JP2002112522A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stepping motor, which prevents leakage of magnetic flux and becoming unstable of magnetic paths caused by defects through joining of an external yoke and an internal yoke by press-fitting and adhesion, i.e., caused by the difference between jointing gaps, the difference between magnetic reluctances, and the difference between jointing intensities of the motor, and prevents differences (variations) in the quality of motors. SOLUTION: In addition to joining of the yokes by press-fitting and adhesion, the yokes are jointed by laser welding. Moreover, the internal and external yokes are electroplated in semi-bright-manner for preventing laser beam reflection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor mounted on a digital camera or the like.

[0002]

2. Description of the Related Art Conventionally, a stepping motor has yokes on both sides (inside and outside) of a magnet which is magnetized to form a magnetic path. As shown in FIG. Was formed by press-fitting or bonding with an adhesive. In FIG. 2, reference numeral 1 denotes a joint gap portion between the inner and outer yokes, 2 denotes an outer yoke, 3 denotes an inner yoke, 4 denotes a coil bobbin, 5 denotes a laser welded portion, and 6 denotes a magnetized magnet. Therefore, the structure is liable to cause a difference in press-fit of a joint or a difference in adhesive force due to bonding due to a difference between individual components.

[0003]

In the above-mentioned conventional example, the difference between the press-fitting and the bonding performance is the same as the joint GAP of the motor.
This results in a difference, a difference in magnetic resistance, and a difference in joining strength, resulting in leakage of magnetic flux and instability of a magnetic path, which eventually causes a difference (variation) in motor quality. In addition, the adhesion of the adhesive or the like to the motor drive unit has been detrimental to the drive.

[0004] Therefore, a first object of the present invention is to add a yoke joint on both sides (inside and outside) of a magnet magnetized to form a magnetic path for driving a motor in addition to the conventional press-fitting. By joining by laser welding, the form of the GAP portion of the joining portion is stabilized, the leakage of magnetic flux by reducing the GAP portion is reduced, and the joining by welding further increases the joining strength, stabilizing the magnetic path, An object of the present invention is to provide a stepping motor capable of improving the quality of a motor by stabilizing the amount of magnetic flux.

[0005] A second object of the present invention is to perform laser welding in addition to the conventional press-fitting, in which joints of yokes on both sides (inside and outside) of a magnet magnetized to form a magnetic path for driving a motor are provided. An object of the present invention is to provide a stepping motor capable of obtaining a stable and high laser welding force by applying semi-glossy plating to an inner yoke and an outer yoke in order to prevent reflection of a laser beam for joining at a step.

[0006]

In order to achieve the first object, the present invention is characterized in that the conventional yoke joining by press-fitting or bonding is joined by laser welding in addition to the conventional press-fitting.

[0007] In the above configuration, the form of the joint GAP is stabilized by means of joining by laser welding, so that the magnetic path and the amount of magnetic flux can be stabilized. Further, in the above configuration, the gap by the laser welding reduces the gap portion at the joint, thereby reducing the leakage of the magnetic flux, so that high driving quality can be obtained. Further, in the above configuration, the joining strength of the joining portion is increased by joining by laser welding, and the quality can be stabilized. In addition, since no adhesive is used, it is possible to prevent the adhesion of the adhesive from sticking to the motor drive unit and to eliminate the adverse effect on the motor drive.

[0008] In order to achieve the second object, the present invention relates to a method in which a laser is welded to an inner yoke and an outer yoke which are welded in order to join the yoke by laser welding in addition to the conventional press-fitting or bonding. It is characterized by semi-glossy plating to prevent light reflection.

[0009] In the above structure, the means for applying semi-glossy plating to the inner yoke and the outer yoke to be welded,
Preventing diffusion can stabilize the welding force.

[0010]

(Embodiment 1) FIG. 1 is a sectional view and a side view of each embodiment of a stepping motor according to the present invention. In FIG. 1, 1 is a joint GAP portion of the inner and outer yokes, 2 is an outer yoke,
Reference numeral 3 denotes an inner yoke, 4 denotes a wound coil bobbin, 5 denotes a laser weld, and 6 denotes a magnetized magnet.

