JPH1023490A - Cylindrical micro vibration motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain more vibration quantity by fitting an eccentric weight to a rotary shaft without forming a projected rotary shaft fitting base part causing the reduction of vibration quantity on an eccentric weight face formed in a counter gravity center direction. SOLUTION: A rotary shaft fitting groove 6 having a semicircular shape at the time of observing it from an axial direction is formed on the center part of a rotational trace of an eccentric weight 3 without forming a vibration quantity reducing projection such as a rotary shaft fitting base part on the face 9 of the weight 3 which is opposite side to the gravity center G direction. Plural fine projections 7 are formed on the inner surface 8 of the groove 6. The rotary shaft 2 is brought into contact with the groove 6 and the fine projections 7 are deposited from the surface of the shaft 2, so that the shaft 2 can be welded and fixed on the inner surface 8 of the groove 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical micro-vibration motor in which an eccentric weight attached to a rotary shaft of a cylindrical micro-motor is rotated to obtain vibration due to centrifugal force. Paging device (pager), used for mobile phones.

[0002]

2. Description of the Related Art A cylindrical micro vibration motor is used as a vibration generator in a pager or a portable telephone so that the call is made by vibration other than sound. In this cylindrical micro-vibration motor, as shown in FIG. 4, an eccentric weight 3 'having a substantially semicircular shape as viewed from the axial direction made of a high-ratio heavy metal such as a tungsten alloy is formed on a rotating shaft 2 of the cylindrical micromotor 1. And by rotating the eccentric weight 3 'together with the rotating shaft 2, vibration is obtained by the centrifugal force of the eccentric weight 3'. Since this vibration force is transmitted to the case of the pager or the mobile phone, if these are equipped, the vibration can be sensed by the body, and it can be understood that the telephone call has been made.

Here, there are various methods for attaching the eccentric weight 3 'to the rotating shaft 2, and a typical method is disclosed in Japanese Utility Model Publication No. 4-13860. This will be described with reference to FIGS. 4 and 5. After inserting the rotating shaft 2 of the cylindrical micromotor 1 into the shaft hole 4 of the eccentric weight 3 ′, the center of gravity of the weight portion 3 ′ a of the eccentric weight 3 is adjusted. The eccentric weight 3 'is attached to the rotating shaft 2 by caulking with a tool such as a punch (not shown) at the position shown by the caulking portion 5 on the surface of the rotating shaft attaching base 3'b in the opposite direction. The method shown in FIGS. 4 and 5 is a method of attaching the eccentric weight 3 'to the rotating shaft 2 which is very excellent in mass productivity.

According to the method of attaching the eccentric weight 3 'to the rotating shaft 2 as described above, since the load is applied in the direction of arrow a with reference to FIG. 5, the rotating shaft is attached in the direction opposite to the direction of the center of gravity G. Base 3 '
If there is b, the rotation shaft mounting base 3'b in the direction of the center of gravity G cancels the vibration amount. Therefore, the method shown in FIGS. 4 and 5 is limited to a cylindrical micro-vibration motor having an outer diameter size of Φ6 mm or more, and is even larger when the outer diameter size is smaller, for example, Φ4 mm or less. There is a limit to obtaining vibration, and it is not possible to obtain sufficiently large vibration. Similar to the pager, the mobile phone is also required to be further miniaturized. Therefore, the cylindrical micro-vibration motor is also required to be miniaturized, but as the size becomes smaller, larger vibration cannot be obtained. In particular, unlike a pager, a mobile phone has a large housing, so using a cylindrical micro-vibration motor that does not provide a large amount of vibration does not provide sufficient vibration as a calling effect, making it unsuitable. .

[0005] That is, as the micro-vibration motor having a very fine shape becomes smaller, the outer diameter of the eccentric weight also becomes smaller, the weight of the eccentric weight is reduced, and the torque of the motor is also deteriorated to obtain a large vibration amount. Absent. In order to prevent this deterioration, it can be prevented to some extent by rotating the motor at a high speed. However, FIGS. 4 and 5
In the case of the cylindrical micro-vibration motor described above, since the volume of the rotary shaft mounting base 3′b is large, the rotary shaft mounting base 3′b
The volume and weight of the weight portion 3'a in the direction of the center of gravity, which causes the magnitude of the vibration of the eccentric weight 3 ', are offset by the volume integral, and as a result, the generated vibration force is reduced. Therefore, according to the method of attaching the eccentric weight 3 'to the rotating shaft 2 shown in FIGS. 4 and 5, it is difficult to obtain a microscopic cylindrical micro-vibration motor that generates a large vibration force, and is not suitable for a mobile phone. Will be.

