JP4538290B2 - Vibration motor - Google Patents

Description

  The present invention relates to a vibration motor incorporated in various mobile communication devices (for example, mobile phones) and used as a vibration generation source.

The mobile phone has a built-in vibration motor as a vibration source for notifying incoming calls. In recent years, the vibration motor has been reduced in size, and a single-phase flat type is increasingly used. As such a single-phase flat type vibration motor, there is one described in Patent Document 1. The vibration motor described in this publication has a substantially cylindrical case, in which a flat rotor with a main coil embedded in a frame, and N and S poles are alternately arranged. An annular magnet is accommodated, and the rotor is rotatably disposed above the magnet fixed to the inner surface of the case. Then, when a current is passed through the main coil, the rotor rotates and the case vibrates.
Japanese Patent Laid-Open No. 10-336983

  By the way, in the single layer motor, in order to rotate the rotor in one direction, the direction of the current flowing through the main coil is reversed according to the change in magnetism of the magnet. The switching of the current direction is performed by a commutator electrically connected to the main coil. However, if the rotor stops at the current switching position, the main coil may not be energized at the next startup. Therefore, the rotor of the vibration motor described in the above publication is provided with a magnetic pin that restricts the stationary position of the rotor. However, since a magnetic attractive force is generated between the magnetic pin and the magnet, there is a problem that the rotor is difficult to start when starting.

  Accordingly, an object of the present invention is to provide a vibration motor with improved startability.

  In order to solve the above problems, the vibration motor according to the present invention has a flat rotor in which a main coil is embedded in a frame accommodated in a case, and allows a current to flow through the commutator piece to the main coil. In the vibration motor that rotates the rotor on the magnet in the case, the rotor is embedded in the frame and is positioned on the boundary between the N pole and the S pole of the magnet when the rotor is stationary to regulate the stationary position of the rotor. The magnetic body has an auxiliary coil that is electrically connected to the main coil and wound around the magnetic body, and has a magnet opposite to the magnetism induced by the magnet at the start of energization of the main coil. The auxiliary coil is electrically connected to the main coil so as to be generated.

  In this configuration, when energization of the main coil is started when the vibration motor is started, a current also flows through the auxiliary coil wound around the magnetic body that regulates the stationary position of the rotor. At this time, magnetism opposite to that induced by the magnet is generated in the magnetic body. As a result, the magnetic attractive force generated between the magnetic body and the magnet when the rotor is stationary is reduced, and the rotor can be started smoothly.

  Moreover, it is preferable that the magnetic body of the vibration motor according to the present invention is embedded in a position where the rotor can be activated, shifted in the circumferential direction from the center line of the main coil. In this case, it is possible to easily improve the startability by effectively using an existing rotor in which the center line of the main coil and the center line of the commutator piece substantially coincide with each other.

  Furthermore, it is preferable that the magnetic body of the vibration motor according to the present invention is embedded in the frame outside the main coil, and the weight of the rotor frame is provided between the magnetic body and the main coil. In this case, since the magnetic body is embedded in the frame outside the main coil, magnetism can be generated in the magnetic body only by the current flowing through the auxiliary coil when the main coil is energized. The magnetic attractive force between the magnet and the magnetic material can be reliably reduced. Further, since the eccentric amount of the rotor can be increased by the weight, the amount of vibration can be increased.

  According to the vibration motor according to the present invention, the vibration motor can be started smoothly.

  Hereinafter, preferred embodiments of a vibration motor according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 4, the vibration motor 1 has a substantially cylindrical case C composed of a disk-shaped metal base plate 10 and a metal cylindrical cover 20. The flat rotor 30 is accommodated. The vibration motor 1 is a single-phase motor and is downsized to have a diameter of about 10 mm and a height of about 3 mm. The vibration motor 1 is built in a mobile phone and used as a vibration source.

  An annular magnet 11 is bonded and fixed on the base plate 10. The magnet 11 is equally divided into four regions, magnetized in a direction substantially perpendicular to the upper surface of the base plate 10, and N poles 11a and 11c and S poles 11b and 11d are alternately arranged. Yes.

