JPS6250716A - Electromagnetically driven optical diaphragm device - Google Patents

Abstract

PURPOSE:To improve the operation efficiency of a device by forming a magnetic material layer on the inner peripheral side of a rotor part and a rotor on the outer peripheral side of the rotor part by multipole magnetization, and arranging comb-shaped stator yokes outside it. CONSTITUTION:When exciting coils arranged on the stator 22 are powered on with a pulse signal from a driving circuit, a rotor 21 is rotated stepwise clockwise or counterclockwise and a diaphragm blade 26 is set to a specific diaphragm aperture by the rotary ring part 21a of the rotor. Then, the magnetic material layer is formed on the rotor 21 on the inner peripheral side of its rotor part 21b, and when its outer peripheral side is magnetized, lines of magnetic force penetrate the rotor part 21b radially, so an irregularity in magnetization is reduced, the permeance is increased, and the magnetic path resistance is reduced, so magnetic flux from the rotor part 21b is converged on the stator 22. Therefore, the torque of a pulse motor is increased and the device is driven with high efficiency.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electromagnetic drive optical diaphragm device that intermittently drives the aperture blades of a photographing lens of a still camera, cine camera, television camera, etc. by step control. be.

<Prior Art> Conventionally, this type of diaphragm drive device has either been mechanically driven by a combination of springs, levers, etc., or driven by a gear such as a pulse motor 4 provided on the outer periphery of the diaphragm mechanism 1 as shown in FIG. Transmission mechanism 3
The aperture blades 2 were driven through the.

However, such conventional examples have a complicated structure, require a large amount of space, and are heavy.

Therefore, in recent years, in order to achieve compactness, an aperture drive device using a hollow pulse motor has been developed.
The one described in Japanese Patent No. 65825 is known.

That is, as shown in FIG. 9, in this aperture drive device, a hollow pulse motor 11 is composed of an outer ring-shaped stator and an inner ring-shaped magnet rotor, and a bottle 12 provided integrally with the rotor is connected to an aperture mechanism 13. The diaphragm blades 14 of the rotor are engaged with the retaining portion 15 formed on the operating ring, and the rotor is rotated by an external signal, and the operating ring is rotated clockwise or counterclockwise via the pin 12. The aperture blades 14 are set at a predetermined aperture opening.

<Problems to be Solved by the Invention> By the way, in the conventional hollow pulse motor described above, the cylindrical portion of the rotor is multi-pole magnetized.
Since the permeance was low, it was difficult for the magnetic flux to penetrate deeply in the radial direction, resulting in poor efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and provide an aperture drive device using a hollow pulse motor with good motion efficiency.

<Means for Solving the Problems> The configuration of the present invention for achieving the above-mentioned object will be explained using FIGS. 1 to 4 corresponding to embodiments.

The present invention provides an electromagnetic drive optical diaphragm device in which a hollow pulse motor 20 drives and controls the aperture of a photographing lens up to a set aperture value υ using a pulse signal. The ring-shaped rotor part 21b is integrally molded with a synthetic resin material containing a magnetic substance, and a magnetic layer 21f is formed on the inner circumferential side of the rotor part 21b, and a multi-pole layer is formed on the outer circumferential side of the rotor part 21b. A rotor 21 is formed by applying magnetism, and a comb-like stator yoke 22 is disposed outside the rotor 21.

When the excitation coil disposed in the stator 22 is energized by a pulse signal from a drive circuit (not shown), the rotor 21 is rotated in a stepwise manner clockwise or counterclockwise, and the rotor 21 is throttled by the rotating ring portion 21a of the rotor 21. The blades 26 are set at a predetermined diaphragm aperture.

Since the rotor 21 has a magnetic layer formed on the inner circumferential side of the rotor portion 21b, when the outer circumferential side is magnetized, the lines of magnetic force penetrate the rotor portion 21b in the radial direction. Reduce magnetic unevenness, increase permeance,
Since the magnetic path resistance is small, the magnetic flux from the rotor portion 21b can be concentrated on the stator 22.

As a result, the pulse motor's torque is increased and the motor is driven more efficiently.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 6.

