JPS58216230A - Electromagnetically driven shutter - Google Patents

Abstract

PURPOSE:To realize efficient driving with a electromagnetically driving device for lens shutter of camera, by arranging electromagnets at the fixed side and permanent magnets at the rotating side on the same circumference of a circle. CONSTITUTION:An even number of pieces of electromagnets 1-4 are arranged on the holder of a lens shutter for camera to form a circular arc and permanent megnets 5-8 are fitted on a movable ring so that each of the permanent magnets 5-8 is installed to each space caused from the arrangement of the electromagnets 1-4 and the same poles of the electromagnet and permanent magnet are adjacent to each other. This movable ring is put in a movable fulcrum of the sector and, when the ring rotates, the sector is opened or closed. The electric current to the electromagnets is supplied in such a way that their same poles are adjacent to each other. Since rotating forces in the same direction are simultaneously applied to the permanent magnet and the direction of the rotation can be changed by inverting the electric current only, a large driving force is realized and this shutter can be controlled easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetically driven shutter whose shutter blades are opened and closed by electromagnetic force.

Various types of electromagnetic shutters of this size have been proposed, in which the blades are opened and closed using electromagnetic force.
One of these methods is to use a stepping motor to rotate the movable ring that opens the shutter blades (there is also one (4? Publication No. 53-2774)).The electromagnetic drive shutter using this stepping motor is This has the advantage of not requiring a magnetic charging mechanism, and that the shutter blades can be opened and closed using only electrical signals.However, when using a stepping motor, the complicated process of changing the polarity of the electromagnet according to the input pulse is required. A suitable motor drive circuit is required.

Also known is an electromagnetic drive shutter in which a lever is attached to a motor, a shutter blade is connected to one end of the lever, a permanent magnet is fixed to the other end, and electromagnets are further arranged on both sides of the permanent magnet (% Kosho 57 -10408). This shutter reduces power consumption by attracting and holding the core of the electromagnet with a permanent magnet when the shutter blade is in the fully open and fully closed positions. Since a driving section consisting of a magnet must be provided, the device becomes large and complicated. Furthermore, since the shutter blades are mainly driven by a motor, there is also the drawback that the cost is high.

The present invention solves the above-mentioned drawbacks, and aims to provide an electromagnetically driven shutter that has a simple structure and can obtain a large driving force.

In the present invention, an even number of arc-shaped electromagnets are fixed to a holder so as to be arranged in a circle at a predetermined interval, and a corresponding even number of arc-shaped permanent magnets are movable so that the same poles are adjacent to each other. The movable ring is attached to the fixed ring so that the permanent magnets fit between the electromagnets with a predetermined space between them, and when the electromagnets are energized, the permanent magnets simultaneously move between two adjacent electromagnets. Suction/
The repulsion causes the movable ring to rotate, and the movable ring opens and closes the shutter blade.

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

1 and 2 illustrate the principle of the invention. The electromagnet 1 is composed of an arc-shaped magnetic core 1a and a coil 1b. Along with this electromagnet 1, electromagnets 2 to 4 having the same structure are used and are arranged on the same circle at predetermined intervals.

Four arc-shaped permanent magnets 5 to 8 are arranged between these electromagnets 1 to 4, and these permanent magnets 5 to 8 are fixed to a movable ring, and the electromagnets 1 to 4 are attached to a holder. is fixed to. An even number of these electromagnets 1 to 4 and permanent magnets 5 to 8 are used, and repulsion and attraction are simultaneously performed between the poles of the permanent magnets 5 to 8 and the magnetic poles of the two electromagnets facing each other, and the electric energy is effectively used. The strong magnetic force used in the permanent magnets 5 to 8 can be applied to the permanent magnets 5 to 8.

The coils of the electromagnets 1 to 4 are connected in series,
Although they are energized at the same time, current flows in the same direction in electromagnets 1 and 3, and current flows in opposite directions in electromagnets 2 and 4.

Therefore, in the electromagnets 1 to 4, the directions of the lines of magnetic force are opposite between the electromagnets 1 to 4 that are adjacent to each other.

While the shutter blade is closed, the N poles of the permanent magnets 5 to 8 are attracted to the magnetic cores of the electromagnets 1 to 4. When opening the shutter blade, a current is applied to the electromagnets 1 to 4 to magnetize them as shown in FIG. The permanent magnets 5 to 8 generate a repulsive force at the north pole and an attractive force at the south pole, so they move in the direction of the arrow in response to the acting forces of both, and the shutter blades are fully opened as shown in Figure 2. reach the position.

