JP2001174865A - Diaphragm blade driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the error of a diaphragm aperture at the time of setting a diaphragm blade to a stop state. SOLUTION: This diaphragm blade driving device is equipped with a bottom board 1 where a lens aperture 1a is formed, one diaphragm blade 3 turnably attached to one supporting shaft 3b implanted on the board 1, the other diaphragm blade 4 turnably attached to the other supporting shaft 4b implanted on the board 1, and the rotor 2a of an actuator having an actuating pin 2b engaged with both blades 3 and 4 and simultaneously driving the blades 3 and 4 with respect to the lens aperture 1a, and switches a stop-down state where the blades 3 and 4 are superposed on each other on the lens aperture 1a and a totally open state where the blades 3 and 4 are retreated from the lens aperture 1a. The pin 2b is positioned on or near a line linking both supporting shafts 3b and 4b in the stop-down state and positioned far from the line linking both shafts 3b and 4b in the totally open state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for driving an aperture blade for a camera. More specifically, the present invention relates to a diaphragm blade driving device that obtains a desired diaphragm diameter by opening and closing two diaphragm blades with respect to a lens opening.

[0002]

2. Description of the Related Art Generally, an aperture blade driving device for a camera drives an aperture blade with an operating pin connected to an actuator to set a predetermined aperture. The driving modes of the operating pins are roughly classified into a rotary driving type and a linear driving type. The linear drive type in which the operating pin is driven linearly to control the opening and closing of the aperture blade can set the aperture diameter with high accuracy. However, the linear drive type has the disadvantage that the mechanism is complicated and the types of the corresponding actuators are limited. On the other hand, the rotary drive type is widely used because the drive pin driving mechanism is relatively simple and a corresponding actuator can be easily obtained.

[0003] There are a system using one diaphragm blade and a system combining two or more blades. In order to increase the setting accuracy of the aperture, it is effective to provide a predetermined aperture in one aperture blade and open and close the aperture with respect to the lens aperture. However, since it is necessary to completely shield the lens aperture with one sheet, an extra space for disposing the diaphragm blade is required. On the other hand, in the method in which a plurality of diaphragm blades are combined, the area of each light shielding blade is reduced by the division, so that a small storage space is required and a compact diaphragm device can be obtained.

A device for driving a plurality of diaphragm blades with a rotating operating pin is disclosed, for example, in Japanese Patent Application Laid-Open Nos. 2-226129 and 3-166532. FIG.
1 schematically shows an example of a conventional diaphragm blade driving device. As shown in the figure, the aperture blade driving device has a lens aperture 1
a is attached to the main plate 1 on which the a is formed. One aperture blade 3 is rotatably attached to one support shaft 3 b implanted on the main plate 1. Further, the other diaphragm blade 4 is rotatably attached to the other support shaft 4b which is also planted on the main plate 1. A pair of aperture blades 3,
4 is used to drive the actuator. In this conventional example, a moving magnet motor type actuator is used. For simplicity of illustration, only the inner rotor 2a of the actuator is shown. The rotor 2a is rotatable about a rotation shaft 1b, and is integrally provided with an operating pin 2b via a projection 2c. The operating pin 2b is engaged with an elongated hole 3a formed in one of the aperture blades 3 and an elongated hole 4a formed in the other of the aperture blades 4. The pair of aperture blades 3 and 4 are driven to be switched between an aperture state and a fully open state by an operation pin 2b. The figure shows a fully opened state, in which both aperture blades 3 and 4 are retracted to both sides from the lens opening 1a, and the aperture diameter is the largest LA.
It has become. In this fully opened state, the rotor 2a is at the extreme position in the clockwise direction, and the operating pin 2b is located outside the straight line connecting the support shafts 3b and 4b.

FIG. 7 shows the aperture state of the aperture blade driving device shown in FIG. When the rotor 2a rotates from the clockwise limit position shown in FIG. 6 to the counterclockwise limit position in FIG. 7, the operating pin 2b moves from the outside to the inside of the straight line connecting the support shafts 3b and 4b. As a result, one of the aperture blades 3
Rotates clockwise around the support shaft 3b, and its tip abuts the stopper 3t. The other diaphragm blade 4 is also a support shaft 4b.
, And its tip abuts against the stopper 4t and stops. As a result, the pair of diaphragm blades 3 and 4 overlap each other on the lens opening 1a to form a diaphragm having a diameter SA. In this conventional example, both support shafts 3b,
The rotation angle of the rotor 2a is divided equally between the fully open side in FIG. 6 and the throttle side in FIG. 7 with reference to the straight line connecting 4b.