Reference numeral 21 designates a hollow inner rotor, in which a rotating ring portion 21a and a ring-shaped rotor portion 21b are integrally molded with a synthetic resin material containing a magnetic substance and a lubricant such as molybdenum disulfide or fluororesin). Dowels 26a protruding from one surface of the aperture blades 26 of the double bed plate 21e are rotatably fitted into the rotating ring portion 21a in a plurality of holes 21e (six holes in this embodiment) provided at equal intervals in the circumferential direction. A guide wall 21d is provided on the inner circumferential portion of the rotor portion 21b side so as to smoothly guide the rotation of the rotor 21, and a plurality of protrusions 21e are provided at equal intervals in the circumferential direction of the rotating ring portion 21a. , respectively, and the rotor portion 21b has a cylindrical layer 2 of magnetic material on its inner peripheral surface.
1f is installed, and its outer periphery is multi-pole magnetized,
The thickness of the cylindrical layer 21f is such that it does not become magnetically saturated during magnetization.

Reference numeral 22 denotes a ring-shaped stator, which together with the rotor 21 constitutes the hollow pulse motor 20, with a terminal plate 28 sandwiched between the comb-shaped stator yokes 23 and 24 and the excitation coil 25a.
, 25b, 25c, and 25d, the stator yoke 23 is located outside the rotor 21, and a part of the stator yoke 23 is in contact with the guide wall 21d and the projection 21e of the rotor 21, and the comb of the stator yoke 23, 24 is The tooth part is the rotor 2
They are arranged alternately in the circumferential direction while maintaining an air gap concentrically with the first magnetized rotor portion 21b. Further, the stator yoke 24 has stator yoke portions 24a, 24b, 24c which differ in phase by 90 degrees in electrical angle.
, 24d, the excitation coil 25a = 25b,
25c and 25d are provided respectively, and the stator yoke portion 24a, the exciting coil 25a, and the stator yoke portion 24
c and excitation coil 25c are arranged facing each other in the radial direction as A phase and input phase, respectively, and similarly, stator yoke portion 24b and excitation coil 25b and stator yoke portion 24d and excitation coil 25d are arranged as A phase and input phase, respectively. The phases are arranged facing each other in the radial direction, and together with the stator yoke 23, each phase is connected to the magnetized rotor portion 2 of the rotor 21.
1b constitutes a magnetic circuit, but the magnetic resistance is reduced,
In addition, in order to make each phase nearly separated, cutout portions 24e, 24f, 24g = 24 are provided at the inner diameter portion of the stator yoke 24 at the boundary portion of each phase, as shown in FIG.
h, and the A phase, phase input and B phase, and phase input are the stator yoke 24 relative to the magnetized position of the rotor portion 21b.
The position of the comb teeth is shifted.

The aperture blade 26 is made up of a plurality of blades (six blades in this embodiment), and has a dowel 26a on one surface and a dowel 26a on the other surface.
The dowels 26a are rotatably fitted into the plurality of holes 21c provided in the rotating ring portion 21a of the rotor 21, respectively, as described above, and the dowels 26b are provided on the aperture blades 2.
The turbo blades 26b are fitted into a plurality of cam holes 27a formed at equal intervals in the circumferential direction of the aperture blade case 27 which houses the rotor 21, and as the rotor 21 rotates, the tabs 26b are fitted into the cam holes 27a. The aperture blades 26 move from the fully open position to the predetermined aperture open position.

The aperture blade case 27 is molded from a plastic material, and is designed to reduce friction between the aperture blades 26 and the turbo 26b so that the aperture blades 26 can rotate smoothly. It is fixed well.

Figure 5 shows a two-phase bipolymer for operating a pulse motor.
The drive circuit diagram, FIG. 6, shows its operation time chart.

In FIG. 5, excitation coils 25a, 25c and 2
5b and 25d are connected in series, respectively, and transistors 'rr and # are connected to the excitation coils 25a and 25c, respectively.
Tr2 # Tr31Tr4 is the excitation coil 25b
, 25d for transistor Tr+ * Tra *
Tr and +Tra each constitute a bridge circuit as shown in the figure, and excitation coils 25a and 25 are driven by an input pulse signal proportional to the step control from the drive circuit 30.
c and excitation coils 25b and 25d.

