JPH0526577Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an aperture device for a camera.

Conventionally, it is well known that a meter is used as a mechanism for controlling the opening and closing of camera aperture blades. This is an attempt to control the opening and closing of the aperture blades by using a step-like cam mechanism or the like to control the movement of the pointer of an electric exposure meter, which is linked to the brightness of the subject. However, the accuracy of the indicated position of the meter is determined by the balance between the force of the hairspring and the magnetomotive force caused by the applied current, so high precision is required of the components, which is economically disadvantageous and resistant to shock. It has drawbacks such as easy failure.

In addition, in order to improve the drawbacks of the above-mentioned mechanism using a meter, there is a mechanism that uses two plungers or solenoids to operate the aperture blades and control three types of aperture diameters, but this method does not require the plunger or solenoid to be energized. When not in use, an external force such as a spring is required to hold the aperture blades in a neutral position. For this reason, the plunger or solenoid must operate the throttling mechanism against this external force, so it has the disadvantage that it is difficult to downsize and consumes a large amount of current. Furthermore, in order to operate the aperture, a permanent magnet is mounted on the movable member, and the magnetic pole of the electromagnet is made to correspond to this permanent magnet.When the electromagnet is not excited, the neutral position is maintained by the attraction between the permanent magnet and the electromagnet. There is a mechanism that controls three types of aperture diameters by attraction and repulsion of a permanent magnet depending on the direction of excitation during excitation (for example, Japanese Patent Application Laid-Open No. 12628/1983).
This method also requires an external force such as a spring to bring it to the neutral position, and has the same drawbacks as mentioned above.

Therefore, the present invention eliminates the above-mentioned drawbacks and provides a small-sized, low current consumption type diaphragm device that has a simple structure.

In order to achieve the above object, the camera diaphragm device of the present invention includes a permanent magnet rotor that is radially magnetized with two poles and is rotatably supported, and a permanent magnet rotor that is magnetically coupled to the rotor. A pair of stator magnetic poles are arranged facing each other at an angle of 180 degrees, and have arc-shaped magnetic pole surfaces concentric with the rotation center of the rotor. A stator comprising a pair of narrow width parts integrally connecting both stator magnetic pole parts on a straight line perpendicular to the target center line, and an excitation coil wound around and connected to both ends of the stator. An electric circuit that controls whether the coil is energized or de-energized in the forward or reverse direction depending on subject information, and when the coil is de-energized, the rotor faces the narrow part. The air gap between the narrow part and the rotor is formed to be smaller than that between the magnetic pole face of the stator and the rotor, and an engagement pin is provided at one end so that the narrow part and the rotor stand still. , a drive lever that has a pair of legs protruding in a fork shape with an opening angle of 120 degrees or less at the other end, and is fixed to the shaft of the rotor at the middle part and can be oscillated. When the coil is in a non-energized state, it is fixedly disposed so that it is located at an intermediate position between both legs of the drive lever, and works together with these legs to adjust the rotation angle of the drive lever and rotor. A regulating pin, and an aperture blade arranged to open and close in conjunction with the displacement of the pin of the drive lever;
It is characterized by consisting of.

