JPS5943537Y2 - Automatic iris diaphragm control device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic iris diaphragm control device that automatically controls an iris diaphragm using a hollow annular rotary electric motor.

In conventional devices of this kind, the rotor, which is a permanent magnet, may be placed on the outside or inside, but an inside rotor type is usually used, as it is less susceptible to external magnetic force.

That is, a rotary electric motor includes an annular rotor and an annular stator concentrically arranged around the outer periphery of the rotor.The stator has a magnetic pole core protruding radially from the inner surface of the annular stator core, and a stator coil is wound around the magnetic pole core. are doing.

In this way, conventional automatic iris diaphragm control devices require quite advanced technology to wind the coil around the magnetic pole core with one inner protrusion, and it is extremely difficult to miniaturize the device, and in practical terms, The outer diameter of the stator core was limited to about 40 m, making it impossible to downsize the device.

In addition, since the iron core and the magnetized poles of the permanent magnets of the rotor directly oppose each other, it is possible to meet the necessary conditions for a rotary motor for an automatic throttle device, that is, to correctly stop at the -1 position when the power is cut off. In order to satisfy this requirement, the magnetic pole iron part of the core is bent and then tilted, or the magnetized pole of the permanent magnet is tilted so that the sum of the opposing areas of the magnetic pole iron core of the core and the magnetized pole of the permanent magnet is It must be made so that it does not change even with the rotating device.

This is extremely difficult in practice, as it is nearly impossible to obtain a uniform magnetic flux density over the entire facing area of the permanent magnet with such a structure. Even if it is configured to remain unchanged, slight unevenness in suction cannot be avoided.

Therefore, the rotary motor cannot stand still at a specific position11
It becomes the original seal that causes hunting.

The object of the present invention is to provide a practical automatic diaphragm that overcomes the above-mentioned drawbacks.

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

FIG. 1 is a vertical sectional view of the automatic iris diaphragm control device of this embodiment.

Reference numeral 1 denotes a rear optical tube in which a rear lens group 2 is built-in, and 3 is a front optical tube in which a front lens group 4 is built-in.

These optical barrels 1 and 3 are attached to the front and rear of the internal mounting barrel 5.

Reference numeral 6 denotes iris diaphragm blades through which a shaft 7 is attached. A plurality of iris diaphragm blades 6 are arranged between the rear lens group 2 and the front lens group 4.

Each shaft 7 of these iris diaphragm blades 6 is pivotally supported by a flange portion 5 of the internal mounting cylinder 5.

Reference numeral 8 denotes an external mounting cylinder which is arranged concentrically around the outer periphery of the internal mounting cylinder 5, and is supported by the outer end of the internally mounted flange portion 5a, with a required gap being formed therebetween.

Reference numeral 9 denotes an aperture blade drive mechanism arranged concentrically around the outer periphery of the internal mounting cylinder 5.

This drive mechanism 9 includes an annular rotor 10 arranged concentrically on the outer periphery of the internal mounting cylinder 5, and
a rotary frame 12 fixed to the ronita 10 and arranged concentrically around the outer periphery of the internal mounting cylinder 5;
It is formed with a roller 13 that rotatably supports this rotating frame 12 as a main part.

The rotor 10 and the stator 11 constitute an annular electric motor 14 which is a driving source for the iris diaphragm.

As shown in FIG. 2, the rotor 10 is housed in annular permanent magnets 15 made of ferrite magnets, and N is arranged alternately along the annular shape.
-8 poles are magnetized with 6 poles.

As shown in FIG. 2, the stator 11 includes a relatively thin cylindrical iron ring 16 that does not have a radial magnetic pole core on its inner surface, and six cylindrical iron rings 16 that are point-symmetrically fixed at predetermined intervals in the circumferential direction on the inner surface of the ring 16. 3
An air core coil 17 as shown in the figure is housed therein.

Each air-core coil 17 is made by inserting a simple hole 21 molded from plastic or the like into a completely collapsed pipe 22 and gluing it together, as shown in FIG.

Alternatively, it may be directly fixed to the inner surface of the cylindrical iron ring 16 with an adhesive.

The distance between the magnetized surface of the permanent magnet and the inner surface of the cylindrical marking member 16 is equal to one of the magnetic pole distance of the permanent magnet.

These air-core coils 17 are symmetrically arranged with respect to the center of the stator 11 and are simultaneously excited.