As a method of solving the above disadvantages, as disclosed in JP-A-6-30544 and JP-A-6-98496, for example, as shown in FIG. The weight of the attachment base 3 ″ b is reduced by reducing the volume of the attachment base 3 ″ b, and the weight and weight of the attachment base 3 ″ b are less offset by the volume and weight of the weight 3 ″ a. There is a method of obtaining a large vibration by "a". Even a slight reduction in the volume and weight of the rotating shaft mounting base 3 ″ b does not significantly affect the magnitude of the vibration force generated by the micro-vibration motor having an extremely fine cylindrical shape such as Φ3 to Φ4. The same motor can be judged very easily by replacing the eccentric weight 3 '' and trying.

[0007]

As described above, the method of attaching the eccentric weights 3 'to the rotary shaft 2 shown in FIGS. 4 and 5 is applied to a cylindrical micro vibration motor having a relatively large outer diameter. This is a very useful method because it is the simplest. However, since the volume and weight of the mounting base 3'b on the opposite side of the center of gravity G become large, the amount of eccentric vibration of the eccentric weight 3 'cannot be maximized. Not suitable for cylindrical micro vibration motors.

On the other hand, the method of attaching the eccentric weight 3 ″ to the rotating shaft 2 shown in FIG. 6 requires a large volume and weight of the attachment base 3 ″ b on the opposite side of the center of gravity G. By maximizing the amount of eccentric vibration of the eccentric weight 3 ″, it is suitable for a cylindrical micro vibration motor having a small diameter size, for example, a Φ4 mm size.

However, also in the method of attaching the eccentric weight 3 ″ to the rotating shaft 2 shown in FIG. 6, when a cylindrical micro vibration motor of Φ4 mm size is applied to a mobile phone, the mobile phone has a smaller size than a pager. In such a case, since the housing is large, it is necessary to obtain a larger vibration amount.

That is, an object of the present invention is to generate a larger vibration by preventing the eccentric weight from forming any vibration reduction projection such as a rotation shaft mounting base on the surface opposite to the center of gravity direction. An object of the present invention is to obtain a cylindrical micro-vibration motor that can be driven.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In a cylindrical micro-vibration motor in which a centrifugal force is obtained by rotating an eccentric weight having a substantially semicircular shape as viewed from the axial direction attached to a rotating shaft of the cylindrical micromotor, the eccentric weight is The center of the eccentric weight on the rotation trajectory is formed in a semicircular rotation shaft at the center on the rotation trajectory without forming a vibration reduction projection such as a rotation shaft attachment base on the surface opposite to the center of gravity direction. Forming an attachment groove, forming a plurality of minute projections on the inner surface of the rotation shaft attachment groove,
This can be achieved by bringing the rotating shaft into contact with the rotating shaft mounting groove and welding the minute shaft from the surface of the rotating shaft to weld the rotating shaft to the rotating shaft mounting groove surface.

Operation: Referring to FIG. 2, the rotary shaft 2 of the cylindrical micro vibration motor according to one embodiment of the present invention is inserted into the rotary shaft mounting groove 6 from the side. A plurality of minute projections 7 are formed on the inner surface 9 of the rotating shaft attachment groove 6. From the outer periphery of the rotating shaft 2 facing the minute projection 7, the minute projection 7 is welded by, for example, spot welding means, and the rotating shaft mounting groove 6 is formed.
The rotary shaft 2 is fixed by welding to the inner surface of. The welding method is not limited to spot welding, and may be another method.

According to the eccentric weight 3 as described above, the surface 9 on the side opposite to the center of gravity G does not have a protruding rotary shaft mounting base for reducing the amount of vibration, and the eccentric weight 3 itself entirely vibrates. When the cylindrical micromotor 1 rotates, the eccentric weight 3 attached to the rotating shaft 2 rotates while performing a partial circular motion, so that the centrifugal force causes the cylindrical microvibration. Vibrating the housing of the mobile phone or pager with the motor attached,
A person wearing a mobile phone or pager is made to feel the vibration to notify that a telephone call has been made.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
FIG. 2 is an explanatory view of a cylindrical micro-vibration motor as an embodiment in which an eccentric weight 3 is attached to a rotating shaft 2 by welding means. FIG. 2 shows an eccentric weight 3 attached to the rotating shaft 2 by welding means. FIG. 3 is an explanatory view showing the case of attachment, and FIG. Hereinafter, a cylindrical micro-vibration motor according to an embodiment of the present invention will be described with reference to FIGS.

