JPH02306214A - Rocking mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnet rotation type swing mechanism used for changing the optical path of laser light or the like.

[Prior Art] As a conventional device for changing the optical path, a rotating polygon mirror 401 as shown in FIG. Mechanisms that operate light back and forth are known.

FIG. 4 is a sectional view of the swing actuator.

It is composed of a rotor 501 made of soft magnetic material, a permanent magnet 502, and an armature 504 around which a drive coil 503 is wound. In the state shown in FIG. 4(a) in which the drive coil 503 is not excited, magnetic flux flows in the armature as shown by an arrow 505 in the figure, and the rotor 501 is held.

By energizing the drive coil, the rotor moves as shown in (b) due to the magnetic flux generated by the drive coil and the magnetic flux from the permanent magnet.
Rotate to the position shown. By changing the current direction,
It has a structure that allows the rotor to perform rocking motion.

Furthermore, there is an example in which a permanent magnet type step motor (hereinafter referred to as PM motor) 601 shown in FIG. 5 is used as a driving motor.

In a device using a PM momo, one excitation coil 6
02, in order to hold the rotor 603, which has a permanent magnet magnetized with multiple poles on its circumference, in a fixed position, a constant current is always applied, and the other excitation coil 602 is driven with a sine wave and a triangular wave. A structure was known in which a rotor 603 is oscillated and a mirror 606 fixed to a rotating shaft 605 is oscillated left and right.

[Problems to be Solved by the Invention] However, the conventional optical path changing mechanism using the rotating polygon mirror shown in FIG. Precision machining is required to manufacture polygon mirrors.Also, because polygon mirrors have a large mass, it takes time for the motor to reach a constant rotation, and the swinging device is large and heavy. Therefore, it has not been used for hand-held barcode scanners, and the swing mechanism having the structure shown in FIGS. 4 and 5 has been used for small devices.

However, in the mechanism shown in Fig. 4 that uses a permanent magnet to position the center of rotation and uses the difference (change) in magnetic resistance to perform rocking motion, and in the mechanism shown in Fig. 5 that uses a PM momo, the drive In order to install the mirror above or below the motor, the driving section and the polarizing section are separated, which inevitably increases the size.

Furthermore, if the drive current is large, the rotational position will shift in units of magnetic pole pairs due to overshoot, so a positioning member for regulating the swinging position or swinging angle is required outside the swinging mechanism.

Furthermore, in the mechanism using the PM motor shown in FIG. 5, it is required that the position of the comb teeth of the motor yoke on the holding side and the position of the comb teeth of the drive yoke be accurately shifted by half a pitch. If there is a misalignment in the positional relationship between the drive yoke and the holding yoke, a difference in speed between left and right rotations will occur, causing a code reading error. In the case of PM motors, the comb yoke is usually manufactured by combining four press-manufactured parts.
Assembly errors and component errors directly result in misalignment of the comb teeth, and the difference in rotational speed between the left and right sides during rocking motion has become a major problem.

[Means for Solving the Problems] The swinging mechanism of the present invention includes a rotor having a cylindrical permanent magnet magnetized with multiple poles in the circumferential direction, and an excitation coil for swinging the rotor. In a swing mechanism having an armature made of a wound soft magnetic material, a rotor having a permanent magnet is rotatably supported on the outer periphery of the armature, and a back yoke made of a soft magnetic material is attached to the outer periphery of the cylindrical permanent magnet. It is characterized by having a mirror provided on the outer peripheral surface of the back yoke to change the optical path of a laser beam or the like. Further, the swinging mechanism of the present invention is a swinging mechanism having a rotor having a permanent magnet and an armature made of a soft magnetic material wrapped with an excitation coil, in which the permanent magnet is fan-shaped and the soft magnetic material is installed on the outer periphery. It is characterized by the back yoke consisting of the body being track-shaped.

[Embodiment] FIG. 1 shows an embodiment according to the present invention, in which (a) is a longitudinal cross-sectional view and (b) is a cross-sectional view. The rotor 101 has a structure in which a back yoke 103 made of a soft magnetic material is provided on the outer periphery of a permanent magnet 102 which is multi-pole magnetized in the circumferential direction.
4 via a bearing 105 so as to be rotatable. On the other hand, the stator side is manufactured by winding a driving coil 108 around a soft magnetic body part 106 made of a silicon steel plate or the like and a non-magnetic bobbin part 107. When stopped, the magnetic circuit becomes as shown in FIG. 1(b), so that the permanent magnet stably stops at the position shown. When the driving coil is excited, a magnetic flux 301 shown in FIG. 2 is generated, so that the rotor rotates by half the length of the magnetic poles. Next, by energizing the excitation coil in the opposite direction, it can be rotated in the opposite direction.

This is a mechanism that causes rocking motion by continuously performing the above excitation. The mirror for changing the optical path is installed on the outer periphery of the soft magnetic yoke and is integrated with the rotor, thus realizing a compact swing mechanism.

Since two fan-shaped permanent magnets 301 are installed in a track-shaped soft magnetic yoke 302, the amount of permanent magnets used is reduced and the weight of the rotor is reduced.

Furthermore, since the back yoke is shaped like a track, the rotor and stator come into contact after rotating through a certain angle, which causes a large amount of current to flow to the excitation coil, for example. It has a structure that prevents rotational position shift due to overshoot.

Furthermore, since the mirror can be installed on the flat portion 303, it becomes easy and the swing mechanism is lightweight and highly reliable.

[Effects of the Invention] As described above, according to the present invention, a part of the mirror can be integrated with the motor yoke, which not only makes it possible to realize a compact swinging mechanism, but also makes it possible to realize a compact swing mechanism by making the rotor into a track shape, which makes it possible to The mechanism for preventing rotational position deviation due to overshoot can also be made into an integrated structure, making it possible to create a highly reliable device without mis-seeking.

[Brief explanation of the drawing]

FIG. 1(a) is a longitudinal sectional view of the swing mechanism of the present invention. FIG. 1(b) is a cross-sectional view of the swinging mechanism of the present invention. FIG. 2 is a sectional view of the swinging mechanism of the present invention when it is driven. Figure 5 is a sectional view of an example using a conventional PM type motor. Figure 1 <b> 10mm Figure 1 (α) Figure 3 Figure 4 (α Figure 5

Claims (3)

[Claims] (1) A rotor that has a rotor that has a cylindrical permanent magnet that is multi-pole magnetized in the circumferential direction and an armature that is made of a soft magnetic material and is wound with an excitation coil that causes the rotor to oscillate. A swinging mechanism, characterized in that a rotor having the permanent magnet is rotatably supported on an outer periphery of an armature. (2) A back yoke made of a soft magnetic material is provided on the outer periphery of the cylindrical permanent magnet, and a mirror for changing the optical path of a laser beam or the like is provided on the outer periphery of the back yoke. The swinging mechanism according to claim 1. (3) In a swinging mechanism having a rotor having a permanent magnet and an armature made of a soft magnetic material wrapped with an excitation coil,
A rocking mechanism characterized in that the permanent magnet is fan-shaped, and the back yoke made of a soft magnetic material installed on the outer periphery is track-shaped.