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

First, FIGS. 1 to 4 show a first embodiment of the present invention, in which a rotor 1 consisting of permanent magnets magnetized with two poles of N and S in the radial direction is integrally fixed to a rotor shaft 2. has been done. One end of the rotor shaft 2 is rotatably supported by a hole in the lower plate 3, and the other end is rotatably supported by a hole in the upper plate 4. A drive lever 5 is fixed. A stator 6 has two magnetic pole parts 6a facing the outer periphery of the rotor 1, and the magnetic pole part 6a has a magnetic pole surface facing the rotor 1 formed into an arcuate surface concentric with the center of the rotor. They are integrally connected via the narrow portion 6b. The narrow portion 6b is formed to reduce the cross-sectional area and increase the magnetic resistance, and when electricity is applied, it is magnetically separated at this portion, so that the narrow portion 6b is separated from the magnetic pole portions 6a, 6a. The magnetic flux effectively acts on the rotor 1. Further, the gap between the stator 6 and the rotor 1 is such that the gap δ1 of the narrow portion 6b is smaller than the gap δ2 of the magnetic pole portion 6a, and the inner shape of the stator 6 is an oval hole.
Furthermore, the center lines (Y-axis) of the two magnetic pole parts 6a and the center lines (X-axis) of the two narrow width parts are set to be orthogonal to each other. With this stator configuration, when the rotor 1 is in a non-energized state, the N and S poles of the rotor receive strong static magnetic force from the narrow part 6b, so that the N and S poles of the rotor 1 are stably stationary on the X axis. It's getting old. On the other hand, the magnetic pole portion 6a of the stator
A coil 7 that generates a magnetic field is connected to an electric circuit to be described later and is wound around a coil frame 8 in which an iron core 9 is inserted in the center. The stator 6 is positioned on the lower plate 3 by a guide means (not shown), the iron core 9 is superimposed so as to be magnetically connected to the stator 6, and the upper plate 4 and the lower plate 3 are connected with set screws 10. It is fixed by screwing. Above rotor shaft 2
The drive lever 5 fixed to the upper plate 4 controls the rotational movement of the drive lever 5 and the legs 5a and 5b, which regulates the rotation range in the forward and reverse directions in conjunction with the pin 4a provided on the upper plate 4, as will be described later. It has a connecting pin 5c that transmits information to the lever 11. Reference numeral 11 designates a control lever, which includes a groove portion 11a that engages with the connecting pin 5c, and a locking portion 11b that engages with an aperture cam lever 12, which will be described later.
It has a shaft and is rotatably supported. 12 is an aperture cam lever, which is connected to the locking portion 11 of the control lever.
a three-step stepped cam portion 12a that engages with b; and a locking portion 12b that engages with a release lever 13, which will be described later.
and an operating section 12c for operating the aperture mechanism 14, which is rotatably supported by a shaft and a spring 1.
5 in the clockwise direction. Reference numeral 13 denotes a release lever, which is a locking portion 12b of the aperture cam lever.
It has a claw portion 13a that engages with the shaft, is rotatably supported, and is biased clockwise by a spring 16.

FIG. 4 is an electrical circuit diagram for driving the diaphragm device of the present invention, and shows examples of its application in the case of aperture control normally based on the brightness of a subject and in the case of aperture control corresponding to distance information during strobe photography. These are realized by a known window comparator circuit. 21 and 22 are comparators, with non-inverting input terminals
The voltage input to P1, P2 is the inverted input terminal Q1, Q2
When the voltage is lower than the input voltage, the output becomes low level. First, let us explain the case of normal aperture control based on the brightness of the subject.
A switch S10 for switching between normal photography is connected to the S10a side by the user. Inverting input terminal Q1 of comparator 21 and non-inverting input terminal of comparator 22
P2 is a constant current source 24 for setting the aperture switching level.
The terminal Q1 of the comparator 21 is connected to the resistors R1, R2, and R3 connected in series with the terminal P2 of the comparator 22.
Higher voltage is input. The variable resistor RS is a resistor for introducing film sensitivity, and a resistance value corresponding to the film sensitivity is set.When the sensitivity is high, the resistance value of RS is made small, and when the sensitivity is low, it becomes large. Resistors R1, R2, and R3 are constant current sources 24
Since the voltage at terminals P2 and Q1 changes depending on the resistance value of variable resistor RS, as will be explained later,
Since the current flowing through the coil 7 is in the direction A or B, or is not flowing, the aperture may have a small aperture, an intermediate aperture, or a large aperture depending on the film sensitivity even if the brightness is the same. Note that the difference between the voltage at terminal P2 and the voltage at Q1 does not change. On the other hand, the terminal P1 of the comparator 21 and the terminal Q2 of the comparator 22 are connected to the midpoint of the diode D connected in series with Cds23, respectively.
A voltage is input according to the amount of light received. S1, S2, S3, and S4 are transistors for switching, and when the output of comparator 21 is low level and the output of comparator 22 is high level, current flows to the bases of transistors S1 and S2, and as shown in FIG. A current flows in the A direction (positive direction) in the coil 7, and contrary to the above, when the output of the comparator 21 is high level and the output of the comparator 22 is low level, a current flows in the bases of the transistors S3 and S4. As a result, the coil 7 is connected so that a current flows in the B direction (reverse direction).

The operation of the configuration of the first embodiment described above will be described below.

