JPS5840576Y2 - release type electromagnet device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a release type electromagnet device, and more specifically to a release type electromagnet in which the magnetic force of a permanent magnet is used as an attraction magnetic force, and the magnetic force of the electromagnet is used as a demagnetization force of the attraction magnetic force.

2. Description of the Related Art Conventionally, release type electromagnets called permanent magnet core type electromagnets have been used as electromagnets for restraining and releasing movable members, which are used in electric shutter mechanisms of cameras and the like.

In this electromagnet, a permanent magnet is supported by a yoke to form a permanent magnet for attraction, and an electromagnet winding is wound around the yoke, through which an excitation current is passed to demagnetize the attraction magnetic force. , the movable member is attracted and restrained by the magnetic force of the permanent magnet, and when releasing this restraint, an excitation current is passed through the electromagnet winding to excite the electromagnet consisting of the yoke and the winding. The magnetic force is used to demagnetize the attracting magnetic force of the permanent magnet body, thereby releasing the restraint of the movable member.

Unlike ordinary electromagnets, this release-type electromagnet restrains the movable member by mechanically attracting the movable member using the magnetic force of a permanent magnet. There is no need for any holding current to maintain the magnet in the attracted state, and when releasing the restraint of the movable member, the excitation current only needs to flow through the electromagnet winding for a short period of time, resulting in significantly lower power consumption. It has the advantage that the electromagnet can also be constructed very compactly.

Next, an example of a conventional release type electromagnet will be explained with reference to FIG.

Yoke 1 a, 1 that constitutes a permanent magnet and an electromagnet
b, 1e are prismatic pieces of soft magnetic material such as ferrite, and are formed in a U-shape.

The left and right yokes la and lb are arranged parallel to each other, and a small and strong permanent magnet 2 such as a rare earth metal magnet is placed at the bottom between the yokes la and lb. The permanent magnet 2 is supported by both the yokes la and lb by having the end faces of the permanent magnet 2 adhered to the yokes la and lb, respectively, thereby forming a permanent magnet body 1A.

That is, by supporting the permanent magnet 2, the upper end faces IC, ld of both yokes la, lb become magnetic poles N, S, and both end faces 1c.

1d comes to attract the movable iron piece 3, which is an armature.

Then, the electromagnet is connected to the yoke la formed as described above.
, lb, an electromagnet winding 4 is wound around one yoke 1a of the yokes la and lb, and a bypass portion formed by a yoke 1e that connects the bottoms of the yokes la and lb.

The movable iron piece 3 is fitted by a shaft 7 to one end of a support lever 6 whose fulcrum is slidably pivoted by a shaft 5 .

Note that a spring 8 for separating is applied to the lever 6.

The movable iron piece 3 can be restrained by moving the movable iron piece 3 against the elasticity of the spring 8 to a range where the attraction magnetic force of the permanent magnet body 1A acts, by a mechanism not shown. It is attracted and held in a predetermined position by the action of magnetic force.

Further, when releasing the restraint, the attracting magnetic force is demagnetized by the excitation force of the electromagnet, and the movable iron piece 3 is separated from the end surfaces 1C91d of the yokes la and lb by the elasticity of the separating spring 8.

In the conventional electromagnet configured in this way, when the movable iron piece 3 is moved to a range where the attracting magnetic force of the permanent magnet body 1A acts, the lines of magnetic force of the permanent magnet 2 are formed like a loop a. As a result, it is held by suction on the end faces IC, ld of the yoke.

To release this restraint, the electromagnet winding 4
An excitation current that generates a magnetic field in the opposite direction to that of the permanent magnet 2 is passed through the yoke 1e to generate a magnetic field line loop b that passes through the bypass section of the yoke 1e, and this loop b, which is in the opposite direction to the loop a, causes the magnetic field lines from the permanent magnet 2 to flow through the loop b. is weakened, and with the help of the elasticity of the spring 8, the movable iron piece 3 is separated from the end faces IC, ld.

The above is an example of a conventional release type electromagnet.

By the way, in the conventional electromagnet configured in this way, a bypass section by the yoke 1e is provided in order to pass the lines of magnetic force of the electromagnet.

