JP2001045702A - Miniature dc motor and usage thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mount a miniature DC motor on a printed circuit board or the like without having to provide a mounting angle or the like and attain high efficiency by forming it into a rectangular shape and a radial-void type, thereby permitting a permeance coefficient to become large. SOLUTION: This miniature DC motor is formed by disposing a radial magnetic field type magnet 2 magnetized to N and S poles alternately in a case 1 and accommodating an eccentric rotor inside the magnet through a radial void. The case is formed so as to have a substantially a square-shaped cross section, and the magnet is formed so that the respective centers of the poles almost coincide with the corner parts of the case. The eccentric rotor has an eccentric core 3 and a plurality of armature coils 5 disposed eccentrically around the eccentric core so as to face the magnet via the void or a plurality of eccentric salient poles and armature coils wound around the eccentric salient poles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a radio calling device,
The present invention relates to a small DC motor having a rectangular shape used for a silent information source of a mobile communication device and a method of using the same.

[0002]

2. Description of the Related Art Cylindrical coreless motors as shown in FIG. 4 are known as small cylindrical DC motors used as silent sound sources such as pagers, alarm clocks and mobile communication devices. In order to use this motor as a vibration source, a high-density eccentric weight W made of a tungsten alloy is arranged on the output shaft S of the motor so that vibration is generated by centrifugal force during rotation.

[0003]

However, such a cylindrical type has a drawback that it is inconvenient to handle the device when mounting it on a device and has to be separately mounted on a printed wiring board or the like via a mounting angle or the like. In the case of a flat motor, it can be directly fixed to a printed wiring board or the like via a double-sided adhesive tape on the bottom surface or the upper surface. Some recent double-sided pressure-sensitive adhesive tapes reach 2 kg per 1 cm of adhesive strength, and are sufficiently practical.

An object of the present invention is to pay attention to the fact that the occupied arrangement space hardly changes on a device side, whether it is a cylindrical type or a square type. And
Another object is to increase the permeance coefficient and provide a small-sized DC motor having a rectangular cylindrical shape for high efficiency and a method of using the motor.

[0005]

In order to solve the above problems, a radial field magnetized to N and S poles is provided in a cylindrical case which is long in the axial direction as in the first aspect of the present invention. In a small DC motor containing a mold magnet and a rotor disposed inside the magnet via a radial gap,
A mounting portion having a flat surface that can be placed on a printed wiring board and soldered and mounted on at least a part of the outer peripheral surface of the case, and a terminal that can be soldered to the printed wiring board from a bracket disposed in an opening of the case Can be achieved by deriving. Specifically, as in the invention as set forth in claim 2, the case has a mounting portion having at least a part of a substantially square cross section so that the case can be mounted on a printed wiring board or the like. It is preferable to arrange the magnet so that the end of the magnetic pole is thin and the center is thick on the peripheral surface. In such a motor, the rotor is preferably eccentric so as to function as a vibration motor.
In order to use such a motor, the mounting portion is attached to the printed wiring board via an adhesive as described in claim 4, and the terminal is connected to the printed wiring board,
What is necessary is just to mount it in a device.

[0006] In this case, since it is square, it can be fixed to a printed wiring board or the like by bonding with a double-sided adhesive tape. Since the corners of the square of the field magnet become thick, the substantial permeance coefficient becomes large.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a feature of the present invention, which is applied to a rectangular tube type slotless vibration motor. Numeral 1 is a square-tube type case having a square cross section, in which a field magnet 2 made of rare earth plastic is integrally formed. The field magnet 2 is magnetized alternately N and S equally into four poles such that the center of the magnetic pole is located at the corner of the case. Three
Is an eccentric slotless core formed by laminating a silicon steel plate disposed inside the field magnet 2 with an air gap therebetween. Are arranged to form the rotor R. 3a
Is a through hole that emphasizes the amount of eccentricity.

FIG. 2 shows a mounting example as a method of using the motor, in which the motor is fixed to a printed wiring board 6 via a double-sided adhesive tape 7.
9 is connected to predetermined patterns 6a and 6b of the printed wiring board 6 to supply power.

FIG. 3 shows an application to a salient pole type rotor, in which a lower half of an iron core having six salient poles is cut out.
The three salient poles 10 are arranged eccentrically on one side.
In this case, since the radius of the radial field magnet 2 is thick, a magnetization curve showing a sine curve is obtained while increasing the permeance coefficient, and the cogging torque is reduced.

Although the above is an embodiment applied to a vibration motor having an eccentric rotor, it goes without saying that the present invention can also be applied to a normal rotary type.

[0011]

As described above, since the present invention has a rectangular tube shape having a substantially square cross section as described above, the device can be easily fixed to a printed wiring board with a double-sided adhesive tape. In addition, since the corner portions are thick, the permeance coefficient becomes large, high efficiency is obtained, and a sine curve magnetization curve is obtained, and cogging torque can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a small DC motor of an eccentric slotless vibration type as one embodiment of the present invention.

FIG. 2 is a perspective view of an embodiment of the mounting structure of the motor.

FIG. 3 is a cross-sectional view of a main part of another embodiment.

FIG. 4 is a perspective view of a conventional small cylindrical DC motor.

[Explanation of symbols]

 Reference Signs List 1 case 2 field magnet 3 eccentric slotless iron core 4 shaft 5 armature 10 salient pole

Claims (4)

[Claims] An N, S-type cylinder is provided in a cylindrical case that is long in the axial direction.
In a small DC motor containing a radial field magnet magnetized to the poles and a rotor disposed inside the magnet via a radial gap, at least a part of the outer peripheral surface of the case is provided. A small direct current characterized by providing a mounting portion having a flat surface so that it can be laid on a printed wiring board and mounted by soldering, and a terminal that can be connected to the printed wiring board is derived from a bracket disposed in an opening of the case. motor. 2. The case has a mounting portion having at least a part of a substantially square cross section so that the case can be mounted on a printed wiring board or the like. The end of the magnetic pole is thin on the inner peripheral surface of the case. 2. The small DC motor according to claim 1, wherein the magnet is arranged so that the center is thick. 3. The small DC motor according to claim 1, wherein the rotor is eccentric to function as a vibration motor. 4. A method of using a small DC motor, wherein said mounting portion is mounted on a printed wiring board via an adhesive, and said terminal is connected to said printed wiring board so as to be mounted on a device.