JPH0965639A - Step motor and step motor driving shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the disorderly movement of the shaft of a rotor in a bearing and the occurrence of noise and to improve the performance of a step motor by providing the rotor having permanent magnets, stators which are magnetically coupled with the rotor, coils which excite the stators, and an energizing means which can give a side pressure to the shaft of the rotor. SOLUTION: A step motor M is constituted of a rotor 1 having permanent magnets, a pair of stators 12 and 12 which are provided on both sides of the rotor 1, and coils 13 which excite the stators 12 and 12. A side pressure is always applied to the shaft 1a of the rotor 1 from an energizing means 15 which is supported by a supporting projection 10d provided on a lower plate 10. The energizing means 15 is composed of a coiled spring formed by coiling a piano wire and one arm section 15a of the means 15 is supported by a projection 10e protruded from the lower plate 10. The other arm 10b of the means 15 is elastically brought into contact with the shaft 1a of the rotor 1 so that the arm 10b can apply the side pressure to the shaft 1a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor and a step motor driving shutter.

[0002]

2. Description of the Related Art Generally, a step motor for driving a shutter of a small camera includes a rotor composed of a permanent magnet rotatably supported by a bearing, a stator magnetically coupled to the rotor, and a stator. It is composed of a coil to be excited (e.g.
1683). In order to allow smooth rotation of the rotor, it is essential to provide some clearance between the rotor shaft and the bearing portion. However, such a gap causes the rotor to violently vibrate in its axial direction and radial direction due to the moment of inertia of the rotor itself and the force received from the driven member when the rotor rotates. For this reason,
There are problems such as large hunting when the rotor is stopped, out-of-step of the rotor, and imbalance of the rotational force and rotational speed of the rotor. Therefore, the shutter driven by this is likely to cause hunting, and there has been a concern that the opening / closing operation of the shutter may be uneven.
In addition, these vibrations also cause an increase in shutter operating noise.

To solve this problem, the present applicant has previously arranged a pair of stators in a V shape on the same horizontal plane and rotated a rotor having a permanent magnet between the tips of the legs of both stators. It has been proposed that the magnetic center plane of the rotor and the magnetic center planes of the magnetic pole portions of both stators are arranged so as to be freely arranged (Act No. 6-24814). this is,
By displacing the magnetic center planes of the two, a magnetic biasing force is applied in the axial direction of the rotor so that one end of the rotor is pressed by the rotor support member. In this way, it is possible to absorb the vibration of the rotor during rotation and to obtain a uniform and stable rotation of the rotor. As a result, the accuracy of the rotor stop position and the accuracy of the step angle have been improved, and the shutter employing this motor has also achieved stable shutter opening / closing operations.

[0004]

The above-mentioned prior art is effective in terms of the action of the urging force in the axial direction of the rotor and the prevention of vibration due to frictional resistance, but measures against vibration in the radial direction are taken. Since no measures have been taken, there is still a problem that the rotor shaft violates in the bearing during the rotation of the rotor, causing vibration and noise, which adversely affects the performance and durability of the motor. After all, when this motor is used as a shutter drive motor, it causes hunting and an increase in operating noise, which causes a problem in improving the performance of the shutter.

Therefore, an object of the present invention is to prevent the rotor shaft from moving around in the bearing by exerting an urging force in the radial direction of the rotor shaft, thereby improving the performance of the step motor and the step motor driving shutter and preventing noise. It is to plan.

[0006]

To achieve the above object, a step motor of the present invention includes a rotor rotatably supported and having a permanent magnet, a stator magnetically coupled to the rotor, and a stator. A coil that excites
It is characterized in that it has an urging means which is provided so that lateral pressure can be applied to the rotor shaft. The rotor shaft is biased by the biasing means in a plane substantially parallel to the rotation plane of the rotor and in a direction substantially equal to the direction in which the resultant magnetic attractive force between the stator and the rotor acts. I chose

The pair of stators of the step motor are provided so that the magnetic pole portions face each other in a state in which one pair is tilted by a predetermined angle, and the urging direction of the urging means is the resultant magnetic attraction force between the respective stators and rotors. It is desirable that the direction is substantially equal to.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a rotor 1 having a permanent magnet is integrally fixed to a rotor shaft 1a, and a rotor pinion 2 for transmitting the rotation of the motor to a shutter mechanism is provided at the tip of the rotor shaft 1a. It's stuck.

A base plate (not shown) is attached to the lower surface side of the base plate 3 for holding the lens by screws, and an opening O for lens opening is formed at the center of the base plate 3 and the base plate. , A pair of sectors 4,
A sector room for storing 4 is formed. A sector drive lever 5 is swingably attached to a support shaft 3a projecting from the main plate near the supporting portions of the pair of sectors 4 and 4. The sector drive lever 5 is supported by the lower surface of the step motor M so as not to slip out.