  A support shaft 12 that rotatably supports the rotor 30 is disposed in the center of the base plate 10. The support shaft 12 is press-fitted into a boss portion 13 formed in the center of the base plate 10, for example. It is fixed. A flexible substrate 14 is arranged on the base plate 10 so as to surround the boss portion 13. The flexible substrate 14 has a pair of terminals 14b and 14c embedded in an insulating substrate 14a. A portion of the flexible substrate 14 is connected to the peripheral wall 10a of the base plate 10 in order to connect to an external power source (not shown). It protrudes outward from the formed notch.

  Then, one end of the pair of terminals 14b and 14c is exposed from the board 14a to the protruding portion, and is electrically connected to an external power source. The other ends of the pair of terminals 14b and 14c are joined to the base ends of the pair of brushes 15a and 15b disposed around the boss portion 13 by solder. Thereby, electric power can be supplied to the pair of brushes 15a and 15b from the external power source. Further, the free ends of the pair of brushes 15 a and 15 b protrude toward the rotor 30 from the flexible substrate 14 side in order to ensure sliding contact with the commutator 31 of the rotor 30. The free end of the brush 15a is positioned near the boundary between the N pole 11a and the S pole 11b, and the free end of the brush 15b is positioned near the boundary between the S pole 11b and the N pole 11c.

  The rotor 30 has a semi-disc-shaped frame 32 made of resin, and a main coil 33 as a coreless coil is integrally embedded in the frame 32, and a substantially cylindrical to be the center of rotation of the rotor 30. A shaped bearing 34 is embedded. The rotor 30 is rotatably supported by the support shaft 12 via a bearing 34.

  Since the bearing 34 extends toward the lower side (base plate 10 side) than the bottom surface 32a of the frame 32 so that a gap is formed between the rotor 30 and the magnet 11 (see FIG. 2), the rotor 30 is Rotates smoothly without hitting the magnet 11. Further, a spacer 41 is provided between the bearing 34 and the boss portion 13 so that the rotor 30 can easily rotate. Further, when the rotor 30 is accommodated in the case C, a collar portion 42 is fixed to the upper portion of the bearing 34 so that the rotor 30 does not rattle in the axial direction of the support shaft 12.

  Further, the frame 32 is provided with a commutator 31 around the bearing 34. As shown in FIG. 3, the commutator 31 includes four substantially fan-shaped commutator pieces 31 a, 31 b, 31 c, and 31 d arranged in an annular shape. The brushes 15a and 15b are in sliding contact with the two commutator pieces. Moreover, commutator pieces 31a and 31c facing each other among the commutator pieces 31a to 31d are electrically connected, and the commutator pieces 31b and 31d are electrically connected. The commutator piece 31 a and one end of the main coil 33 are connected, and the commutator piece 31 d and the other end of the main coil 33 are connected.

  The main coil 33 is substantially fan-shaped and is substantially line symmetric with respect to the center line L1 of the main coil 33 along the radial direction of the rotor 30. The opening angle α1 of the main coil 33 is about 90 degrees, like the opening angle α2 of the commutator pieces 31a to 31d, and the center line L1 substantially coincides with the center line of the commutator piece 31a. 11 is arranged so as to face 11.

  With the above configuration, when a current flows through the main coil 33 through the terminals 14b and 14c, the pair of brushes 15a and 15b, and the commutator 31, torque is generated in the main coil 33 facing the magnet 11, and therefore, together with the main coil 33 The rotor 30 rotates. And when the rotor 30 rotates, according to the change of the magnetic pole of the magnet 11, the direction of the electric current which flows into the main coil 33 by the commutator 31 is reversed, so that the rotor 30 rotates in one direction.

  The commutator pieces adjacent to each other among the four commutator pieces 31a to 31d are spaced apart from each other by a predetermined width so that the commutator pieces are not short-circuited via the brushes 15a and 15b. Is formed. When the brushes 15a and 15b are positioned on the intermediate pad 31e, a so-called dead point is generated, which is a region where no current flows through the main coil 33 and no torque is generated.

