JP2005218206A - Eccentric rotor and vibration motor using the eccentric rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eccentric rotor that is small and excellent in strength and a vibration motor using the an eccentric rotor. <P>SOLUTION: The eccentric rotor (R) is constituted such that a commutator of a printed wiring board (1) wherein a plurality of commutator pieces (2) are print-formed, a plurality of winding air-core armature coils (20A, 20B) are placed, and a shaft insertion hole (5a) is formed is flatly integrated to the eccentric rotor. The plurality of the winding air-core armature coils (20A, 20B) are arranged on the centroid side from the center of rotation. In a resin portion (15) formed by resin molding, a recessed portion (18) in which the outer edge of the eccentric rotor forms a wall (19) is formed at the opposite side to the centroid with the shaft insertion hole positioned between. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a small vibration motor used for notifying an incoming call by vibration in a mobile communication terminal device such as a mobile phone.

A mobile communication terminal device such as a mobile phone is equipped with a vibration motor to notify the user of an incoming call by vibrating the device.
The vibration motor is mainly a cylindrical housing with a cylindrical housing with a weight fixed to the output shaft protruding outside the housing, and a flat housing with a coin-shaped housing with the shaft fixed to the housing and the rotor in the housing being eccentric. There is a type vibration motor.
Since the rotor of the flat vibration motor is eccentric and eccentrically supported on a shaft fixed to the housing, a structure in which a bearing, a weight and a coil are integrally molded with a resin together with a printed wiring board constituting a commutator board is used. It is done.

For example, in Japanese Patent Application Laid-Open No. 2002-177895, three air-core armature coils are arranged on one half of a disk-shaped rotor on a printed wiring board constituting a commutator substrate, and a weight is arranged on the other half of the one side. A configuration in which each member (printed wiring board, coil, weight, etc.) is integrally molded with resin is disclosed.
Japanese Patent Application Laid-Open No. 2002-28570 and Japanese Patent Application Laid-Open No. 2001-104882 disclose a configuration in which two air-core armature coils and a weight are integrally molded together with a printed wiring board using a resin.
Japanese Patent Laid-Open No. 2002-177858 JP 2002-28570 A JP 2001-104882 A

  Each of the configurations disclosed in these publications forms a flat eccentric rotor by placing weights and coils on a printed wiring board constituting a commutator board and integrating them by resin molding. Generally, it is manufactured by resin molding by injection molding.

In recent years, with the progress of miniaturization of devices on which vibration motors are mounted, vibration motors are also required to be miniaturized. Since it is necessary to ensure the amount of vibration even if the motor is downsized, the area occupied by the coil and the proportion of the size of the weight are higher than the size of the motor in order to increase the rotation speed and eccentricity. come.
However, if the size of the vibration motor itself is reduced, the size of the weight to be mounted must be relatively small, and it is necessary to increase the amount of eccentricity at a portion other than the weight in order to secure the amount of vibration. .
Furthermore, since the strength of each member becomes smaller as the members constituting the motor become smaller, it is necessary to supplement the strength of each member by integrating the rotor with resin.
The present invention solves these problems associated with miniaturization of the motor, and provides an eccentric rotor that is small in size and excellent in strength, and a vibration motor that uses the rotor.

In order to solve the above-described problems, in the present invention, as in the configuration of the first aspect, a plurality of commutator pieces are printed on one surface and a plurality of wound air-core armature coils are placed on the other surface and rotated. A flat commutator substrate having a shaft insertion hole through which a central shaft is inserted is an eccentric rotor integrated into a flat plate shape by resin molding together with the wound air-core armature coil, and the plurality of windings The wire-core armature coil is arranged so as to be offset toward the center of gravity with respect to the center of rotation, and the resin portion formed by resin molding is provided with a recess on the opposite side of the center of gravity with the shaft insertion hole therebetween. To do.
In this way, sinking and distortion can be prevented and the amount of eccentricity can be increased by removing the resin.

When the concave portion is formed as described in claim 2, the outer edge of the rotor has a predetermined thickness so that the strength of the rotor can be maintained.
3. The eccentric rotor according to claim 1, wherein the eccentric rotor is supported rotatably by a shaft on a housing comprising a case and a bracket, a magnet attached to the housing, a terminal to which electric power is supplied from the outside of the housing, and the terminal electrically. If it comprises a brush to be connected, this eccentric rotor can be used to constitute a shaft fixed vibration motor or a shaft rotation vibration motor.