Therefore, the path of the magnetic field lines of the permanent magnet 2 is the loop a
The line of magnetic force passing through the bypass yoke 1e reduces the line of magnetic force for attraction going to the movable iron piece 3 due to the loop a.
This has the disadvantage that the force for attracting the movable iron piece 3 is weak.

In other words, the electromagnet bypass passes the magnetic lines of force of the permanent magnet, and a part of the lines of magnetic force of the permanent magnet are wasted for purposes other than the action of attracting the iron piece.

In addition, in order for the lines of magnetic force generated by the electromagnet to form the closed circuit of loop b, a bypass material made of a material with high magnetic permeability is required, but if the magnetic permeability of the bypass yoke 1e is increased, the lines of magnetic force of the permanent magnet can be wasted. will continue to increase.

Therefore, a permanent magnet with a strong magnetic force must be used to compensate for the amount wasted in this bypass, and the permanent magnet has the disadvantage of being large.

An object of the present invention is to provide a release type electromagnet device that can completely eliminate the drawbacks of the conventional release type electromagnets as described above by making the bypass section movable.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 2 is a plan view of a release type electromagnet device showing an embodiment of the present invention.

In this embodiment, the permanent magnet body 1A includes yokes 1a and 1b made of a material with high magnetic permeability, a permanent magnet 2, an electromagnet winding 4, a movable iron piece 3, a support lever 6, a pull-out Since the spring 8 and the like are constructed in the same manner as the conventional one shown in FIG. 1, their explanation will be omitted.

In the present invention, the bypass member 9 connecting the bottoms of the yokes la and lb is formed of a piece of soft iron separated from the bottoms of the yokes la and lb.

The bypass member 9 is supported by having its central portion fitted by a shaft 12 onto the distal end portion of a support arm 11 whose base portion is pivotably attached to a support shaft 10 .

The support arm 11 is rotated counterclockwise around the support shaft 10 by the relatively weak tension elasticity of the flat spring 13 until its one side edge comes into contact with the stopper pin 14, and this rotation causes the bypass The member 9 is spaced apart from the bottom of the yokes 1a, lb by a spatial distance d.

In the electromagnet device of this embodiment configured in this way, when the movable iron piece 3 is attracted as shown in FIG.
is hardly formed, and most of the magnetic lines of force of the permanent magnet 2 are concentrated in the closed circuit of the loop a without any waste.

Therefore, the suction force of the suction end faces IC, ld of the yokes la, lb increases, and the movable iron piece 3 is reliably and firmly suctioned.

Next, in order to release this restraint, the electromagnet winding 4
An excitation current that generates a magnetic field in the opposite direction to that of the permanent magnet 2 is passed through the permanent magnet 2, and as shown in FIG. 3, lines of magnetic force in loop b are generated in the opposite direction to the lines of magnetic force in loop a.

Then, along the movable bypass member 9, the magnetic flux that is trying to form this loop b and the magnetic flux that is coming out of the permanent magnet 2 and trying to form the loop C are combined to generate a strong magnetic force. By magnetic force, the bypass member 9
As shown in FIG. 3, the yoke l resists the elasticity of the spring 13
a, sucked into the bottom of lb.

When this is sucked, the movable bypass member 9
, lb, and the spatial distance d disappears, so the lines of magnetic force of the electromagnet form a loop b1 passing through the movable bypass member 9, and the lines of magnetic force of the permanent magnet 2 also form a loop C passing through the movable bypass member 9. The lines of magnetic force in loop a of magnet 2 decrease.

The magnetic field lines of the loop b are directed in the direction of the movable iron piece 3.
Since the direction is opposite to the line of magnetic force forming the loop a, the magnetic force of the loop a is canceled out, and the movable iron piece 3 is pulled by the elasticity of the spring 8, as shown in FIG.
It moves away from the suction end surface 1C91d, and the restraint of the movable iron piece 3 is released.

This action of releasing the restraint is instantaneously performed when the excitation current is applied.

Then, when the excitation current is cut off, most of the magnetic lines of force of the permanent magnet 2 gather in the movable bypass member 9, and the loop C
passes through a closed circuit.

Therefore, even if the current is cut off, the bypass member 9 will remain connected to the yoke la,
Do not move away from lb.

In order to separate the movable bypass member 9, as shown in FIG. Bye.