When closing the shutter blades, a current in the opposite direction is passed through the electromagnets 1 to 5 to magnetize them as shown in FIG. A repulsive force is generated at the S poles of the permanent magnets 5 to 8, and an attractive force is generated at the N poles, so that the permanent magnets return to the fully closed position shown in FIG. 1 in response to these two acting forces.

Here, since the amount of movement of the permanent magnets 5 to 8 changes depending on the timing of changing the direction of the current supplied to the electromagnets 1 to 5, the opening amount of the shutter blade can be controlled. For example, when the release button is pressed, electromagnets 1 to 4 are magnetized as shown in FIG. It is sufficient to magnetize the electromagnets 1 to 4, and then stop energizing the electromagnets 1 to 4 when the permanent magnets 5 to 8 return to the positions shown in FIG.

3 to 5 show an electromagnetically driven shutter of the present invention. The ring-shaped holder 10 has a recess 11
The electromagnets 1 to 4 described above are disposed inside, and each of these electromagnets 1 to 4 has a coil wound around a magnetic core, as shown in FIGS. 4 and 5. Further, a cylindrical portion 13 having a light transmission hole 12 is formed in the center of the holder 10, and a movable ring 15 is provided on a shoulder portion 14 of this cylindrical portion 13.
is on board. This movable ring 15 has four parts shown in FIG.
permanent magnets 5 to 8 are fixed. This movable ring 15 has four pins 16 to 19, and is biased clockwise by a weak spring 20.

In order to prevent the movable ring 15 from coming out from the holder 10, a lower ring 22 is placed over the holder 10. This lower ring 22 has elongated holes 23 to 26 into which the pins 16 to 19 of the movable ring 15 are inserted, respectively;
Holes 31 to 34 are formed into which four bottles 27 to 30 provided in the holder 10 are inserted, respectively.

Four shutter blades 36 to 39 are stacked on the lower ring 22, and holes 40 to 39 in each shutter blade 36 to 39 are stacked on top of the lower ring 22.
holder 10 with 43 protruding through holes 31-34;
The pins 27 to 30 are fitted into each other to act as a fulcrum. Further, the holes 44-47 of the shutter blades 36-39 fit into the pins 16-19 of the movable ring 15 which protrude through the elongated holes 23-26, respectively.

The shutter blades 36 to 39 are housed between the lower ring 22 and the upper ring 51, which are opposed to each other with spacers 49 and 50 interposed therebetween. These upper ring 51 and lower ring 22 are connected by screws 52.5 inserted through spacers 49.50.
3, it is fixed to the holder 10. Note that this upper ring 51 has the same structure as the lower ring 22, so a detailed explanation will be omitted.

Said holder 10. Movable ring 15. Lower ring 22.
The upper ring 51 is made of a non-magnetic material, such as plastic. Note that when the number of permanent magnets is small, such as four or two, the movable ring 15 may be made of a magnetic material such as iron.

In this electromagnetically driven shutter, when the electromagnets 1 to 4 are excited as shown in FIGS. 1 and 2, the movable ring 15 rotates and the shutter blades 36 to 39 are pivoted by the pins 16 to 19. The blades 36 to 39 can be opened and closed.

In the present invention having the above configuration, a large driving force can be obtained because the movable ring for opening and closing the shutter blade is rotated by simultaneously applying an attractive force and a repulsive force to both ends of the permanent magnet. .

In addition, by simply switching the direction of the current supplied to the electromagnet,
Since the rotational direction of the movable ring can be controlled, the electromagnet drive circuit becomes simple and the cost is low.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing the principle of the present invention, Figure 3 is an exploded perspective view showing one embodiment of the invention, Figure 4 is a half sectional view thereof, and Figure 5 is a cross section of the main part. It is a diagram. 1-4... Electromagnet 5-8... Permanent magnet 10... Holder 15... Movable ring 22... Lower ring 36-39 ...Shutter blade 51 ... Upper ring 9-

Claims (1)

[Claims] An even number of arc-shaped electromagnets are arranged on concentric circles at predetermined intervals in the holder, and an even number of arc-shaped permanent magnets are arranged on concentric circles at predetermined intervals in the movable ring so that the same poles are next to each other. The movable ring is attached to the holder so that the permanent magnets and electromagnets are lined up alternately with appropriate spacing, and each electromagnet is energized so that the direction of the magnetic field lines is opposite between two adjacent electromagnets. An electromagnetic drive shutter characterized in that a movable ring is rotated by simultaneously applying a repulsive force to one magnetic pole and an attractive force to the other magnetic pole, and the movable ring opens and closes seven blades.