According to the present invention, since the strength of the rotor can be increased, the strength of the eccentric rotor can be maintained even when, for example, a thin commutator substrate is used.
Further, by forming the concave portion by removing the resin on the side opposite to the center of gravity, it is possible to increase the amount of eccentricity of the rotor, and it is possible to prevent the rotor from being distorted due to resin sink or distortion.

1A and 1B are diagrams showing an eccentric rotor of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA.
FIG. 2 is a plan view showing a printed wiring board constituting the eccentric rotor shown in FIG.
3A and 3B are views showing the weights constituting the eccentric rotor shown in FIG. 2, wherein FIG. 3A is a plan view thereof, and FIG.
FIG. 4 is a cross-sectional view showing a principal part of a side surface of a vibration motor using the eccentric rotor of the present invention.

The rotor R used in the vibration motor M includes a thin printed wiring board 1 such as a so-called glass epoxy board or a flexible board as a commutator board, and a wound-type air core machine having an effective conductor opening angle of 40 to 90 degrees disposed thereon. The weights 30 and the sintered oil-impregnated bearings (hereinafter referred to as bearings) 40 are formed in a D-shaped flat plate shape by resin molding such as injection molding as weights that decenter the center of gravity of the child coils (hereinafter referred to as coils) 20A and 20B and the rotor R.
The printed wiring board 1 directly or indirectly includes the coil placement surfaces 3A and 3B on which the coils are placed, the terminal connection portions 4A and 4B, the center portion 5 on which the bearing 40 is placed, and the holding convex portion 31 of the weight 30. It comprises a holding part 6 that holds it automatically.
The terminal connection portions 4A and 4B are areas where terminal connection patterns 7A, 8A, 7B and 8B for connecting the coil terminals 22A, 23A, 22B and 23B to the corresponding segment 2 are arranged.

In order to increase the weight as much as possible, the weight 30 has a thickness exposed on both surfaces of the flat rotor R and is disposed between the two coils. The weight 30 has a portion embedded in the resin so as to be fixed to the resin while maintaining its strength. For example, the C surface 32 of the outer portion 37 has an outer peripheral side of the rotor R, and the C surface 33 has an inner peripheral side. Then, holding convex portions 31 thinner than the thickness of the rotor R are embedded in the resin portion 15, respectively.
Guide recesses 34, 35, and 36 are formed in the portion of the weight 30 embedded in the resin as positioning portions that determine the position of the rotor when the resin is molded.

The bearing 40 is formed in a cylindrical shape from a sintered oil-impregnated metal, and chamfers are usually formed on the outer periphery and the inner periphery at both ends. The shaft 11 fixed to the housing of the motor M is inserted into the bearing 40, and the rotor R is rotatably supported inside the motor M.
A shaft insertion hole 5a is formed in the central portion 5 of the printed wiring board 1 on which the bearing 40 is placed. The diameter of the shaft insertion hole 5a is larger than the rotation shaft, smaller than the outer diameter of the bearing 40, and The end portion of the bearing 40 is placed so as to touch the center portion 5 so that the resin is not exposed from the shaft insertion hole 5a.
The rotor M is molded from, for example, a polyester-based thermoplastic resin. As a characteristic of the resin molding, the rotor M is attracted or distorted. Therefore, the concave portion 18 is formed on the D-cut side of the resin portion 15 while providing the wall portion 19 on the outer peripheral portion.

A first embodiment of the present invention will be described with reference to FIGS.
In the rotor R, the printed wiring board 1, the two coils 20 </ b> A, 20 </ b> B, the weight 30 and the bearing 40 placed on the printed wiring board 1 are formed in a flat plate shape by resin molding such as injection molding. It is formed in a D shape.
The reason why it is D-shaped is to make the opposite side lighter across the rotating shaft of the weight 30 in order to increase the amount of eccentricity as a vibration motor.
The weight 30 is made of a high specific gravity material such as a tungsten alloy, and the substrate may be a circular substrate as long as the weight effect is sufficient.
The coils 20A and 20B are wound air-core coils having an effective conductor opening angle of 40 ° to 90 °, and each coil has two terminals 22A, 23A and 22B, 23B. The coils 20A and 20B are arranged on the rotor R at an arrangement of about 140 °. With respect to this coil arrangement, for example, a plurality of coils 20A and 20B can be stacked, and two coils can be provided, and the effective conductor opening angle and arrangement angle can be appropriately determined. . The number of coils can also be set to 3 (3 locations).

