JPH07199268A - Image pickup unit - Google Patents

Abstract

PURPOSE:To perform photographing in an aperture-priority mode by using an IG meter by controlling current amount according to the detection output of the diameter of the opening of an aperture means controlling the diameter of the opening of an aperture based on a current. CONSTITUTION:In the case of the aperture-priority mode AP, the diameter of the opening of a stop blade 3 is fixed, and adequate exposure is obtained by feeding back the brightness 10a of an image plane to an accumulation time controlling circuit ATC by an SW3. Thus, the SW10 supplies a signal 10c obtained by converting the signal 10b detected by a hole element 55 as a feedback signal 10e to the aperture diameter of the opening at a CPU 9, and the CPU 9 supplies a signal 10f expressing the aperture diameter of the opening set at a manual aperture setting circuit AS as a reference signal 10d to an aperture driving circuit 6. The feedback signal 10e is compared with the reference signal 10d by a comparator at the aperture driving circuit, and a value obtained by multiplying the difference by a specified factor by an amplifier is added to the current flowing in a present driving coil. Consequently, the aperture diameter of the opening is always fed back so as to approach the set diameter of the opening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device.

[0002]

2. Description of the Related Art Conventionally, what is called an IG meter is used as a diaphragm device of a video camera. FIG. 3 is a block diagram of a portion related to a diaphragm device of a conventional video camera. In FIG. 3, reference numeral 1 is a taking lens, which is composed of 1a and 1b and a diaphragm blade 3 provided in the optical path of the taking lens 1. 2 is C
It is located on the image plane of the taking lens 1 on a CD and converts a subject image into an electric signal. A diaphragm driving member 5 drives the diaphragm blades 3. Reference numeral 4 is a signal processing circuit for processing an electric signal from the CCD into an image signal, and 8 is a recording system for recording the image signal. In addition, the signal processing circuit 4 integrates the image signal to generate a signal representing the brightness of the photographic screen, and the diaphragm drive circuit 6 uses this to control the diaphragm. A unit in which the diaphragm blade 3 and the diaphragm driving member 5 are integrated is generally called an IG meter.

Next, the details of the operation and control of the IG meter and diaphragm drive circuit 6 will be described with reference to FIGS. 4 (a) to 4 (c). In the diaphragm drive member 5 shown in FIGS. 4A to 4C, 51 is a drive coil, and 52 is a rotor integrally formed with a permanent magnet. 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 includes pins 53a,
53b is provided. Reference numeral 54 is a spring for urging the diaphragm blade drive plate 53 counterclockwise in the drawing. Aperture blade 3a,
3b is locked to the pins 53a and 53b, and is held by a mechanism (not shown) so as to move in parallel in the directions indicated by the arrows in the drawing as the diaphragm blade drive plate 53 rotates. In addition, 3c is an opening provided in the blade 3a, 3d is a blade 3
It is an opening provided in b. Next, the operation of the IG meter will be described. When no current is flowing through the drive coil 51,
The diaphragm blade drive plate 53 is biased counterclockwise in the drawing by a spring 54, and is positioned at the position shown in FIG. 4A by a stopper (not shown). At this time, the diaphragm blades 3a and 3b are shown in FIG.
As shown in (b), the openings 3c and 3d are closed without overlapping. 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. Along with the rotation of the rotor 52, the biasing force of the spring 54 also increases, 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. 4C, and the opening 3e due to the overlap is open. Figure 4
As shown in (b) and (c), the diameter of the diaphragm opening 3e due to the overlapping of the openings 3c and 3d by the diaphragm blades 3a and 3b changes with the rotation angle of the rotor 52.
Since this electromagnetic force is proportional to the current of the coil, it is possible to control the current flowing through the coil so that the balance position, that is, the rotor 5
The rotation angle of 2 and the diameter of the aperture opening 3e can be controlled. Next, a method of controlling the current flowing through the drive coil 51 will be described. A comparator 61 compares a signal representing the brightness of the photographic screen detected by the signal processing circuit 4 with a reference signal representing the brightness of the screen at the proper exposure, and the difference is multiplied by a predetermined coefficient by an amplifier 62 to obtain a value. It is added to the current drive current.

Therefore, the brightness of the photographing screen is always fed back so as to approach the proper exposure. The above is the configuration and control method of the IG meter used in the video camera.