The eccentric weight 3 has a semi-circular shape as viewed from the axial direction without forming a vibration amount reducing projection such as a rotation shaft mounting base on a surface 9 opposite to the direction of the center of gravity G (see FIG. 3). It is formed using a tungsten alloy or the like having a large specific gravity so as to obtain a sufficient vibration and suitable for employing a means such as caulking.

The eccentric weight 3 forms a rotary shaft mounting groove 6 having a semicircular shape as viewed from the axial direction at the center on the rotation locus. The rotation shaft attachment groove 6 is formed to have a length of about half the axial length of the eccentric weight 3. This means that when the rotary shaft mounting groove 6 is formed extending over the entire length of the eccentric weight 3 and the rotary shaft 2 is inserted into the rotary shaft mounting groove 6 over the entire length, the rotation protruding in the direction of the surface 9 is achieved. This is because the area, volume and weight of the shaft 2 are increased, and only the increased portion acts in the direction of decreasing the vibration amount as much as possible.

A plurality of minute projections 7 are integrally formed on the inner surface 9 of the rotary shaft mounting groove 6. The rotary shaft 2 is contact-inserted into the rotary shaft mounting groove 6 from a side surface thereof at a welding location of a welder, for example, a spot welder. In this state, the minute protrusion 7 is moved from the surface of the rotating shaft 2 facing the minute protrusion 7.
And the rotating shaft 2 is fixed to the inner surface 9 of the rotating shaft mounting groove 6 by welding. Thus, the eccentric weight 3 can be fixed to the rotating shaft 2. Further, on the surface 9 of the eccentric weight 3 in the direction opposite to the center of gravity G, there is no need to form a projection for reducing the amount of vibration such as a projection-shaped rotating shaft mounting base. The means for welding the rotating shaft 2 to the inner surface 9 of the rotating shaft attachment groove 6 is not limited to spot welding.
Full-surface welding or welding means based on other principles may be used.

[0018]

[Effect] According to the present invention, it is not necessary to form a protrusion for reducing the amount of vibration such as a protruding rotation shaft mounting base on the surface of the eccentric weight opposite to the center of gravity. As a result, more vibration can be obtained as an eccentric weight in the motor.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a cylindrical micro-vibration motor as an embodiment when an eccentric weight is attached to a rotating shaft of a cylindrical micromotor by welding means.

FIG. 2 is an explanatory diagram in a case where an eccentric weight is attached to a rotating shaft by welding means.

FIG. 3 is an explanatory diagram showing a contact relationship between a minute projection and a rotating shaft.

4 and 5 are explanatory views of a conventional eccentric weight and a method of fixing the eccentric weight to a rotating shaft.

FIG. 6 is an explanatory view of a conventional eccentric weight which has solved the drawbacks of FIGS. 4 and 5, and a method of fixing the eccentric weight to a rotating shaft.

[Explanation of symbols and symbols]

 G Center of gravity 1 Cylindrical micromotor 2 Rotating shaft 3, 3 ', 3' 'Eccentric weight 3'a, 3''a Weight 3'b, 3''b Rotating shaft mounting base 4 Shaft hole 5 Caulking Part 6 Rotating shaft mounting groove 7 Minute projection 8 Inner surface 9

Claims (1)

[Claims] 1. A cylindrical micro-vibration motor in which a centrifugal force is obtained by rotating an eccentric weight having a substantially semicircular shape as viewed from the axial direction attached to a rotating shaft of the cylindrical micromotor. The eccentric weight has a half-shape viewed from the axial direction at the center on the rotation locus of the eccentric weight without forming a vibration reduction projection such as a rotation shaft mounting base on the surface opposite to the center of gravity direction. Forming a circular rotary shaft mounting groove, forming a plurality of microprojections on the inner surface of the rotary shaft mounting groove, bringing the rotary shaft into contact with the rotary shaft mounting groove, Wherein a rotary shaft is welded to the rotary shaft mounting groove surface by welding.