Therefore, in FIG. 4, both the A phase and the human phase are currently rotor portion 21b.
The stator yoke portions 24a, 24 facing the N poles of
Assuming that the comb teeth c attract each other with different S poles, the other B phase and 9 phase are shifted by the step angle (θ,) and are connected to the N pole of the rotor part 21b and the stator yoke part 2.
The comb teeth 4b and 24d have the same north pole and repel each other. At this time, physiognomy.

The B phase is at high level D, and the λ phase and i phase are at low level. And the whole thing is at a standstill.

Next, the drive circuit 30 switches the direction of the current flowing through the excitation coils 25a, 25b, 25e, and 25d so that the IC1A phase is at a low level, the B phase is at a high level, the input phase is high level, and the input phase is at a low level. If phase B,
When the phase input is N pole, the stator yoke portion 24b.

It is attracted to the S pole of the rotor portion 21b closest to the comb teeth 24d. That is, the rotor 21 rotates one step in one direction and then stops. On the other hand, physiognomy and entry phase lose their attractive power, and 1
It shifts by the step angle and stops.

Therefore, the rotor 21 is sequentially rotated in a stepwise manner clockwise or counterclockwise by continuously switching the selection and direction of the current flowing through each phase.

As a result, the aperture blades 26 are set to a predetermined aperture depending on the rotational direction of the rotor 21.

In this embodiment, the excitation coils 25a to 25d are wound in the circumferential direction of the stator yoke 24, but if it is desired to effectively utilize the space factor, they may be wound in the optical axis direction as shown in FIG. .

Furthermore, the step control electromagnetic drive device of the present invention can also be used as an electromagnetic drive device for a shutter.

<Effects of the Invention> As explained above, the present invention includes integrally molding the rotating ring portion that drives the aperture blades and the ring-shaped rotor portion that is magnetized with multiple poles from a synthetic resin material containing a magnetic substance. By forming a magnetic material layer on the inner circumferential side of the rotor part, uneven magnetization of the shirrotor part is reduced, permeance is increased, and magnetic resistance is reduced, which increases the torque of the pulse motor and improves motion efficiency. This has the effect of stabilizing drawing accuracy and reducing component costs by reducing the number of components.

[Brief explanation of the drawing]

FIG. 1 is a front view of an electromagnetically driven optical diaphragm device which is an embodiment of the present invention, FIG. 2 is an exploded perspective view showing its schematic structure, FIG. The figure is an enlarged front view of the pulse motor, Figure 5 is a two-phase bipolar drive circuit diagram for operating the pulse motor, Figure 6 is a time chart during its operation, and Figure 7 is the excitation coil of the pulse motor. 8 is a perspective view showing a schematic configuration of a conventional aperture drive device, and FIG. 9 is a perspective view showing a schematic structure of another conventional aperture drive device using a hollow pulse motor. It is a diagram. 20...Hollow type pulse motor, 21...Rotor, 2
1a... Rotating ring part, 21b... Ring-shaped rotor part,
21f... Cylindrical layer of magnetic material, 22... Ring-shaped stator, 23, . 24... Comb tooth-shaped stator yoke, 25a. 25b, 25c, 25d...excitation coil, 26
...Aperture 9 blades, 27...Aperture blade case, 28...
・Terminal board Figure 1 Figure 3 F1 Figure 5 Figure 6 □ STETSUA Figure 7 Figure 9 Figure 8 Procedural amendment July 2, 1986

Claims (1)

[Claims] 1. In an electromagnetic drive optical diaphragm device in which a hollow pulse motor drives and controls the aperture of a photographic lens up to a set aperture value using a pulse signal, the pulse motor uses a magnetic material to connect a rotating ring portion that drives the aperture blades and a ring-shaped rotor portion. A rotor is formed by integrally molding a synthetic resin material containing An electromagnetically driven optical diaphragm device characterized in that a comb-like stake yoke is disposed on the outside of the diaphragm.