  Therefore, a magnetic pin 35 made of iron or nickel is embedded in the frame 32 so as to restrict the stationary position of the rotor 30 so that the rotor 30 does not stop at a dead point when the rotor 30 is stopped. As shown in FIG. 4, the magnetic pin 35 is arranged at a position where the arrangement angle β with respect to the center line L <b> 1 of the main coil 33 is about 112.5 degrees (90 degrees + 22.5 degrees). The longitudinal direction is embedded in the frame 32 so as to substantially coincide with the tangential direction with respect to the circumferential direction. Here, the arrangement angle β is an angle between a center line L2 passing through the center between the both end portions 35a and 35b of the magnetic pin 35 and the center of the bearing 34 and the center line L1 of the main coil 33.

  When the rotor 30 is stopped (that is, when no power is supplied), magnetism is induced in the magnetic pin 35 by the magnet 11 and a magnetic attractive force is generated between the magnetic pin 35 and the magnet 11. As a result, as shown in FIG. 5, the rotor 30 stops so that the magnetic pin 35 is positioned on the boundary between the S pole 11b and the N pole 11c, for example. At this time, since the arrangement angle β is 112.5 degrees, the center line L1 of the main coil 33 is shifted from the boundary between the north pole and the south pole of the magnet 11, and the stationary position of the rotor 30 is the startable position. It has become. This position is also a position where the brushes 15a and 15b and the main coil 33 are reliably energized when the vibration motor 1 is started.

  Furthermore, in order to cancel the magnetic attractive force generated between the magnet 11 and the magnetic pin 35 when the energization of the main coil 33 is started, the magnetic pin 35 is provided on the outer peripheral portion of the magnetic pin 35. An auxiliary coil 36 serving as a core is wound. The auxiliary coil 36 is connected in series to the main coil 33 so as to cause the magnetic pin 35 to generate magnetism opposite to that induced by the magnet 11.

  Therefore, when the rotor 30 is stationary, as shown in FIG. 5, even when the south pole and the north pole are respectively induced in the end portions 35 a and 35 b of the magnetic pin 35, As shown in FIG. 6, the flowing current causes an N pole and an S pole at the ends 35 a and 35 b, respectively. As a result, the rotor 30 starts smoothly with the torque T generated by the current flowing through the main coil 33. At this time, the electromagnet composed of the auxiliary coil 36 and the magnetic pin 35 also generates torque in the same direction as the torque T, and assists the starting force.

  After the start-up, the current flowing through the auxiliary coil 36 is switched in accordance with the switching of the direction of the current flowing through the main coil 33. Therefore, the induced magnetization of the magnetic pin 35 induced by the magnet 11 at the dead point is generated each time. As a result, the rotor 30 rotates smoothly. Further, since the rotor 30 is disposed in an eccentric state with respect to the axis 12 in the case C, the case C vibrates by the rotation of the rotor 30.

  In order to further increase the vibration of the case C, as shown in FIGS. 1 to 4, a disk-like nonmagnetic weight 37 is embedded in the frame 32 between the magnetic pin 35 and the main coil 33. Has been. As a result of the weight 37 shifting the center of gravity of the rotor 30 and increasing the amount of eccentricity, vibration can be increased.

  Next, the operation of the vibration motor 1 will be described. Since no current flows through the auxiliary coil 36 when the vibration motor 1 is stopped, the magnetic pin 35 is located on the boundary between the S pole 11b and the N pole 11c of the magnet 11, as shown in FIG. The rotor 30 is stationary at the startable position. Thereafter, when a current is supplied to the main coil 33 through the brushes 15 a and 15 b and the commutator 31 when the vibration motor 1 is started, a current also flows through the auxiliary coil 36. As a result, the magnetic attractive force between the magnetic pin 35 and the magnet 11 used for regulating the stationary position of the rotor 30 is almost canceled. Therefore, the rotor 30 starts to rotate smoothly due to the torque T generated when the main coil 33 is energized.

  In the vibration motor 1, since the magnetic pin 35 is embedded in the frame 32 outside the main coil 33, the magnetic pin 35 is magnetized only by the current flowing through the auxiliary coil 36 when the main coil 33 is energized. Can be generated. Accordingly, the magnetic attractive force between the magnet 11 and the magnetic pin 35 is reliably reduced when the vibration motor 1 is started.

