JPS62163556A - Step motor - Google Patents

Abstract

PURPOSE:To minimize the torque fluctuations by forming poles of a rotor so as to set two neighbouring regions in the same polarity when a rotor is divided into eight (8) in the circumferential direction. CONSTITUTION:Magnetic poles 1a and 2a on the one side for cores 1 and 2 formed in U-shape are fixed to the poles to which a rotor 4 lies next and magnetic poles 1b and 2b on the other side are fixed to a base plate 3 to bring them into line with the outside circumference of an opening 3a so as to be situated synmetrically each other across the two (2) poles of a rotor 4. Around the outside circumference driving coils 5 and 6 are wound to constitute a stator. In addition, the rotor 4 is fixed to the rotating shaft and rotatably supported between the base plate 3. On the circumferential surface of the rotor 4 eight (8) poles 4a-4h are provided so that each two of the same polarity may face in magnetizing four (4) pole couples so as to face the same polarity side each as shown in the figure. Thus, by the alternate change-over of polarity for two (2) cores land 2, the rotor 4 can continuously be rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a step motor suitable for driving a shutter for a camera.

(Prior Art) As cameras become more electronic, shutter devices in which sectors are driven by step motors have come into widespread use.

Incidentally, the stem motor used in such a shutter device is required to be constructed as compact as possible in order to be incorporated into the camera body.

In order to meet such demands, the present applicant has
As shown in Japanese Patent No. 140935, the cores A and B forming the stator are arranged in a "V" shape, and the magnetic poles a,
We proposed a step motor in which a four-pole magnetized rotor C is arranged in the area surrounded by a', b, and b' (
Figure 6). This step motor not only allows for miniaturization, but also eliminates wasted space because it matches the shape of the camera body. Since the rotational torque is large, fluctuations in the rotational torque are large, and since there is a stable point between the magnetic poles of the stator, there is a disadvantage that the stopping torque is small and the stopping position is unstable.

(Purpose) The present invention was made in view of the above problems, and its purpose is to make the magnetic poles of the stator and rotor face each other one-on-one, thereby achieving stable step drive and torque generation. The object of the present invention is to provide a small-sized step motor that can be realized.

(Structure) Therefore, details of the present invention will be described below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, and reference numeral 1.2 in the figure indicates a core formed in a U-shape, and one magnetic pole [a] and 2a are in contact with a of the rotor 4. The other magnetic poles 1b and 2b are fixed to the substrate 3.3 along the outer periphery of the opening 3a so as to have a symmetrical position M relationship across the two magnetic poles of the rotor 4, and a drive coil 5 is attached to the outer periphery. .6 is wound to form the stator. The rotor 4 is fixed to a rotating shaft 7 and rotatably supported between substrates 3.3, and has four pairs of magnetic poles on its circumferential surface with the same poles facing each other as shown in FIG. Eight magnetic poles 4a, 4b, 4c, . . . , 4h are formed so that two of the same polarities are adjacent to each other.

Next, the operation of the loading device constructed in this way will be explained based on FIG. 3.

Now, as shown in Figure 3, the magnetic poles of cores 1 and 2]a,
1b, 2a, 2b, and a rotor 4 facing these magnetic poles.
If the phase of the drive pulse to one of the cores 1 is reversed while the rotor 4 is stopped at a position where the magnetic poles maintain an attractive relationship, that is, at a stable point, the polarity of the magnetic poles 1a and 1b of the core 1 will not be reversed. (■ in the same figure) is attracted to the magnetic pole of the rotor 4 located one pole upstream in the rotational direction (the area surrounded by the dotted line circle in H in the figure) or the magnetic pole pieces 1a and 1b, respectively. The rotation starts after shaking off the stopping torque that is already being applied by the other core 2. In this way, after passing the non-magnetized region between the magnetic poles of the rotor 4, the magnetic pole piece 2a of the other core 2
, 2b (the part surrounded by the dotted rectangle in the figure) is attracted to the magnetic pole pieces 2a and 2b of the core 2, generates torque, and moves toward the dynamic stable point ( ■). When the dynamic stability point is reached, when the phase of the drive pulse to the other core 2 is reversed (■ in the same figure), the polarity of the magnetic pole pieces 2a and 2b of the core 2 is reversed, and the magnetic pole pieces 2a and 2b of the core 2 are reversed by one pole upstream in the rotation direction. The magnetic poles of the rotor 4 located at (the part surrounded by the dotted circle in the same figure) are attracted to the magnetic pole pieces 2a and 2b, respectively, so the rotation is stopped by shaking off the stopping torque of the core 1 on the − blade side. continue. In this way, after passing through the non-magnetized region between the magnetic poles of the rotor 4, the magnetic pole located upstream of the magnetic pole pieces [a] and 1b of the core 1 (the area surrounded by the dotted rectangle in the same figure) becomes the magnetic pole piece. Since it is attracted by 1a and 1b, it generates torque and continues rotating to move to the next dynamic stable point (V). By roughly switching the polarity of one core 1, it moves to the next dynamic stable point (■, ■) and returns to the initial state (n). Thereafter, by alternately switching the polarity of the two cores, the above-mentioned processes (1) to (2) are repeated to continue rotation.

When the predetermined rotational movement is performed in this way, if the switching of the phase of the drive pulse input to the core 1.2 is stopped, the rotor 4 will remain at the dynamic stable point.
Magnetic poles 1a, 1 h' of cores 1 and 2) OOh L
, -tenn low k) A /TIA Tsukuda/Tl All of the rotors 46 are in the suction state, and the rotor 4 can stop rotating at a stable point with a strong stopping torque.

FIG. 4 shows a second embodiment of the rotor according to the present invention, in which reference numerals 8.9 are rotor pieces, and each rotor piece 8.9 is divided into four parts in the circumferential direction. Magnetic pole 8a~
8d, 9a to 9d are magnetized, and one rotor piece 8
The two rotor pieces 9 are overlapped so that the center of the magnetic pole of the other rotor piece 9 is located at the magnetic pole boundary, and two areas forming the same magnetic pole are formed in a staggered manner.

FIG. 5 shows a third embodiment of the rotor according to the present invention, in which protrusions 12a to 12 extend from the magnetic pole side to the circumferential surface.
d, 13a to 13d8 formed magnetic pole pieces] 2.13,
They are arranged so as to wrap around a cylindrical magnet 1 which is magnetized so as to form a magnetic pole in the direction of the rotation axis, and are alternately combined to form two protruding pieces or pairs. According to this embodiment, it is possible to reduce the weight of the rotor and simplify the magnetic work.

(Effects) As explained above, according to the present invention, the magnetic poles of the rotor are formed by dividing the circumferential direction into 8 areas so that two adjacent areas have the same polarity. Even if the core of the stator is arranged in a V-shape along the opening, each magnetic pole of the stator can face the magnetic pole of the rotor one-on-one, which not only creates a reliable stable point, but also allows the rotor to By increasing the number of magnetic poles, it is possible to reduce the distance between the magnetic poles of the stator and rotor, thereby reducing fluctuations in rotational torque.

[Brief explanation of drawings]

Figures 1 (a) and (b) are a plan view and a cross-sectional view of a snow making device showing an embodiment of the present invention, respectively. FIG. 3 is a plan view showing an example of a step motor. 1.2...Core

Claims (1)

[Claims] A rotor in which the circumferential direction is divided into eight parts and two adjacent areas are formed with the same polarity, and one magnetic pole faces an adjacent magnetic pole of the rotor, and the other magnetic pole faces a magnetic pole separated by two poles of the rotor. A step motor with a stator consisting of two cores arranged as follows.