The pair of sectors 4 and 4 are swingably supported by the pins 3b and 3b provided on the base plate 3, and the size of the opening O is large between the two sectors 4 and 4 arranged symmetrically. It is configured to determine the height.

The sector drive lever 5 is attached to the sector drive vehicle 6.
Is rotatably attached, and the groove 5b provided on the sector drive lever and the adjustment pin 7 fixed to the sector drive wheel 6 are engaged with each other, whereby the rotation of both is restricted. Further, the sector drive lever 5 has a sector pin 5a which penetrates the main plate 3 and engages with a groove (not shown) of the sector 4.

The sector drive wheel 6 is attached to the sector drive lever 5 and has a toothing portion 6a which meshes with an idler wheel 8 which will be described later and a degree determining portion 6b which regulates rotation in relation to a pin 3c provided on the main plate 3. And a pin (not shown) that engages with a spring (not shown), and is biased counterclockwise by this spring. The adjustment pin 7 fixed to the sector drive vehicle 6 has an eccentric radial portion engaged with the sector drive vehicle 6 and a radial portion engaged with the groove portion 5b of the sector drive lever 5, and the sector drive vehicle 6 is rotatably fixed with a predetermined friction slip torque by crimping or the like. Therefore, by turning the groove of the adjustment pin 7 with a screwdriver,
The phase relationship between the tooth portion 6a of the sector drive wheel 6 and the sector pin 5a of the sector drive lever 5 can be adjusted.

The idler wheel 8 has a pinion 8a that meshes with the tooth portion 6a of the sector drive wheel 6 and a gear 8b that meshes with the rotor pinion 2, and is rotatably supported by a rotary shaft 3b provided on the main plate 3, It is supported by the lower surface of the step motor M so as not to come out. Further, columns 3e and 3e for mounting the step motor M are provided on the main plate 3, and the rotor pinion 2 and the idler wheel 8 mesh with each other by fixing the step motor to the column 3e with a set screw.
Rotation can be transmitted between the two.

Next, the structure of the step motor M will be described in detail. As shown in FIG. 2, the step motor M is composed of a rotor 1 having a permanent magnet, a pair of stators 12 and 12 provided so as to sandwich the rotor, and coils 13 and 13 for exciting each stator. . As shown in FIG. 3, one end of the rotor shaft 1 a integrated with the rotor 1 is rotatably supported by the through hole 11 a of the upper plate 11, and the other end passes through the through hole 10 a provided in the lower plate 10. The rotor pinion 2 for transmitting the rotation of the rotor 1 is fixed to the tip of the rotor pinion 2. The stator 12 shown in FIG.
Has a U shape and is positioned by a guide pin 10b provided on the lower plate 10. For this reason, the magnetic pole portions 12a are arranged so as to be biased toward the inner side (downward in FIG. 2) so that the resultant magnetic attraction force between the stator and the rotor acts inward (downward in FIG. 2) as described later. I am doing it. Further, two coils 13, 13 for generating a magnetic field in the magnetic pole portion 12 a of each stator are wound around the coil frame 14 and inserted in the leg portions of the stator 12.

On the other hand, the lower plate 10 and an upper plate 11 which will be described later are formed by plastic molding, and the lower plate 10 is provided with locking claws 10c and 10c for mounting and fixing the upper plate 11. . Further, as shown in FIG. 3, the upper plate 11 has a guide hole that fits with the guide pin 10b of the lower plate 10 and a hooking portion (all not shown) that engages with the locking claw. .
And the two stators 1 in which the coils 13, 13 are inserted
After the rotors 2 and 12 and the rotor 1 are attached to the lower plate 10, the upper plate 11 is placed from above to engage the locking claws 10c and the hooking portions (not shown).
The lower plate 10, the upper plate 11 and the stator 12 are fixed by engaging with each other, and the rotor shaft 1a is fixed to the through hole 10a,
The rotor 1 is rotatably supported by the shaft 11a (see FIG. 3).

As shown in FIG. 3, the rotor shaft 1a is loaded with lateral pressure by a biasing means 15 supported by a support projection 10d provided on the lower plate 10. The urging means 15 is a torsion coil spring formed by processing a piano wire, one arm portion 15a is supported by a protrusion 10e protruding from the lower plate 10, and the other arm 15b can apply a lateral pressure to the rotor shaft 1a. Is in contact with.

As shown in FIG. 4, the rotor shaft 1a, which is displaced while rotating as shown by the one-dot chain line in the through hole 11a, is shown by the solid line due to the impulsive force of the biasing means. It will be in a fixed position and rotatable. Urging means 15
Is applied to the rotor shaft 1a in a plane substantially parallel to the rotation plane of the rotor 1 and is substantially the same as the direction in which the resultant magnetic attraction force between the stator and the rotor acts. It is designed to be. (See Figure 4). As a result, the resultant force of the urging force of the urging means 15 and the magnetic attraction force acting in the same direction acts on the rotor shaft 1a as a lateral pressure, and the urging force of the urging means 15 does not have to be increased. Is done.