  Further, when the energization of the main coil 33 is stopped to stop the vibration of the vibration motor 1, no current flows to the auxiliary coil 36, and thus magnetism is induced in the magnetic pin 35 by the magnet 11 ( (See FIG. 5). As a result, a magnetic attraction force is generated between the magnetic pin 35 and the magnet 11, so that the rotor 30 can be reliably stopped at the startable position by the magnetic attraction force.

  As described above, in the vibration motor 1, the startability of the vibration motor 1 is improved by newly generating a magnetic field by the electromagnet composed of the auxiliary coil 36 and the magnetic pin 35 at the time of start-up. Therefore, in the vibration motor 1, in order to overcome the dead weight of the frame 32 and the weight 37, the friction between the brushes 15 a and 15 b and the commutator 31, etc., the magnetic body pin 35 and the magnet are stopped. Even when the magnetic attraction force acting between the rotor 11 and the rotor 30 is increased, the rotor 30 can be easily started. As a result, a heavier weight 37 or the like can be used, and the amount of vibration of the vibration motor 1 can be increased.

  As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to the said embodiment. For example, the magnetic pin 35 is arranged at a position shifted by 22.5 degrees as a deviation angle γ (see FIG. 4) from a position shifted by 90 degrees in the circumferential direction with respect to the center line L1 of the main coil 33. The position of the magnetic pin 35 is not limited to this case. For example, the arrangement angle β may be a multiple of 90 degrees plus a deviation angle γ when the number of poles of the magnet 11 is four. The deviation angle γ is not necessarily 22.5 degrees.

  Furthermore, it goes without saying that the arrangement angle β is changed according to the number of poles of the magnet 11, and the position of the magnetic pin 35 with respect to the main coil 33 is a startable position where the torque T is surely generated in the main coil 33 at the start. It only has to be.

  Furthermore, although the magnet 11 is formed in an annular shape by integral molding, a plurality of fan-shaped magnets 11 magnetized on the N pole and the S pole may be arranged in an annular shape. Further, the shape of the magnetic pin 35 is not limited to a rod shape, and may be a plate shape. Further, although the auxiliary coil 36 is connected in series to the main coil 33, it can be connected in parallel to the main coil 33. However, the series connection is preferable from the viewpoint of the amount of heat generated. The magnetic pin 35 is made of iron, but may be made of other magnetic material.

It is an exploded perspective view showing one embodiment of a vibration motor concerning the present invention. It is a longitudinal cross-sectional view of the vibration motor shown by FIG. It is a bottom view of the rotor which makes a part of vibration motor shown by FIG. FIG. 2 is a plan view of the vibration motor shown in FIG. 1. FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4 at rest. It is sectional drawing of the vibration motor at the time of a start start.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vibration motor, 11 ... Magnet, 11a, 11c ... N pole, 11b, 11d ... S pole, 30 ... Rotor, 31 ... Commutator, 31a-31d ... Commutator piece, 32 ... Frame, 33 ... Main coil, 35 ... magnetic pin (magnetic substance), 36 ... auxiliary coil, 37 ... weight, C ... case, L1 ... center line of the main coil.

Claims (3)

A vibration motor in which a flat rotor with a main coil embedded in a frame is accommodated in a case, and the rotor is rotated on a magnet in the case by passing a current through the commutator piece to the main coil. In
The rotor is
A magnetic body embedded in the frame and positioned on the boundary between the north and south poles of the magnet when the rotor is stationary, and restricts the stationary position of the rotor;
An auxiliary coil that is electrically connected to the main coil and wound around the magnetic body;
The auxiliary coil is electrically connected to the main coil so that a magnet opposite to the magnetism induced in the magnetic body by the magnet is generated in the magnetic body at the start of energization of the main coil. And vibration motor.   2. The vibration motor according to claim 1, wherein the magnetic body is embedded in a position where the rotor can be activated, shifted in a circumferential direction from the center line of the main coil. The magnetic body is embedded in the frame outside the main coil,
The vibration motor according to claim 1, wherein a weight is provided between the magnetic body and the main coil in the frame of the rotor.

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