The maximum thickness of the resin portion 15 is the same as the maximum thickness of the weight 30 and the printed wiring board 1 and the coils 20A and 20B mounted thereon. Then, the maximum thickness portion 38 of the weight 30 is exposed on both surfaces of the rotor R, and the lower surface 1A of the printed wiring board 1 and the upper surfaces of the coils 20A and 20B are exposed from the rotor R. In this way, the thickness of the rotor R can be minimized while effectively using each member. In particular, the weight 30 can increase the amount of eccentricity up to the thickness of the printed wiring board.
The step 16 is a step for causing the upper end portion 40 </ b> B of the bearing 40 to protrude from the upper surface of the resin portion 15.
The printed wiring board 1 has coil placement portions 3A and 3B on which the coils 20A and 20B are placed on the upper surface 1B side, and terminal connection patterns 7A for connecting the terminals 22A and 23A and 22B and 23B of the coils 20A and 20B. Terminal connection portions 4A and 4B are formed in which 8A, 7B and 8B are formed on the upper surface 1B side. A plurality of commutator pieces 2 (six in this embodiment) are printed on the lower surface 1 </ b> A side of the printed wiring board 1.
Since the circuit configuration for connecting these patterns and commutator pieces is not directly related to the present invention, the description thereof will be omitted.
A shaft insertion hole 5a through which the shaft 11 passes is formed in the central portion 5 of the printed wiring board 1, and a cylindrical bearing 40 is disposed on the upper surface 1B side. The opening diameter of the shaft insertion hole 5a is slightly larger than the shaft 11 and smaller than the outer diameter of the bearing 40 so that the one end portion 40A of the bearing 40 and the upper surface 1B of the printed wiring board 1 are in direct contact with each other.

The bearing 40 is made of, for example, sintered oil-impregnated metal, and a C surface 41 is often formed as a chamfer at both end portions 40A and 40B. The bearing 40 and the printed wiring board 1 are arranged so that the entire circumference of the end of the cylinder is in contact with the end other than the C surface 41.
If the bearing is placed on the printed wiring board and the rotor R is formed by resin molding in this way, the bearing is supported by the printed wiring board even if an impact in the direction of the shaft 11 is applied to the motor M. Thus, the rotor R can be configured to be extremely resistant to impact.

  The coils 20A and 20B are arranged on the rotor R at an arrangement angle of about 140 °, and a weight 30 for decentering the rotor R is arranged between the coils on the 140 ° side. The weight 30 is a high specific gravity weight formed by, for example, sintering a tungsten alloy, and the outer shape portion 37 is formed in a T shape formed in an arc shape along the outer periphery of the rotor R. If the maximum thickness portion 38 is the same as the thickness of the rotor R and is exposed on both surfaces of the rotor R, the amount of eccentricity can be increased. A concave notch 9 is formed in the printed wiring board 1 so as to expose the maximum thickness portion 38 of the weight.

Around the maximum thickness portion 38, a C surface 32 for embedding the weight 30 in the resin is formed in an arc shape along the outer periphery of the rotor R, and a C surface 33 is also formed in an arc shape along the outer shape of the coils 20A and 20B. Has been. The weight 30 is firmly fixed to the rotor R by embedding the weight 30 in the resin portion 15 so that the resin is well wound around the weight 30 at the time of molding using the C surface. The weight 30 is also formed with a holding convex portion 31 continuously with the C surface 33 in the direction of the axis 11.
The holding convex portion 31 is embedded in the resin portion 15 and is supported in the direction of the axis 11 by the holding portion 6 formed on the printed wiring board 1. If the thickness of the holding convex portion 31 is reduced, the resin flows between the upper surface 1B of the printed wiring board 1 and the holding convex portion 31, and the weight 30 can be stably fixed to the rotor R. It will be indirectly supported in the thickness direction.
Guide recesses 34 and 35 for determining the position of the weight 30 at the time of resin molding are formed in the outer portion of the weight 30 where the C surface 32 and the C surface 33 intersect. When the weight 30 is attached to the molding die during resin molding, the guide recesses 34 and 35 are attached to the guide pins attached to the die.
The guide recesses 34 and 35 are not formed in the maximum thickness portion 38, but can be avoided as much as possible by reducing the amount of eccentricity of the weight 30 by providing the guide recesses 34 and 35 in the portions of the C surfaces 32 and 33. Since the C surfaces 32 and 33 are for embedding the outer portion of the weight 30 in the resin, the shape is not limited to the C surface, and the outer portion may be continuously formed in a concave shape. Further, a plurality of guide recesses 34 and 35 may be provided on the C surface 32 or the C surface 33 to the extent that the flow of the resin is not hindered instead of the intersection of the C surfaces 32 and 33.
The hole 17 formed in the resin portion 15 is formed by the guide pin.

