embodiment, a digital still camera or a digital video camera having an image pickup device such as CCD 2 is used. In another embodiment, a silver salt camera using film or a film having both film and CCD is used. It is clear that even in a camera capable of taking a still image, the present invention can be used for the front curtain of the shutter without using the shutter function of the CCD.

[0037]

As described above, according to the first, second or third aspect of the present invention, the diaphragm blades stop the play of the diaphragm blades which is driven by the driving means before the diaphragm blades start to open. By making the amount larger than the amount of collision and bouncing, it is possible to prevent the diaphragm blade from opening again due to the bouncing and causing extra exposure.

According to the second aspect of the present invention, the play of the diaphragm blade is increased as described above to allow a margin for rebounding. Therefore, the speed at which the diaphragm blade is closed is controlled according to the size of the diaphragm opening diameter. This allows the shutter speed to have a wider range than ever before.

According to the third aspect of the present invention, further, the smaller the aperture diameter is, the faster the closing speed is, so that an image without blur can be taken even for a rapidly moving subject.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part structure of a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a diaphragm aperture diameter and a rotation angle of a rotor according to the first embodiment of the present invention.

FIG. 3 is a program diagram of the second embodiment of the present invention.

FIG. 4 is a block diagram of the entire apparatus.

FIG. 5 is a diagram showing the operation of the apparatus over time.

FIG. 6 is a diagram showing a relationship between a rotation angle of a rotor of the device and a bound.

7A and 7B are diagrams showing a main part structure of a conventional example, in which FIG. 7A is a diagram in which a diaphragm is closed, and FIG. 7B is a diagram in which a diaphragm is opened.

FIG. 8 is a diagram showing a relationship between a diaphragm aperture diameter and a rotation angle of a rotor in a conventional example.

FIG. 9 is a program diagram of a conventional example.

[Explanation of symbols]

 1 Photographic lens 2 CCD 3 Aperture blade 4 Signal processing circuit 5 Aperture drive means 6 Aperture drive circuit 8 Recording unit 9 CPU

Claims (3)

[Claims] 1. A diaphragm blade, drive means for driving the diaphragm blade in a closing direction and an opening direction, and a stopper for restricting movement of the diaphragm blade in a closing direction beyond a certain level and holding the diaphragm blade in a closed position. An imaging device having a diaphragm device in which the diaphragm blade starts to open after a certain amount of the diaphragm blade is driven in the opening direction from the closed position by the driving means, the diaphragm is closed when the diaphragm blade is closed from a maximum diaphragm aperture diameter. An image pickup apparatus having a configuration in which the fixed amount is larger than an amount by which the blade collides with the stopper and rebounds. 2. The image pickup apparatus according to claim 1, further comprising a unit capable of forming a plurality of diaphragm aperture diameters by the diaphragm blades, and controlling the closing speed of the diaphragm blades according to the size of the diaphragm aperture diameters by the diaphragm blades. The image pickup apparatus according to claim 1, wherein 3. The image pickup apparatus according to claim 2, wherein the closing speed is controlled to be faster as the small aperture has a smaller aperture opening diameter.