When this is pressed, the closed circuit loop a of the magnetic lines of force of the permanent magnet 2 is formed again, and the magnetic flux of the loop C becomes weaker, so the bypass member 9 is pulled by the elasticity of the spring 13 and moves away from the yokes la and lb. A spatial distance d is formed and the state returns to the initial state shown in FIG.

As described above, according to the electromagnet device of the present invention, there is no waste of the magnetic lines of force of the permanent magnet, and all of them are used effectively.

Next, a case will be described in which the electromagnet device of the above embodiment of the present invention is used to release the restraint of the rear curtain of a focal plane type electric shutter of a camera.

In this case, the electromagnet device of the present invention is arranged near the rewinding drum 17 as shown in FIG.

In this application example, the bypass member 9 is pivotally supported at the end of one arm of a holding lever 11 supported by a shaft 10 so as to be swingable about its fulcrum.

A pin 43 is installed at the end of the other arm of the lever 11, and a spring 13 wound around the shaft 10 is stretched between the pin 43 and the fixed pin 44. The amount of pulling force is adjusted.

Furthermore, since the amount of movement of the lever 11 needs to be finely adjusted, in this application example, the stopper pin 14 is formed as an eccentric pin, thereby adjusting the spatial distance when the movable bypass member 9 is separated. It has become.

In this application example, when the shutter is released, the front curtain 19 moves in the direction of arrow F, an exposure window (not shown) is opened, and exposure of the film is started.

Furthermore, as is well known, photometry starts at the same time, and the exposure control circuit of the electric shutter is activated.

Then, when the film has been properly exposed, an excitation current is caused to flow through the electromagnet winding 4 by the control circuit.

When this current flows, the electromagnet device of the present invention is
It operates as shown in FIG. 4, and the support lever 6 rotates counterclockwise around the support shaft 5.

When this rotates, the hook 23 is also rotated counterclockwise around the spindle 5 by the pin 24, so the hook 23
is removed from the locking pawl 22a, and the restraint of the trailing curtain drum 17 is released.

When this is released, the trailing curtain 16 moves in the direction of arrow F, the exposure window is closed, and the exposure ends here.

Next, the film advance lever 31 is rotated counterclockwise, and the sprocket wheel 33 is rotated once counterclockwise via the gear train consisting of gears 32 a , 32 b , and 34 .
When the exposed film is wound up, gear 3
5, 36, and 37 one rotation each.

Then, just before the end of one rotation of the charge cam 38 integrated with the gear 37, the protrusion 38a pushes the rotor 39, so the actuating arm 41 moves around the support shaft 40 with the spring 42.
It rotates clockwise against the elastic force of.

When this rotates, the stopper pin 29 also moves clockwise, so the bell crank 26, with the other arm 26b in contact with this pin 29, swings counterclockwise around the support shaft 27 by the spring 28. , the pushing piece 6a of the lever 6 is pushed by the tip of the arm 26a.

When this is pushed, the lever 6 swings clockwise around the support shaft 5 against its own tendency, and the movable iron piece 3 is pressed against the yokes la and lb.

When this is pressed, as explained in FIG. 5 above,
The bypass member 9 is separated from the yokes la and lb, and the electromagnet device returns to the initial state shown in FIG.

Further, when the lever 6 swings clockwise, the hook 23 follows the movement of the pin 24 and rotates clockwise around the support shaft 5 due to the elasticity of the spring 25, and its tip end is attached to the disk 22.
Press it against the circumferential surface of the

On the other hand, as is well known, the shutter charge mechanism and the mirror charge mechanism operate in conjunction with the film advance operation, so when the film is wound up, the shutter front curtain 19 has its traction cords 20a and 20b. The rewinding drum 17 of the trailing curtain is rotated counterclockwise by the gear 21, and the shutter is rotated counterclockwise by the gear 21. Rewind the second curtain 16.

When this is unwound, the restraining disk 22 fixed to the drum shaft also rotates counterclockwise.

Then, at the end of the rotation, the protrusion 22a is attached to the hook 23
1, and the drum 17 is again restrained by the string.

Note that the reference numeral 30 in FIG. 6 is a stopper pin of the lever 6.

As described above, the electromagnetic device of the present invention is optimally applied to release the restraint of the rear curtain of a focal plane type electric shutter of a camera.

Next, other embodiments of the present invention are shown in FIGS. 7 and 8, respectively.