A bottle 18 is protruded from the rotating frame 12 fixed to the rotor 10, and the bottle 18 passes through a long hole 19 provided in the flange portion 5a of the internal mounting cylinder 5 in the same direction. It is engaged with a notch in the outer end of the diaphragm blade 6 to rotate the diaphragm blade 6 about its axis 7.

Reference numeral 20 denotes a casing arranged to surround each of the above-mentioned parts.

In the device configured in this way, when a signal current proportional to the amount of light is applied from a photometry section on the light receiving surface (not shown) to the air-core coil 17 of the stator 11, the air-core coil 1T is moved toward the center line direction. N-8 polarity appears at both ends of
Depending on the polarity, the rotor 10 and rotating frame 12 are rotated by attraction and repulsion with the N-8 pole of the rotor 10, thereby rotating the aperture blades 6 via the pin 18.

Conventionally, it has been common sense to increase magnetic efficiency by winding the stator coil around an iron core with high magnetic permeability. An air-core coil without an iron core is placed around a magnetized permanent magnet as shown in FIG. Since the distance between the inward parts of the members is much smaller (1,/44 poles), the magnetic circuit is surrounded by magnetic members, and the leakage magnetic flux is extremely small. With the help of the members, the magnetic lines of force generated in the coil act on the permanent magnet in almost the same way as in the case of a coil with an iron core.

The torque generated in this example is 7.5% for the same current value when the number of coils is the same, and for the iron-core coil.
0%, and by converting a conventional 4-pole motor into a 6-pole motor, it was possible to obtain the same or higher torque and put it into practical use.

In addition, when the photometering section reaches a predetermined brightness on its photometering surface,
A circuit is provided for supplying a signal current to stop the supply of signal current, and to rotate the rotor 10 in the direction of closing the diaphragm blades 6 if it is too bright, and in the direction of opening the diaphragm blades 6 if the casing is too dark. There is.

When the supply of the signal current is stopped, the permanent magnet 15 and the stator core 16 are attracted to each other and the stator core 16 stops at that position.

At this point, the stator core 16 does not have magnetic pole cores at specific positions on its OJ inner surface, and therefore the rotor 10 remains stably stationary at any rotational position.

As explained above, in the automatic iris diaphragm control device according to the present invention, the stator of the annular electric motor in the iris drive mechanism is fixed to the inner circumference of the annular stator core at predetermined intervals in the circumferential direction. Since the plurality of air-core coils are made of cedar plates, there is no magnetic pole core protruding inward from the stator, and therefore the stator stands stably at rest even in a tilted rotational position, and hunting can be prevented when the rotor is stopped.

In addition, a simple holder is sufficient for attaching the coil, and it is extremely easy to attach the coil, making it possible to easily manufacture a compact device with a lens diameter of 10 m and an outer diameter of about 20 m.

Furthermore, in the past, manufacturing the iron core was a major factor in this type of equipment, but with the present invention, it is only a matter of processing a thin-walled cylinder, and it is extremely easy to handle changes in diameter and number of poles. This is a major manufacturing advantage.

Furthermore, there is no need to tilt the air protruding pole portion or the magnetized pole like a screw, and processing can be performed at extremely low cost.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of the device according to the present invention, Figure 2 is a plan view of the rotor and stator used in the present invention, Figure 3 is a perspective view of the air-core coil used in the present invention, and Figure 4 is a perspective view of the air-core coil used in the present invention. The figure shows the coil holder. 2.4... Lens group, 6... Iris diaphragm blades, 9... Aperture drive mechanism, 10... Rotor, 11... Stator, 14...Electric motor, 15...Permanent magnet, 16...Annular stator core, 17...Air core coil.

Claims (1)

[Scope of utility model registration request] An aperture drive mechanism is placed around the optical system that has a lens group,
The diaphragm driving and driving mechanism is an annular rotating electric motor consisting of a rotor made of a hollow annular permanent magnet arranged concentrically with the optical axis of the optical system, and a hollow annular stator arranged concentrically opposite to the rotor. In an automatic iris diaphragm control device, the electric motor is driven by a signal from a fast light section, and the rotational force of the rotor operates the iris diaphragm. The stator is formed of an annular stator core placed concentrically with the light m of the optical system, and a plurality of air-core coils fixed at predetermined intervals in the circumferential direction on the inner periphery of the annular stator core. An automatic iris diaphragm control device characterized in that the distance between the magnetic surface and the inner surface of the stator core is made sufficiently smaller than the distance between the magnetized poles of the rotor.