When the coil 7 is not energized, due to the difference between the gap δ1 and δ2 between the stator 6 and the rotor 1, the attractive force between the NS pole of the rotor 1 and the narrow part 6b of the stator is stronger than the attractive force between the stator's magnetic pole part 6a. Therefore, the NS pole of rotor 1 is the narrow part 6 of the stator.
It stops along the center line (X-axis) of b and continues to maintain this state unless energized. Then the first
In the diagram, for example, the N pole of rotor 1 is negative
On the axis, the S pole is on the plus X axis, and when the coil 7 is energized in the positive direction, a magnetic field is generated, and this magnetic field
is transmitted to the stator 6 via the positive Y-axis, and the magnetic pole 6a on the positive Y-axis has an N pole.The magnetic pole 6a on the negative Y-axis has an S
When a pole occurs, the attractive force between the NS pole of the rotor 1 and the magnetic pole part 6a of the stator is stronger than the attractive force between the NS pole of the rotor 1 and the narrow part 6b of the stator, so the rotor 1 rotates counterclockwise. At the beginning, rotate until the determining part 5a of the drive lever touches the pin 4a of the upper plate,
The rotor 1 is stopped in this state while the coil 7 is energized in the positive direction. Then, when the current to the coil is cut off, the NS pole of the rotor 1 and the narrow width part 6b of the stator are attracted again, and the state in which the NS pole of the rotor 1 and the narrow width part 6b of the stator are opposed to each other is restored. Also, in FIG. 1, contrary to the above, the coil 7
When a current in the opposite direction is applied to the magnetic pole part 6a of the stator, an S pole is generated in the positive Y-axis direction, and a N pole is generated in the negative Y-axis direction, and the rotor 1 is moved clockwise between the driving lever's determining part 5b and the top plate. It rotates until the pin 4a hits it and then stops. When the current to the coil 7 is cut off, the coil 7 returns to its non-energized state. Note that the rotation angle of the rotor 1 and the drive lever 5 is appropriately set to an angle of 1/6 rotation or less in each direction, taking into consideration the return operation when the energization is cut off, the response speed when the energization is applied, the rotational output torque, etc. It is something that

On the other hand, FIG. 3 shows the state before the aperture device is activated, in which the locking part 12b of the aperture cam lever and the claw part 13a of the release lever are engaged, and the clockwise rotation of the aperture cam lever 12 is restricted. ing.
Furthermore, since the coil 7 is not energized, the drive lever 5 is stopped at the neutral position, and the locking part 11b of the control lever that is interlocked with the drive lever 5 corresponds to the central stepped part of the cam part 12a of the aperture cam lever. It is stopped at the desired position.

In this state, the power switch S11 of the electric circuit is turned on by the release means of the camera (not shown) and photometry starts, but first the subject is dark and the Cds23
If the amount of light received is small, the terminals of comparators 21 and 22
Since the input voltages of terminals P2 and Q1 are higher than the input voltages of P1 and Q2, the output of comparator 21 is at a low level, and the output of comparator 22 is at a high level, causing current to flow to the bases of switching transistors S1 and S2. A current flows in the A direction (positive direction) through the flow coil 7. Next, when the brightness of the subject is medium and the amount of light received by Cds 23 is medium, the outputs of comparators 21 and 22 are both low level, so the transistor
Since no current flows through the bases of S2 and S3, no current flows through coil 7. Furthermore, if the brightness of the subject is bright and the amount of light received by Cds23 is large, comparator 2
From the input voltage of terminals P1 and Q2 of terminals 1 and 22, terminal P2 and
Since the input voltage of Q1 is lower, comparator 21
The output of the comparator 22 is at a high level, and the output of the comparator 22 is at a low level, causing current to flow through the bases of the transistors S3 and S4, and current flowing through the coil 7 in the B direction (reverse direction). The explanation so far has been about aperture control based on the brightness of the subject, but the same applies to strobe photography. In this case, selector switch S1
0 is connected to the S10b side. The resistor RD is a resistor set corresponding to the distance, and divides the power supply voltage together with the resistor R5. The resistance RD is increased when the distance is long, and decreased when the distance is short. The following operation is the same as in the previous case; when shooting at long distances, current flows in the direction of A in coil 7, increasing the aperture diameter, and at intermediate distances, current does not flow in either direction of A or B, but at short distances. In the case of , a current flows in the direction B to reduce the aperture diameter and set appropriate exposure conditions. Further, the film sensitivity operates in the same manner as in the case described above.

Therefore, if the brightness of the subject is dark, coil 7
A current flows in the A direction (positive direction) and the rotor 1 rotates counterclockwise.When the brightness of the subject is medium, no current flows in the coil 7, so the rotor 1 is at the medium position. When the subject is stopped and the brightness of the subject is bright, current flows in the coil 7 in the B direction (reverse direction) and the rotor 1 rotates clockwise. The lever 5 also has three positions: a counterclockwise rotation position, a neutral position, and a clockwise rotation position. Then, the stopping position of the locking portion 11b of the control lever interlocked with the drive lever 5 is determined.