In the above configuration, the coil bobbin 4 is inserted into the outer yoke 2, and the inner yoke 3 is inserted into a hollow (cylindrical) portion at the center of the outer yoke 2. Then, after the inner yoke 3 is pressed into the outer yoke 2 at the joint GAP portion 1, the laser welded portion 5 is welded and joined by laser. As a result, the yokes (the outer yoke 2 and the inner yoke 3) are arranged inside and outside the magnetized magnet 6. When a current flows through the coil bobbin 4, a magnetic flux is generated in the inner yoke 3, the magnetic flux flows to the outer yoke 2 via the joint GAP 1, and a magnetic path is formed between the outer yoke 2 and the inner yoke 3. Is done.
Then, the magnetized magnet 6 is driven by interposing the magnetized magnet 6 in the magnetic path, thereby forming a stepping motor.

[0012] Of course, FIG. 1 shows three laser-welded portions as examples in the drawing, but the welding locations and welding points may be arbitrary.

According to the above embodiment, stabilization of the joint GAP portion,
It is possible to reduce the GAP portion by welding the GAP portion, improve the bonding strength, and the like, and thereby have effects unique to the present embodiment, such as stable formation of a magnetic path, stable magnetic flux, and improved quality.

Second Embodiment A second embodiment has the same basic configuration as the first embodiment. That is, as shown in FIG.
The winding coil bobbin 4 is inserted therein, and the inner yoke 3 is inserted into a hollow (cylindrical) portion at the center of the outer yoke. Then, after the inner yoke 3 is press-fitted into the outer yoke 2 at the joint GAP part 1, the laser welded part 5 is welded and joined by laser. As a result, the yokes (the outer yoke 2 and the inner yoke 3) are arranged inside and outside the magnetized magnet 6. When a current flows through the coil bobbin 4, a magnetic flux is generated in the inner yoke 3, the magnetic flux flows to the outer yoke 2 via the joint GAP 1, and a magnetic path is formed between the outer yoke 2 and the inner yoke 3. Is done. Then, the magnet 6 magnetized in the magnetic path
The stepping motor is formed by driving the magnet by interposing the outer yoke. The entire surface of the outer yoke 2 and the inner yoke 3 joined by laser welding is semi-glossy plated.

Of course, regarding the type of plating, it is possible to prevent laser light from being reflected and diffused, and furthermore, the outer yoke 2 and the inner yoke 3
Any plating may be used as long as it can prevent corrosion of the plating.

According to the above embodiment, reflection and diffusion of laser light required for laser welding can be prevented, laser light power can be stabilized, and more stable laser welding can be achieved. is there.

[0017]

As described above, according to the present invention,
First, regardless of the difference in press-fit due to the difference in shape of the components required for joining, and the difference in adhesive force due to the variation in bonding, stable joining of components is possible, and thereby the magnetic path and magnetic flux can be stabilized. Become. Further, since the total area of the joint GAP portion is reduced, the leakage of the magnetic flux can be reduced, and as a result, high driving quality can be obtained. Further, high joining strength can be obtained irrespective of a difference in press-fitting due to a difference in shape of parts required for joining and a difference in adhesive force due to a variation in adhesion. In addition, since no adhesive is used, it is possible to prevent the adhesion of the adhesive from sticking to the motor drive unit and to eliminate the adverse effect on the motor drive.

According to the present invention, secondly, it is possible to maintain a stable laser welding force without attenuating a welding force due to reflection and diffusion of laser light due to gloss of a part to be welded by laser light. Become.

[Brief description of the drawings]

FIG. 1 is a sectional view and a side view of a stepping motor according to the present invention.

FIG. 2 is a sectional view and a side view of a conventional stepping motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joint GAP part of inner and outer yokes, press-fitting part, adhesion part, joint part by laser 2 outer yoke 3 inner yoke 4 winding coil bobbin 5 laser welding part 6 magnetized magnet

Claims (2)

[Claims] 1. A joining portion for joining an inner yoke and an outer yoke required on both inner and outer sides of a magnet magnetized to form a magnetic path for driving a motor in addition to press-fitting and joining by laser welding. A stepping motor. 2. When laser welding an inner yoke and an outer yoke required on both inner and outer sides of a magnet magnetized to form a magnetic path for driving a motor, a laser beam for preventing laser beam reflection for joining is used. A stepping motor characterized in that semi-glossy plating is applied to an inner yoke and an outer yoke.