In the electromagnet device according to another embodiment of the present invention shown in FIG. 7, the movable bypass member is formed of a piece of soft iron, and this is skillfully supported to make the electromagnet device small in bulk. be.

In this embodiment, the permanent magnet 2 is placed beside the movable iron piece 3.

That is, in the upper part between the yokes la and lb, the yokes 1a and lb
It is fixed and placed in the

A shaft mounting plate 46 made of a non-magnetic material is fixed to the lower surface of the permanent magnet 2, and a support shaft 47 is screwed into and fixed to the center of the shaft mounting plate 46 from below.

Therefore, this support shaft 47 is located at the center between the yokes la and lb.

Then, a movable bypass member 49 made of a single soft iron plate is loosely inserted into the support shaft 47 from below, a ring washer 48 is fitted into the shaft 47, and a set screw 50 is inserted into the lower end surface of the support shaft 47. screwed in, thereby supporting the movable bypass member 49.

The shaft mounting plate 46 and the movable bypass member 49 are adapted to be acted upon by the elasticity of a coil spring 51 which is wound around the support shaft 47 and has a weak extensional elasticity. Under normal conditions, the movable bypass member 49 moves downward due to its elasticity and is separated from the bottom end surfaces of the yokes 1a and 1b.

The rest of the structure is similar to that of the previous embodiment shown in FIGS. 2 to 5.

It goes without saying that the apparatus of this embodiment constructed in this manner operates in exactly the same manner as the apparatus of the previous embodiment (FIGS. 2 to 5).

However, in this embodiment, the distance d between the bottom end faces of the yokes la, lb and the movable bypass member 49 is adjusted by changing the thickness of the ring washer 48.

Further, another embodiment of the present invention shown in FIG.
The support arm 111 (
2 to 5) is replaced with a support lever 52, and the other arm of the lever 52 and the other arm of the support lever 6 of the movable iron piece 3 are connected by a weakly compressible spring 53.

The rest of the structure is exactly the same as that of the previous embodiment shown in FIG.

Further, the spring 53 functions as the spring 13 in the above embodiment with respect to the lever 52, but if both levers 6 and 52 are connected as in this embodiment, the tension elasticity of the spring 53 is reduced. Accordingly, the movable iron piece 3 and the movable bypass member 9 are
Forces are always applied in directions that move them away from each other.

When the movable iron piece 3 is attracted to the yokes la and lb, this elasticity causes the movable bypass member 9 to be attached to the yokes la and lb.
When the movable bypass part 9 is attracted to the yokes la and lb,
It doubles as a force to separate the movable iron piece 3 from the yokes la and lb.

Therefore, not only the separation operation between the two becomes smooth, but also the operation of the electromagnet device can be made very quick.

As described above, according to the present invention, the open type electromagnet can eliminate the waste of magnetic lines of force, which is a drawback of conventional open type electromagnets, and can perform completely waste-free operation using a smaller permanent magnet and electromagnetic current. equipment can be provided.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an example of a conventional release type electromagnet, Fig. 2 is a plan view of a release type electromagnet device showing an embodiment of the present invention, and Figs. Fig. 6 is a perspective view of the release type electromagnet device of the present invention when applied to the rear curtain release mechanism of a focal plane type electric shutter of a camera, and Fig. 7 and 8 are other diagrams of the proposed release type electromagnet device. FIG. 3 is a plan view of a release type electromagnetic device showing examples. 1A...Permanent magnet body, LA, LB...
Yoke, 2... Permanent magnet, 3... Movable iron piece, 4... Electromagnet winding, 9, 49...
...Bypass member.

Claims (1)

[Claims for Utility Model Registration] A pair of yokes supporting a permanent magnet, and a permanent magnet wound around at least one of the pair of yokes,
When an excitation current is applied, the electromagnet winding that forms an electromagnet together with the yoke is attracted to each end face of one side of the pair of yokes by the magnetic force of the permanent magnet, and when the electromagnet is excited, the permanent magnet is attracted. The movable piece detaches when the magnetic force of the electromagnet is canceled by the magnetic force of the electromagnet, and when the electromagnet is excited, the movable piece is attracted to the other end face of the yoke by both the magnetic force of the electromagnet and the magnetic force of the permanent magnet. A release type electromagnet device comprising a bypass member.