As described above, when the release lever 13 is rotated counterclockwise by an external operation in a state where the stop position of the locking portion 11b of the control lever is determined depending on the brightness of the subject, the locking of the claw portion 13a is released. The aperture cam lever 12 begins to rotate clockwise and stops when a predetermined stepped portion of the stepped cam portion 12a engages with the locking portion 11b. Operation part 12 of the aperture cam lever
c, the aperture device 14 is operated and the aperture is determined. In addition, the stepped cam portion 12 of the aperture cam lever
A is provided in three stages, and the locking part 11b of the control lever corresponds to the stage cam part 12a, so there are three types of operating angles of the aperture cam lever 12, and three types of aperture can be selected in conjunction with these operating angles. be done.

Next, FIGS. 5 and 6 show a second embodiment of the present invention, which is composed of the same electric circuit, coil, stator, rotor, and drive lever as in the first embodiment, and drives the aperture device. This is an example of direct drive using a lever. The aperture blade 51 has a hole 51a that fits into a pin 53 fixed on a base plate (not shown), and a notch groove 51b that fits into a drive lever 55 fixed on a rotor shaft 54 similar to the first embodiment.
It is fitted into a pin 55a provided in and rotatably supported. On the other hand, the aperture blade 52 has a hole 52a that fits with the rotor shaft 54, and an elongated hole 52 that fits with the rotor shaft 54.
b fits into the pin 55a of the drive lever and is rotatably supported. and aperture blades 51, 52
The size of the opening S is changed by the rotation of the opening S. Note that the elongated hole 52c provided in the aperture blade 52 is for allowing the pin 53 to escape.

The operation of the above configuration will be explained below. First, when the electric circuit is inactive or the brightness of the subject is medium, the rotor and drive lever 5 are connected by the NS pole of the rotor and the second magnetic pole of the stator narrow part.
5 is stopped at a neutral position, and the openings S of the aperture blades 51 and 52 have a medium diameter. Next, when the brightness of the subject is dark, a current flows in the A direction (positive direction) in the coil, the rotor and drive lever 55 rotate counterclockwise, and the aperture S of the aperture blades 51 and 52 has a large aperture. becomes. Furthermore, when the brightness of the subject is bright, a current flows in the B direction (reverse direction) to the coil, the rotor and drive lever 55 rotate clockwise, and the aperture S of the aperture blades 51 and 52 becomes small in diameter. . Therefore, as in the first embodiment, three apertures are selected depending on the brightness of the subject.

As explained above, in the present invention, an aperture device for a camera is configured using an electromagnetic drive device that is an improved stator type step motor.
Position control is performed using the poles of the rotor and stator as a means of obtaining an intermediate position, so external forces such as springs are not required, resulting in high efficiency, low current consumption, and miniaturization, as well as a simple structure and fewer components. It is also economically advantageous because there are fewer Furthermore, even if the rotor and drive lever become inoperable due to exhaustion of the camera's built-in battery, etc., the aperture remains at an intermediate aperture, which avoids the worst situation of shooting at an extreme aperture. It is.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the first embodiment of the present invention, Fig. 2 is a sectional view of Fig. 1, Fig. 3 is a perspective view of the first embodiment, and Fig. 4 shows the first and second embodiments. FIG. 5 is a plan view of the second embodiment of the present invention, and FIGS. 6a and 6b are plan views of the aperture blades used in the second embodiment. 1... Rotor, 5, 55... Drive lever, 6
... Stator, 7 ... Coil, 11 ... Control lever, 12 ... Aperture cam lever.

Claims (1)

[Claims for Utility Model Registration] A permanent magnet rotor that is magnetized with two poles in the radial direction and is rotatably supported; a pair of stator magnetic pole parts that are arranged facing each other and have arcuate magnetic pole faces that are concentric with the rotation center of the rotor; a stator comprising a pair of narrow width portions integrally connecting both stator magnetic pole portions in a straight line; and an iron core around which an excitation coil is wound and connected to both ends of the stator. , an electric circuit that controls whether to energize or de-energize the coil in a forward or reverse direction according to subject information; and when the coil is in a de-energized state, the rotor faces the narrow portion. to stand still,
The air gap between the narrow part and the rotor is formed smaller than that between the magnetic pole face and the rotor, and has an engaging pin at one end and an air gap at the other end. a drive lever having a pair of protruding legs in a fork shape with an opening angle of 120 degrees or less, the drive lever being fixed to the shaft of the rotor at the middle part and capable of sliding displacement; and the coil. a regulation that is fixedly disposed so as to be located at an intermediate position between the legs when the lever is in a non-energized state, and cooperates with the legs to regulate the rotation angle of the drive lever and the rotor; An aperture device for a camera, comprising: a pin; and aperture blades arranged to open and close in conjunction with displacement of the pin of the drive lever.