FIG. 5 shows the relationship between the changes in the polarities of the four magnetic poles 12a located at the tips of the legs of the stator 12 and the positions of the magnetic poles of the permanent magnets of the rotor 1 rotating in response to the changes. Is shown. When the polarities of the magnetic pole portion 12a of the stator are in the states (a) and (c) in the drawing, almost no upward magnetic attraction force is generated, so only the downward magnetic attraction force B is in operation. On the other hand, the acting direction of the lateral pressure on the rotor shaft 1a by the urging means 15 is downward in the figure, and therefore coincides with the direction of the magnetic attraction force B. In the states of (b) and (d) of FIG. 5, although the upward magnetic attraction force is somewhat generated, it can be seen that when the downward magnetic force is offset, the downward magnetic attraction force C still acts largely.

In FIG. 4, the alternate long and short dash line indicates the through hole 10a.
This shows a state where the rotor shaft 1a located inside is swaying during rotation. 4 and 5 are drawn so that the vertical direction is the same. As shown here, the rotor shaft 1a
, The combined force of the magnetic attraction force and the urging force generated by the urging means 15 act in substantially the same direction, and the combined force of these forces acts on the rotor shaft 1a. In the prior art, the rotor shaft 1a changes its position within the through hole 11a (10a) as shown by the alternate long and short dash line, but in the present invention, it is pressed downward by the urging means 15 in the drawing. Therefore, it is always possible to rotate in the same position (see Fig. 4).

FIG. 6 shows another embodiment, in which a permanent magnet 16 is provided in the vicinity of the rotor shaft as an urging means, and the rotor shaft is attracted by this permanent magnet to exert a lateral pressure on the rotor shaft 1a. It is the one to try. The permanent magnet 16 is installed at a position where the magnetic attraction force between the stator and the rotor is substantially equal to the magnetic attraction force between the rotor shaft and the permanent magnet. If a collar made of a ferromagnetic material is fixed to the rotor shaft at a position facing the permanent magnet, a larger lateral pressure can be obtained.

As the other urging means, other urging means such as a leaf spring or a coil spring may be adopted. As described above, the rotor shaft 1a reduces the turbulence of the rotor shaft by the urging force of the urging means and the magnetic attraction force generated between the stator and the rotor. If the vibration is absorbed by applying the urging force in the axial direction that has already been proposed (Japanese Utility Model Publication No. 6-24814), the effect of vibration and sound insulation becomes more remarkable.

Although the rotor and the rotor shaft are described as separate members, they may be integrated. The step motor of the present invention has been described for driving the shutter of the camera, but the invention is not limited to this, and is applicable to all motors that stably rotate the rotor shaft.

[0023]

In the step motor of the present invention, since the rotor shaft is biased by the biasing means, the stepping motor does not run away during the rotation of the rotor, and the magnetic attraction force between the stator and the rotor acts. Since the urging force acts in a direction substantially equal to, the turbulence of the rotor shaft can be reduced by only urging with a small urging force.

Therefore, if the step motor of the present invention is used as a shutter drive motor for a camera, it is possible to obtain a camera with reduced shutter hunting and high vibration and noise reduction effects.

[Brief description of drawings]

FIG. 1 is a plan view showing a shutter opening / closing mechanism of a camera to which a step motor of the present invention is attached.

FIG. 2 is a plan view of a main part of a step motor according to the present invention.

FIG. 3 is an enlarged cross-sectional view showing a state of a rotor and members around the rotor.

FIG. 4 is an explanatory view showing a state in which the biasing means suppresses the displacement of the rotor shaft in the shaft hole.

FIG. 5 is an explanatory diagram showing a relationship between a change in polarity of a magnetic pole portion of a stator, a position of a magnetic pole of a rotor, and a magnetic attraction force.

FIG. 6 is an enlarged cross-sectional view showing a state of a rotor and its periphery in another embodiment.

[Explanation of symbols]

 M step motor 1 rotor 1a rotor shaft 4 shutter blades (sector) 12 stator 13 coils 15 and 16 urging means

Claims (3)

[Claims] 1. A rotor that is rotatably supported and has a permanent magnet, a stator that applies a magnetic field to the rotor to rotate it, a coil that excites the stator, and a rotor shaft that is integrally provided with the rotor. A stepping motor for biasing the rotor shaft in a direction substantially parallel to a rotation plane of the rotor. 2. The step motor according to claim 1, wherein the urging direction of the urging means is a direction substantially equal to a resultant force of magnetic attraction forces between the stator and the rotor. . 3. A step motor drive shutter comprising: the step motor according to claim 1; and shutter blades driven by rotation of the rotor.