Conventionally, proper exposure in photographing has been obtained in a camera by a combination of aperture diameter and exposure time. Therefore, in the camera's exposure control mode, for the brightness of the subject, the aperture priority mode that determines the exposure time to specify the aperture diameter to obtain the proper exposure, and to specify the exposure time to obtain the proper exposure There are an exposure time (shutter speed) priority mode for determining the aperture diameter and a program mode for determining the aperture diameter and the exposure time in a predetermined relationship. On the other hand, with a video camera, the exposure time is 1 for normal shooting.
/ 60 seconds, 1 / exposure time for fast-moving subjects
I fixed it at 1000 seconds or 1/2000 seconds and took a picture,
There was only the exposure time (shutter speed) priority mode that the camera said. This means that when you shoot and play back a subject with varying brightness as a continuous image (movie), you do not have to worry about changes in the depth of field due to changes in the aperture diameter, but the brightness of the screen changes due to changes in exposure time. The adverse effects of change were greater. Therefore, in the video camera, the exposure time is fixed, and the IG meter, which is the diaphragm device, is feedback-controlled to the brightness of the image formed on the image pickup element as described above to obtain an appropriate exposure.

[0006]

A device capable of shooting not only a movie but also a still image by using these image pickup devices or a device dedicated to still image shooting has been devised. The above-described IG meter control method However, under the present circumstances, only the so-called exposure time (shutter speed) priority mode photography can be performed, and it is not possible to perform various photography according to the user's intention.

Therefore, an object of the present invention is to use an IG meter to enable photographing in a so-called aperture priority mode.

[0008]

According to the present invention, in claim 1, the aperture means for controlling the aperture diameter of the aperture according to the amount of current, the detecting means for detecting the aperture diameter of the aperture means, and the detecting means. 3. A control means for controlling the current amount by the output of the aperture means, and a diaphragm means for controlling the aperture diameter of the diaphragm according to the current amount, and a first detection for detecting the aperture diameter of the diaphragm means. Means, second detecting means for detecting the brightness of the photographing screen, selecting means for selecting the outputs of the first detecting means and the second detecting means, and controlling the current amount by the output of the selecting means. Since it has a control means for controlling, it is possible to shoot in the so-called aperture priority mode.

[0009]

1 and 2 show an embodiment of the present invention. Among the configurations in the drawings, those having the same numbers as those described in the conventional examples of FIGS. 3 and 4 are the same. That is,
In FIG. 1, 1 is a taking lens including 1a and 1b and an aperture blade 3, 2 is a CCD, 5 is an aperture drive member, 6 is an aperture drive circuit, and 9 is a CPU. 4 is a signal processing circuit, and 8
Is a recording system. Further, the signal processing circuit 4 integrates the image signal as in the conventional example to generate the signal 10a representing the brightness of the photographing screen. SW1 is a mode switching operation member, SP is a shutter priority mode, AP is
Is the aperture priority mode. Further, AS is a manual aperture value setting circuit. ATC is C as an image sensor.
It is a storage time control circuit that variably controls the storage time of CD2, and feedback-controls the storage time so that the level of 10a becomes constant when the signal 10a is input via the switch SW3. In FIG. 2, 51 is a drive coil, and 52 is a rotor integrally formed with a permanent magnet.
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 is provided with pins 53a and 53b. Reference numeral 54 is a spring for urging the diaphragm blade drive plate 53 counterclockwise in the drawing. When no current flows through the drive coil 51, the diaphragm blade drive plate 53 is biased counterclockwise in the drawing by the spring 54, and is positioned at the position shown in FIG. 2A by a stopper (not shown). 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. With the rotation of the rotor 52, the urging force of the spring 54 also increases, and the rotor 52 is placed at a position where the two are in balance.
Stops rotating. The diaphragm blades 3a and 3b are pins 53a,
Since it is locked to 53b, it is held by a mechanism (not shown) so as to move in parallel to each other in the directions of the arrows in the drawing as the diaphragm blade drive plate 53 rotates, and the aperture diameter 3e is changed. At this time, the Hall element 55 detects the amount of rotation of the permanent magnet provided integrally with the rotor as a voltage. The voltage 10b is read by the CPU 9, and the diaphragm aperture diameter data 1 is calculated according to a voltage-aperture diameter relationship table that is measured and stored in advance.
Converted to 0c. SW10 is a diaphragm drive circuit 6 described later.
The input signal to the signal 1 representing the brightness of the above-mentioned shooting screen
A switch for switching to either 0a or the signal 10c representing the aperture diameter of the diaphragm.