[0006]

In the drawing state shown in FIG. 7, the operating pin 2 is not moved due to a manufacturing error or an assembly error.
b may deviate from the normal position. In FIG. 7, the operating pin 2B shifted from the normal position in the direction approaching the rotation axis 1b of the rotor 2a is represented by a dotted line. In this case, the long hole 4a of the diaphragm blade 4 engaged with the operation pin 2B is not greatly affected, but the long hole 3a of the diaphragm blade 3 similarly engaged with the operation pin 2B is greatly affected and indicated by a dotted line. In the same way as the normal position. Since the longitudinal direction of the long hole 4a is aligned with the straight line connecting the operating pin 2B and the rotating shaft 1b, there is no great effect even if the operating pin 2B is displaced in the linear direction. Since it intersects with the straight line connecting the rotary shaft 2b and the rotary shaft 1b, if the operating pin 2B is displaced in the linear direction, the position of the long hole 3a is greatly shifted. As a result, the aperture blade 3 slightly rotates counterclockwise about the support shaft 3b. The position is indicated by 3A. As a result, the aperture area increases as shown by hatching, and appears as an exposure error. Also, the center of the aperture opening is shifted from the center of the lens opening 1a. As described above, in the conventional diaphragm blade driving device, when the longitudinal dimension from the rotary shaft 1b to the operating pin 2b is changed due to a manufacturing error, an assembly error, or the like in the state of the diaphragm, the diaphragm blade 4 is displaced with respect to the displacement amount of the diaphragm blade 4. The amount of displacement of the blades 3 becomes large, and as a result, the amount of opening changes as shown by hatching, and there is an inconvenience that an exposure error occurs. In addition, there is a disadvantage that the center of the opening is also shifted.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the diaphragm blade driving device according to the present invention includes a base plate having a lens opening formed therein, one of the diaphragm blades rotatably attached to one of the support shafts planted on the base plate, and a base plate formed on the base plate. An other diaphragm blade rotatably mounted on the other supporting shaft provided, an actuator having an operating pin engaged with both diaphragm blades, and simultaneously driving each diaphragm blade with respect to the lens aperture; And switches between an aperture state in which both aperture blades overlap each other above the lens aperture and a fully open state in which both aperture blades are retracted from the lens aperture. In such a diaphragm blade drive device, when in the aperture state, the operating pin is located on or near a straight line connecting both spindles, and when fully open, the operating pin is located far from the straight line connecting both spindles. Features. Specifically, the operating pin is engaged with a long hole formed in each of the aperture blades, and in the throttle state, the longitudinal direction of each of the long holes is along a straight line connecting both support shafts. The operating pin is located at an intermediate position between the two support shafts, and rotates the respective aperture blades in directions opposite to each other.

According to the present invention, when the diaphragm is in the aperture state, the operating pin is located on or near a straight line connecting the respective spindles serving as the rotation centers of the pair of aperture blades. Further, the rotation axis of the actuator, which is the center of rotation of the operating pin, is also located on substantially the same straight line. In other words, the operation pin, the rotation center of the operation pin, the rotation center of one of the diaphragm blades, and the rotation center of the other diaphragm blade are arranged substantially in a straight line. In such a configuration, even if the dimension from the rotation center of the operation pin to the center of the operation pin varies due to a manufacturing error or an assembly error, a change in the aperture diameter in the aperture state is small and a stable aperture value can be obtained.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic plan view showing an embodiment of an aperture blade driving device according to the present invention. FIG. 1 shows the aperture state of the aperture blade driving device. Parts corresponding to those in the conventional example shown in FIG. 7 are assigned the same reference numerals to facilitate understanding. As shown in the drawing, the present aperture blade driving device is assembled to a base plate 1 having a lens opening 1a formed therein. One of the aperture blades 3 is rotatably attached to a support shaft 3b planted on the main plate.
The other diaphragm blade 4 is rotatably attached to the other support shaft 4b which is also implanted on the main plate 1. The rotor 2a of the actuator is rotatable about a rotation shaft 1b and integrally has an operation pin 2b via a projection 2c. The operating pin 2b moves clockwise and counterclockwise about the rotation axis 1b as the rotor 2a rotates. In the illustrated throttle state, the operating pin 2b is at the extreme counterclockwise position. The rotor 2a switches the pair of aperture blades 3 and 4 between an aperture state and a fully open state by an operating pin 2b. As shown, in the aperture state, both aperture blades 3 and 4 overlap each other on the lens aperture 1a, forming a small aperture SA. In the fully opened state, both diaphragm blades 3 and 4 are retracted to both sides from the lens opening 1a. In the present invention, when in the illustrated throttle state, the operating pin 2b is located on or near a straight line connecting the two support shafts 3b and 4b. At this time, the rotating shaft 1b of the rotor 2a is also
It is almost located on the straight line connecting b. The operating pin 2b is engaged with long holes 3a, 4a formed in the respective aperture blades 3, 4. In the drawing state shown in the drawing, the longitudinal direction of the elongated holes 3a is aligned along a straight line connecting the two support shafts 3b and 4b. Similarly,
The longitudinal direction of the long holes 4a is also aligned along a straight line connecting the two support shafts 3b, 4b. In this way, by arranging the position of the operating pin 2b on a straight line passing through the rotating shaft 1b, the supporting shaft 3b, and the supporting shaft 4b, even if the position of the operating pin 2b is shifted in a linear direction from the rotating shaft 1b, the operating pin 2b Moves only along the longitudinal direction of the long holes 3a, 4a, and the diaphragm blades 3, 4 themselves do not rotate at all and remain in contact with the corresponding stoppers 3t, 4t. Therefore, the aperture diameter SA does not fluctuate and can be stably maintained.