The guide concave portion may be provided in the holding convex portion 31. For example, as shown in FIG. 3, by providing the concave portion 36 in the holding convex portion 31, the eccentric amount of the maximum thickness portion 38 is not reduced. The recess 36 may be an opening penetrating in the thickness direction, and if necessary, an opening is provided at a corresponding position of the printed wiring board 1 so that the relative position with the substrate can be adjusted simultaneously.
On the outer shape portion 37 of the weight 30, two convex portions 39 that are spherical toward the outside of the rotor R are formed. When the weight 30 is attached to the molding die, play is provided between the guide pin and the guide recesses 34 and 35 for easy attachment. If the outer portion 37 contacts the inner wall surface of the mold when the weight 30 rattles due to the play, the flow of resin to the outer peripheral side of the weight 30 becomes worse.
When the weight 30 rattles, the convex portion 39 hits the inner wall surface of the mold to prevent the outer portion 37 from coming into contact with the inner wall surface of the mold, and the resin flows well to the weight 30 so that the resin portion 15 Can be formed. The shape of the convex portion 39 is not limited to a spherical shape, and any shape may be used as long as the tip side has a small area and comes into contact with the mold and does not hinder the flow of the resin.

In the above configuration, the maximum thickness portion of the weight 30 is exposed on both sides of the rotor R. However, the entire weight 30 is placed on the upper surface 1B of the printed wiring board 1 and the maximum thickness portion is exposed on one side of the rotor. However, if a guide recess or guide opening is provided in the part embedded in the resin and a guide pin hole is formed in the corresponding position of the printed wiring board, the weight can be reduced without sacrificing the eccentricity of the maximum thickness portion of the weight. Positioning becomes possible.
In addition, by positioning the weight 30 with the guide pins of the mold, it is not necessary to bond the weight 30 on the substrate, so that the process is reduced.

As described above, in the rotor R, the printed wiring board 1, the coils 20 </ b> A and 20 </ b> B, the weight 30 and the bearing 40 are integrated by resin molding, and the resin portion 15 is formed into a D-shaped flat plate shape. At this time, the coils 20A and 20B and the weight 30 may all be within a range of 180 ° (center of gravity side) with respect to the axis 11, but are often difficult depending on the size of each member.
Also in this embodiment, a part of the coils 20A and 20B, the connection patterns 7A, 8A, 7B, and 8B must be arranged on the opposite side of the weight 30 with the bearing 40 interposed therebetween, that is, on the opposite side to the center of gravity. In such a case, it is necessary to reduce the weight of the portion opposite to the center of gravity as much as possible.
Further, in the case of resin molding, if the thickness of the resin is large, sinking or distortion occurs, so that it is desirable that the thickness is thin.
However, since the printed wiring board 1 is extremely thin with the miniaturization of the eccentric rotor, the resin formed in the portions of the connection patterns 7A, 8A, 7B, and 8B in order to maintain the strength as the eccentric rotor. The portion 15 needs to be thick to some extent in order to solder the terminals 22 and 23 and to cover the connection portion with resin to prevent disconnection.
Therefore, with the wall portion 19 on the outer edge of the printed wiring board 1, the resin portion 15 on the opposite side of the center of gravity has a recess that avoids the connection patterns 7A, 8A, 7B, 8B and the terminals 22A, 23A, 22B, 23B. 18 is provided. The wall portion 19 is set to be equal to or lower than the aforementioned maximum thickness and higher than the thickness 18b of the recess.

The concave portion 18 reduces the weight opposite to the center of gravity and prevents distortion due to the thickness, and the wall portion 19 ensures the strength of the outer edge of the rotor and maintains the flatness and strength of the rotor R.
The shape of the recess can be appropriately determined by the arrangement of the connection patterns 7A, 8A, 7B, 8B and the terminals 22A, 23A, 22B, 23B.
Further, the outer edge of the wall portion 19 and the outer edge of the printed wiring board 1 do not necessarily coincide with each other. Even if the outer edge of the printed wiring board 1 is inside as shown in FIG.
Further, when the required amount of vibration can be obtained by arranging the air-core armature coil eccentrically, or when the necessary amount of vibration can be obtained by arranging three or more coils eccentrically, the weight 30 is not provided. Also good.