Next, a method of controlling the diaphragm driving member 5 will be described. First, the case where the shutter speed priority mode SP is selected as the shooting mode by the operation member SW1 will be described. In the case of the shutter speed priority mode SP, the shutter speed is fixed and the brightness of the screen is fed back to the diaphragm driving device to obtain a proper exposure. Therefore, the SW 10 supplies the signal 10a representing the brightness of the photographic screen detected by the signal processing circuit 4 as the feedback signal 10e, and the CPU 9 supplies the signal representing the brightness of the screen at the proper exposure to the diaphragm drive circuit as the reference signal 10d. To do. In the diaphragm drive circuit, the feedback signal 10e and the reference signal 10d are compared by the comparator 61, and a value obtained by multiplying the difference by a predetermined coefficient by the amplifier 62 is added to the current flowing in the current drive coil 51. Therefore, the aperture of the aperture 3 should be adjusted so that the brightness of the shooting screen is always close to the proper exposure.
The diameter of e is feedback controlled. Next, operation member SW
A case where the aperture priority mode AP is selected as the shooting mode according to 1 will be described. In the case of the AP in the aperture priority mode, the diameter of the aperture opening 3e is fixed, and the brightness 10a of the screen is fed back to the accumulation time control circuit ATC by SW3 to obtain the proper exposure. Therefore, the SW 10 converts the signal 10b detected by the Hall element 55 into the aperture opening diameter by the CPU 9 as the feedback signal 10e and the CPU 9 converts the signal 10c into the aperture opening diameter set by the manual aperture setting circuit AS as the reference signal 10d. Is supplied to the diaphragm drive circuit. In the diaphragm drive circuit, the comparator 61 compares the feedback signal 10e with the reference signal 10d, and the difference is multiplied by a predetermined coefficient by the amplifier 62 to add the value to the current flowing through the drive coil 51 at present. Therefore, the aperture opening diameter is always fed back so as to approach the set opening diameter. In this way, the aperture diameter is fixed, and at this time, SW3 is also switched to the AP side.
Proper exposure is obtained by feedback variably controlling the electronic shutter speed according to 0a. The above is the embodiment of the present invention.

In the embodiment of the present invention, the shutter speed priority mode SP and the aperture priority mode AP have been described, but it is obvious that the program mode can be implemented with the same configuration. That is, the brightness of the subject is measured by a known photometric mechanism, the aperture opening diameter and the shutter speed are determined according to a predetermined program, the aperture opening diameter is controlled by the method of the above-described embodiment, and the shutter speed is determined by the known method. Is controlled to enter the program mode.

In the present embodiment, the Hall element is used to detect the aperture diameter. However, a method is provided in which a slit is provided in the aperture blade drive plate 53 or the aperture blade 3 and the movement thereof is detected by a photo interrupter. But good. It is obvious that the present invention can be implemented by any of the methods and the same effect can be obtained.

[0013]

According to the present invention, a detector for detecting the aperture diameter of the diaphragm blade of the IG meter is provided, and the IG meter is controlled by feeding back the output of this detector. Can be controlled to any value. Therefore, even if the IG meter is used, the so-called aperture priority mode and the program mode can be photographed, and various photographing modes can be provided to the user.

[Brief description of drawings]

FIG. 1 is a block diagram of an entire apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a main part of an embodiment of the present invention.

FIG. 3 is a block diagram of an entire conventional apparatus.

FIG. 4 is a block diagram of a main part of a conventional example.

[Explanation of symbols]

 1 Photographic lens 2 CCD 3 Aperture blade 4 Signal processing circuit 5 Aperture drive member 6 Aperture drive circuit 8 Recording system 9 CPU 10 SW

Claims (2)

[Claims] 1. A diaphragm means for controlling an aperture diameter of a diaphragm according to an electric current amount, a detecting means for detecting an aperture diameter of the diaphragm means, and a control means for controlling the electric current amount by an output of the detecting means. An image pickup apparatus comprising: 2. A diaphragm means for controlling the opening diameter of the diaphragm according to the amount of current, a first detecting means for detecting the opening diameter of the diaphragm means, and a second detecting means for detecting the brightness of the photographing screen. An image pickup apparatus comprising: a selection unit that selects the output of the first detection unit and the second detection unit; and a control unit that controls the current amount by the output of the selection unit.