FIG. 2 shows a fully opened state of the diaphragm blade driving device shown in FIG. As shown, the rotor 2a is rotated from the counterclockwise limit position in FIG. 1 to the clockwise limit position. Along with this, one of the diaphragm blades 3 becomes a support shaft 3b.
, And retreats to the left from the lens opening 1a. Similarly, the other diaphragm blade 4 is supported by a support shaft 4b.
And retreats to the right from the lens opening 1a. As a result, the lens opening 1a is fully opened and the maximum aperture LA is obtained. The operating pin 2b is a double support shaft 3.
It moves so as to draw an arc around the rotation axis 1b at a position intermediate between b and 4b. For this reason, in the fully opened state shown in the drawing, the operating pin 2b is closer to the other support shaft 4b than the one support shaft 3b. For this reason, the rotation amount of the diaphragm blade 4 becomes larger than the rotation amount of the diaphragm blade 3, and in the fully opened state, both the diaphragm blades 3,
4 is not a symmetric position. As is clear from the figure, the diaphragm blade 4 is larger than the diaphragm blade 3 and retracts from the lens opening 1a. However, in the fully opened state, both aperture blades 3 and 4 need only be completely retracted from the lens opening 1a, and there is no problem with being asymmetric. Also, FIG.
In the fully opened state shown in FIG. 2, when the distance between the operating pin 2b and the rotating shaft 1b varies in the fully opened state shown in FIG. 2, the position of the diaphragm blade 3 in particular fluctuates, but completely retracts from the lens opening 1a. As long as there is no problem in exposure accuracy.

FIG. 3 is a schematic sectional view of the diaphragm blade driving device shown in FIGS. On the upper side of the main plate 1, the actuator 2 is mounted, while on the lower side, a pair of diaphragm blades 3, 4 are mounted. 1 and 2 are:
FIG. 4 is a plan view seen from a lower side of FIG. 3. The actuator 2 is a moving magnet motor type that holds the rotor 2a between the coil upper frame 8a and the coil lower frame 1u. The actuator 2 is connected to the screws 11, 12 via the coil lower frame 1u.
Is attached on the main plate 1 by the The rotor 2a is made of a permanent magnet that is magnetized in two poles, and the operating pin 2b is integrally formed by molding. The rotor 2a is rotatable about a rotation shaft 1b. The coil 8 is wound around the coil upper frame 8a, and the rotor 2a is rotated in both directions by controlling the direction of current flow. A cylindrical yoke 7 is mounted around the coil upper frame 8a. The magnetic material 6 is mounted inside the coil upper frame 8a, and holds the rotor 2a at the clockwise limit position or the counterclockwise limit position when no power is supplied.