FIG. 4 shows an example of a vibration motor using the above-described rotor.
In the motor M, a stainless steel thin disc-shaped bracket 52 is fixed to a stainless steel thin plate cylindrical case 51 to form a housing, the shaft 11 is fixed to the burring portion 55 of the bracket 52, and the rotor R rotates to the shaft 11. It is supported.
The bracket 52 is formed of a thin printed wiring board such as a flexible substrate or a glass epoxy substrate, and a brush base 53 for supplying electric power to the rotor by a brush 54 is attached.
A pair of brushes 54 (one side is shown in FIG. 1) is attached around the shaft 11 of the brush base 52, and one end side is led out from the opening 51a to the outside of the housing as a power supply terminal 52a. The bracket 52 is provided with a terminal placement portion 52a on which the power supply terminal 55 is placed. The free end side of the brush 54 is in sliding contact with the commutator piece 2 of the rotor R.
A ring-shaped magnet G is attached to the inner surface of the bracket 52. The magnet G is an axial gap type magnet with four poles magnetized in the circumferential direction, and faces the rotor R.

One end of the shaft 11 is press-fitted and fixed to a burring portion 55 provided in the center of the bracket 52, and the other end is attached to a recess 51 a provided in the center of the housing 51 with a sliding sheet 56 interposed therebetween. The rotor R is rotatably supported on the shaft 11 by a bearing 40.
Since the rotor R is always pushed to the case 51 side by the brush 54, the upper surface side of the rotor R is in direct contact with the sliding sheet 56 and the lower surface side is the center of the printed wiring board 1 on the lower surface 1A side. The part 5 is opposed to a thrust receiver 57 made of a slidable washer.
When an impact in the direction of the shaft 11 is applied to the vibration motor, the rotor R moves in the axial direction. When moved upward, the end 40B of the bearing 40 hits the housing, and when moved downward, the lower surface 1A hits the thrust receiver 57.
In any case, since the bearing 40 and the printed wiring board 1 are integrated in contact with each other, the attachment strength of the bearing 40 to the rotor is large, and the bearing portion is not damaged.
Various configurations of the rotor R such as the housing and the brush base 53 constituting the vibration motor M are conceivable and need not be limited to the above embodiment. For example, it may be a shaft fixed type vibration motor as in the present embodiment, or a shaft rotation type vibration motor in which a rotating shaft is fixed to a rotor and a rotating shaft is rotatably supported by a bearing fixed to a housing.

1A and 1B are views showing an eccentric rotor of the present invention, in which FIG. 1A is a plan view thereof, and FIG. FIG. 2 is a plan view showing a printed wiring board constituting the eccentric rotor shown in FIG. FIGS. 3A and 3B are views showing weights constituting the eccentric rotor shown in FIG. 2, wherein FIG. 3A is a plan view thereof, and FIG. FIG. 4 is a cross-sectional view of the main part of the side of a vibration motor using the eccentric rotor of the present invention.

Explanation of symbols

R rotor 1 printed wiring board 2 segment 5a shaft insertion hole 15 resin part 18 concave part 19 wall part 20A, 20B coil

Claims (3)

A flat commutator substrate having a shaft insertion hole through which a plurality of commutator pieces are printed and formed on one surface and a plurality of wound air-core armature coils are mounted on the other surface and a shaft serving as a rotation center is inserted. The eccentric rotor integrated into a flat plate shape by resin molding together with the wound air-core armature coil, wherein the plurality of wound air-core armature coils are arranged offset toward the center of gravity with respect to the rotation center, An eccentric rotor, wherein a resin portion formed by resin molding is provided with a recess on the opposite side of the center of gravity with the shaft insertion hole therebetween. The eccentric rotor according to claim 1, wherein the concave portion is formed such that an outer edge portion of the eccentric rotor becomes a wall portion. 3. The eccentric rotor according to claim 1, wherein the eccentric rotor is supported rotatably by a shaft on a housing comprising a case and a bracket, a magnet attached to the housing, a terminal to which electric power is supplied from the outside of the housing, and an electric connection to the terminal. A vibration motor, wherein electric power is supplied from the brush to the eccentric rotor.

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