Focusing on the lower side of the base plate 1, the diaphragm blade 3 is mounted so as to be rotatable about a support shaft 3b.
The aperture blade 4 is also mounted so as to be rotatable about the support shaft 4b. Both diaphragm blades 3 and 4 are protected by the receiving member 1v. The operation pins 2b of the actuator 2 described above are inserted into the long holes formed in the aperture blades 3 and 4, respectively.
Are engaged. In the aperture state, the tip of the aperture blade 3 contacts the stopper 3t, and the tip of the aperture blade 4 also contacts another stopper 4t. Here, factors that cause the position of the tip of the operating pin 2b to vary with respect to the rotating shaft 1b include an assembly error and a manufacturing error. For example, the coil upper frame 8a, the coil lower frame 1u, and the screw 1 used for assembling the actuator 2
If there is a dimensional error in the actuators 1, 12, etc., the entire actuator 2 may be tilted due to backlash or the like. When the actuator 2 is tilted, the operating pin 2b is also tilted from the vertical direction, so that the distance between the tip of the rotor 2a and the rotary shaft 1b of the rotor 2a that is engaged with the diaphragm blades 3 and 4 varies. Alternatively, when the operation pin 2b is integrally molded with the rotor 2a by molding, the operation pin 2b itself may be bent or vary depending on the outsert condition of the mold.

FIG. 4 is a schematic plan view of the diaphragm blade driving device shown in FIG. 3 as viewed from above the main plate 1, and shows a diaphragm state. In the throttle state, the two-pole magnetized rotor is held at the extreme counterclockwise position by the magnetic member 6 in a non-energized state. The pair of diaphragm blades 3 and 4 abut against the corresponding stoppers 3t and 4t, respectively, so that a desired diaphragm aperture SA can be set.

FIG. 5 is a plan view of the diaphragm blade driving device shown in FIG. 3 viewed from above the main plate 1 and shows a fully opened state. In order to switch from the throttled state shown in FIG. 4 to the fully open state shown in FIG. 5, it is necessary to energize the coil 8 once. As a result, the rotor moves around the rotation shaft 1b as shown in FIG.
From the extreme clockwise position in FIG. 5 to the extreme clockwise position in FIG. Here, when the energization is cut off, the rotor
Is held as it is by the magnetic attraction force. In a non-energized state, the pair of diaphragm blades 3 and 4 are retracted from the lens opening 1a.

[0015]

As described above, according to the present invention,
When in the aperture state, the operating pins are substantially arranged on a straight line connecting the respective support shafts of the two aperture blades. Thus, even if the position of the operating pin is displaced in the linear direction, the position of the aperture blade itself does not change, a highly accurate aperture diameter can be realized with two blades, and the center of the aperture diameter does not change. .

[Brief description of the drawings]

FIG. 1 is a plan view of an aperture blade driving device according to the present invention.

FIG. 2 is a plan view of an aperture blade driving device according to the present invention.

FIG. 3 is a sectional view of an aperture blade driving device according to the present invention.

FIG. 4 is a plan view of an aperture blade driving device according to the present invention.

FIG. 5 is a plan view of an aperture blade driving device according to the present invention.

FIG. 6 is a plan view showing an example of a conventional diaphragm blade driving device.

FIG. 7 is a plan view showing a conventional diaphragm blade driving device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ground plate, 1a ... Lens opening, 1b ... Rotation axis, 2 ... Actuator, 2a ... Rotor, 2b
... operating pin, 2c ... projection, 3 ... aperture blade,
3a ... long hole, 3b ... support shaft, 3t ... stopper, 4 ... aperture blade, 4a ... long hole, 4b ... support shaft, 4t ... stopper

Claims (3)

[Claims] 1. A base plate having a lens opening formed therein, one diaphragm blade rotatably attached to one support shaft planted on the base plate, and the other support shaft planted on the base plate. And the other diaphragm blade rotatably mounted with respect to the first and second diaphragm blades, and an actuator having an operating pin engaged with both diaphragm blades and simultaneously driving each diaphragm blade with respect to the lens aperture. A diaphragm blade driving device that switches between a diaphragm state in which the diaphragm blades overlap each other on the lens aperture and a fully opened state in which both diaphragm blades are retracted from the lens aperture. A diaphragm blade driving device, which is located close to and fully distant from a straight line connecting both spindles when fully opened. 2. The operation pin is engaged with an elongated hole formed in each of the aperture blades, and in a throttle state, the longitudinal direction of each of the elongated holes is directed to a straight line connecting both support shafts. An aperture blade driving device according to claim 1. 3. The diaphragm blade driving device according to claim 1, wherein the operating pin is located at an intermediate position between the two support shafts, and rotates the respective diaphragm blades in directions opposite to each other.